CN106007674A - High-quality-factor stable-temperature microwave dielectric ceramic LiFeGe2O6 - Google Patents

Abstract

The invention discloses high-quality-factor stable-temperature ultralow dielectric constant microwave dielectric ceramic LiFeGe2O6 and a preparation method thereof. The preparation method comprises the following steps: (1) weighing and proportioning original powder (with the purity of 99.9% or above by weight) of Li2CO3, Fe2O3 and GeO2 according to composition of LiFeGe2O6; (2) performing wet-type ball-milling and mixing on the raw materials obtained in the step (1) for 12 h, drying and then pre-burning for 6 h in the atmosphere of 1100 DEG C, wherein the ball-milling medium is distilled water; (3) adding a binder into the powder prepared in the step (2), pelletizing, then pressing for shaping, and finally, sintering for 4 h in the atmosphere of 1,150-1,200 DEG C, wherein the binder is a polyvinyl alcohol solution with the mass concentration of 5%, and polyvinyl alcohol accounts for 3% of the total mass of the powder. The prepared high-quality-factor stable-temperature microwave dielectric ceramic LiFeGe2O6 has excellent sintering performance below 1,200 DEG C, has the dielectric constant of 6.5-6.9 and the quality factor Qf of 80,000-101,000 GHz, is small in temperature coefficient of resonance frequency and has an extremely high application value in the industry.

Description

High quality factor temperature-stable microwave dielectric ceramic LiFeGe2O6

Technical field

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

Background technology

Microwave dielectric ceramic refers to be applied to conduct in microwave frequency band (mainly UHF and SHF frequency range) circuit Dielectric material also completes the pottery of one or more functions, is widely used as resonator, filtering in modern communication The components and parts such as device, dielectric substrate and medium wave circuit, are the key foundation materials of modern communication technology, exist The aspects such as portable mobile phone, automobile telephone, wireless phone, television satellite accepter and military radar have Highly important application, modern communication instrument miniaturization, integrated during just playing increasing Effect.

It is applied to the dielectric ceramic of microwave frequency band, the requirement of following dielectric property should be met: (1) seriation is situated between Electric 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 system of resonant frequency Number τ_fThe least to ensure the heat stability that device has had ,-10ppm/ DEG C≤τ of general requirement_f≤+10 ppm/℃.Just have tried to from late 1930s in the world dielectric substance is applied to microwave technology, 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 being relatively situated between Electric constant ε_rSize different from use frequency range, generally can have been developed that and the microwave-medium developed Pottery is 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 being combined between them System MWDC material.Its ε_r=20～35, Q=(1～2) × 10⁴(under f >=10GHz), τ_f≈0.Main As dielectric resonance device in the microwave communication equipments such as the direct broadcasting satellite of f >=8GHz to be applied to.

(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(f=3～- Under 4GHz), τ_f≤5ppm/℃.Be mainly used in the microwave military radar in 4～8GHz frequency ranges and As dielectric resonance device in communication system.

(4) high ε_rAnd the microwave dielectric ceramic that Q-value is relatively low, it is mainly used in 0.8～4GHz frequency range Civilian mobile communcations system, this is also the emphasis of microwave dielectric ceramic research.Since the eighties, Kolar, Kato et al. finds and have studied perovskite-like tungsten bronze type BaO Ln in succession₂O₃—TiO₂Series (Ln=La, Sm, Nd or Pr etc., be called for short BLT system), complex perovskite structure CaO Li₂O—Ln₂O₃—TiO₂System Row, lead base series material, Ca_1-xLn_2x/3TiO₃It is contour ε_rMicrowave dielectric ceramic, wherein BLT system BaO—Nd₂O₃—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 Ag and Cu etc. Low-melting-point metal burns formation multilayer ceramic capacitor altogether.In recent years, along with LTCC Technology (Low Temperature Co-fired Ceramics, LTCC) development and microwave multilayer device development requirement, state Some low grade fever's system materials have been carried out exploring widely and studying by inside and outside research worker, mainly use micro- Crystal 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 low fired microwave dielectric without glass phase is developed Ceramic material is the emphasis of current research.

