CN1187285C

CN1187285C - High-frequency dielectric niobate ceramics and preparing method thereof

Info

Publication number: CN1187285C
Application number: CNB03128132XA
Authority: CN
Inventors: 张辉; 方亮; 洪学鹍; 孟范成; 杨俊峰; 黄涛华; 袁润章; 刘韩星
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2003-06-10
Filing date: 2003-06-10
Publication date: 2005-02-02
Anticipated expiration: 2023-06-10
Also published as: CN1472171A

Abstract

The present invention discloses a class of high-frequency niobate dielectric ceramics for microwave components, and ceramic capacitors or temperature compensating capacitors. The ceramics uses (Ba<1-y>Sr<y>)<7-x>(La<s>Nd<t>Bi<u>)<x>Ti<2+x>Nb<4-x>O21 as a main phase, wherein x is more than or equal to 0.00 and is less than or equal to 3, y is more than or equal to 0.00 and is less than or equal to 1, and s+t+u is equal to 1. The ceramics which is prepared by a corresponding method has the advantages of good ceramic sintering, low consumption, small temperature coefficient of resonance frequency and very large application value in industry, and the high-frequency dielectric constant of the ceramics can reach 50 to 95.

Description

Niobate high-frequency dielectric ceramic and preparation method thereof

Technical field

The present invention relates to dielectric ceramic material, particularly relate to microwave devices such as the dielectric resonator that uses in microwave frequency, wave filter, and the dielectric ceramic material of ceramic condenser or thermo-compensation capacitor and preparation method thereof.

Background technology

Microwave dielectric ceramic is meant and is applied in microwave frequency band (mainly being UHF, the SHF frequency range) circuit as dielectric material and finishes the pottery of one or more functions, in modern communication, be widely used as components and parts such as resonator, wave filter, dielectric substrate, 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, military radars crucial application is arranged, in the miniaturization of modern communication instrument, integrated process, just bringing into play increasing effect.

Because the size of microwave dielectric resonator and the DIELECTRIC CONSTANT of material therefor _rSquare root be inversely proportional to ε _rThe big more miniaturization of devices that helps more.Pursuing high-k ε _rThe time, also to guarantee little and high thermal stability (the temperature factor τ of resonant frequency of material quality factor Q value height or dielectric loss tan δ _fAs far as possible near zero) ^[1-3]In the world from late 1930s just the someone attempt dielectric substance is applied to microwave technology.

According to relative permittivity ε _rSize with use the different of frequency range, the microwave-medium ceramics that is developed He developing can be divided into 3 classes usually.

(1) low ε _rWith the microwave dielectric ceramic of high Q value, mainly be 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=(1～3) * 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.

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

(3) 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 also is the emphasis of microwave dielectric ceramic research.Since the eighties, physiognomy secondary such as Kolar, Kato are existing and studied perovskite-like tungsten bronze type BaO-Ln ₂O ₃-TiO ₂Series (Ln=La, Sm, Nd, Pr etc., abbreviation 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.)

Accelerated development along with information technology, mobile communication system develops to high frequencyization, miniaturization, integrated, high reliability direction, medium dielectric constant material system specific inductivity is on the low side, is difficult to satisfy the demand of further miniaturization under the prerequisite that keeps the Q value not reduce.And high-k mainly is that over-all properties is relatively poor, and the Qf value is less, is difficult to satisfy the growth requirement of high frequencyization, high reliability.

Summary of the invention

The purpose of this invention is to provide a class and have low-loss and good thermostability, have the high-frequency dielectric constant simultaneously and reach dielectric ceramic material of 50～95 and preparation method thereof.

Niobate high-frequency dielectric ceramic material of the present invention by Ba, the Sr of oxide form, La, Nd,

Bi, Ti and Nb form, and with following composition be principal phase mutually,

(Ba _1-ySr _y) _7-x(La _sNd _tBi _u) _xTi _2+xNb _4-xO ₂₁

In the formula, 0.00≤x≤3,0.00≤y≤1

s+t+u＝1

This high-frequency dielectric ceramic material is prepared from as follows.

At first, with purity be BaCO more than 99.9% ₃, SrCO ₃, La ₂O ₃, Nd ₂O ₃, Bi ₂O ₃, TiO ₂With Nb ₂O ₅Starting powder by batching in the above-mentioned compositing range, wet ball-milling mixed 12～24 hours, solvent is a distilled water, the pre-burning 4～8 hours in 1280～1450 ℃ of air atmosphere of oven dry back, after in preburning powder, adding binding agent and granulation then, compression moulding again, sintering 1～8 hour in 1380～1500 ℃ of air atmosphere at last.

It is that principal phase is made earlier pre-burning principal phase powder as stated above that this dielectric ceramic material has the preparation method of principal phase and parafacies, the oxide compound starting powder of purity more than 99.9% of contained element in forming with parafacies simultaneously, in the ratio batching of setting, wet ball-milling mixed 12～24 hours, solvent is a distilled water, the pre-burning 3 hours in 1280～1450 ℃ of air atmosphere of oven dry back, synthetic parafacies powder, then principal phase composition powder was mixed 12～24 hours by the weight percent wet ball-milling of setting with parafacies composition powder, solvent is a distilled water, binding agent and granulation are added in oven dry back, compression moulding again, sintering 1～8 hour in 1380～1500 ℃ of air atmosphere at last.

