CN104058747B - Can low-temperature sintered microwave dielectric ceramic LiMgV 3o 9and preparation method thereof - Google Patents

Abstract

The invention discloses one can low-temperature sintered microwave dielectric ceramic LiMgV ₃o ₉and preparation method thereof.(1) be the Li of more than 99.9% by purity ₂cO ₃, MgO and V ₂o ₅starting powder press LiMgV ₃o ₉composition 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, then compression moulding, finally in 700 ~ 730 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for 3% of powder total mass.Pottery prepared by the present invention is good at 700-730 DEG C of sintering, and its specific inductivity reaches 17.6 ~ 18.3, and quality factor q f value is up to 71000-93000GHz, and temperature coefficient of resonance frequency is little, industrially has great using value.

Description

Can low-temperature sintered microwave dielectric ceramic LiMgV 3o 9and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to the microwave devices such as the medium substrate used in microwave frequency, and the dielectric ceramic material of ceramic condenser or thermo-compensation capacitor 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, 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-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 _?≤ 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.

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, tungstate architecture compound and tellurate architecture compound get the attention and research, wherein a large amount of exploratory developments concentrates on Li base binary or ternary compound, and have developed as Li ₂tiO ₃, Li ₂moO ₄and Li ₂mTi ₃o ₈serial microwave-medium ceramics of good performance etc. such as (M=Mg or Zn), but can the microwave-medium ceramics system of low fever still more limited, and the τ of the low single-phase microwave dielectric ceramic of intrinsic sintering temperature _?usually comparatively large, the requirement of device thermostability can not be met, which greatly limits the development of low temperature co-fired technology and microwave multilayer device.

We find single-phase LiMgV ₃o ₉pottery have excellent comprehensive microwave dielectric property simultaneously sintering temperature lower than 730 °c, can be widely used in the manufacture of the microwave devices such as various resonator, medium substrate, can meet the technology needs 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 of there is low-loss and good thermostability, simultaneously low temperature sintering microwave dielectric ceramic material and preparation method thereof.

The chemical constitution of microwave dielectric ceramic material of the present invention is LiMgV ₃o ₉.

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

(1) be the Li of more than 99.9% by purity ₂cO ₃, MgO and V ₂o ₅starting powder press LiMgV ₃o ₉composition 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, then compression moulding, finally in 700 ~ 730 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for 3% of powder total mass.

LiMgV of the present invention ₃o ₉pottery is single-phase, and sintering temperature is low, and 700 ~ 730 DEG C of sintering are good; Its dielectric properties are excellent, and especially temperature coefficient of resonance frequency nearly zero, can meet the thermal stability requirement of device; Quality factor q f value, up to 71000-93000GHz, 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.

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 communications.

Table 1:

Claims (1)

1. a low temperature sintering microwave dielectric ceramic, is characterized in that the chemical constitution of described microwave dielectric ceramic is: LiMgV ₃o ₉;

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

(1) be the Li of more than 99.9% by purity ₂cO ₃, MgO and V ₂o ₅starting powder press LiMgV ₃o ₉composition 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, then compression moulding, finally in 700 ~ 730 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for 3% of powder total mass.