TWI820610B - Zno-based varistor material, and the zno-based varistor applying the same - Google Patents
Zno-based varistor material, and the zno-based varistor applying the same Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 50
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims abstract description 130
- 239000011787 zinc oxide Substances 0.000 claims abstract description 65
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- 238000001816 cooling Methods 0.000 claims description 29
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- 229910015902 Bi 2 O 3 Inorganic materials 0.000 claims description 21
- 239000000843 powder Substances 0.000 claims description 12
- 239000013078 crystal Substances 0.000 claims description 10
- 238000002360 preparation method Methods 0.000 claims description 6
- 229910000314 transition metal oxide Inorganic materials 0.000 claims description 6
- 229910020599 Co 3 O 4 Inorganic materials 0.000 claims description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 5
- 239000003292 glue Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 229910052709 silver Inorganic materials 0.000 claims description 5
- 239000004332 silver Substances 0.000 claims description 5
- 238000000498 ball milling Methods 0.000 claims description 3
- 238000001354 calcination Methods 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 75
- 229910052760 oxygen Inorganic materials 0.000 description 75
- 239000001301 oxygen Substances 0.000 description 75
- 238000004458 analytical method Methods 0.000 description 27
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- 239000007791 liquid phase Substances 0.000 description 7
- 239000004065 semiconductor Substances 0.000 description 7
- 238000002981 Mott–Schottky analysis Methods 0.000 description 6
- 239000011701 zinc Substances 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
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- 230000004580 weight loss Effects 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
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- 238000002474 experimental method Methods 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 238000003746 solid phase reaction Methods 0.000 description 2
- 238000010671 solid-state reaction Methods 0.000 description 2
- 238000010183 spectrum analysis Methods 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 229910004247 CaCu Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- VJFCXDHFYISGTE-UHFFFAOYSA-N O=[Co](=O)=O Chemical compound O=[Co](=O)=O VJFCXDHFYISGTE-UHFFFAOYSA-N 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 229910002367 SrTiO Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 229910000416 bismuth oxide Inorganic materials 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910001429 cobalt ion Inorganic materials 0.000 description 1
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 description 1
- 238000004455 differential thermal analysis Methods 0.000 description 1
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- 229910001437 manganese ion Inorganic materials 0.000 description 1
- GEYXPJBPASPPLI-UHFFFAOYSA-N manganese(iii) oxide Chemical compound O=[Mn]O[Mn]=O GEYXPJBPASPPLI-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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- SWELZOZIOHGSPA-UHFFFAOYSA-N palladium silver Chemical compound [Pd].[Ag] SWELZOZIOHGSPA-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
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- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
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- Compositions Of Oxide Ceramics (AREA)
- Apparatuses And Processes For Manufacturing Resistors (AREA)
Abstract
Description
本發明係關於一種氧化鋅變阻器材料、及應用其之氧化鋅變阻器，特別係關於一種利用晶界添加劑提升變阻性質之氧化鋅變阻器材料、及應用其之氧化鋅變阻器。The present invention relates to a zinc oxide varistor material and a zinc oxide varistor using the same. In particular, it relates to a zinc oxide varistor material that utilizes grain boundary additives to improve the varistor properties, and a zinc oxide varistor using the same.
隨著半導體蓬勃發展與5G時代的來臨，保護元件的需求日益增加，且電子設備日趨輕薄短小之高性能化發展，而設備中使用之積體電路(Integrated circuit, 簡稱IC)非常容易受到靜電放電(Electrostatic discharge, 簡稱ESD)破壞，因此ESD保護元件變阻器被廣泛使用於電子設備中。With the booming development of semiconductors and the advent of the 5G era, the demand for protective components is increasing day by day, and electronic devices are becoming increasingly thinner, lighter, smaller, and more high-performance. The integrated circuits (ICs) used in the devices are very susceptible to electrostatic discharge. (Electrostatic discharge, or ESD for short) damage, so ESD protection element varistors are widely used in electronic equipment.
變阻器之材料有許多種：ZnO、TiO 2、SrTiO 3、CaCu 3Ti 4O 12、BaTiO 3、SnO 2、WO 3等，目前最常見仍以氧化鋅變阻器為主。傳統之氧化鋅變阻器主要以鉍系(Bismuth, Bi)與鐠系(Praseodymium, Pr)為主。Bi系變阻器易於燒結過程中產生絕緣性之尖晶石二次相，導致變阻性質下降。積層式Pr系變阻器雖具有優異之靜電放電(ESD)特性，但燒結溫度過高，導致需使用Pd含量較高之銀-鈀(Ag-Pd)內電極，因而使元件製作成本大幅增高。釩系變阻器由於V 2O 5具有較大之毒性，不利於工業生產。 There are many kinds of materials for varistor: ZnO, TiO 2 , SrTiO 3 , CaCu 3 Ti 4 O 12 , BaTiO 3 , SnO 2 , WO 3, etc. At present, zinc oxide varistor is still the most common. Traditional zinc oxide varistors are mainly based on bismuth (Bismuth, Bi) and praseodymium (Pr) series. Bi-based varistors tend to produce insulating spinel secondary phases during the sintering process, resulting in a decrease in varistor properties. Although the multilayer Pr-based varistor has excellent electrostatic discharge (ESD) characteristics, the sintering temperature is too high, which requires the use of silver-palladium (Ag-Pd) internal electrodes with a high Pd content, thus significantly increasing the device manufacturing cost. Vanadium varistors are not conducive to industrial production due to the high toxicity of V 2 O 5 .
為了將燒結溫度降至900℃以下，加入低熔點的燒結助劑將有效降低緻密化之溫度，並藉由液相促使具變阻性質提升功能之添加劑能夠均勻分布在晶界，進而使變阻性質提升。因為低熔點的玻璃添加劑在燒結過程中會形成玻璃液相，達到液相輔助燒結的效果，因為液相輔助燒結的關係，使原本散布於晶界的摻雜劑得以分布得更加均勻，使有效之晶界數量提升，進而提升非線性指數。In order to reduce the sintering temperature to below 900°C, adding low melting point sintering aids will effectively reduce the densification temperature, and promote the additives with the function of improving varistor properties through the liquid phase to be evenly distributed in the grain boundaries, thereby making the varistor Nature improvement. Because low melting point glass additives will form a glass liquid phase during the sintering process, achieving the effect of liquid phase assisted sintering. Because of the liquid phase assisted sintering, the dopants originally dispersed in the grain boundaries can be distributed more evenly, making the effective The number of grain boundaries increases, thereby increasing the nonlinear index.
然而，另外液相的變阻性質形成劑Bi 2O 3會在燒結過程中被消耗掉並反應生成焦綠石(pyrochlore)二次相Zn 2Bi 3Sb 3O 14。由於位於晶界之玻璃液相或焦綠石均為絕緣之二次相，將使得變阻器耐受突波電流的過程中，產生高熱而使得在晶界處低熔點之Bi 2O 3熔融，進而使突波吸收能力下降，變阻性質劣化。 However, the other liquid phase varistor property forming agent Bi 2 O 3 will be consumed during the sintering process and react to form a pyrochlore secondary phase Zn 2 Bi 3 Sb 3 O 14 . Since the glass liquid phase or pyrochlore located at the grain boundary is an insulating secondary phase, when the varistor withstands the surge current, it will generate high heat and melt the Bi 2 O 3 with a low melting point at the grain boundary, thereby melting the varistor. The surge absorption capacity is reduced and the varistor properties are deteriorated.
針對現有技術所存在的不足及缺點，本發明合成出一種氧化鋅變阻器材料、及應用其之氧化鋅變阻器，以提升變阻性質。In view of the shortcomings and shortcomings of the existing technology, the present invention synthesizes a zinc oxide varistor material and a zinc oxide varistor using the same to improve the varistor properties.
