CN104311030B - A kind of temperature-stable ultralow dielectric microwave dielectric ceramic and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of low temperature sintering temperature-stable ultralow dielectric microwave dielectric ceramic La ₂bi ₅v ₃o ₁₈and preparation method thereof.(1) be 99.9%(percentage by weight by purity) more than La ₂o ₃, Bi ₂o ₃and V ₂o ₅starting powder press La ₂bi ₅v ₃o ₁₈composition 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 650 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 700 ~ 750 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.Pottery prepared by the present invention is good at 700 ~ 750 DEG C of sintering, and dielectric constant reaches 19.4 ~ 19.8, and its quality factor q f value is up to 51000-66000GHz, and temperature coefficient of resonance frequency is little, industrially has great using value.

Description

A kind of temperature-stable ultralow dielectric microwave dielectric ceramic and preparation method thereof

Technical field

The present invention relates to microwave dielectric ceramic material, particularly relate to dielectric ceramic material of the microwave devices such as medium substrate, ceramic resonator and the filter used for the manufacture of microwave frequency 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, resonator is widely used as in modern communication, filter, the components and parts such as dielectric substrate and medium wave circuit, it is the key foundation material of modern communication technology, at portable mobile phone, automobile telephone, cordless telephone, there is very important application the aspects such as telstar recipient and military radar, in the miniaturization of modern communication instrument, increasing effect is just being played in integrated process.

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 _flittle of as far as possible to ensure the thermal stability that device has had, General Requirements-10/ DEG C≤τ _f≤+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 _f≤ 10ppm/ DEG 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=20 ~ 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, mainly with BaTi ₄o ₉, Ba ₂ti ₉o ₂₀(Zr, Sn) TiO ₄deng the MWDC material for base, its ε _r=30 ~ 50, Q=(6 ~ 9) × 10 ³(under f=3 ~-4GHz), τ _f≤ 5ppm/ DEG 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 DEG 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 due to three performance index (ε of microwave dielectric ceramic _rwith Qf and τ _f) between be that the relation of mutually restriction is (see document: the restricting relation between microwave dielectric ceramic materials dielectric property, Zhu Jianhua, Liang Fei, Wang little Hong, Lv Wenzhong, electronic component and material, phase March the 3rd in 2005), meet three performance requirements and the single-phase microwave-medium ceramics of low temperature sintering is considerably less, their the temperature coefficient of resonance frequency usually too large quality factor of excessive or loss is on the low side and cannot production application.Current is the summary of experience drawn by great many of experiments to the research major part of microwave-medium ceramics, but complete theory is not had to set forth the relation of its microstructure and dielectric property, therefore, in theory also cannot predict whether it has the number range of microwave dielectric property and the performance parameter such as temperature coefficient of resonance frequency and quality factor from the composition of compound and structure, which greatly limits the development of low temperature co-fired technology and microwave multilayer device.Therefore, explore and develop low-temperature sintering can have near-zero resonance frequency temperature coefficient (τ simultaneously _f≤ 10ppm/ DEG C) be that those skilled in the art thirst for solving always but are difficult to the difficult problem that succeeds all the time with the microwave dielectric ceramic of higher figure of merit (Qf>=50000GHz).We are to consisting of La ₂bi ₅v ₃o ₁₈, Nd ₂bi ₅v ₃o ₁₈, Sm ₂bi ₅v ₃o ₁₈, Pr ₂bi ₅v ₃o ₁₈vanadate carried out the research of microwave dielectric property, wherein find that their sintering temperature is lower than 900 DEG C, but only have La ₂bi ₅v ₃o ₁₈there is near-zero resonance frequency temperature coefficient and high quality factor, the temperature coefficient of resonance frequency (>30ppm/ DEG C) all bigger than normal of other composition pottery

Summary of the invention

The object of this invention is to provide and a kind of there is low-loss and good thermal stability, simultaneously low temperature sintering ultralow dielectric microwave dielectric ceramic material and preparation method thereof.

The chemical composition of microwave dielectric ceramic material of the present invention is La ₂bi ₅v ₃o ₁₈.

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

(1) by purity be the La of more than 99.9% (percentage by weight) ₂o ₃, Bi ₂o ₃and V ₂o ₅starting powder press La ₂bi ₅v ₃o ₁₈composition 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 650 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 700-750 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.

Pottery prepared by the present invention is good at 700 ~ 750 DEG C of sintering, and dielectric constant reaches 19.1 ~ 19.8, the temperature coefficient τ of its resonance frequency _flittle, temperature stability is good; Its quality factor q f value, up to 51000-66000GHz, 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 low temperature co-fired technology and microwave multilayer device, 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.

This pottery can be widely used in the manufacture of the microwave devices such as various medium substrates, can meet the technology needs of the system such as mobile communication and satellite communication.

Table 1:

Claims (2)

1. a temperature-stable ultralow dielectric microwave dielectric ceramic, is characterized in that, the chemical composition of described microwave dielectric ceramic is: La ₂bi ₅v ₃o ₁₈, the dielectric constant of this temperature-stable ultralow dielectric microwave dielectric ceramic is 19.1 ~ 19.8.

2. the preparation method of temperature-stable ultralow dielectric microwave dielectric ceramic according to claim 1, it is characterized in that, concrete steps are:

(1) by purity be the La of more than 99.9% percentage by weight ₂o ₃, Bi ₂o ₃and V ₂o ₅starting powder press La ₂bi ₅v ₃o ₁₈composition 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 650 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 700-750 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.