CN104446441B - A kind of temperature-stable microwave dielectric ceramic NaMgTi 3o 7f and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of temperature-stable ultralow dielectric microwave dielectric ceramic NaMgTi ₃o ₇f and preparation method thereof.(1) be 99.9%(weight percent by purity) more than NaF, MgO and TiO ₂starting powder press NaMgTi ₃o ₇the composition weigh batching of F; (2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is dehydrated alcohol, pre-burning 6 hours in 900 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 950 ~ 980 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for 3% of powder total mass.Ceramic post sintering prepared by the present invention is good, and specific inductivity reaches 14.1 ~ 15.3, and its quality factor q f value is up to 74100-78500GHz, and temperature coefficient of resonance frequency is little, industrially has great using value.

Description

A kind of temperature-stable microwave dielectric ceramic NaMgTi 3o 7f and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to dielectric ceramic material of the microwave devices such as ceramic substrate, resonator and the wave filter used for the manufacture of microwave frequency 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, the components and parts such as resonator, wave filter, dielectric substrate and medium wave circuit are widely used as in modern communication, it is the key foundation material of modern communication technology, in portable mobile phone, automobile telephone, cordless telephone, telestar susceptor and military radar etc., there is very important application, in the miniaturization, integrated process of modern communication instrument, just playing increasing effect.

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 low dielectric loss tan δ to reduce noise, general requirement Qf>=3000GHz; (3) the temperature factor τ of resonant frequency _?little of as far as possible to ensure the thermostability that device has had, general requirement-10ppm/ DEG C≤τ _?≤+10ppm/ DEG C.From late 1930s, just someone attempts dielectric substance to be applied to microwave technology in the world, and prepares TiO ₂microwave dielectric filter, but its temperature coefficient of resonance frequency τ _?too greatly cannot be practical.Since the seventies in last century, start the large-scale development to medium ceramic material, 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 ε _r≤ 20, quality factor q × f>=50000GHz, τ _?≤ 10ppm/ ° of C.Be 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-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=20 ~ 35, Q=(1 ~ 2) × 10 ⁴(under f>=10GHz), τ _?≈ 0.Be mainly used in the microwave communication equipments such as the direct broadcasting satellite of f >=8GHz as dielectric resonance device.

(3) medium ε _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 ε _r=35 ~ 45, Q=(6 ~ 9) × 10 ³(under f=3 ~-4GHz), τ _?≤ 5ppm/ ° of 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 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.

Due to three performance index (ε of microwave dielectric ceramic _rwith Qf and τ _?) between be that the relation of mutually restriction is (see document: the restricting relation between microwave dielectric ceramic materials dielectric properties, Zhu Jianhua, Liang Fei, Wang little Hong, Lv Wenzhong, electronic component and material, phase March the 3rd in 2005), meet the single-phase microwave-medium ceramics of three performance requriementss considerably less, mainly their temperature coefficient of resonance frequency is usually excessive or quality factor are on the low side and cannot application request.Current is the summary of experience drawn by great many of experiments to the research major part of microwave-medium ceramics, but complete theory is not had to set forth the relation of microtexture and dielectric properties, therefore, in theory also cannot predict its microwave dielectric property such as temperature coefficient of resonance frequency and quality factor from the composition of compound and structure, explore and exploitation near-zero resonance frequency temperature coefficient (-10ppm/ DEG C≤τ _?≤+10ppm/ DEG C) be that those skilled in the art thirst for solving always but are difficult to the difficult problem that succeeds all the time with the serial differing dielectric constant microwave dielectric ceramic of higher figure of merit, which greatly limits the development of microwave dielectric ceramic and device.We are to composition NaMgTi ₃o ₇f, NaZnTi ₃o ₇f, NaCuTi ₃o ₇the series compound of F has carried out the research of microwave dielectric property, finds that their sintering temperature is lower than 1000 DEG C, wherein only has NaMgTi ₃o ₇f has near-zero resonance frequency temperature coefficient and high quality factor.NaZnTi ₃o ₇the temperature coefficient of resonance frequency τ of F pottery _?(being-24ppm/ DEG C) bigger than normal and cannot as practical microwave-medium ceramics; And NaCuTi ₃o ₇f cannot as microwave-medium ceramics because dielectric loss is too large under microwave frequency band.

Summary of the invention

The object of this invention is to provide one and there is good thermal stability and low-loss dielectric constant microwave dielectric ceramic material and preparation method thereof.

The chemical constitution of microwave dielectric ceramic material of the present invention is NaMgTi ₃o ₇f.

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

(1) be 99.9%(weight percent by purity) more than NaF, MgO and TiO ₂starting powder press NaMgTi ₃o ₇the composition weigh batching of F.

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is dehydrated alcohol, pre-burning 6 hours in 900 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 950 ~ 980 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for 3% of powder total mass.

Advantage of the present invention: NaMgTi ₃o ₇f ceramic dielectric constant reaches 14.1 ~ 15.3, the temperature factor τ of its resonant frequency _?little, temperature stability is good; Quality factor q f value, up to 74100-78500GHz, can be widely used in the manufacture of the microwave devices such as various dielectric resonator and wave filter, can meet the technology needs of low temperature co-fired technology and microwave multilayer device, 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. a temperature-stable ultralow dielectric microwave dielectric ceramic, is characterized in that the chemical constitution of described microwave dielectric ceramic is: NaMgTi ₃o ₇f;

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

(1) be 99.9%(weight percent by purity) more than NaF, MgO and TiO ₂starting powder press NaMgTi ₃o ₇the composition weigh batching of F;

(2) step (1) raw material wet ball-milling is mixed 12 hours, ball-milling medium is dehydrated alcohol, pre-burning 6 hours in 900 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 950 ~ 980 DEG C of air atmosphere, sinter 4 hours; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and polyvinyl alcohol addition accounts for 3% of powder total mass.