據此，本發明提供一種氧化鋅變阻器材料，其製備方法包含： (a)步驟：將ZnO、及過渡金屬氧化物混合煆燒以製備晶粒； (b)步驟：將該晶粒及晶界添加劑混合且球磨後，烘乾並研磨得到粉末；(c)步驟：將該粉末倒入模具中，加壓成型並得到生坯，將該生坯放入高溫爐升溫至850℃燒結，並降溫至400℃，後爐冷至室溫以得到坯，後於該坯之雙面塗上高溫銀膠作成電極。 Accordingly, the present invention provides a zinc oxide varistor material, and its preparation method includes: (a) Step: Mix and calcine ZnO and transition metal oxides to prepare crystal grains; (b) Step: Mix the crystal grains and grain boundary additives and ball-mill, dry and grind to obtain powder; (c) Step: Pour the powder into a mold, press it to form and obtain a green body, and use the green body to Put it into a high-temperature furnace and heat it up to 850°C for sintering, and then cool it down to 400°C. Then the furnace is cooled to room temperature to obtain a blank. Then, high-temperature silver glue is coated on both sides of the blank to make an electrode.
進一步地，(a)步驟之過渡金屬氧化物可選自Co3O4、或Mn3O4中至少一種。 Further, the transition metal oxide in step (a) can be selected from at least one of Co 3 O 4 or Mn 3 O 4 .
進一步地，(b)步驟之晶界添加劑可為Bi2O3。 Furthermore, the grain boundary additive in step (b) may be Bi 2 O 3 .
進一步地，(b)步驟之晶界添加劑可為ZnBi2O4。 Furthermore, the grain boundary additive in step (b) may be ZnBi 2 O 4 .
進一步地，(b)步驟之晶界添加劑可為Bi2O3混合ZnBi2O4，混合比例為重量比1：1~1：4。 Further, the grain boundary additive in step (b) may be Bi 2 O 3 mixed with ZnBi 2 O 4 , and the mixing ratio is 1:1 to 1:4 by weight.
進一步地，(c)步驟從850℃降溫至400℃之方式，可以爐冷、2℃/min、或5℃/min之方式降溫。 Furthermore, in step (c), the temperature can be lowered from 850°C to 400°C by furnace cooling, 2°C/min, or 5°C/min.
進一步地，該氧化鋅變阻器材料之非線性係數α值可為65以上。 Furthermore, the nonlinear coefficient α value of the zinc oxide varistor material can be above 65.
進一步地，該氧化鋅變阻器材料之崩潰電壓可為1300V/mm以上。 Furthermore, the breakdown voltage of the zinc oxide varistor material can be above 1300V/mm.
進一步地，該氧化鋅變阻器材料之漏電流可為0.1μA以下。 Furthermore, the leakage current of the zinc oxide varistor material can be less than 0.1 μA.
本發明亦提供一種氧化鋅變阻器，其包含如前述之氧化鋅變阻器材料。 The present invention also provides a zinc oxide varistor, which includes the zinc oxide varistor material as mentioned above.
本發明藉由添加適量過渡金屬氧化物，可使較多三價固溶進ZnO取代Zn；並於燒結過程過渡金屬因還原反應造成離子半徑變大易往晶界處富集，進而使α值增加。By adding an appropriate amount of transition metal oxide, the present invention can make more trivalent solid solution into ZnO to replace Zn; and during the sintering process, the ionic radius of the transition metal becomes larger due to the reduction reaction and is easy to be enriched at the grain boundary, thereby increasing the α value. Increase.
本發明合成出一種利用p型半導性質之ZnBi 2O 4做為晶界添加劑之氧化鋅變阻器材料，ZnBi 2O 4除有助於形成晶粒為n型半導體，晶界為p型半導體之n-p-n界面外，亦可促進氧藉由ZnBi 2O 4擴散進入材料內部，使晶界附近之吸附氧增加，提升蕭特基能障，進而使氧化鋅變阻器可於低溫燒結，同時擁有高α值、低漏電流、高崩潰電壓之特性。 The present invention synthesizes a zinc oxide varistor material that uses ZnBi 2 O 4 with p-type semiconductor properties as a grain boundary additive. ZnBi 2 O 4 not only helps to form grains into n-type semiconductors, but grain boundaries into p-type semiconductors. Outside the npn interface, it can also promote the diffusion of oxygen into the interior of the material through ZnBi 2 O 4 , increasing the adsorbed oxygen near the grain boundaries and increasing the Schottky energy barrier, thereby enabling the zinc oxide varistor to be sintered at low temperature and have a high α value. , low leakage current and high breakdown voltage characteristics.
本發明發現添加1wt%的晶界添加劑ZnBi 2O 4且燒結降溫速率2℃/min時，氧化鋅變阻器材料可使樣品具有良好的電性能：非線性係數α值為65.43、崩潰電壓提升為1361 V/mm及漏電流降至0.1μA。 The present invention found that when adding 1wt% of the grain boundary additive ZnBi 2 O 4 and the sintering cooling rate is 2°C/min, the zinc oxide varistor material can make the sample have good electrical properties: the nonlinear coefficient α value is 65.43, and the collapse voltage is increased to 1361 V/mm and leakage current are reduced to 0.1μA.
以下藉由實施方式、實施例說明本發明之氧化鋅變阻器材料、及應用其之氧化鋅變阻器之性能。應注意，下述實施方式、實施例僅用以說明本發明，而非用以限制本發明之範圍。The performance of the zinc oxide varistor material of the present invention and the zinc oxide varistor using it will be described below through embodiments and examples. It should be noted that the following embodiments and examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.
［氧化鋅變阻器材料之製備］ 下述表1所示為使用之實驗原料： [Preparation of zinc oxide varistor materials] Table 1 below shows the experimental raw materials used:
表1
實驗流程如下： 「製備晶粒」：將表1之ZnO、Co 3O 4、Mn 3O 4以重量比100-x-y: x: y混合(0＜x≤1; 0≤y≤1)，例如以重量比為97.96：1.72：0.32混合，並以600°C煆燒6小時(讓Co離子主要以三價形式取代ZnO中之Zn，產生較多的施體濃度 )完成晶粒。其中，以煆燒處理而非使用化學沉澱法等方法，具有使製備晶粒之成本降低、實驗方法更簡單等優點。 The experimental process is as follows: "Preparation of crystal grains": Mix ZnO, Co 3 O 4 and Mn 3 O 4 in Table 1 in a weight ratio of 100-xy: x: y (0＜x≤1; 0≤y≤1), For example, mix with a weight ratio of 97.96:1.72:0.32 and calcine at 600°C for 6 hours (allowing Co ions to mainly replace Zn in ZnO in the trivalent form, resulting in a higher donor concentration ) to complete the grain. Among them, methods such as calcination treatment instead of chemical precipitation have the advantages of reducing the cost of preparing crystal grains and making the experimental method simpler.
「製備晶界添加劑」：晶界添加劑的部份有三種配方：第一種為Bi 2O 3、第二種為Bi 2O 3及ZnO藉由固態反應法合成p型材料ZnBi 2O 4、第三種則為Bi 2O 3和ZnBi 2O 4依不同比例混合製備而成。 其中，藉由固態反應法將Bi 2O 3及ZnO合成p型材料ZnBi 2O 4之方法如 下：將Bi 2O 3及ZnO以莫耳比1:1混合好，裝入250ml球磨罐中，並倒入99.5 vol%酒精及5mm之氧化鋯球球磨12小時，球磨完成後放入100°C烘箱進行烘乾，接著再經700 oC煆燒6小時，即獲得ZnBi 2O 4粉末。 "Preparation of grain boundary additives": There are three formulas for grain boundary additives: the first is Bi 2 O 3 , the second is Bi 2 O 3 and ZnO. The p-type material ZnBi 2 O 4 is synthesized by a solid-state reaction method. The third type is prepared by mixing Bi 2 O 3 and ZnBi 2 O 4 in different proportions. Among them, the method of synthesizing Bi 2 O 3 and ZnO into the p-type material ZnBi 2 O 4 through a solid-state reaction method is as follows: Mix Bi 2 O 3 and ZnO at a molar ratio of 1:1, and put them into a 250 ml ball mill jar. Pour in 99.5 vol% alcohol and 5mm zirconia balls and ball mill for 12 hours. After the ball milling is completed, place it in a 100°C oven for drying, and then calcine at 700 ° C for 6 hours to obtain ZnBi 2 O 4 powder.
