CN101260001A - High-Q microwave dielectric ceramic material and preparing method thereof - Google Patents

Abstract

The invention relates to a plurality of novel high-Q microwave medium ceramic materials and preparation methods thereof, belonging to the special ceramic material process technical field. The novel high-Q microwave medium ceramic materials comprise the following four chemical formulas: (1) (1-x)Li2TiO3-xMgO with x ranging between 0 and 0.981; (2) Li2+xTi1-4xNb3xO3 with x ranging from 0 and 0.1; (3) Li2+xTiO3 with x ranging between minus 0.85 and 0.20; (4) Li3Mg2NbO6. The preparation method comprises the following steps: according to the specified chemical formulas, the mass of each raw material is calculated; the raw material adopts chemical analytically pure with the purity of the raw materials including Li2CO3, TiO2, MgO and Nb2O5 more than 99 percent; the specified raw materials, zirconia grinding ball and dehydrated alcohol are packed in a resin ball milling tank according the to weight ratio of 1:2:0.75, and then are dried and screened after 24-hour ball milling; then, polyvinyl alcohol solution is added to carry out granulation and then the mixture is screened; particles are packed in a mould and are formed through dry stamp under 150 MPa pressure; and finally, blocks are calcined two hours under 1,200 DEG C to 1,350 DEG C to obtain the required high-Q microwave medium ceramic materials of rock-salt structures.

Description

Novel high-Q microwave dielectric ceramic material and preparation method thereof

Technical field:

The present invention relates to several novel high-Q microwave dielectric ceramic materials and preparation method thereof, belong to special ceramic material Technology field.

Background technology:

The microwave resonator and the wave filter that are applied to 3G and 4G base station in the future must have good frequency selective characteristic, bandwidth, miniaturization and cost degradation.Though original metal cavitg resonator low price, but the nonloaded Q of metal cavitg resonator very low (～6000GHz) and the resonant frequency temperature stability very poor, and dielectric resonator has the Q-unloaded height usually, frequency-temperature coefficient is little and adjustable and characteristics such as miniaturization, thereby is subjected to application more and more widely.The microwaves corresponding dielectric material must have simultaneously the high quality factor of (1) high specific inductivity (20-50) (2) (Qf＞40000GHz) (3) is though nearly zero adjustable temperature coefficient of resonance frequency. the specific inductivity of medium is high more, it is more little that the size of resonator and wave filter can be done, but the specific inductivity of medium is excessive, electromagnetic field concentrates in the medium more in the dielectric resonator, causes a little less than the coupling too between the resonator bandwidth of cavity body filter being diminished.And the Q value and the specific inductivity of dielectric material be inversely proportional to, usually specific inductivity surpass 50 and less its Qf value of dielectric material of temperature coefficient of resonance frequency be no more than 35000GHz.Since NodeB with the microwave power of dielectric resonator carrying very big (＞200W), therefore to the quality factor of the dielectric material (Qf＞60000GHz) that has higher requirement.The frequency of utilization of mobile communication such as present base station is mostly less than 2GHz, in recent years, increase along with the global communication quantity of information, the frequency of micro-wave communication constantly develops to high frequency direction, the frequency of utilization of satellite communications such as satellite radio television technology is usually more than 10GHz, because dielectric loss and the frequency of dielectric material are inversely proportional to, generally dielectric material uses being higher than under the 10GHz frequency, because of the Q value not high enough and satisfied not requirement.The higher microwave dielectric material of Q value of commercialization mainly contains MgTiO at present ₃-CaTiO ₃System, Ba ((Zn, Mg) _1/3Ta _2/3) O ₃(BMT, BZT), LnAlO ₃-CaTiO ₃System, Zr-Ti-Sn-O system, ZrTiO ₄One ZnNb ₂O ₆System etc., the specific inductivity of these materials mostly between 20-45, Q-unloaded except that BMT, BZT, Qf＜60000GHz, but that such quality factor also show concerning 3G and satellite communications is too low.

In fact, concerning resonator or wave filter, higher Q value means lower differential loss and signal noise and better frequency selective characteristic.Therefore, resonator design person prefers adopting the complex perovskite structure pottery with higher Q value as Ba (Zn _1/3Ta _2/3) O3 (BZT) (Qf=150000GHz), (Ba (Mg _1/2Ta _2/3) O ₃(BMT) (Qf=400000GHz).But the raw material Ta that BZT and BMT are used ₂O ₅Cost an arm and a leg (2000 yuan/kg), sintering temperature very high (1600 ℃ have been limited the large-scale commercial applications application of this material.In a word, present mobile base station is (ε when satisfying specific inductivity and temperature coefficient of resonance frequency with the development trend of microwave-medium ceramics _r=20-50, τ _f＜5ppm/ ℃), as far as possible constantly improve its Q value (Qf 〉=80000GHz), reduce production costs, stability of enhancing product performance and repeatability.

