CN104003721B - Low temperature sintering microwave dielectric ceramic Li 2w 2zn 3o 10and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of low temperature sintering temperature-stable microwave dielectric ceramic Li ₂w ₂zn ₃o ₁₀, its preparation method concrete steps are: purity is the Li of more than 99.9% by (1) ₂cO ₃, WO ₃li is pressed with the starting powder of ZnO ₂w ₂zn ₃o ₁₀chemical formula weigh batching; (2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is distilled water, pre-burning 6 hours in 620 DEG C of air atmosphere after oven dry; (3) in the powder that step (2) is obtained, binding agent is added and after granulation, more compressing, finally in 670 ~ 700 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the poly-vinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for 3% of powder gross mass.Ceramic sintering temperature prepared by the present invention is low, and its temperature coefficient of resonance frequency is little, and temperature stability is good, and dielectric constant reaches 21 ~ 22, and quality factor q f value, up to 74000-97000GHz, industrially has great using value.

Description

Low temperature sintering microwave dielectric ceramic Li 2w 2zn 3o 10and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to the microwave devices such as medium substrate, resonator and the filter used in microwave frequency, and the dielectric ceramic material of ceramic capacitor or temperature compensating capacitor and preparation method thereof.

Background technology

Microwave dielectric ceramic refers to and to be applied in microwave frequency band (mainly UHF and SHF frequency range) circuit as dielectric material and to complete the pottery of one or more functions, the components and parts such as resonator, filter, dielectric substrate and medium wave circuit are widely used as in modern communication, it is the key foundation material of modern communication technology, in portable mobile phone, automobile telephone, cordless telephone, telstar recipient and military radar etc., there is very important application, in the miniaturization, integrated process of modern communication instrument, just playing increasing effect.

Be applied to the dielectric ceramic of microwave frequency band, the requirement of following dielectric property should be met: (1) seriation DIELECTRIC CONSTANT ε _rto adapt to the requirement of different frequency and different application occasion; (2) high quality factor q value or dielectric loss tan δ to reduce noise, General Requirements Qf>=3000GHz; (3) the temperature coefficient τ of resonance frequency _?as far as possible close to zero to ensure the thermal stability that device has had, General Requirements-10/ DEG C≤τ _?≤+10ppm/ DEG C.From late 1930s, just someone attempts dielectric substance to be applied to microwave technology in the world.

According to relative dielectric constant ε _rsize from use frequency range different, usually the microwave-medium ceramics be developed and developing can be divided into 4 classes.

(1) ultralow dielectric microwave dielectric ceramic, main representative is Al ₂o ₃-TiO ₂, Y ₂baCuO ₅, MgAl ₂o ₄and Mg ₂siO ₄deng, its ε _r≤ 20, quality factor q × f>=50000GHz, τ _?≤ 10ppm/ ° of C.Be mainly used in microwave base plate and high-end microwave device.

(2) low ε _rwith the microwave dielectric ceramic of high q-factor, mainly BaO-MgO-Ta ₂o ₅, BaO-ZnO-Ta ₂o ₅or BaO-MgO-Nb ₂o ₅, BaO-ZnO-Nb ₂o ₅system or the hybrid system MWDC material between them.Its ε _r=25 ~ 30, Q=(1 ~ 2) × 10 ⁴(under f>=10GHz), τ _?≈ 0.Be mainly used in the microwave communication equipments such as the direct broadcasting satellite of f >=8GHz as dielectric resonance device.

(3) medium ε _rwith the microwave dielectric ceramic of Q value, mainly with BaTi ₄o ₉, Ba ₂ti ₉o ₂₀(Zr, Sn) TiO ₄deng the MWDC material for base, its ε _r=35 ~ 40, Q=(6 ~ 9) × 10 ³(under f=3 ~-4GHz), τ _?≤ 5ppm/ ° of C.Be mainly used in microwave military radar in 4 ~ 8GHz frequency range and communication system as dielectric resonance device.

(4) high ε _rand the microwave dielectric ceramic that Q value is lower, be mainly used in civilian mobile communcations system in 0.8 ~ 4GHz frequency range, this is also the emphasis of microwave dielectric ceramic research.Since the eighties, the people such as Kolar, Kato in succession find and have studied perovskite-like tungsten bronze type BaO-Ln ₂o ₃-TiO ₂series (Ln=La, Sm, Nd or Pr etc. are called for short BLT system), complex perovskite structure CaO-Li ₂o-Ln ₂o ₃-TiO ₂series, lead base series material, Ca _1-xln _2x/3tiO ₃be contour ε _rmicrowave dielectric ceramic, the wherein BaO-Nd of BLT system ₂o ₃-TiO ₂material dielectric constant reaches 90, lead base series (Pb, Ca) ZrO ₃dielectric constant reaches 105.