It is 5% polyvinyl alcohol solution that described binding agent can adopt concentration, and dosage is generally and accounts for 5%～15% of powder total amount.

Description of drawings

Fig. 1 consists of Ba ₆LaTi ₃Nb ₃O ₂₁X ray diffracting spectrum

Embodiment

Further specifying dielectric ceramic material of the present invention below by embodiment forms and performance

Table 1 shows several specific exampless and the microwave dielectric property thereof that constitutes each component content of the present invention.Its preparation method as mentioned above, performance test is to carry out material phase analysis with the ceramic sample of powder X-ray diffractometry after to sintering, Fig. 1 is the X ray diffracting spectrum of embodiment 2, and carries out the evaluation of microwave dielectric property with the cylindrical dielectric resonator method.

As known from Table 1, high dielectric constant dielectric materials provided by the invention, its specific inductivity are 50～95, and have low-loss and less temperature coefficient of resonance frequency simultaneously.Utilize high dielectric constant dielectric materials provided by the invention can make the further miniaturization of microwave device, and can be applicable to radio ceramics electrical condenser or thermo-compensation capacitor etc.Therefore, the present invention has great value industrial.

Have and Nd La, the element of Bi analog structure and chemical property such as Y, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, Lu etc. are with the element such as the Ca of Ba analog structure and chemical property, Pb etc., with the element of Nb analog structure and chemical property such as Ta etc., and with the element such as the Sn of Ti analog structure and chemical property, Zr and the dielectric ceramic that also can make with analogous crystalline structure of the present invention and performance.

[table 1]

Embodiment	x	y	s	t	u	Molecular formula	ε _r	Qf (GHz)	τ _f(ppm/℃)
Embodiment	x	y	s	t	u	Molecular formula	ε _r	Qf (GHz)	τ _f(ppm/℃)	1	0	0	-	-	-	Ba ₇Ti ₂Nb ₅O ₂₁	55	27000	35
2	1	0	1	0	0	Ba ₆LaTi ₃Nb ₃O ₂₁	95	18000	40	1	0	0	-	-	-	Ba ₇Ti ₂Nb ₅O ₂₁	55	27000	35
2	1	0	1	0	0	Ba ₆LaTi ₃Nb ₃O ₂₁	95	18000	40	3	1	0	0	0.9	0.1	Ba ₆Nd _0.9Bi _0.1Ti ₃Nb ₃O ₂₁	80	24000	32
4	1	1	0.8	0	0.2	Sr ₆La _0.8Bi _0.2Ti ₃Nb ₃O ₂₁	75	20000	25	3	1	0	0	0.9	0.1	Ba ₆Nd _0.9Bi _0.1Ti ₃Nb ₃O ₂₁	80	24000	32
4	1	1	0.8	0	0.2	Sr ₆La _0.8Bi _0.2Ti ₃Nb ₃O ₂₁	75	20000	25	5	2	0	1	0	0	Ba ₅La ₂Ti ₄Nb ₂O ₂₁	61	15000	55
6	2	0.6	0	0.9	0.1	Ba ₂Sr ₃Nd _1.8Bi _0.2Ti ₄Nb ₂O ₂₁	58	21000	18	5	2	0	1	0	0	Ba ₅La ₂Ti ₄Nb ₂O ₂₁	61	15000	55
6	2	0.6	0	0.9	0.1	Ba ₂Sr ₃Nd _1.8Bi _0.2Ti ₄Nb ₂O ₂₁	58	21000	18	7	2	0.4	0.5	0.45	0.05	Ba ₃Sr ₂LaNd _0.9Bi _0.1Ti ₄Nb ₂ O ₂₁	62	12000	22
8	3	0	1	0	0	Ba ₄La ₃Ti ₅NbO ₂₁	54	19000	90	7	2	0.4	0.5	0.45	0.05	Ba ₃Sr ₂LaNd _0.9Bi _0.1Ti ₄Nb ₂ O ₂₁	62	12000	22
8	3	0	1	0	0	Ba ₄La ₃Ti ₅NbO ₂₁	54	19000	90	9	3	0.5	0.35	0.5	0.15	Ba ₂Sr ₂La _1.05Nd _1.5Bi _0.45Ti ₆ NbO ₂₁	50	24000	-5

Claims

1, a class niobate high-frequency dielectric ceramic is characterized in that being made up of Ba, Sr, La, Nd, Bi, Ti and the Nb of oxide form, and is principal phase mutually with following composition

(Ba _1-ySr _y) _7-x(La _sNd _tBi _u) _xTi _2+xNb _4-xO ₂₁

In the formula, 0.00≤x≤3,0.00≤y≤1

s+t+u＝1

2, the preparation method of the described high-frequency dielectric ceramic of claim 1 is characterized in that: at first, be BaCO more than 99.9% with purity ₃, SrCO ₃, La ₂O ₃, Nd ₂O ₃, Bi ₂O ₃, TiO ₂With Nb ₂O ₅Starting powder by batching in the described compositing range of claim 1, wet ball-milling mixed 12～24 hours, solvent is a distilled water, the pre-burning 4～8 hours in 1280～1450 ℃ of air atmosphere of oven dry back, after in preburning powder, adding binding agent and granulation then, compression moulding again, sintering 1～8 hour in 1380～1500 ℃ of air atmosphere at last, described binding agent employing concentration is 5% polyvinyl alcohol solution, and its dosage accounts for 5%～15% of powder total amount.