CN104744039B - Low-loss, temperature-stabilized and ultra-low dielectric constant type microwave dielectric ceramic LiZnV5O14 - Google Patents

Abstract

The invention discloses a temperature-stabilized and ultra-low dielectric constant type microwave dielectric ceramic LiZnV5O1 capable of being sintered at low temperature and a preparation method thereof. The method comprises the following steps: (1) weighting and mixing raw powder with purity exceeding 99.9% by weight of Li2CO3, ZnO and V2O5 according to the composition of the LiZnV5O1; (2) performing ball milling and mixing for the raw materials obtained in step (1) by a wet manner for 12 hours, wherein distilled water is used as a ball mill medium; pre-sintering for 6 hours in the atmosphere at temperature of 750 DEG C after drying; and (3) adding an adhesive to the powder obtained in the step (2), granulating, pressing and forming, and then sintering for 4 hours in the atmosphere at the temperature of 800 to 850 DEG C, wherein the adhesive is a polyving akohol solution with mass concentration of 5%; the quantity of added polyving akohol is 3% of the total mass of the powder. The ceramic prepared by the method can be sintered well at the temperature not greater than 850 DEGG C; the dielectric constant is up to 15.6 to 16.2; the quality factor (QF) is up to 119000 to 161000GHz; the resonant frequency temperature coefficients are small; the ceramic has extremely large application value in the industry.

Description

Low-loss temperature-stabilized ultralow dielectric microwave dielectric ceramic LiZnV5O14

Technical field

The present invention relates to dielectric ceramic material, particularly relate to for manufacturing dielectric ceramic materials of microwave device such as the ceramic substrate of microwave frequency use, resonator and wave filter and preparation method thereof.

Background technology

Microwave dielectric ceramic refers to be applied in microwave frequency band (mainly UHF and SHF frequency range) circuit as dielectric material the pottery that completes one or more functions, the components and parts such as resonator, wave filter, dielectric substrate and medium wave circuit it are widely used as in modern communication, it it is the key foundation material of modern communication technology, have highly important application at aspects such as portable mobile phone, automobile telephone, wireless phone, television satellite accepter and military radars, modern communication instrument miniaturization, integrated during just playing increasing effect.

It is applied to the dielectric ceramic of microwave frequency band, should meet the requirement of following dielectric property: (1) seriation DIELECTRIC CONSTANT ε_rTo adapt to different frequency and the requirement of different application occasion；(2) high quality factor q value or low dielectric loss tan δ, to reduce noise, typically require Qf >=3000GHz；(3) the temperature coefficient τ of resonant frequency_fThe least to ensure the heat stability that device has had ,-10ppm/ DEG C≤τ of general requirement_f≤+10ppm/℃.Just have tried to be applied to dielectric substance microwave technology in the world from late 1930s, and prepare TiO₂Microwave dielectric filter, but its temperature coefficient of resonance frequency τ_fToo greatly cannot be practical.Since the seventies in last century, start the large-scale development to medium ceramic material, according to relative dielectric constant ε_rSize different from use frequency range, generally can will have been developed that and the microwave-medium ceramics developed be divided into 4 classes.

(1) ultralow dielectric microwave dielectric ceramic, main representative is Al₂O₃-TiO₂、Y₂BaCuO₅、MgAl₂O₄And Mg₂SiO₄Deng, its ε_r≤ 20, quality factor q × f >=50000GHz, τ_f≤10ppm/℃.It is 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-Ta₂O₅,BaO-ZnO-Ta₂O₅Or BaO-MgO-Nb₂O₅,BaO-ZnO-Nb₂O₅System or the hybrid system MWDC material between them.Its ε_r=20～35, Q=(1～2) × 10⁴(under f >=10GHz), τ_f≈0.As dielectric resonance device in the microwave communication equipments such as the direct broadcasting satellite being mainly used in f >=8GHz.

