CN103922721B - Low-temperature sintering available microwave dielectric ceramic Li4P2O7 and preparation method thereof - Google Patents

Abstract

The invention discloses an application of a phosphor-containing compound Li4P2O7 serving as a low-temperature sintering available microwave dielectric ceramic. The microwave dielectric ceramic is prepared by the following steps: (1) preparing original powders of 99.9% Li2CO3 and 99.9% NH4H2PO4 according to the chemical formula of Li4P2O7; (2) mixing the raw material in the step (1) and carrying out wet ball milling for 12 hours, baking, and then pre-sintering for 6 hours in the atmosphere at 820 DEG C, wherein the ball milling medium is ethanol; and (3) adding adhesive into the powder prepared in the step (2), granulating, pressing to mold, and finally sintering for 4 hours in the atmosphere at 880-900 DEG C, wherein the adhesive is a 5% polyvinyl alcohol solution, and accounts for 3 percent of the total mass of the powder. The ceramic prepared by the method can be excellently sintered at 880-900 DEGC, the dielectric constant is 13-14, the quality factor Qf value is up to 67,000-79,000GHz; the temperature coefficient of resonance frequency is small, and the microwave dielectric ceramic has a great application value in industry.

Description

Can low-temperature sintered microwave dielectric ceramic Li 4p 2o 7and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to the microwave devices such as medium substrate, resonator and the wave filter 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, resonator is widely used as in modern communication, wave 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 telestar susceptor 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 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 are to reduce noise, and one requires Qf>=3000GHz; (3) the temperature factor τ of resonant frequency _flittle of as far as possible to ensure the thermostability that device has had, one requires-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 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 ￡ _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 ￡ _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 ￡ _r=25 ~ 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 ￡ _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 ￡ _r=35 ~ 40, Q=(6 ~ 9) × 10 ³(under f=3 ~-4GHz), τ _f≤ 5ppm/ DEG 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 ￡ _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.

Above these material systems sintering temperature one higher than 1300 DEG C, 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.

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 ultralow dielectric microwave-medium ceramics system of low fever still more limited, the material that temperature stability is good is less, 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 one and there is ultralow dielectric, Heat stability is good and low-loss low temperature sintering microwave dielectric ceramic material and preparation method thereof simultaneously.

The chemical constitution of microwave dielectric ceramic material of the present invention is Li ₄p ₂o ₇.

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

(1) be the Li of more than 99.9% by purity ₂cO ₃and NH ₄h ₂pO ₄starting powder press Li ₄p ₂o ₇composition weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is ethanol, pre-burning 6 hours in 820 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 880 ~ 900 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 880-900 DEG C of sintering at the pottery of preparation, the temperature factor τ of its resonant frequency _flittle, temperature stability is good; Specific inductivity reaches 13 ~ 14, quality factor q f value is up to 67000-79000GHz, the manufacture of the microwave devices such as various medium substrate, resonator and wave filter can be widely used in, the technology needs of low temperature co-fired technology and microwave multilayer device can be met, 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 substrate, resonator and wave filter, can meet the technology needs of the system such as mobile communication and satellite communications.

Table 1:

。

Claims (1)

1. P contained compound is as can the application of low-temperature sintered microwave dielectric ceramic, it is characterized in that the chemical constitution of described P contained compound is: Li ₄p ₂o ₇;

Preparation method's concrete steps of described P contained compound are:

(1) be the Li of more than 99.9% by purity ₂cO ₃and NH ₄h ₂pO ₄starting powder press Li ₄p ₂o ₇composition weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is ethanol, pre-burning 6 hours in 820 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 880 ~ 900 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.