CN103113104A

CN103113104A - Low temperature sintered microwave dielectric ceramic Li2W4O13 and preparation method thereof

Info

Publication number: CN103113104A
Application number: CN2013100945410A
Authority: CN
Inventors: 方亮; 邓婧; 唐莹
Original assignee: Guilin University of Technology
Current assignee: Suzhou Hongwu Technology Intermediary Service Co.,Ltd.
Priority date: 2013-03-24
Filing date: 2013-03-24
Publication date: 2013-05-22
Anticipated expiration: 2033-03-24
Also published as: CN103113104B

Abstract

The invention discloses a low temperature sintered microwave dielectric ceramic Li2W4O13 and a preparation method thereof. The chemical formula of the dielectric ceramic material is Li2W4O13. The preparation method comprises the following steps of: (1) proportioning original powder of Li2CO3 and WO3 with purity over 99.9% according to the composition of Li2W4O13; (2) mixing the raw material in step (1) by a wet ball mill for 12 hours by taking distilled water as a solvent, and drying and pre-sintering for 6 hours in atmosphere at 500 DEG C; and (3) adding an adhesive to the prepared powder obtained in step (2) and prilling, then pressing and forming, and finally, sintering for 4 hours in atmosphere at 540-560 DEG C, wherein the adhesive is a polyvinyl alcohol liquor with mass concentration of 5%, and accounts for 3% of the total weight of the powder. Ceramic prepared by the invention is well sintered at 540-560 DEG C, and the dielectric constant reaches 11-12, and the quality factor Qf value reaches 71000-75000GHz. The ceramic is less in temperature coefficient of resonance frequency and has an extremely large application value in industry.

Description

But low-temperature sintered microwave dielectric ceramic Li 2W 4O 13And preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to the microwave devices such as the dielectric resonator that uses in microwave frequency, wave filter, and the dielectric ceramic material of ceramic condenser or thermo-compensation capacitor and preparation method thereof.

Background technology

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

Be applied to the dielectric ceramic of microwave frequency band, should satisfy the requirement of following dielectric characteristics: (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 are to reduce noise, general requirement Qf 〉=3000GHz; (3) the temperature factor τ of resonant frequency _fAs far as possible little of guaranteeing that device has good thermostability, general requirement-10/ ℃≤τ _f≤+10ppm/ ℃.Just someone attempts dielectric substance is applied to microwave technology from late 1930s in the world.

According to relative permittivity ε _rSize from use the different of frequency range, usually the microwave-medium ceramics that is developed He 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 _f≤ 5ppm/ ℃.Be mainly used in microwave base plate and high-end microwave device.

(2) low ε _rWith the microwave dielectric ceramic of high Q value, be mainly BaO-MgO-Ta ₂O ₅, BaO-ZnO-Ta ₂O ₅Or BaO-MgO-Nb ₂O ₅, BaO-ZnO-Nb ₂O ₅System or the composite system MWDC material between them.Its ε _r=25～30, Q=(1～2) * 10 ⁴(under f 〉=10GHz), τ _f≈ 0.Be mainly used in the microwave communication equipments such as direct broadcasting satellite of f 〉=8GHz as the dielectric resonance device.

(3) medium ε _rWith the microwave dielectric ceramic of Q value, be mainly with BaTi ₄O ₉, Ba ₂Ti ₉O ₂₀(Zr, Sn) TiO ₄Deng the MWDC material that is base, its ε _r=35～40, Q=(6～9) * 10 ³(f=3～-4GHz under), τ _f≤ 5ppm/ ℃.Be mainly used in the interior microwave military radar of 4～8GHz range of frequency and communication system as the dielectric resonance device.

(4) high ε _rAnd the lower microwave dielectric ceramic of Q value is mainly used in civilian mobile communcations system in 0.8～4GHz range of frequency, and this is also the emphasis of microwave dielectric ceramic research.Since the eighties, the people such as Kolar, Kato find and have studied perovskite-like tungsten bronze type BaO-Ln in succession ₂O ₃-TiO ₂Series (Nd, Pr etc. are called for short BLT system for Ln=La, Sm), 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 ₃Specific inductivity reaches 105.