(3) medium ε_rWith the microwave dielectric ceramic of Q-value, it is mainly with BaTi₄O₉、Ba₂Ti₉O₂₀(Zr, Sn) TiO₄Deng the MWDC material for base, its ε_r=35～45, Q=(6～9) × 10³(under f=3～-4GHz), τ_f≤5ppm/℃.It is mainly used in the microwave military radar in 4～8GHz frequency ranges and communication system as dielectric resonance device.

(4) high ε_rAnd the microwave dielectric ceramic that Q-value is relatively low, it being mainly used in civilian mobile communcations system in 0.8～4GHz frequency range, this is also the emphasis of microwave dielectric ceramic research.Since the eighties, Kolar, Kato et al. find and have studied perovskite-like tungsten bronze type BaO Ln in succession₂O₃—TiO₂Series (Ln=La, Sm, Nd or Pr etc. are called for short BLT system), complex perovskite structure CaO Li₂O—Ln₂O₃—TiO₂Series, lead base series material, Ca_1-xLn_2x/3TiO₃It is contour ε_rMicrowave dielectric ceramic, wherein the BaO Nd of BLT system₂O₃—TiO₂Material dielectric constant reaches 90, lead base series (Pb, Ca) ZrO₃Dielectric constant reaches 105.

The sintering temperature of the above material system is generally greater than 1300 DEG C, it is impossible to directly and the low-melting-point metal such as Ag and Cu burns formation multilayer ceramic capacitor altogether.In recent years, along with LTCC Technology (Low Temperature Co-fired Ceramics, LTCC) development and the requirement of microwave multilayer device development, some low grade fever's system materials have been carried out exploring widely and studying by research worker both domestic and external, mainly use devitrified glass or glassceramic composites system, have of a relatively high dielectric loss mutually because of low-melting glass, the existence of glass phase substantially increases the dielectric loss of material.Therefore the emphasis that the low fired microwave dielectric ceramic material without glass phase is current research is developed.

Explore novel with exploitation can be during low fired microwave dielectric ceramic materials, the material systems such as Li based compound, Bi based compound, tungstates architecture compound and tellurate architecture compound that intrinsic sintering temperature is low get the attention and study, but due to three performance indications (ε of microwave dielectric ceramic_rWith Q f and τ_fIt is that the relation of mutually restriction is (see document: the restricting relation between microwave dielectric ceramic materials dielectric properties between), Zhu Jianhua, Liang Fei, Wang little Hong, Lv Wenzhong, electronic component and material, phase March the 3rd in 2005), meet three performance requirements and the single-phase microwave-medium ceramics of low temperature sintering be considerably less, mainly their temperature coefficient of resonance frequency is the most excessive or quality factor are on the low side and cannot application request.Research major part to microwave-medium ceramics is the summary of experience drawn by great many of experiments at present, but there is no complete theory to illustrate the relation of microstructure and dielectric properties, therefore, the most also its microwave dielectric property such as temperature coefficient of resonance frequency and quality factor be cannot predict from the composition of compound with structure, low temperature co-fired technology and the development of microwave multilayer device which greatly limits.Explore and low-temperature sintering can have near-zero resonance frequency temperature coefficient (-10ppm/ DEG C≤τ with exploitation simultaneously_f≤+10ppm/ DEG C) it is that those skilled in the art thirst for solving always but are difficult to the difficult problem succeeded all the time with the microwave dielectric ceramic of higher figure of merit.

We are to composition LiZnV₅O₁₄、LiCuV₅O₁₄、LiNiV₅O₁₄Series compound carried out the research of microwave dielectric property, find their sintering temperature less than 900 DEG C, but only LiZnV₅O₁₄There is near-zero resonance frequency temperature coefficient and high quality factor, LiNiV₅O₁₄The temperature coefficient of resonance frequency τ of pottery_f(respectively-77ppm/ DEG C) bigger than normal and dielectric loss the highest and cannot as can be practical microwave-medium ceramics.LiCuV₅O₁₄Resonance peak is not had at microwave frequency band for ion conductor.

