CN105601256A

CN105601256A - Microwave dielectric ceramic BaLi2Ge7O16 capable of being sintered at low temperature and preparation method thereof

Info

Publication number: CN105601256A
Application number: CN201610010865.5A
Authority: CN
Inventors: 李纯纯; 方维双; 苏和平
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2016-01-09
Filing date: 2016-01-09
Publication date: 2016-05-25

Abstract

The invention discloses high-quality-factor, stable-temperature and ultra-low-dielectric-constant microwave dielectric ceramic BaLi2Ge7O16 capable of being sintered at low temperature and a preparation method thereof. Firstly, original powder of CaCO3, Li2CO3 and GeO2 with purity being 99.9% (by weight percentage) is weighed and matched according to composition of BaLi2Ge7O16; secondly, the raw materials in the first step are mixed for 12 h in a raw material wet ball mill, ball milling media are distilled water, and pre-sintering is performed for 6 h in 750 DEG C atmosphere after drying; thirdly, after an adhesion agent is added in the powder prepared in the second step and pelleting is performed, pressing and forming are performed, and finally, sintering is performed for 4 h in 800-850 DEG C atmosphere; a polyvinyl alcohol solution with the mass concentration being 5% is adopted as the adhesion agent, and the adding amount of polyvinyl alcohol accounts for 3% of the total mass of the powder. The prepared ceramic can be well sintered at 850 DEG C, the dielectric constant reaches 16.1-16.9, the quality factor Qf of the ceramic reaches as high as 74000-121000 GHz, the resonant frequency temperature coefficient is small, and the ceramic has great application value industrially.

Description

Low temperature sintering microwave dielectric ceramic BaLi2Ge7O16And preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to the ceramic substrate, the resonance that use for the manufacture of microwave frequencyDielectric ceramic material of the microwave device such as device and wave filter and preparation method thereof.

Background technology

Microwave dielectric ceramic refers to and is applied in microwave frequency band (being mainly UHF and SHF frequency range) circuit as dielectric materialAnd complete the pottery of one or more functions, in modern communication, be widely used as resonator, wave filter, dielectric substrate and mediumThe components and parts such as guided wave loop are the key foundation materials of modern communication technology, in portable mobile phone, automobile telephone, nothingThere is very important application aspect such as rope phone, telstar recipient and military radar etc., small-sized at modern communication instrumentIn change, 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 property: (1) seriation DIELECTRIC CONSTANTS_rTo adapt to the requirement of different frequency and different application occasion; (2) high quality factor q value or low dielectric loss tan δ are to reduceNoise, General Requirements Qf >=3000GHz; (3) the temperature coefficient τ of resonant frequency_?As far as possible little of to ensure what device had hadHeat endurance, General Requirements-10ppm/ DEG C≤τ_?≤+10ppm/ DEG C. From late 1930s, just someone attempts in the worldDielectric substance is applied to microwave technology, and prepares TiO₂Microwave dielectric filter, but its temperature coefficient of resonance frequency τ_?Too large and cannot be practical. Since the seventies in last century, start the large-scale development to medium ceramic material, rootAccording to relative dielectric constant ε_rSize from use frequency range different, conventionally can be by the microwave-medium pottery being developed and developingPorcelain is divided into 4 classes.

(1) ultralow dielectric microwave dielectric ceramic, main representative is Al₂O₃-TiO₂、Y₂BaCuO₅、MgAl₂O₄WithMg₂SiO₄Deng, its ε_r≤ 20, quality factor q × f >=50000GHz, τ_?≤ 10ppm/ ° of C. Be mainly used in microwave base plate and heightEnd microwave device.

(2) low ε_rWith the microwave dielectric ceramic of high Q value, be mainly BaO-MgO-Ta₂O₅,BaO-ZnO-Ta₂O₅Or BaO-MgO-Nb₂O₅,BaO-ZnO-Nb₂O₅System or the hybrid system MWDC material between them. Its ε_r=20～35,Q=(1～2)×10⁴(under f >=10GHz), τ_?≈ 0. Be mainly used in the microwave communication equipments such as the direct broadcasting satellite of f >=8GHz as mediumResonating device.

(3) medium ε_rWith the microwave dielectric ceramic of Q value, be mainly with BaTi₄O₉、Ba₂Ti₉O₂₀(Zr, Sn) TiO₄Deng beingThe MWDC material of base, its ε_r＝35~45，Q=（6～9）×10³(under f=3～-4GHz), τ_?≤ 5ppm/ ° of C. Be mainly used in 4In microwave military radar in～8GHz frequency range and communication system as dielectric resonance device.

(4) high ε_rAnd the lower microwave dielectric ceramic of Q value is mainly used in civilian movement in 0.8～4GHz frequency range and leads toNews system, this is also the emphasis of microwave dielectric ceramic research. Since the eighties, the people such as Kolar, Kato in succession find and have studiedPerovskite-like tungsten bronze type BaO-Ln₂O₃—TiO₂Series (Ln=La, Sm, Nd or Pr etc. are called for short BLT system), composite perofskiteStructure C aO-Li₂O—Ln₂O₃—TiO₂Series, lead base series material, Ca_1-xLn_2x/3TiO₃Be contour ε_rMicrowave dielectric ceramic,Wherein BaO-the Nd of BLT system₂O₃—TiO₂Material dielectric constant reaches 90, lead base series (Pb, Ca) ZrO₃Dielectric constant reachesTo 105.