「製備粉末」：如上所述，晶粒及晶界添加劑製備好後，將其等裝入250ml球磨罐中，並倒入99.5 vol%酒精及5mm之氧化鋯球球磨15小時，球磨完成後放入100°C烘箱進行烘乾，接著再使用研缽將粉末磨細、過60目之篩網，即完成實驗所需之粉末。"Preparation of powder": As mentioned above, after the crystal grains and grain boundary additives are prepared, put them into a 250ml ball mill jar, pour in 99.5 vol% alcohol and 5mm zirconia balls, and ball mill for 15 hours. After the ball milling is completed, place Put it into a 100°C oven for drying, and then use a mortar to grind the powder into fine pieces and pass it through a 60-mesh screen to complete the powder required for the experiment.
「單軸加壓成型方式製備樣品」：秤取0.09克上述粉末倒入模具中，以300kg加壓成型，完成直徑8mm、厚度約0.5mm之生坯。"Preparing samples by uniaxial pressure molding": Weigh 0.09 grams of the above powder and pour it into the mold, and press it with 300kg to form a green body with a diameter of 8mm and a thickness of about 0.5mm.
「燒結生坯」：將製備好之生坯放入高溫爐，在空氣氣氛下以5°C/min升溫至850°C燒結持溫2小時，接著降溫至400°C，最後爐冷至室溫。"Sintered green body": Put the prepared green body into a high-temperature furnace, raise the temperature to 850°C for 2 hours in an air atmosphere, then lower the temperature to 400°C, and finally cool the furnace to room temperature. Warm.
「製作電極」：將燒結完成後將坯之雙面塗上高溫銀膠，以固化溫度765°C並持溫5分鐘製成電極。"Making electrodes": After sintering is completed, coat both sides of the blank with high-temperature silver glue, and set the curing temperature to 765°C and hold it for 5 minutes to make the electrodes.
以下以實施例示例性說明本發明之氧化鋅變阻器材料。The following examples illustrate the zinc oxide varistor material of the present invention.
［實施例1~7］ 根據上述實驗流程製備氧化鋅變阻器材料，其中，僅改變「製備晶界添加劑」、及「燒結生坯」中之步驟如下所述，其他皆以與前述實驗流程相同進行操作： 「製備晶界添加劑」之步驟中，依照表2所示製備不同晶界添加劑之樣品。各樣品之代號命名如表2所示：若添加之晶界添加劑為Bi 2O 3以B表示，ZnBi 2O 4以BZ表示，且每個代號前的數字則代表所添加的晶界重量百分比，例如：1B即1wt%Bi 2O 3的晶界添加量。並且，重量百分率(wt%)的計算方式為：晶界添加劑重量/(晶粒加上晶界添加劑之總重量)。 「燒結生坯」之步驟中，實施例1~7之「燒結生坯」中850°C降溫至400°C皆係以爐冷方式降溫。 [Examples 1 to 7] Zinc oxide varistor materials were prepared according to the above experimental process. Only the steps of "preparing grain boundary additives" and "sintering green body" were changed as follows. The rest were carried out in the same manner as the above experimental process. Operation: In the step of "Preparing Grain Boundary Additives", prepare samples of different grain boundary additives as shown in Table 2. The code names of each sample are shown in Table 2: If the added grain boundary additive is Bi 2 O 3 , it is represented by B, and ZnBi 2 O 4 is represented by BZ, and the number before each code represents the weight percentage of the added grain boundary. , for example: 1B is the grain boundary addition amount of 1wt% Bi 2 O 3 . Moreover, the weight percentage (wt%) is calculated as: weight of grain boundary additives/(total weight of grains plus grain boundary additives). In the step of "sintering the green body", the "sintering green body" in Examples 1 to 7 was cooled from 850°C to 400°C by furnace cooling.
表2
［實施例8~16］ 根據上述實驗流程製備氧化鋅變阻器材料，其中，僅改變「製備晶界添加劑」、及「燒結生坯」中之步驟如下所述，其他皆以與前述實驗流程相同進行操作： 「製備晶界添加劑」之步驟中，總共製成3種晶界添加劑之樣品：1B、1BZ、1B2BZ。 此外，以上三種樣品各別在「燒結生坯」中分別以爐冷、2°C/min、5°C/min之方式從850°C降溫至400°C(命名以0C、2C、5C加於樣品名稱後表示)，因此共製作9組樣品如表3所示，分別為實施例8~16。 [Examples 8~16] Zinc oxide varistor materials were prepared according to the above experimental process. Only the steps in "preparing grain boundary additives" and "sintering green body" were changed as follows. The other operations were the same as the previous experimental process: In the step of "preparing grain boundary additives", a total of 3 samples of grain boundary additives were prepared: 1B, 1BZ, and 1B2BZ. In addition, the above three samples were respectively cooled from 850°C to 400°C in the "sintered green body" by furnace cooling, 2°C/min, and 5°C/min (named with 0C, 2C, and 5C plus (indicated after the sample name), therefore a total of 9 sets of samples were produced as shown in Table 3, which are Examples 8 to 16 respectively.
表3
以下，針對上述實施例1~7所製備之氧化鋅變阻器材料進行進一步說明、分析，探討不同晶界添加劑對變阻器緻密化、微結構及變阻性質之影響。請注意，每項分析並不會均對實施例1~7進行分析，而係僅挑選較具有比較意義的實施例進行討論。In the following, the zinc oxide varistor materials prepared in the above Examples 1 to 7 will be further described and analyzed, and the effects of different grain boundary additives on the densification, microstructure and varistor properties of the varistor will be discussed. Please note that each analysis will not analyze Embodiments 1 to 7, but only select the embodiments with comparative significance for discussion.
《結晶相分析》"Crystal Phase Analysis"
圖1示出不同晶界添加劑及添加量之樣品的XRD圖。從XRD圖可看到除了主成分ZnO之外亦生成二次相ZnBi 12O 20。 Figure 1 shows the XRD patterns of samples with different grain boundary additives and amounts. It can be seen from the XRD pattern that in addition to the main component ZnO, the secondary phase ZnBi 12 O 20 is also generated.
為了確認各配方之二次相含量，將實施例1、2、4之樣品燒結後並磨細，接著混入10wt%的Al 2O 3作為標準物進行半定量分析(即1B、1BZ及1B2BZ之半定量分析)，如圖2所示。 In order to confirm the secondary phase content of each formula, the samples of Examples 1, 2, and 4 were sintered and ground finely, and then 10 wt% Al 2 O 3 was mixed as a standard substance for semi-quantitative analysis (i.e., 1B, 1BZ and 1B2BZ Semi-quantitative analysis), as shown in Figure 2.
並且，將二次相及標準物Al 2O 3的峰積分後進行分析，如表4所示。可看出1B2BZ之二次相含量遠較1BZ及1B樣品為多。 Moreover, the peaks of the secondary phase and standard Al 2 O 3 were integrated and analyzed, as shown in Table 4. It can be seen that the secondary phase content of 1B2BZ is much higher than that of 1BZ and 1B samples.
表4
《熱收縮行為分析》"Analysis of Thermal Shrinkage Behavior"
圖3(a)、圖3(b)、及表5為實施例1、2、4之不同晶界添加劑之樣品熱收縮曲線圖及分析表。根據結果，可觀察到三者皆在650℃~740℃即開始收縮，且當晶界添加量為1BZ時，收縮率較大。因此決定各實施例之實驗燒結條件選定為850℃燒結2小時。Figure 3(a), Figure 3(b), and Table 5 are the heat shrinkage curves and analysis tables of samples of different grain boundary additives in Examples 1, 2, and 4. According to the results, it can be observed that all three begin to shrink at 650°C~740°C, and when the grain boundary addition amount is 1BZ, the shrinkage rate is larger. Therefore, it was decided that the experimental sintering conditions for each example were sintering at 850°C for 2 hours.
