CN103553607A - Stable-temperature microwave dielectric ceramic Nb2WO8 and preparation method thereof - Google Patents

Abstract

The invention discloses a stable-temperature microwave dielectric ceramic Nb2WO8 and a preparation method thereof. The chemical composition general formula of the microwave dielectric ceramic is Nb2WO8. The preparation method comprises the following steps: (1) weighing and proportioning analytically pure Nb2O5 and WO3 original powders according to the chemical formula Nb2WO8; (2) carrying out wet-type ball milling mixing on the raw materials in the step (1) for 12 hours by using distilled water as a solvent, drying, and presintering at 1200 DEG C in an air atmosphere for 6 hours; and (3) adding an adhesive into the powder prepared in the step (2), granulating, carrying out compression molding, and finally, sintering at 1250-1280 DEG C in an air atmosphere for 4 hours, wherein the adhesive is a 5 wt% polyvinyl alcohol solution, and accounts for 3 wt% of the powders. The ceramic disclosed by the invention is well sintered at 1250-1280 DEG C; the dielectric constant is up to 37-38, the quality factor Qf is up to 53000-66000 GHz, and the temperature coefficient of resonance frequency is small; and thus, the ceramic has a great application value in industry.

Description

Temperature-stable microwave dielectric ceramic Nb 2wO 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

Microwave dielectric ceramic refers to and is applied in microwave frequency band (being mainly UHF, SHF frequency range) circuit as dielectric material and completes the pottery of one or more functions, in modern communication, be widely used as the components and parts such as resonator, wave filter, dielectric substrate and medium guided wave loop, it is the key foundation material of modern communication technology, at aspects such as portable mobile phone, automobile telephone, cordless telephone, telestar susceptor and military radars, there is very important application, in the miniaturization of modern communication instrument, integrated process, just bringing into play increasing effect.

Be applied to the dielectric ceramic of microwave frequency band, should meet 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>=3000 GHz; (3) the temperature factor τ of resonant frequency _?the as far as possible little thermostability to guarantee that device has had, general requirement-10/ ℃≤τ _?≤+10 ppm/ ℃.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 the different of frequency range, conventionally the microwave-medium ceramics being 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 _?≤ 10 ppm/ ° C.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 the GHz of f>=10), τ _?≈ 0.Be mainly used in the microwave communication equipments such as direct broadcasting satellite of f >=8 GHz as 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(under f=3～-4GHz), τ _?≤ 5 ppm/ ° C.Be mainly used in microwave military radar in 4～8 GHz range of frequency and communication system as 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, 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. 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 temperature factor τ of current resonant frequency _?medium dielectric constant microwave medium microwave dielectric ceramic kind close to zero is limited, can not meet the demand of the applying frequency seriation of mobile communcations system.

 

Summary of the invention

The object of this invention is to provide a kind of Heat stability is good, medium dielectric constant microwave medium ε _rmicrowave dielectric ceramic with high Q value .

The chemical constitution formula of microwave dielectric ceramic of the present invention is: Nb ₂wO ₈.

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

(1) by analytically pure Nb ₂o ₅and WO ₃starting powder press Nb ₂wO ₈chemical formula weigh batching chemical formula weigh batching.

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 1200 ℃ of air atmosphere after oven dry.

(3) in the powder making in step (2), add after binding agent granulation, then compression moulding, finally sintering 4 hours in 1250 ~ 1280 ℃ of air atmosphere; Described binding agent adopts the polyvinyl alcohol solution that mass concentration is 5%, and dosage accounts for 3% of powder total mass.

Pottery prepared by the present invention is good at 1250 ~ 1280 ℃ of ℃ of sintering, and its temperature coefficient of resonance frequency is little, and specific inductivity reaches 37～38, and quality factor q f value is up to 53000-66000GHz,, industrial, there is a great using value.

Embodiment

Embodiment:

Table 1 shows 4 specific exampless and the microwave dielectric property thereof that forms each component content of the present invention.Its preparation method as mentioned above, carries out the evaluation of microwave dielectric property by cylindrical dielectric resonator method.

The present invention is never limited to above embodiment.As Ta, Sb, V etc., also can make the dielectric ceramic with analogous crystalline structure of the present invention and performance with the element of Nb analog structure and chemical property.

This pottery can be widely used in the manufacture that various dielectric resonances play the microwave devices such as device, wave filter, can meet the Technology Need of the systems such as mobile communication, satellite communications.

Table 1:

Claims (1)

1. composite oxides, as an application for temperature-stable microwave dielectric ceramic, is characterized in that the chemical constitution general formula of described composite oxides is: Nb ₂wO ₈;

Preparation method's concrete steps of described tungstate are:

(1) by analytically pure Nb ₂o ₅and WO ₃starting powder press Nb ₂wO ₈chemical formula weigh batching;

(2) step (1) raw material wet ball-milling is mixed 12 hours, solvent is distilled water, pre-burning 6 hours in 1200 ℃ of air atmosphere after oven dry;

(3) in the powder making in step (2), add after binding agent granulation, then compression moulding, finally sintering 4 hours in 1250 ~ 1280 ℃ of air atmosphere; Described binding agent adopts the polyvinyl alcohol solution that mass concentration is 5%, and dosage accounts for 3% of powder total mass.