Summary of the invention

It is an object of the invention to provide and a kind of there is good heat stability and low-loss, simultaneously low temperature sintering ultralow dielectric microwave dielectric ceramic material and preparation method thereof.

The chemical composition of the microwave dielectric ceramic material of the present invention is LiZnV₅O₁₄。

The preparation method step of this microwave dielectric ceramic material is:

(1) by Li that purity is more than 99.9% (percentage by weight)₂CO₃, ZnO and V₂O₅Starting powder press LiZnV₅O₁₄Composition weigh dispensing.

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after drying in 750 DEG C of air atmosphere pre-burning 6 hours.

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally sinter 4 hours in 800～850 DEG C of air atmosphere；Described binding agent uses mass concentration to be the poly-vinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for the 3% of powder gross mass.

Advantages of the present invention: LiZnV₅O₁₄Ceramic sintering temperature is low, and cost of material is low；Dielectric constant reaches 15.6～16.2, the temperature coefficient τ of its resonant frequency_fLittle, temperature stability is good；Quality factor q f value is up to 119000-161000GHz, can be widely used for the manufacture of the microwave devices such as various medium substrate, resonator and wave filter, can meet the technology needs of low temperature co-fired technology and microwave multilayer device.

Detailed description of the invention

Embodiment:

Table 1 shows 3 specific embodiments and the microwave dielectric property thereof of the different sintering temperatures constituting the present invention.Its preparation method as it has been described above, carry out the evaluation of microwave dielectric property by cylindrical dielectric resonator method.

This pottery can be widely used for 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 communication.

Table 1:

Claims (3)

1. the preparation method of a low-loss temperature-stabilized ultralow dielectric microwave dielectric ceramic, it is characterised in that the chemical composition of described microwave dielectric ceramic is: LiZnV₅O₁₄, dielectric constant is 15.6, and quality factor are 119000, and resonant frequency is-3；

The preparation method step of described microwave dielectric ceramic is:

(1) be 99.9%(percentage by weight by purity) more than Li₂CO₃, ZnO and V₂O₅Starting powder press LiZnV₅O₁₄Composition weigh dispensing；

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after drying in 750 DEG C of air atmosphere pre-burning 6 hours；

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally sinter 4 hours in 800 DEG C of air atmosphere；Described binding agent uses mass concentration to be the poly-vinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for the 3% of powder gross mass.

2. the preparation method of a low-loss temperature-stabilized ultralow dielectric microwave dielectric ceramic, it is characterised in that the chemical composition of described microwave dielectric ceramic is: LiZnV₅O₁₄, dielectric constant is 16.2, and quality factor are 161000, and resonant frequency is-3；

The preparation method step of described microwave dielectric ceramic is:

(1) be 99.9%(percentage by weight by purity) more than Li₂CO₃, ZnO and V₂O₅Starting powder press LiZnV₅O₁₄Composition weigh dispensing；

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after drying in 750 DEG C of air atmosphere pre-burning 6 hours；

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally sinter 4 hours in 830 DEG C of air atmosphere；Described binding agent uses mass concentration to be the poly-vinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for the 3% of powder gross mass.

3. the preparation method of a low-loss temperature-stabilized ultralow dielectric microwave dielectric ceramic, it is characterised in that the chemical composition of described microwave dielectric ceramic is: LiZnV₅O₁₄, dielectric constant is 16.0, and quality factor are 143000, and resonant frequency is-3；

The preparation method step of described microwave dielectric ceramic is:

(1) be 99.9%(percentage by weight by purity) more than Li₂CO₃, ZnO and V₂O₅Starting powder press LiZnV₅O₁₄Composition weigh dispensing；

(2) by step (1) raw material wet ball-milling mix 12 hours, ball-milling medium is distilled water, after drying in 750 DEG C of air atmosphere pre-burning 6 hours；

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally sinter 4 hours in 850 DEG C of air atmosphere；Described binding agent uses mass concentration to be the poly-vinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for the 3% of powder gross mass.