1B2BZ在650℃開始收縮，而1BZ在740℃才開始收縮，但其收縮率很快就追上並超過1B2BZ。此係由於1B2BZ在燒結過程中產生了較多二次相ZnBi 12O 20，故導致收縮速率變緩，而1BZ析出二次相較慢且較少，故其收縮開始溫度較高但最終緻密度較高。 1B2BZ starts to shrink at 650°C, while 1BZ only starts to shrink at 740°C, but its shrinkage rate quickly catches up with and exceeds 1B2BZ. This is because 1B2BZ produces more secondary phases ZnBi 12 O 20 during the sintering process, which causes the shrinkage rate to slow down, while 1BZ precipitates slower and less secondary phases, so its shrinkage start temperature is higher but its final density is higher.
表5
《變阻性質分析》"Analysis of Rheostatic Properties"
將實施例1~7之不同晶界添加劑及添加量之樣品於850°C下燒結2小時並爐冷至室溫，接著進行I-V曲線之量測，其結果如圖4及表6所示(其中I L為漏電流)。從表6中顯知當晶界添加量從1wt%Bi 2O 3改為1wt%ZnBi 2O 4時，非線性係數α值從42.37提升至54.47，崩潰電壓(V b)從775V/mm提升至1011V/mm。此係由於ZnBi 2O 4為p型半導體材料，除有助於形成晶粒為n型半導體，晶界為p型半導體之n-p-n界面外，亦可促進氧藉由ZnBi 2O 4擴散進入材料內部，使晶界附近之吸附氧增加，提升蕭特基能障，進而提升α值；然而，過量的晶界添加量會使得α值從1B2BZ的47.86降至1B4BZ之25.98，崩潰電壓從1232V/mm降至718V/mm。其詳細原因如後所述。 Samples of different grain boundary additives and amounts of Examples 1 to 7 were sintered at 850°C for 2 hours and furnace cooled to room temperature, and then the IV curve was measured. The results are shown in Figure 4 and Table 6 ( where IL is the leakage current). It can be seen from Table 6 that when the grain boundary addition amount is changed from 1wt%Bi 2 O 3 to 1wt%ZnBi 2 O 4 , the nonlinear coefficient α value increases from 42.37 to 54.47, and the collapse voltage (V b ) increases from 775V/mm. to 1011V/mm. This is because ZnBi 2 O 4 is a p-type semiconductor material. In addition to helping to form an npn interface where the grains are n-type semiconductors and the grain boundaries are p-type semiconductors, it can also promote oxygen diffusion into the material through ZnBi 2 O 4 , which increases the adsorbed oxygen near the grain boundaries, increases the Schottky energy barrier, and thereby increases the α value; however, excessive addition of grain boundaries will cause the α value to drop from 47.86 in 1B2BZ to 25.98 in 1B4BZ, and the collapse voltage will drop from 1232V/mm down to 718V/mm. The detailed reasons are described later.
表6
《微結構及阿基米德密度分析》"Microstructure and Archimedean Density Analysis"
將實施例1~7之不同晶界添加劑及添加量樣品的表面進行研磨、拋光、酸腐蝕，透過SEM觀察微觀結構，結果如圖5所示。圖5(a)~圖5(g)分別為樣品1B、1BZ、2BZ、1B1BZ、1B2BZ、1B3BZ及1B4BZ之顯微結構。The surfaces of the samples with different grain boundary additives and additive amounts in Examples 1 to 7 were ground, polished, and acid etched, and the microstructure was observed through SEM. The results are shown in Figure 5. Figures 5(a) to 5(g) show the microstructure of samples 1B, 1BZ, 2BZ, 1B1BZ, 1B2BZ, 1B3BZ and 1B4BZ respectively.
將各樣品晶粒尺寸分析後如表7所示，其中G為平均晶粒大小，σ為標準差。The analysis of the grain size of each sample is shown in Table 7, where G is the average grain size and σ is the standard deviation.
表7
從圖5中可以發現1BZ(圖5(b))之平均晶粒尺寸及標準差較小，代表相同坯體厚度下所擁有的晶界個數較多且為結構較均勻，因此其崩潰電壓及α值較其他樣品優異。1B2BZ、1B3BZ及1B4BZ(圖5(e)~ 圖5(g))之平均晶粒尺寸有越來越大趨勢，故導致崩潰電壓(V b)逐漸降低( )。其中V gb為晶界之崩潰電壓，Ｎ為樣品之晶界數目。 From Figure 5, it can be found that the average grain size and standard deviation of 1BZ (Figure 5(b)) are smaller, which means that under the same thickness of the body, it has more grain boundaries and a more uniform structure, so its collapse voltage and α value are better than other samples. The average grain size of 1B2BZ, 1B3BZ and 1B4BZ (Figure 5(e) ~ Figure 5(g)) has an increasing trend, which leads to a gradual decrease in the breakdown voltage (V b ) ( ). Where V gb is the collapse voltage of the grain boundary, and N is the number of grain boundaries in the sample.
表8為不同晶界添加劑及添加量之樣品進行阿基米德密度量測之結果。從表8中可發現在相同燒結條件下，燒結體密度會隨添加添加劑BZ由1wt%增至2wt%時，達到最大5.38 g/cm 3，且其助燒結之效果遠較Bi 2O 3為佳；對複合型晶界添加劑，即Bi 2O 3加上ZnBi 2O 4之燒結體密度，則會隨著ZnBi 2O 4添加量增加而逐漸減少，此係因為過多的晶界添加量會使得氧化鋅變阻器的緻密度降低進而使變阻性質劣化。 Table 8 shows the results of Archimedean density measurement of samples with different grain boundary additives and additive amounts. It can be found from Table 8 that under the same sintering conditions, the density of the sintered body will increase from 1wt% to 2wt% with the addition of additive BZ, reaching a maximum of 5.38 g/cm 3 , and its sintering assistance effect is much greater than that of Bi 2 O 3 Good; for composite grain boundary additives, that is, the density of the sintered body of Bi 2 O 3 plus ZnBi 2 O 4 will gradually decrease as the addition amount of ZnBi 2 O 4 increases. This is because too much grain boundary addition will The density of the zinc oxide varistor is reduced and the varistor properties are deteriorated.
表8
《阻抗分析》"Impedance Analysis"
為了解氧化鋅變阻器中晶粒、晶界之電阻值，將實施例1、2、4持溫在300˚C下進行交流阻抗分析，分別以電阻及電抗為x軸及y軸，結果如圖6所示。In order to understand the resistance values of grains and grain boundaries in zinc oxide varistor, Examples 1, 2, and 4 were kept at 300˚C for AC impedance analysis. The resistance and reactance were used as the x-axis and y-axis respectively. The results are shown in the figure 6 shown.
將材料內部電阻分為ZnO晶粒電阻、晶界電阻及二次相電阻，因晶粒電阻極小無法在軟體中擬合出，故擬合過程中將忽略晶粒電阻，如圖7所示以串聯的兩組RC電路並聯為等效電路，恆相元件(CPE)係由兩部分組成：CPE-T及CPE-P。CPE-T為一個贗電容，CPE-P與複數阻抗圖中的凹陷半圓有關。其中R 1為二次相電阻，CPE 1為二次相電容，R 2為晶界電阻，CPE 2為晶界電容，擬合結果如表9所示可發現1BZ之總電阻約為5.0至5.5( )Ω遠大於1B及1B2BZ之總電阻2.0至2.5( )Ω，係因為總電阻主要受晶界數目影響，樣品在相同厚度下，當晶粒越小代表其所擁有之晶界數越多，因此所累積之總電阻值也就越大。 The internal resistance of the material is divided into ZnO grain resistance, grain boundary resistance and secondary phase resistance. Since the grain resistance is extremely small and cannot be fitted in the software, the grain resistance will be ignored during the fitting process, as shown in Figure 7. Two sets of RC circuits connected in series are connected in parallel to form an equivalent circuit. The constant phase element (CPE) is composed of two parts: CPE-T and CPE-P. CPE-T is a pseudocapacitor, and CPE-P is related to the depressed semicircle in the complex impedance diagram. Among them, R 1 is the secondary phase resistance, CPE 1 is the secondary phase capacitance, R 2 is the grain boundary resistance, and CPE 2 is the grain boundary capacitance. The fitting results are shown in Table 9. It can be found that the total resistance of 1BZ is about 5.0 to 5.5 ( )Ω is much larger than the total resistance of 1B and 1B2BZ 2.0 to 2.5( )Ω, because the total resistance is mainly affected by the number of grain boundaries. When the sample has the same thickness, the smaller the grains, the more grain boundaries it has, so the accumulated total resistance value is greater.