The sintering temperature of these material systems is generally higher than 1300 ° of C above, can not be directly and the low melting point gold such as Ag and CuBelong to burning altogether and form multilayer ceramic capacitor. In recent years, along with LTCC Technology (LowTemperatureCo-firedCeramics, LTCC) development and the requirement of microwave multilayer device development, researcher both domestic and external is to some low fever's systemsMaterial has carried out exploring widely and studying, and is mainly to adopt devitrified glass or glass-ceramic composite system, because of low melting pointGlassy phase has relatively high dielectric loss, and the existence of glassy phase has improved the dielectric loss of material greatly. Therefore develop nothingThe 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 Li base that intrinsic sintering temperature is lowThe material systems such as compound, Bi based compound, tungstates architecture compound and tellurate architecture compound get the attention withResearch, but due to three performance indications (ε of microwave dielectric ceramic_rWith Qf and τ_?) between be that the relation of mutually restriction (is shown inDocument: the restricting relation between microwave dielectric ceramic materials dielectric properties, Zhu Jianhua, Liang Fei, Wang little Hong, Lv Wenzhong, electronics unitPart and material, the 3rd phase of March in 2005), meet three performance requirements and the single-phase microwave-medium ceramics of low temperature sintering veryFew, be mainly that their temperature coefficient of resonance frequency is conventionally excessive or quality factor are on the low side and cannot application request. OrderFront is the summary of experience drawing by great many of experiments to the research major part of microwave-medium ceramics, does not but have complete theorySet forth the relation of microstructure and dielectric properties, therefore, in theory also cannot predict it from the composition of compound and structureThe microwave dielectric property such as temperature coefficient of resonance frequency and quality factor, this has limited low temperature co-fired technology and micro-to a great extentThe development of ripple multilayer device. Explore with exploitation and can low-temperature sintering there is near-zero resonance frequency temperature coefficient (10ppm/ simultaneously℃≤τ_?≤+10ppm/ DEG C) with the microwave dielectric ceramic of higher figure of merit be those skilled in the art thirst for solving always butAll the time be difficult to the difficult problem succeeding.

Summary of the invention

The object of this invention is to provide a kind of have good heat endurance and low-loss, low temperature sintering is ultralow simultaneouslyDielectric constant microwave dielectric ceramic material and preparation method thereof.

The chemical composition of microwave dielectric ceramic material of the present invention is BaLi₂Ge₇O₁₆。

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

(1) be 99.9%(percentage by weight by purity) above BaCO₃、Li₂CO₃And GeO₂Starting powder press BaLi₂Ge₇O₁₆Composition weigh batching.

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after oven dry at 750 DEG C of atmospherePre-burning 6 hours in atmosphere.

(3) in the powder making in step (2), add after binding agent granulation, more compressing, finally at 800 ~ 850 DEG CSintering 4 hours in air atmosphere; Described binding agent adopts the poly-vinyl alcohol solution that mass concentration is 5%, polyvinyl alcohol additionAccount for 3% of powder gross mass.

Advantage of the present invention: BaLi₂Ge₇O₁₆Ceramic sintering temperature is low, and cost of material is low; Its quality factor q f value up to74000-121000GHz, dielectric constant reaches 16.1～16.9, the temperature coefficient τ of its resonant frequency_?Little, temperature stabilityGood; Can be widely used in the manufacture of the microwave devices such as various medium substrates, resonator and wave filter, can meet low temperature co-fired technology andThe Technology Need of microwave multilayer device.

Detailed description of the invention

Embodiment:

Table 1 shows 3 specific embodiments and the microwave dielectric property thereof that form different sintering temperatures of the present invention. Its preparation sideMethod 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 and wave filter, can meet and moveThe Technology Need of the systems such as moving communication and satellite communication.

Table 1:

Claims

1. a low temperature sintering high quality factor temperature-stable ultralow dielectric microwave dielectric ceramic, is characterized in thatThe chemical composition of described microwave dielectric ceramic is: BaLi₂Ge₇O₁₆；

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

(1) be 99.9%(percentage by weight by purity) above BaCO₃、Li₂CO₃And GeO₂Starting powder press BaLi₂Ge₇O₁₆Composition weigh batching;

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after oven dry 750 DEG C of air atmosphereMiddle pre-burning 6 hours;

(3) in the powder making in step (2), add after binding agent granulation, more compressing, finally at 800 ~ 850 DEG C of atmosphereSintering 4 hours in atmosphere; Described binding agent adopts the poly-vinyl alcohol solution that mass concentration is 5%, and polyvinyl alcohol addition accounts for powder3% of end gross mass.