Explore novel with exploitation can be during low fired microwave dielectric ceramic materials, intrinsic sintering temperature is low The material bodies such as Li based compound, Bi based compound, tungstates architecture compound and tellurate architecture compound System gets the attention and studies, 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 system between microwave dielectric ceramic materials dielectric properties between) About relation, Zhu Jianhua, Liang Fei, Wang little Hong, Lv Wenzhong, electronic component and material, in March, 2005 3rd phase), meet three performance requirements and the single-phase microwave-medium ceramics of low temperature sintering is considerably less, mainly Be that 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, does not but have Complete theory illustrates the relation of microstructure and dielectric properties, therefore, and the most also cannot be from chemical combination Predict its microwave dielectric property such as temperature coefficient of resonance frequency and quality factor in the composition of thing and structure, this Largely limit low temperature co-fired technology and the development of microwave multilayer device.Exploring can low temperature with exploitation Sintering has near-zero resonance frequency temperature coefficient (-10ppm/ DEG C≤τ simultaneously_f≤+10ppm/ DEG C) and relatively The microwave dielectric ceramic of high quality factor be those skilled in the art always thirst for solve but be difficult to all the time obtain A successfully difficult problem.We are to consisting of LiFeGe₂O₆、LiAlGe₂O₆And LiBGe₂O₆Pottery carry out Sintering and Study on microwave dielectric property, find that their sintering temperature is less than 1200 DEG C, wherein LiFeGe₂O₆ There is near-zero resonance frequency temperature coefficient and high quality factor, LiAlGe₂O₆And LiBGe₂O₆Pottery is partly to lead Body, its dielectric loss is big and does not has resonance peak, therefore cannot as can be practical microwave-medium ceramics.

Summary of the invention

It is an object of the invention to provide that a kind of to have good heat stability micro-with low-loss ultralow dielectric Ripple dielectric ceramic material and preparation method thereof.

The chemical composition of the microwave dielectric ceramic material of the present invention is LiFeGe₂O₆。

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、Fe₂O₃And GeO₂Original Powder presses LiFeGe₂O₆Composition weigh dispensing.

(2) being mixed 12 hours by step (1) raw material wet ball-milling, ball-milling medium is distilled water, after drying Pre-burning 6 hours in 1100 DEG C of air atmosphere.

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally 1150～1200 DEG C of air atmosphere sinter 4 hours；Described binding agent use mass concentration be 5% poly- Glycohol solution, polyvinyl alcohol addition accounts for the 3% of powder gross mass.

Advantages of the present invention: LiFeGe₂O₆Ceramic sintering temperature is relatively low, and cost of material is low；Its quality factor Qf value is up to 80000-101000GHz, and dielectric constant reaches 6.5～6.9, the temperature coefficient τ of its resonant frequency_fLittle, temperature stability is good；Can be widely used for the microwave devices such as various medium substrate, resonator and wave filter Manufacture, the technology needs of low temperature co-fired technology and microwave multilayer device can be met.

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 Energy.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 (1)

1. germanate is as an application for high quality factor temperature-stable microwave dielectric ceramic, its feature The chemical composition being described germanate is: LiFeGe₂O₆；

The preparation method of described germanate concretely comprises the following steps:

(1) by Li that purity is more than 99.9% (percentage by weight)₂CO₃、Fe₂O₃And GeO₂Original Powder presses LiFeGe₂O₆Composition weigh dispensing；

(2) being mixed 12 hours by step (1) raw material wet ball-milling, ball-milling medium is distilled water, after drying Pre-burning 6 hours in 1100 DEG C of air atmosphere；

(3) after adding binding agent pelletize in the powder that step (2) prepares, re-compacted molding, finally 1150～1200 DEG C of air atmosphere sinter 4 hours；Described binding agent use mass concentration be 5% poly- Glycohol solution, polyvinyl alcohol addition accounts for the 3% of powder gross mass.