表9
《X光電子光譜儀分析》"X-ray electronic spectrometer analysis"
圖8為1B、1BZ、1B2BZ(實施例1、2、4)之氧之XPS鍵結能圖。晶格氧之束縛能位在530.2eV處、氧空缺為531.3eV處，而吸附氧則在532.2eV處。Figure 8 is the XPS bonding energy diagram of oxygen in 1B, 1BZ, and 1B2BZ (Examples 1, 2, and 4). The binding energy of lattice oxygen is at 530.2eV, the oxygen vacancy is at 531.3eV, and the adsorbed oxygen is at 532.2eV.
將各材料之鍵結峰經過積分並計算每一種鍵結所佔之比例整理於表10。由表10中可發現吸附氧之比例1BZ及1B2BZ皆較1B多，而氧空缺比例1B較1BZ及1B2BZ多。The bonding peaks of each material were integrated and the proportion of each bond was calculated and summarized in Table 10. From Table 10, it can be found that the proportions of adsorbed oxygen 1BZ and 1B2BZ are both greater than that of 1B, and the oxygen vacancy proportion 1B is greater than that of 1BZ and 1B2BZ.
表10
此係因為ZnBi 2O 4為氧的快速擴散路徑，利於氧擴散進入材料內部與晶界附近的電子反應生成吸附氧。除此之外，降溫過程中富集在晶界之部分過渡金屬離子Co 2+、Mn 2+會氧化變成Co 3+、Mn 3+，氧化所失去的電子( )會被氧氣( )接收，形成吸附氧( 、 )，如下述式A、式B；而1BZ及1B2BZ氧空缺較少的原因則是因帶負電的吸附氧( )易與帶正電的氧空缺( )結合而成晶格氧( )，如下述式C。因此在同個燒結條件下，1BZ及1B2BZ之晶界附近吸附氧會較多、氧空缺會較少。吸附氧較多的情況下會使蕭特基能障提升，進而使α值增加。 式A 式B 式C This is because ZnBi 2 O 4 is a fast diffusion path for oxygen, which is conducive to the diffusion of oxygen into the interior of the material and the reaction with electrons near the grain boundaries to generate adsorbed oxygen. In addition, some transition metal ions Co 2+ and Mn 2+ enriched in the grain boundaries during the cooling process will be oxidized into Co 3+ and Mn 3+ , and the electrons lost in the oxidation ( ) will be absorbed by oxygen ( ) is absorbed to form adsorbed oxygen ( , ), as shown in the following formulas A and B; the reason why 1BZ and 1B2BZ have fewer oxygen vacancies is due to the negatively charged adsorbed oxygen ( ) easily interacts with positively charged oxygen vacancies ( ) combine to form lattice oxygen ( ), as shown in the following formula C. Therefore, under the same sintering conditions, there will be more oxygen adsorbed near the grain boundaries of 1BZ and 1B2BZ, and there will be fewer oxygen vacancies. When there is more adsorbed oxygen, the Schottky energy barrier will increase, thereby increasing the α value. Formula A Formula B Formula C
《Mott-Schottky分析》"Mott-Schottky Analysis"
圖9及表11為1B、1BZ及1B2BZ經 Mott-Schottky圖譜分析所得之電性數據。由結果可發現1BZ之蕭特基位障高度Φ b較1B及1B2BZ高，且α值之變化趨勢也與能障高度相同。根據Mott Schottky之關係式 ， (其中，N d為晶粒之施體濃度；N t為晶界上之受體濃度；W為空乏區寬度；e 為 1eV 之基本電荷1.6×10 -19C；ɛ 0為真空介電常數8.85×10 -12F/m；ɛ r為氧化鋅之介電常數8.5×ɛ 0F/m)，能障高度主要受到晶界上之受體濃度影響，除了ZnO存在之帶一價及二價負電之鋅空缺( )外，添加過渡金屬取代Zn時也伴隨產生鋅空缺( )，此外氧氣於降溫過程中也會接收電子形成吸附氧( )。結合前述X光電子光譜儀分析結果，1BZ之吸附氧較多，而氧空缺較少，係因為添加晶界添加劑ZnBi 2O 4能夠利於氧之遷移，使進入材料內部的氧氣與晶界附近的電子反應生成吸附氧，因而擁有較高之Φ b。 Figure 9 and Table 11 show the electrical data of 1B, 1BZ and 1B2BZ obtained by Mott-Schottky spectrum analysis. From the results, it can be found that the Schottky barrier height Φ b of 1BZ is higher than that of 1B and 1B2BZ, and the changing trend of the α value is also the same as the energy barrier height. According to Mott Schottky's relationship , (Among them, N d is the donor concentration of the crystal grain; N t is the acceptor concentration on the grain boundary; W is the width of the depletion region; e is the basic charge of 1eV 1.6×10 -19 C; ɛ 0 is the vacuum dielectric constant 8.85×10 -12 F/m; ɛ r is the dielectric constant of zinc oxide 8.5×ɛ 0 F/m). The energy barrier height is mainly affected by the acceptor concentration on the grain boundary, except for the one-valent and two-valent bands present in ZnO. Negatively charged zinc vacancies ( ), when a transition metal is added to replace Zn, zinc vacancies are also produced ( ), in addition, oxygen will also receive electrons during the cooling process to form adsorbed oxygen ( ). Combined with the aforementioned X-ray electron spectrometer analysis results, 1BZ has more adsorbed oxygen and fewer oxygen vacancies. This is because the addition of the grain boundary additive ZnBi 2 O 4 can facilitate the migration of oxygen, allowing the oxygen entering the material to react with electrons near the grain boundaries. It generates adsorbed oxygen and therefore has a higher Φ b .
而降溫過程中吸附氧會經由晶界快速擴散至ZnO晶粒表面與氧空缺結合成晶格氧，導致氧空缺濃度下降。施體濃度(N d)受到ZnO本身存在之帶一價及二價正電之氧空缺( 及添加過渡金屬氧化物Co 3O 4與Mn 3O 4提供之帶一價正電取代鋅離子之鈷離子及錳離子 影響，因此導致1BZ之能障高度較高及施體濃度低於其他兩者。 During the cooling process, the adsorbed oxygen will quickly diffuse to the ZnO grain surface through the grain boundaries and combine with oxygen vacancies to form lattice oxygen, resulting in a decrease in the oxygen vacancy concentration. The donor concentration (N d ) is affected by the existence of one-valent and two-valent positively charged oxygen vacancies in ZnO itself ( And add transition metal oxides Co 3 O 4 and Mn 3 O 4 to provide cobalt ions and manganese ions with a positive charge that replaces zinc ions. influence, thus causing the energy barrier height of 1BZ to be higher and the donor concentration to be lower than the other two.
表11
以下，針對上述實施例8~16所製備之氧化鋅變阻器材料進行進一步說明、分析。請注意，每項分析並不會均對實施例8~16進行分析，而係僅挑選較具有比較意義的實施例進行討論。In the following, the zinc oxide varistor materials prepared in the above-mentioned Examples 8 to 16 will be further explained and analyzed. Please note that each analysis will not analyze Embodiments 8 to 16, but only select the embodiments with comparative significance for discussion.
《變阻性質分析》"Analysis of Rheostatic Properties"
將實施例8~16之材料進行I-V曲線之量測並轉換成變阻性質，結果如圖10和表12所示。The I-V curves of the materials in Examples 8 to 16 were measured and converted into varistor properties. The results are shown in Figure 10 and Table 12.
