CN103159477A

CN103159477A - Low-temperature sintered tungstate microwave dielectric ceramic Li2MW2O8 and preparation method thereof

Info

Publication number: CN103159477A
Application number: CN2013101126657A
Authority: CN
Inventors: 方亮; 巩美露; 唐莹
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2013-04-02
Filing date: 2013-04-02
Publication date: 2013-06-19

Abstract

The invention discloses a low-temperature sintered tungstate microwave dielectric ceramic Li2MW2O8 and a preparation method thereof. The low-temperature sintered tungstate microwave dielectric ceramic is made of a material with the component of Li2MW2O8, wherein M is selected from one of Zn, Mg and Cu. The preparation method of the low-temperature sintered tungstate microwave dielectric ceramic Li2MW2O8 comprises the following steps of: (1) weighting and proportioning initial Li2CO3, MO and WO3 powders with the purities of over 99.9% according to the chemical formula Li2MW2O8, wherein M is selected from one of Zn, Mg and Cu; (2) performing wet-type ball milling and mixing on the raw materials for 12 hours, drying the raw materials, and then, presintering the raw materials at 600-DEG C atmosphere for 6 hours, wherein distilled water is used as a solvent; and (3) adding a binder into the prepared powder, pelleting, then, carrying out compression moulding, and finally, sintering at 650-700 DEG C atmosphere for 4 hours, wherein the binder is a 5wt% polyvinyl alcohol solution and accounts for 3% of the total quantity of the powder. The ceramic prepared by the invention is good in sintering at the temperature of 650-700 DEG C, high dielectric constant up to 22-24, high quality factor (Qf) value up to 67000-86000GHz and small temperature coefficient of resonance frequency.

Description

But low-temperature sintering tungstate microwave dielectric ceramic Li 2MW 2O 8And 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 wave filter that use in microwave frequency and preparation method thereof.

Background technology

it (is mainly UHF that microwave dielectric ceramic refers to be applied to microwave frequency band, the SHF frequency range) in circuit as dielectric material and complete the pottery of one or more functions, be widely used as resonator in modern communication, wave filter, the components and parts such as dielectric substrate and medium guided wave loop, 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, miniaturization at the modern communication instrument, just bringing into play increasing effect in integrated process.

Be applied to the dielectric ceramic of microwave frequency band, should satisfy the requirement of following dielectric characteristics: (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, general requirement Qf 〉=3000GHz; (3) the temperature factor τ of resonant frequency _fAs far as possible little of guaranteeing that device has good thermostability, general requirement-10/ ℃≤τ _f≤+10ppm/ ℃.Just someone attempts dielectric substance is applied to microwave technology from late 1930s in the world.

According to relative permittivity ε _rSize from use the different of frequency range, usually the microwave-medium ceramics that is developed He 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/ ℃.Be mainly used in microwave base plate and high-end microwave device.

(2) low ε _rWith the microwave dielectric ceramic of high Q value, be 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 _f≈ 0.Be mainly used in the microwave communication equipments such as direct broadcasting satellite of f 〉=8GHz as the dielectric resonance device.

(3) medium ε _rWith the microwave dielectric ceramic of Q value, be mainly with BaTi ₄O ₉, Ba ₂Ti ₉O ₂₀(Zr, Sn) TiO ₄Deng the MWDC material that is base, its ε _r=35～40, Q=(6～9) * 10 ³(f=3～-4GHz under), τ _f≤ 5ppm/ ℃.Be mainly used in the interior microwave military radar of 4～8GHz range of frequency and communication system as the dielectric resonance device.

(4) high ε _rAnd the lower microwave dielectric ceramic of Q value is mainly used in civilian mobile communcations system in 0.8～4GHz range of frequency, and this is also the emphasis of microwave dielectric ceramic research.Since the eighties, the people such as Kolar, Kato find and have studied perovskite-like tungsten bronze type BaO-Ln in succession ₂O ₃-TiO ₂Series (Ln=La, Sm, Nd or Pr etc., abbreviation BLT is), 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 above these material systems is generally higher than 1300 ℃, can not be directly and the low melting point metals such as Ag and Cu burn altogether the formation laminated ceramic capacitor.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 to adopt devitrified glass or glass-ceramic composite system, because low melting glass has relatively high dielectric loss mutually, the existence of glassy phase has improved the dielectric loss of material greatly.Therefore development is the emphasis of current research without the low fired microwave dielectric ceramic material of glassy phase.

