CN104446376B

CN104446376B - Ultralow dielectric microwave dielectric ceramic Li2TiB4O9And preparation method thereof

Info

Publication number: CN104446376B
Application number: CN201410646135.5A
Authority: CN
Inventors: 郭欢欢; 唐莹; 苏和平
Original assignee: Guilin University of Technology
Current assignee: Fuyang Shenbang New Material Technology Co., Ltd
Priority date: 2014-11-15
Filing date: 2014-11-15
Publication date: 2016-05-18
Anticipated expiration: 2034-11-15
Also published as: CN104446376A

Abstract

The invention discloses a kind of low temperature sintering temperature-stable ultralow dielectric microwave dielectric ceramic Li₂TiB₄O₉And preparation method thereof. (1) be 99.9%(percentage by weight by purity) above Li₂CO₃、TiO₂And H₃BO₃Starting powder press Li₂TiB₄O₉Composition weigh batching; (2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is absolute ethyl alcohol, pre-burning 12 hours in 700 DEG C of air atmosphere after oven dry; (3) in the powder making in step (2), add after binding agent granulation, more compressing, finally sintering 10 hours in 800 ~ 840 DEG C of air atmosphere; Described binding agent adopts the poly-vinyl alcohol solution that mass concentration is 5%, and the addition of polyvinyl alcohol accounts for 3% of powder gross mass. Ceramic post sintering prepared by the present invention is good, and dielectric constant reaches 8.3～8.7, and its quality factor q f value is up to 85000-127000GHz, and temperature coefficient of resonance frequency is little, has a great using value industrial.

Description

Ultralow dielectric microwave dielectric ceramic Li2TiB4O9And 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.

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, electronic componentWith material, the 3rd phase of March in 2005), the single-phase microwave-medium ceramics that meets three performance requirements is considerably less, is mainly themTemperature coefficient of resonance frequency is conventionally excessive or quality factor are on the low side and cannot application request. At present to microwave-medium ceramicsResearch major part be the summary of experience drawing by great many of experiments, but do not have complete theory to set forth microstructure and JieThe relation of electrical property, therefore, in theory also cannot predict its temperature coefficient of resonance frequency from the composition of compound and structureWith the microwave dielectric property such as quality factor, explore and (10ppm/ DEG C≤τ of exploitation near-zero resonance frequency temperature coefficient_?≤+10Ppm/ DEG C) with the serial differing dielectric constant microwave dielectric ceramic of high quality factor be that those skilled in the art thirst for solving alwaysBut be difficult to all the time the difficult problem succeeding, this has limited the development of microwave dielectric ceramic and device to a great extent.

Summary of the invention

The object of this invention is to provide one and there is good thermal stability and low-loss ultralow dielectric micro-wave dielectricCeramic material and preparation method thereof.

The chemical composition of microwave dielectric ceramic material of the present invention is Li₂TiB₄O₉。

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

(1) be 99.9%(percentage by weight by purity) above Li₂CO₃、TiO₂And H₃BO₃Starting powder pressLi₂TiB₄O₉Composition weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is absolute ethyl alcohol, large at 700 DEG C after oven dryPre-burning 12 hours in gas atmosphere.

(3) in the powder making in step (2), add after binding agent granulation, more compressing, finally at 800 ~ 840 DEG CSintering 10 hours in air atmosphere; Described binding agent adopts the poly-vinyl alcohol solution that mass concentration is 5%, and polyvinyl alcohol addsAmount accounts for 3% of powder gross mass.

Advantage of the present invention: Li₂TiB₄O₉Ceramic sintering temperature is low, and dielectric constant reaches 8.3～8.7, its resonant frequencyTemperature coefficient τ_?Little, temperature stability is good; Quality factor q f value, up to 85000-127000GHz, can be widely used in various mediaThe manufacture of the microwave devices such as substrate, resonator and wave filter, can meet the technology need of low temperature co-fired technology and microwave multilayer deviceWant, have a great using value industrial.

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 systemPreparation 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 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 temperature-stable ultralow dielectric microwave dielectric ceramic, is characterized in that described microwave is situated betweenThe chemical composition of electroceramics is: Li₂TiB₄O₉；

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

(1) be 99.9%(percentage by weight by purity) above Li₂CO₃、TiO₂And H₃BO₃Starting powder press Li₂TiB₄O₉'sComposition weigh batching;

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is absolute ethyl alcohol, after oven dry 700 DEG C of pre-burnings 12Hour;

(3) in the powder making in step (2), add after binding agent granulation, more compressing, finally at 800 ~ 840 DEG C of atmosphereSintering 10 hours in atmosphere; Described binding agent adopts the poly-vinyl alcohol solution that mass concentration is 5%, and polyvinyl alcohol addition accounts for3% of powder gross mass.