表12
從表12中可以知道當降溫速率為2°C/min，α值皆有提升，以1BZ之效果最為顯著。這係由於冷卻速度慢，而位於晶界之ZnBi 2O 4提供氧的快速擴散路徑，使更多O 2可經由晶界擴散至晶粒，同時富集在晶界之Co 2+被氧化成Co 3+並放出電子，此時電子與進入材料內部的氧結合生成吸附氧，使晶界能障變高進而提升變阻性質。 From Table 12, we can know that when the cooling rate is 2°C/min, the α value increases, and the effect of 1BZ is the most significant. This is due to the slow cooling rate and the ZnBi 2 O 4 located at the grain boundaries providing a fast diffusion path for oxygen, allowing more O 2 to diffuse to the grains through the grain boundaries. At the same time, the Co 2+ enriched in the grain boundaries is oxidized into Co 3+ and releases electrons. At this time, the electrons combine with the oxygen entering the material to form adsorbed oxygen, which increases the grain boundary energy barrier and improves the varistor properties.
而1B0C至1B2C之崩潰電壓有所提升，從圖11之(a)1B2C (b)1BZ2C (c)1B2BZ2C 之微觀結構圖中可以觀察到1B2C之孔洞相較於圖5之1B0C較少，代表緻密度有所提升，推測是因為降溫速度慢，有充裕的時間使液相之ZnBi 2O 4分布更均勻。 The breakdown voltage of 1B0C to 1B2C has increased. From the microstructure diagram of (a) 1B2C (b) 1BZ2C (c) 1B2BZ2C in Figure 11, it can be observed that 1B2C has fewer holes than 1B0C in Figure 5, which means it is dense. The temperature has increased, presumably because the cooling rate is slow and there is sufficient time to make the ZnBi 2 O 4 in the liquid phase more uniformly distributed.
《熱重熱差分析》"Thermal Gravimetric Heat Difference Analysis"
圖12(d)為1B、1BZ及1B2BZ以5℃/min升溫至900℃的熱重曲線；圖12(a)~(c)為1B、1BZ及1B2BZ分別以2℃/min及5℃/min降溫至400℃的熱重曲線。Figure 12(d) shows the thermogravimetric curves of 1B, 1BZ and 1B2BZ heated to 900°C at 5°C/min; Figure 12(a)~(c) shows the thermogravimetric curves of 1B, 1BZ and 1B2BZ heated up to 900°C at 2°C/min and 5°C/min respectively. Thermogravimetric curve when the temperature is lowered to 400℃.
表13為不同降溫速率之熱重損失。Table 13 shows the thermogravimetric loss at different cooling rates.
表13
觀察圖12(a)~(c)可發現降溫速率為2℃/min皆有增重的現象，係因為冷卻速度慢，使因此時氣氛中之氧氣擴散至胚體內部，O 2經由晶界擴散至晶粒，同時富集在晶界之Co 2+被氧化成Co 3+並放出電子，此時電子與進入材料內部的氧結合生成吸附氧。 Observing Figure 12(a)~(c), it can be found that the weight increases even at a cooling rate of 2°C/min. This is because the cooling rate is slow, so that the oxygen in the atmosphere diffuses into the interior of the embryo body, and O 2 passes through the grain boundaries. Diffuses into the crystal grains, and at the same time, the Co 2+ enriched in the grain boundaries is oxidized into Co 3+ and releases electrons. At this time, the electrons combine with the oxygen entering the material to form adsorbed oxygen.
觀察圖12(a)可發現1B、1BZ及1B2BZ在升溫至600℃皆有明顯增重，這係因為CoO在600℃時會與進入材料內部的氧反應生成Co 2O 3造成增重，如下述式D所示。 式D Observing Figure 12(a), it can be found that 1B, 1BZ and 1B2BZ all gain significant weight when the temperature rises to 600°C. This is because CoO reacts with oxygen entering the material at 600°C to form Co 2 O 3 , causing weight gain, as follows It is shown in formula D. Formula D
1B在650℃~900℃有一個明顯的失重曲線，而1BZ與1B2BZ皆無失重，推測在700°~900℃之重量損失可能是因為Bi 2O 3到達ZnO-Bi 2O 3共晶溫度(740℃)及熔點(825℃)，而1BZ及1B2BZ則因事先合成為ZnBi 2O 4而無失重產生。 1B has an obvious weight loss curve at 650°C~900°C, while 1BZ and 1B2BZ have no weight loss. It is speculated that the weight loss at 700°~900°C may be because Bi 2 O 3 reaches the ZnO-Bi 2 O 3 eutectic temperature (740 ℃) and melting point (825℃), while 1BZ and 1B2BZ are synthesized into ZnBi 2 O 4 in advance without any weight loss.
《阻抗分析》"Impedance Analysis"
為了解2˚C/min降溫之ZnO變阻器中晶粒、晶界之電阻值，將材料持溫在300˚C下進行交流阻抗分析，結果如圖13及表14所示。In order to understand the resistance values of grains and grain boundaries in ZnO varistor cooled at 2˚C/min, the material was kept at 300˚C for AC impedance analysis. The results are shown in Figure 13 and Table 14.
表14
由圖13及表14可以發現降溫速率的快慢所量測出來的阻抗皆相似，推測是因不同的降溫速率並不會改變樣品的顯微結構，因此同個厚度下所擁有之晶界數相似，累積之總晶界阻值也就相同。From Figure 13 and Table 14, it can be found that the measured impedances are similar at different cooling rates. It is speculated that different cooling rates do not change the microstructure of the sample, so the number of grain boundaries at the same thickness is similar. , the cumulative total grain boundary resistance is the same.
《X光電子光譜儀分析》"X-ray electronic spectrometer analysis"
圖14為1B2C、1BZ2C及1B2BZ2C之氧之XPS鍵結能圖。將各樣品之鍵結峰經過積分並計算每一種鍵結所佔之比例整理於表15。Figure 14 is the XPS bonding energy diagram of oxygen in 1B2C, 1BZ2C and 1B2BZ2C. The bonding peaks of each sample were integrated and the proportion of each bond was calculated and summarized in Table 15.
表15
由表15中可以發現控制降溫速率2℃/min後所得的吸附氧皆有所增加，而氧空缺也有所下降。由於降溫速率慢，會使氣氛中的氧沿著晶界擴散進入材料內部，使氧與聚集在晶界處的電子反應生成吸附氧，而部分的吸附氧會與氧空缺反應生成晶格氧，因此造就吸附氧增加、氧空缺減少的情形。此外，ZnBi 2O 4為一個良好的氧通道，相對於Bi 2O 3會有較多的氧進入材料內部補足空缺位置，因此1BZ2C及1B2BZ2C又比1B2C的氧空缺少。較多的吸附氧使得N t上升，較少的氧空缺使得N d下降，最終使蕭特基能障及變阻性質提升。 It can be found from Table 15 that the adsorbed oxygen obtained after controlling the cooling rate to 2°C/min has increased, and the oxygen vacancies have also decreased. Due to the slow cooling rate, oxygen in the atmosphere will diffuse into the material along the grain boundaries, causing oxygen to react with electrons gathered at the grain boundaries to generate adsorbed oxygen, and part of the adsorbed oxygen will react with oxygen vacancies to generate lattice oxygen. This results in an increase in adsorbed oxygen and a decrease in oxygen vacancies. In addition, ZnBi 2 O 4 is a good oxygen channel. Compared with Bi 2 O 3, more oxygen will enter the material to fill the vacancies. Therefore, 1BZ2C and 1B2BZ2C have less oxygen vacancies than 1B2C. More adsorbed oxygen causes N t to increase, and fewer oxygen vacancies cause N d to decrease, ultimately improving the Schottky energy barrier and varistor properties.
《Mott-Schottky分析》"Mott-Schottky Analysis"
圖15及表16為1B、1BZ、1B2BZ分別以爐冷及2℃/min降溫至400℃後，經 Mott-Schottky圖譜分析所得之電性數據。Figure 15 and Table 16 show the electrical data obtained by Mott-Schottky spectrum analysis of 1B, 1BZ, and 1B2BZ after cooling to 400°C using furnace cooling and 2°C/min respectively.