In exploration and development of new can be hanged down the process of fired microwave dielectric ceramic materials, 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 have obtained extensive concern and research, wherein a large amount of exploratory developments concentrates on Li base binary or ternary compound, and has developed as Li ₂TiO ₃, Li ₃NbO ₄, Li ₂MoO ₄And Li ₂MTi ₃O ₈Serial well behaved microwave-medium ceramics such as (M=Mg or Zn) etc., but but low fever's microwave-medium ceramics system is still more limited, and this has limited the development of low temperature co-fired technology and microwave multilayer device to a great extent.We are to consisting of Li ₂MW ₂O ₈The lithium tungstate ceramics that contains of (M=Zn, Mg or Cu) has carried out sintering characteristic and Study on microwave dielectric property, found that such pottery has excellent comprehensive microwave dielectric property while sintering temperature lower than 750 ℃, the manufacturing of the microwave devices such as various resonators and wave filter can be widely used in, the needs of low temperature co-fired technology and microwave multilayer device can be satisfied.

Summary of the invention

The purpose of this invention is to provide a kind of have low-loss and good thermostability, microwave dielectric ceramic material that sintering temperature is low simultaneously and preparation method thereof.

Microwave dielectric ceramic material of the present invention consist of Li ₂MW ₂O ₈, wherein M is a kind of in Zn, Mg and Cu.

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

(1) with purity be Li more than 99.9% ₂CO ₃, MO and WO ₃Starting powder press Li ₂MW ₂O ₈The chemical formula weigh batching, wherein M is a kind of in Zn, Mg and Cu.

(2) step (1) raw material wet ball-milling was mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 600 ℃ of air atmosphere after oven dry.

(3) add binding agent and granulation in the powder that step (2) makes after, then compression moulding, sintering 4 hours in 650～700 ℃ of air atmosphere at last; Described binding agent employing mass concentration is 5% polyvinyl alcohol solution, and dosage accounts for 3% of powder total amount.

The pottery of the present invention preparation is good at 650-700 ℃ of sintering, and its specific inductivity reaches 22～24, and quality factor q f value is up to 67000-86000GHz, and temperature coefficient of resonance frequency is little, industrial great using value is arranged.

Embodiment

Embodiment:

Table 1 shows and consists of different 6 specific embodiments and the microwave dielectric property thereof that forms with sintering temperature of the present invention.Its preparation method carries out the evaluation of microwave dielectric property as mentioned above with the cylindrical dielectric resonator method.

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

This pottery can be widely used in the manufacturing of the microwave devices such as various medium substrates, resonator and wave filter, can satisfy the Technology Need of the systems such as mobile communication, satellite communications.

Table 1:

Claims

1. but the application of a tungstate conduct low-temperature sintered microwave dielectric ceramic, is characterized in that the chemical constitution general formula of described tungstate is: Li ₂MW ₂O ₈, wherein M is a kind of in Zn, Mg and Cu;

Preparation method's concrete steps of described tungstate are:

(1) with purity be Li more than 99.9% ₂CO ₃, MO and WO ₃Starting powder press Li ₂MW ₂O ₈The chemical formula weigh batching, wherein M is a kind of in Zn, Mg and Cu;

(2) step (1) raw material wet ball-milling was mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 600 ℃ of air atmosphere after oven dry;

(3) add binding agent and granulation in the powder that step (2) makes after, then compression moulding, sintering 4 hours in 650 ~ 700 ℃ of air atmosphere at last; Described binding agent employing mass concentration is 5% polyvinyl alcohol solution, and dosage accounts for 3% of powder total amount.