CN103145418B

CN103145418B - Tungstate microwave dielectric ceramic Li4W5O17 capable of being sintered at low temperature and preparation method thereof

Info

Publication number: CN103145418B
Application number: CN201310107853.0A
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: 2013-04-01
Filing date: 2013-04-01
Publication date: 2014-05-14
Anticipated expiration: 2033-04-01
Also published as: CN103145418A

Abstract

The invention discloses tungstate microwave dielectric ceramic Li4W5O17 capable of being sintered at low temperature and a preparation method thereof. The tungstate dielectric ceramic material consists of Li4W5O17. The preparation method comprises the following steps of: (1) weighing and dosing the raw powder of Li2CO3 and WO3 with purity of over 99.9% according to the composition of Li4W5O17; (2) performing wet-type ball milling mixing of the raw materials in step (1) for 12 hours, wherein the solvent is distilled water; and drying, and presintering for 6 hours in atmosphere at 450 DEG C; and (3) adding a binder into the powder prepared in step (2) and granulating, performing compression molding, and finally sintering for 4 hours in atmosphere at 500-520 DEG C, wherein the binder is a polyvinyl alcohol solution with mass concentration of 5%, and the dose accounts for 3% of the total amount of the powder. According to the invention, the prepared ceramic is sintered well at 500-520 DEG C, the dielectric constant reaches 12-13, the quality factor Qf is as high as 65,000-73,000GHz, the temperature coefficient of resonance frequency is small, and the ceramic has great value in industrial application.

Description

Can low-temperature sintering tungstate microwave dielectric ceramic Li 4w 5o 17and preparation method thereof

Technical field

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

Background technology

Microwave dielectric ceramic refers to that being applied to microwave frequency band (is mainly UHF, SHF frequency range) in circuit as dielectric material and complete the pottery of one or more functions, in modern communication, be widely used as resonator, 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, telestar susceptor, there is very important application the aspects such as military radar, in the miniaturization of modern communication instrument, in integrated process, just bringing into play increasing effect.

Be applied to the dielectric ceramic of microwave frequency band, should meet 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, and one requires Qf>=3000GHz; (3) the temperature factor τ of resonant frequency _fthe as far as possible little thermostability to guarantee that device has had, one requires-10/ ℃≤τ _f≤+10ppm/ ℃.From late 1930s, just someone attempts dielectric substance to be applied to microwave technology in the world.

According to relative permittivity ε _rsize from use frequency range different, conventionally the microwave-medium ceramics being 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 _f≤ 10ppm/ ℃.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 the direct broadcasting satellite of f >=8GHz as 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(under f=3～-4GHz), τ _f≤ 5ppm/ ℃.Be mainly used in microwave military radar in 4～8GHz range of frequency and communication system as 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, 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 (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 ₃specific inductivity reaches 105.

Above the sintering temperature of these material systems one higher than 1300 ℃, can not be directly and the low melting point metal such as Ag and Cu burn altogether formation laminated ceramic capacitor.In recent years, along with LTCC Technology (Low Temperature Co-fired Ceramics, 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 developing without the low fired microwave dielectric ceramic material of glassy phase is the emphasis of current research.

Explore with development of new can the process of low fired microwave dielectric ceramic materials in, the material systems such as Li based compound, Bi based compound, tungstate architecture compound and tellurate architecture compound that intrinsic sintering temperature is low get the attention and study, 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 or Zn) etc., still, still more limited for the system 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 current document is also about containing lithium tungstate Li ₄w ₅o ₁₇preparation and the research report of microwave dielectric property, we are to Li ₄w ₅o ₁₇pottery 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 550 ℃, the manufacture of the microwave devices such as various medium substrates, resonator and wave filter can be widely used in, the Technology Need of low temperature co-fired technology and microwave multilayer device can be met.

Summary of the invention

The object of this invention is to provide a kind of have low-loss and good thermostability, simultaneously low temperature sintering tungstate microwave dielectric ceramic material and preparation method thereof.

Tungstate microwave dielectric ceramic material of the present invention consist of Li ₄w ₅o ₁₇.

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

(1) be more than 99.9% Li by purity ₂cO ₃and WO ₃starting powder press Li ₄w ₅o ₁₇composition weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 450 ℃ of air atmosphere after oven dry.

(3) in the powder making in step (2), add after binding agent granulation, then compression moulding, finally sintering 4 hours in 500～520 ℃ of air atmosphere; Described binding agent adopts the polyvinyl alcohol solution that mass concentration is 5%, and dosage accounts for 3% of powder total amount.

Pottery prepared by the present invention is good at 500-520 ℃ of sintering, and its specific inductivity reaches 12～13, and quality factor q f value is up to 65000-73000GHz, and temperature coefficient of resonance frequency is little, has a great using value industrial.

Embodiment

Embodiment:

Table 1 shows 3 specific embodiments and the microwave dielectric property thereof that form different sintering temperatures of the present invention.Its preparation method is described above, carries out the evaluation of microwave dielectric property by cylindrical dielectric resonator method.

This pottery can be widely used in the manufacture of the microwave devices such as various medium substrates, resonator, wave filter, can meet the Technology Need of the system such as mobile communication, satellite communications.

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

Table 1:

Claims

1. tungstate, as a application that can low-temperature sintered microwave dielectric ceramic, is characterized in that consisting of of described tungstate: Li ₄w ₅o ₁₇;

Preparation method's step of described tungstate is:

(1) be more than 99.9% Li by purity ₂cO ₃and WO ₃starting powder press Li ₄w ₅o ₁₇composition weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 450 ℃ of air atmosphere after oven dry;

(3) in the powder making in step (2), add after binding agent granulation, then compression moulding, finally sintering 4 hours in 500 ~ 520 ℃ of air atmosphere; Described binding agent adopts the polyvinyl alcohol solution that mass concentration is 5%, and dosage accounts for 3% of powder total amount.