CN103539444B - Low-temperature sintered microwave dielectric ceramic Ca 2bi 2o 5and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of low-temperature sintered microwave dielectric ceramic and preparation method thereof.Low-temperature sintered microwave dielectric ceramic consist of Ca ₂bi ₂o ₅.(1) be the CaCO of more than 99.9% by purity ₃and Bi ₂o ₃starting powder press Ca ₂bi ₂o ₅chemical formula weigh batching.(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 750 DEG C of air atmosphere after oven dry.(3) in the powder that step (2) is obtained, binding agent is added and after granulation, then compression moulding, finally in 820 ~ 850 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and dosage accounts for 3% of powder total mass.Pottery prepared by the present invention is good at 820 ~ 850 DEG C of sintering, and its specific inductivity reaches 19 ~ 20, and quality factor q f value is up to 62000-89000GHz, and temperature coefficient of resonance frequency is little, industrially has great using value.

Description

Low-temperature sintered microwave dielectric ceramic Ca 2bi 2o 5and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to microwave dielectric ceramic material of the microwave devices such as medium substrate, resonator and the wave filter used in microwave frequency and preparation method thereof.

Background technology

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

Be applied to the dielectric ceramic of microwave frequency band, the requirement of following dielectric characteristics 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 requirement Qf>=3000GHz; (3) the temperature factor τ of resonant frequency _?little of as far as possible to ensure the thermostability that device has had, general requirement-10/ DEG C≤τ _?≤+10ppm/ DEG C.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, usually the microwave dielectric ceramic 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 _?≤ 10ppm/ ° of 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 composite system MWDC material between them.Its ε _r=25 ~ 30, Q=(1 ~ 2) × 10 ⁴(under f>=10GHz), τ _?≈ 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=35 ~ 40, Q=(6 ~ 9) × 10 ³(under f=3 ~-4GHz), τ _?≤ 5ppm/ ° of C.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 microwave dielectric ceramic that Q value is lower, be 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 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 ₃specific inductivity reaches 105.

The sintering temperature of these material systems is generally higher than 1300 ° of C above, can not directly and the low melting point metal such as Ag and Cu burn formation laminated ceramic capacitor altogether.In recent years, along with LTCC Technology (LowTemperatureCo-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 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, current low temperature sintering high performance microwave media ceramic system is still very limited, which greatly limits the development of low temperature co-fired technology and microwave multilayer device.

Summary of the invention

The object of this invention is to provide and a kind ofly have low-loss and good temperature stability, high-frequency dielectric constant reaches 19 ~ 20, Qf value up to 62000-89000GHz simultaneously, microwave dielectric ceramic that can sinter at 820-850 DEG C and preparation method thereof.

The chemical constitution formula of microwave dielectric ceramic of the present invention is: Ca ₂bi ₂o ₅.

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

(1) be the CaCO of more than 99.9% by purity ₃and Bi ₂o ₃starting powder press Ca ₂bi ₂o ₅chemical formula weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 750 DEG C of air atmosphere after oven dry.

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, then compression moulding, finally in 820 ~ 850 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and dosage accounts for 3% of powder total mass.

Pottery prepared by the present invention is good at 720-750 DEG C of sintering, and its specific inductivity reaches 19 ~ 20, and quality factor q f value is up to 62000 ~ 89000GHz, and temperature coefficient of resonance frequency is little, therefore industrially has 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.

The present invention is never limited to above embodiment.Bound, the interval value of sintering temperature can realize the present invention, do not enumerate embodiment at this.

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

Table 1:

Claims (1)

1. composite oxides are as an application for low-temperature sintered microwave dielectric ceramic, it is characterized in that the chemical constitution formula of described composite oxides is Ca ₂bi ₂o ₅:

Preparation method's concrete steps of described composite oxides are:

(1) be the CaCO of more than 99.9% by purity ₃and Bi ₂o ₃starting powder press Ca ₂bi ₂o ₅chemical formula weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 750 DEG C of air atmosphere after oven dry;

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, then compression moulding, finally in 820 ~ 850 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and dosage accounts for 3% of powder total mass.