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

In exploration and development of new can be hanged down the process of fired microwave dielectric ceramic materials, the material systems such as the Li based compound that intrinsic sintering temperature is low, Bi based compound, tungstate architecture compound and tellurate architecture compound have obtained extensive concern and research, wherein a large amount of exploratory developments concentrates on Li base binary or ternary compound, and has developed as Li ₂TiO ₃, Li ₃NbO ₄, Li ₂MoO ₄And Li ₂MTi ₃O ₈Serial well behaved microwave-medium ceramics such as (M=Mg, Zn) etc., still, still more limited for the system that is used for low fever's microwave-medium ceramics, this has limited the development of low temperature co-fired technology and microwave multilayer device to a great extent.

Consider that present document is not also about lithium-containing compound Li ₂W ₄O ₁₃The research report of pottery preparation and microwave dielectric property, we are to Li ₂W ₄O ₁₃Pottery has carried out sintering characteristic and Study on microwave dielectric property, found that this pottery has excellent comprehensive microwave dielectric property while sintering temperature lower than 580 ℃, the manufacturing that various medium substrates, resonance play the microwave devices such as device and wave filter can be widely used in, the Technology Need of low temperature co-fired technology and microwave multilayer device can be satisfied.

Summary of the invention

The purpose of this invention is to provide a kind of have low-loss and good thermostability, have simultaneously dielectric ceramic material of high-frequency dielectric constant and preparation method thereof.

Dielectric ceramic material of the present invention consist of Li ₂W ₄O ₁₃

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

(1) with purity be Li more than 99.9% ₂CO ₃And WO ₃Starting powder press Li ₂W ₄O ₁₃Composition batching.

(2) step (1) raw material wet ball-milling was mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 500 ℃ of air atmosphere after oven dry.

(3) add binding agent and granulation in the powder that step (2) makes after, then compression moulding, sintering 4 hours in 540～560 ℃ of air atmosphere at last; Described binding agent employing mass concentration is 5% polyvinyl alcohol solution, and dosage accounts for 3% of powder total amount.

The pottery of the present invention preparation is good at 540-560 ℃ of sintering, and its specific inductivity reaches 11～12, and quality factor q f value is up to 71000-75000GHz, and temperature coefficient of resonance frequency is little, industrial great using value is arranged.

Embodiment

Embodiment:

Table 1 shows 3 specific embodiments and the microwave dielectric property thereof that consists of different sintering temperatures of the present invention.Its preparation method carries out the evaluation of microwave dielectric property as mentioned above with the cylindrical dielectric resonator method.

This pottery can be widely used in the manufacturing that various medium substrates, resonance play the microwave devices such as device, wave filter, can satisfy the Technology Need of the systems such as mobile communication, satellite communications.

The present invention never is limited to above embodiment, have with the element of W analog structure and chemical property such as Mo and Cr etc. also can make with analogous crystalline structure of the present invention and performance dielectric ceramic.

Table 1:

Claims

1. but the application of a composite oxides conduct low-temperature sintered microwave dielectric ceramic, is characterized in that consisting of of described composite oxides: Li ₂W ₄O ₁₃

Preparation method's step of described composite oxides is:

(1) with purity be Li more than 99.9% ₂CO ₃And WO ₃Starting powder press Li ₂W ₄O ₁₃Composition batching;

(2) step (1) raw material wet ball-milling was mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 500 ℃ of air atmosphere after oven dry;

(3) add binding agent and granulation in the powder that step (2) makes after, then compression moulding, sintering 4 hours in 540 ~ 560 ℃ of air atmosphere at last; Described binding agent employing mass concentration is 5% polyvinyl alcohol solution, and dosage accounts for 3% of powder total amount.