表16
由圖15及表16可發現2℃/min降溫之Φ b及N t較爐冷高，而N d較低。氧空缺濃度會隨著退火時間增加而減少，因此冷卻速度慢，使O 2有充足的時間可經由晶界擴散至晶粒，晶界處富集之Co 2+、Mn 2+被氧化成Co 3+、Mn 3+並放出電子( )，如下述式E、式F，電子與沿著晶界擴散進入的氧( )結合生成吸附氧( 、 )使N t上升，如式G、式H。而氧吸附會與材料內部的帶一價及二價之氧空缺( )結合再次成為晶格氧( )，如式I、式J(其中式I之 為電洞)，其示意圖如圖16所示。因此2℃/min降溫之N d較低。 式E 式F 式G 式H 式I 式J From Figure 15 and Table 16, it can be found that Φ b and N t of 2°C/min cooling are higher than furnace cooling, while N d is lower. The oxygen vacancy concentration will decrease as the annealing time increases, so the cooling rate is slow, allowing sufficient time for O 2 to diffuse to the grains through the grain boundaries, and the Co 2+ and Mn 2+ enriched at the grain boundaries are oxidized into Co 3+ , Mn 3+ and emit electrons ( ), as shown in the following formulas E and F, electrons and oxygen diffused along the grain boundaries ( ) combine to form adsorbed oxygen ( , ) causes N t to rise, such as formula G and formula H. The oxygen adsorption will interact with the monovalent and divalent oxygen vacancies inside the material ( ) combines again to become lattice oxygen ( ), such as formula I and formula J (wherein formula I is is an electric hole), its schematic diagram is shown in Figure 16. Therefore, the N d of cooling at 2°C/min is low. Formula E Formula F Formula G Formula H Formula I Formula J
［檢測儀器］ 將本發明中所使用之儀器、及測量方法詳細描述如下： [Testing instruments] The instruments and measurement methods used in the present invention are described in detail as follows:
《X光繞射儀分析》"X-ray Diffractometer Analysis"
將各樣品生坯燒結後磨成粉使用X光繞射儀(Dandong Fangyuan, DX-2700, Sandong, China)進行相分析，接著參入10wt%的α-Al 2O 3粉末作為標準物，裝入樣品瓶內均勻混合後進行半定量分析，操作條件如表17所示。接著利用國際繞射數據中心的繞射資料庫(International center for diffraction data-powder diffraction file, ICDD-PDF)進行繞射峰位置及相對強度之比對。 The green bodies of each sample were sintered and ground into powder for phase analysis using an Put it into the sample bottle and mix evenly before conducting semi-quantitative analysis. The operating conditions are shown in Table 17. Then, the diffraction peak position and relative intensity were compared using the International center for diffraction data-powder diffraction file (ICDD-PDF).
表17
《燒結收縮曲線分析》"Analysis of Sintering Shrinkage Curve"
將單軸加壓成型之直徑8mm、厚度約2mm生坯放入熱膨脹分析儀(NETZSCH-402PC)，以升溫速率5˚C/min從室溫加熱至1000˚C，量測坯體於升溫過程之厚度變化量，接著將一次微分後之收縮量和溫度作圖輸出。Place the uniaxially pressed green body with a diameter of 8mm and a thickness of about 2mm into a thermal expansion analyzer (NETZSCH-402PC), and heat it from room temperature to 1000˚C at a heating rate of 5˚C/min. Measure the temperature rise process of the green body. The thickness change, and then the shrinkage after first differentiation and the temperature are plotted and output.
《變阻性質分析》"Analysis of Rheostatic Properties"
利用High-Voltage Source Meter (Keithley 2410) 進行量測可得到I-V數據，將數據進行分析即可得以下三種變阻性質：非線性指數α、崩潰電壓V b(V/mm)、漏電流I L(μA)。非線性指數α為0.1mA和1mA所對應之電壓以下式求得； 崩潰電壓(Breakdown voltage)為V 1mA除以坯體厚度(d)所得； 漏電流(Leakage current)為0.8倍的V 1mA所對應之電流： 。 IV data can be obtained by measuring with High-Voltage Source Meter (Keithley 2410). By analyzing the data, the following three varistor properties can be obtained: nonlinear index α, breakdown voltage V b (V/mm), and leakage current I L (μA). The nonlinear index α is the voltage corresponding to 0.1mA and 1mA, which is obtained by the following formula; Breakdown voltage (Breakdown voltage) is V 1mA divided by the thickness of the body (d); Leakage current is 0.8 times the current corresponding to V 1mA : .
《微結構分析》"Microstructural Analysis"
將坯體之表面分別以600、800、1000、1500、2000和4000號之SiC砂紙拋光後，使用稀釋之鹽酸(1%)進行酸蝕，接著將樣品表面濺鍍一層白金增加其導電性，最後透過掃描式電子顯微鏡(Hitachi SU-5000)觀察樣品之微觀結構。After polishing the surface of the body with 600, 800, 1000, 1500, 2000 and 4000 SiC sandpaper, dilute hydrochloric acid (1%) was used for acid etching, and then a layer of platinum was sputtered on the surface of the sample to increase its conductivity. Finally, the microstructure of the sample was observed through a scanning electron microscope (Hitachi SU-5000).
《密度量測》"Density Measurement"
藉由阿基米德法量測燒結之樣品視密度D。先秤量燒結後之坯體乾重(W 1)，接著置於水中煮沸24小時使水進入坯體之開放孔洞後，秤量其飽和含水重(W 2)及水中懸浮重(W 3)，最後代入下述公式得出視密度。 The apparent density D of the sintered sample was measured by Archimedes' method. First, weigh the dry weight of the sintered green body (W 1 ), then boil it in water for 24 hours to allow water to enter the open pores of the green body, then weigh its saturated water weight (W 2 ) and suspended weight in water (W 3 ). Finally, Plug in the following formula to get the apparent density.
《交流阻抗分析》"AC Impedance Analysis"
將雙面塗上銀膠之樣品透過電化學分析儀(SI 1260, Solartron Analytical)量測300°C下之阻抗值，量測條件為：交流小電壓3V、掃描頻率1MHz-1Hz，並透過Zview程式(Scribner Associate. Inc, USA)將數據進行擬合算出晶粒及晶界的電阻。The impedance value of the sample coated with silver glue on both sides at 300°C was measured with an electrochemical analyzer (SI 1260, Solartron Analytical). The measurement conditions were: AC small voltage 3V, scanning frequency 1MHz-1Hz, and through Zview A program (Scribner Associate. Inc, USA) was used to fit the data and calculate the resistance of grains and grain boundaries.
《XPS分析》"XPS Analysis"
將燒結完成之樣品破斷面利用化學分析電子光譜儀(PHI 5000 VersaProbe)觀察內部晶格氧、氧空缺及吸附氧之含量。The broken section of the sintered sample was used to observe the content of internal lattice oxygen, oxygen vacancies and adsorbed oxygen using a chemical analysis electronic spectrometer (PHI 5000 VersaProbe).
《Mott-Schottky 分析》"Mott-Schottky Analysis"
將雙面塗上銀膠之樣品透過電化學分析儀(SI 1260, Solartron Analytical)量測得到不同偏壓下之電容變化，量測條件為：頻率1kHz、直流偏壓0V-6V、交流小電壓3V、Sweep segment為5、掃描速率每秒50mV。接著將C-V之數據利用Mukae等人使用之Mott-schottky分析法得出能障高度Φ b、施體濃度N d、受體濃度N t及空乏層寬度W。 The sample coated with silver glue on both sides was measured with an electrochemical analyzer (SI 1260, Solartron Analytical) to obtain the capacitance changes under different bias voltages. The measurement conditions were: frequency 1kHz, DC bias voltage 0V-6V, AC small voltage 3V, Sweep segment is 5, scan rate is 50mV per second. Then, the CV data was used to obtain the energy barrier height Φ b , donor concentration N d , acceptor concentration N t and depletion layer width W using the Mott-schottky analysis method used by Mukae et al.