The sintering temperature of these material systems is generally higher than 1300 ° of C above, can not directly and the low-melting-point metal such as Ag and Cu burn formation multilayer ceramic capacitor altogether.In recent years, along with LTCC Technology (LowTemperatureCo-firedCeramics, the requirement of development LTCC) and the development of microwave multilayer device, researcher both domestic and external has carried out exploring widely and studying to some low fever's system materials, mainly adopt devitrified glass or glassceramic composites system, because low-melting glass has relatively high dielectric loss mutually, the existence of glassy phase substantially increases the dielectric loss of material.Therefore development is the emphasis of current research without the low fired microwave dielectric ceramic material of glassy phase.

Can in the process of low fired microwave dielectric ceramic materials in exploration and development of new, the material systems such as the Li based compound that intrinsic sintering temperature is low, Bi based compound, tungstates architecture compound and tellurate architecture compound get the attention and research, but the subject matter existed is, the temperature coefficient of resonance frequency of the single-phase microwave dielectric ceramic material of low temperature sintering of most open report is all bigger than normal, cannot ensure the thermal stability that device has had; And also cannot carry out by existing theory or technology the τ predicting monophase materials up to now _?value, which greatly limits the development of low temperature co-fired technology and microwave multilayer device.

We are to consisting of Li ₂w ₂zn ₃o ₁₀noval chemical compound carried out sintering characteristic and Study on microwave dielectric property, found that such pottery have excellent comprehensive microwave dielectric property simultaneously sintering temperature lower than 700 °c, what can realize with Ag is low temperature co-fired, can be widely used in the manufacture of the microwave devices such as various medium substrate, resonator and filter, can meet the needs of low temperature co-fired technology and microwave multilayer device.

Summary of the invention

The object of this invention is to provide a kind of Heat stability is good and low-loss, and can low sintering microwave dielectric ceramic material and preparation method thereof.

The chemical constitution formula of microwave dielectric ceramic material of the present invention is Li ₂w ₂zn ₃o ₁₀.

Preparation method's step of this microwave dielectric ceramic material is:

(1) be the Li of more than 99.9% by purity ₂cO ₃, WO ₃li is pressed with the starting powder of ZnO ₂w ₂zn ₃o ₁₀chemical formula weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is distilled water, pre-burning 6 hours in 620 DEG C of air atmosphere after oven dry.

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, more compressing, finally in 670 ~ 700 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the poly-vinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for 3% of powder gross mass.

Of the present invention advantageous Effectsbe: the ceramic sintering temperature of application claims protection is low, can meet the technology needs of low temperature co-fired technology and microwave multilayer device; The temperature coefficient τ of its resonance frequency _?close to zero, the heat-staple requirement of device can be met; Dielectric constant reaches 21 ~ 22, and quality factor q f value, up to 74000-97000GHz, can be widely used in the manufacture of the microwave devices such as various medium substrate, resonator and filter, industrially have great using value.

Embodiment

Embodiment:

Table 1 shows 3 specific embodiments and microwave dielectric property thereof that form different sintering temperature of the present invention.Its preparation method is described above, carries out the evaluation of microwave dielectric property by cylindrical dielectric resonator method.Just Li ₂w ₂zn ₃o ₁₀powder mixes with the Ag powder accounting for powder quality 20%, compressing after, at 700 DEG C sinter 4 hours;

X-ray diffraction material phase analysis and scanning electron microscopic observation all show Li ₂w ₂zn ₃o ₁₀chemical reaction is not there is not, i.e. Li with Ag ₂w ₂zn ₃o ₁₀can be low temperature co-fired with Ag electrode.This pottery can be widely used in the manufacture of the microwave devices such as various medium substrate, resonator and filter, can meet the technology needs of the system such as mobile communication and satellite communication.

Table 1:

Claims (1)

1. a low temperature sintering microwave dielectric ceramic, is characterized in that the chemical constitution formula of described microwave dielectric ceramic is: Li ₂w ₂zn ₃o ₁₀;

Preparation method's concrete steps of described microwave dielectric ceramic are:

(1) be the Li of more than 99.9% by purity ₂cO ₃, WO ₃li is pressed with the starting powder of ZnO ₂w ₂zn ₃o ₁₀chemical formula weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is distilled water, pre-burning 6 hours in 620 DEG C of air atmosphere after oven dry;

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, more compressing, finally in 670 ~ 700 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the poly-vinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for 3% of powder gross mass.