CN103449814B - Low-temperature-sintering available microwave dielectric ceramic Sr2WCuO6 - Google Patents

Abstract

The invention discloses a low-temperature-sintering available microwave dielectric ceramic Sr2WCuO6 and a preparation method thereof. The chemical composition of the low-temperature-sintering available microwave dielectric ceramic is Sr2WCuO6. The preparation method comprises the following steps: (1) weighing and dosing original powder of SrCO3, CuO and WO3 with purity higher than 99.9% according to the chemical formula of SrWCuO63; (2) wet ball milling and mixing the raw materials of step (1) for 12 h, wherein the solvent is distilled water, drying the raw materials and pre-sintering the raw materials in 600 DEG C atmosphere for 6 h; (3) adding an additive into the powder prepared in the step (2), granulating, and then, press forming the powder, and finally, sintering the powder in 800-830 DEG C atmosphere for 4 h, wherein; the adhesive is a polyvinyl alcohol solution with mass concentration of 5%, and the adhesive accounts for 3% of the total mass of the powder. The ceramic prepared in the invention is well sintered at 800-830 DEG C, the dielectric constant of the ceramic reaches 16-17, the quality factor Qf value is up to 74000-87000 GHz, and the temperature coefficient of resonant frequency is small, so that the ceramic has a large application value in industry.

Description

Low temperature sintering microwave dielectric ceramic Sr 2wCuO 6

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>=3000 GHz; (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 _?≤+10 ppm/ 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-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 _?≤ 10 ppm/ ° 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 the GHz of f>=10), τ _?≈ 0.Be mainly used in the microwave communication equipments such as the direct broadcasting satellite of f >=8 GHz 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 _?≤ 5 ppm/ ° C.Be mainly used in microwave military radar in 4 ~ 8 GHz 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 (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 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.

Summary of the invention

The object of this invention is to provide and a kind of there is low-loss and good thermostability, the microwave dielectric ceramic material that sintering temperature is low simultaneously.

The chemical constitution formula of microwave dielectric ceramic material of the present invention is: Sr ₂wCuO ₆.

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

(1) be the SrCO of more than 99.9% by purity ₃, CuO and WO ₃starting powder press Sr ₂wCuO ₆chemical formula weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 600 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 800 ~ 830 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 800-830 DEG C of sintering, and its specific inductivity reaches 16 ~ 17, and quality factor q f value is up to 74000-87000GHz, and temperature coefficient of resonance frequency is little, therefore industrially has great using value.

Embodiment

Embodiment:

Table 1 shows 4 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; By Sr ₂wCuO ₆powder mixes with the Ag powder accounting for powder quality 20%, after compression moulding, at 830 DEG C, sinter 4 hours; X ray diffraction material phase analysis and scanning electron microscopic observation all show Sr ₂wCuO ₆chemical reaction is not there is not, i.e. Sr with Ag ₂wCuO ₆can be low temperature co-fired with Ag electrode.

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 can the application of low-temperature sintered microwave dielectric ceramic, it is characterized in that consisting of of described composite oxides: Sr ₂wCuO ₆;

Preparation method's step of described composite oxides is:

(1) be the SrCO of more than 99.9% by purity ₃, CuO and WO ₃starting powder press Sr ₂wCuO ₆chemical formula weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 600 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 800 ~ 830 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.