根據下式將 對施加的直流偏壓V作圖可得到一個凹向上圖形，對此圖形上升區段進行直線擬合找出斜率k及截距b，即可求出Φ b、N d、N s、W。其中，C 0和C分別為施加0和V偏壓時所對應之電容值， 為空介電常數(8.85 10 -12F/m)， 為氧化鋅的介電常數(8.5 )，q為電荷(1.6 10 -19C)，Aa為樣品之截面積（m 2）。 According to the following formula, Plotting the applied DC bias voltage V can obtain a concave upward graph. Perform straight line fitting on the rising section of this graph to find the slope k and intercept b, and then Φ b , N d , N s , and W can be obtained. Among them, C 0 and C are the corresponding capacitance values when bias voltages of 0 and V are applied respectively, is the empty dielectric constant (8.85 10 -12 F/m), is the dielectric constant of zinc oxide (8.5 ), q is the charge (1.6 10 -19 C), Aa is the cross-sectional area of the sample (m 2 ).
《介電譜分析》"Dielectric Spectrum Analysis"
將樣品透過阻抗分析儀(Agilent/ HP, 4284A)量測-60、-40、-20、0及25°C下之介電損失(tanδ)，量測條件為：交流小電壓1V、直流偏壓0V、掃描頻率100Hz-1MHz。測量完成後將峰值所對應之頻率帶進阿瑞尼斯 (Arrhenius) 方程式，計算峰值活化能。 The sample was passed through an impedance analyzer (Agilent/HP, 4284A) to measure the dielectric loss (tanδ) at -60, -40, -20, 0 and 25°C. The measurement conditions were: AC small voltage 1V, DC bias Voltage 0V, scanning frequency 100Hz-1MHz. After the measurement is completed, the frequency corresponding to the peak is brought into the Arrhenius equation to calculate the peak activation energy.
其中k為反應之速率常數，A為阿瑞尼斯常數， 為反應之活化能，R為氣體常數，T為絕對溫度。 where k is the rate constant of the reaction, A is the Arenis constant, is the activation energy of the reaction, R is the gas constant, and T is the absolute temperature.
《熱重熱差分析》"Thermal Gravimetric Heat Difference Analysis"
將樣品之粉末透過熱差/熱重分析儀器(DTA/TG, Netzsch STA409PC)以5°C/min升至850°C，再以2°C /min及5°C /min降至400°C，觀察其燒結與降溫過程之重量變化。The powder of the sample was raised to 850°C through a differential thermal/thermogravimetric analysis instrument (DTA/TG, Netzsch STA409PC) at 5°C/min, and then lowered to 400°C at 2°C/min and 5°C/min. , observe the weight changes during sintering and cooling.
無without
〔圖1〕不同晶界添加劑及添加量之樣品的XRD圖。 〔圖2〕1B、1BZ及1B2BZ之半定量分析圖。 〔圖3〕1B、1BZ及1B2BZ之(a)熱收縮曲線 (b)緻密化速率曲線分析圖。 〔圖4〕不同晶界添加劑及添加量之I-V曲線圖。 〔圖5〕不同晶界添加劑及添加量(a)1B (b)1BZ (c)2BZ (d)1B1BZ (e)1B2BZ (f)1B3BZ (g)1B4BZ之SEM圖。 〔圖6〕1B、1BZ及1B2BZ之交流阻抗圖。 〔圖7〕等效電路示意圖。 〔圖8〕1B、1BZ、1B2BZ之氧之XPS鍵結能圖。 〔圖9〕1B、1BZ及1B2BZ之(a)Φ b(b)N d(c)N t(d)w 之Mott Schottky分析圖。 〔圖10〕不同降溫速率之I-V曲線圖。 〔圖11〕(a)1B2C (b)1BZ2C (c)1B2BZ2C 之微觀結構圖。 〔圖12〕(a)1B、1BZ及1B2BZ以5℃/min升溫至900℃的熱重曲線； (b)1B (c)1BZ (d)1B2BZ分別以2℃/min及5℃/min降溫至400℃的熱重曲線圖。 〔圖13〕不同降溫速率之交流阻抗圖。 〔圖14〕1B2C、1BZ2C及1B2BZ2C之XPS圖。 〔圖15〕不同降溫速率樣品之Mott Schottky分析(a)Φ b(b)N d(c)N t(d)w。 〔圖16〕變阻器燒結過程之缺陷反應 (a)煆燒過程 (b)燒結過程 (c)降溫過程之吸附氧 (d)降溫過程之晶格氧之圖。 [Figure 1] XRD patterns of samples with different grain boundary additives and amounts. [Figure 2] Semi-quantitative analysis chart of 1B, 1BZ and 1B2BZ. [Figure 3] Analysis diagram of (a) thermal shrinkage curve (b) densification rate curve of 1B, 1BZ and 1B2BZ. [Figure 4] IV curves of different grain boundary additives and amounts. [Figure 5] SEM images of different grain boundary additives and amounts (a) 1B (b) 1BZ (c) 2BZ (d) 1B1BZ (e) 1B2BZ (f) 1B3BZ (g) 1B4BZ. [Figure 6] AC impedance diagrams of 1B, 1BZ and 1B2BZ. [Figure 7] Equivalent circuit diagram. [Figure 8] XPS bonding energy diagrams of oxygen in 1B, 1BZ, and 1B2BZ. [Figure 9] Mott Schottky analysis diagram of (a)Φ b (b)N d (c)N t (d)w of 1B, 1BZ and 1B2BZ. [Figure 10] IV curves at different cooling rates. [Figure 11] Microstructure diagram of (a) 1B2C (b) 1BZ2C (c) 1B2BZ2C. [Figure 12] (a) Thermogravimetric curves of 1B, 1BZ and 1B2BZ heated to 900°C at 5°C/min; (b) 1B (c) 1BZ (d) 1B2BZ cooled down at 2°C/min and 5°C/min respectively Thermogravimetric curve up to 400°C. [Figure 13] AC impedance diagram at different cooling rates. [Figure 14] XPS images of 1B2C, 1BZ2C and 1B2BZ2C. [Figure 15] Mott Schottky analysis of samples with different cooling rates (a) Φ b (b) N d (c) N t (d) w. [Figure 16] Defect reactions during the sintering process of the varistor (a) Calcining process (b) Sintering process (c) Adsorbed oxygen during cooling process (d) Diagram of lattice oxygen during cooling process.
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Citations (5)
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|---|---|---|---|---|
| TW345665B (en) * | 1997-06-23 | 1998-11-21 | Nat Science Council | Zinc oxide varistor and multilayer chip varistor with low temperature sintering properties |
| EP2276042A2 (en) * | 2009-07-17 | 2011-01-19 | SFI Electronics Technology Inc. | Process for producing a zinc oxide (ZnO) varistor |
| TW201221501A (en) * | 2010-11-26 | 2012-06-01 | Sfi Electronics Technology Inc | Process for producing ZnO varistor particularly having internal electrode composed of pure silver and sintered at a lower sintering temperature |
| CN102633498A (en) * | 2012-03-31 | 2012-08-15 | 中国科学院上海硅酸盐研究所 | Low-temperature sintered zinc oxide voltage-sensitive ceramic material and preparation method thereof |
| US20210238052A1 (en) * | 2018-06-06 | 2021-08-05 | Koa Corporation | Zinc oxide varistor |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW345665B (en) * | 1997-06-23 | 1998-11-21 | Nat Science Council | Zinc oxide varistor and multilayer chip varistor with low temperature sintering properties |
| US5973589A (en) * | 1997-06-23 | 1999-10-26 | National Science Council | Zno varistor of low-temperature sintering ability |
| EP2276042A2 (en) * | 2009-07-17 | 2011-01-19 | SFI Electronics Technology Inc. | Process for producing a zinc oxide (ZnO) varistor |
| TW201221501A (en) * | 2010-11-26 | 2012-06-01 | Sfi Electronics Technology Inc | Process for producing ZnO varistor particularly having internal electrode composed of pure silver and sintered at a lower sintering temperature |
| CN102633498A (en) * | 2012-03-31 | 2012-08-15 | 中国科学院上海硅酸盐研究所 | Low-temperature sintered zinc oxide voltage-sensitive ceramic material and preparation method thereof |
| US20210238052A1 (en) * | 2018-06-06 | 2021-08-05 | Koa Corporation | Zinc oxide varistor |
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