Summary of the invention:

The object of the present invention is to provide a kind of novel high-Q microwave dielectric ceramic material and preparation method thereof.

A kind of novel high-Q microwave dielectric ceramic material of the present invention is characterized in that having following four kinds of chemical formulas:

(1), (1-x) Li ₂TiO ₃-xMgO, wherein x is 0～0.981;

(2), Li _2+xTi _1-4xNb _3xO ₃, wherein x is 0～0.1;

(3), Li _2+xTiO ₃, x=-0.85～0.20 wherein;

(4)、Li ₃Mg ₂NbO ₆。

The preparation method of a kind of novel high-Q microwave dielectric ceramic material of the present invention is characterized in that having following technological process and step:

A. according to above-mentioned each chemical formula, converse the quality of each raw material; Raw material adopts the pure raw material of chemical analysis, i.e. 99.9% Li ₂CO ₃, 97% TiO ₂, 98.5～99.9% MgO, 99.9% Nb ₂O ₅

B. then according to respectively raw material, zirconium oxide balls, the dehydrated alcohol of regulation are packed in resin ball grinder ball milling 24 hours of 1: 2: 0.75 part by weight, after mixing, with it 100 ℃ of oven dry down;

C. calcined 3 hours down at 900～1100 ℃ then, will calcine good powder subsequently and cross 40 mesh sieves;

D. respectively powder, zirconium oxide balls, dehydrated alcohol are packed into according to 1: 2: 0.6 part by weight then and carry out the ball milling 24 hours second time in the resin ball grinder,, and cross 40 mesh sieves subsequently at 100 ℃ of oven dry slurries down;

E. the concentration that adds 7wt% in the powder that obtains is that the polyvinyl alcohol solution of 10wt% carries out granulation, and crosses 40 mesh sieves;

F. the mould of the powder material after the granulation being packed into is dry-pressing formed under the pressure of 150MPa; Then the block of moulding is calcined by following program: the heat-up rate that begins with 1 ℃/minute from room temperature heats, be warming up to 2 hours binder removals of 600 ℃ of constant temperature, be warmed up to 900 ℃ of constant temperature with 5 ℃/minute speed then and carried out pre-burning in 1 hour, cool to room temperature subsequently with the furnace; At last with block 1200～1350 ℃ of following sintering 2 hours, finally obtain the high-Q microwave dielectric ceramic material of required rock salt structure.

The various microwave dielectric ceramic materials that the inventive method makes, having higher Q value is higher no-load quality factor.This kind material can satisfy general specific inductivity and temperature coefficient of resonance frequency.And microwave dielectric ceramic materials of the present invention has preferable performance stability and repeated, and its production cost is also lower.

Embodiment

Now the embodiment with the microwave dielectric ceramic materials of the various chemical formula compositions of the present invention is described below:

Embodiment one: according to (1-x) Li ₂TiO ₃-xMgO (x=0～0.981) chemical equation converses the quality of required each raw material, then accurate each analytical pure raw material: Li of weighing ₂CO ₃(99.9%), TiO ₂(97%), MgO (99.9%).The weighing quality is as follows: table 1

Table 1. (1-x) Li ₂TiO ₃-xMgO allocation sheet (unit: g):

x	MgO	Li 2CO 3	TiO 2
				0.0	0.0000	54.9619	58.3932
0.1	3.1395	52.8071	56.1039
				0.24	5.2012	30.1959	32.7031
0.2	6.7340	50.3400	53.4828
				0.3	10.8900	47.4877	50.4524
0.4	15.7501	44.1520	46.9085
				0.5	21.5098	40.1989	42.7086
0.539	15.0350	23.5751	25.5325
				0.645	20.0306	20.2116	21.8897
0.731	24.9998	16.8659	18.2663
				0.803	30.0056	13.4956	14.6161
0.864	35.0340	10.1101	10.9495
				0.916	40.0495	6.7332	7.2922
0.961	45.0696	3.3532	3.6316
				0.981	47.5427	1.6881	1.8283

Then according to respectively the raw material, zirconia ball mill, the dehydrated alcohol that weigh up are packed in resin ball grinder ball milling 24 hours of 1: 2: 0.75 ratio, after mixing, with it 100 ℃ of oven dry down; Calcined 3 hours down at 900～1100 ℃ then, to calcine good powder again and cross 40 mesh sieves, respectively powder, zirconia ball mill, dehydrated alcohol are packed into according to 1: 2: 0.6 ratio then and carry out the ball milling 24 hours second time in the resin ball grinder, dry slurry down at 100 ℃ then, cross 40 mesh sieves; The concentration that adds 7wt% again in the powder that obtains is that the polyvinyl alcohol solution of 10wt% carries out granulation and crosses 40 mesh sieves; The mould dry-pressing under the pressure of 150MPa of packing into of powder after the granulation is become the cylinder block of Φ 10 * 5mm; Then this block is calcined according to following path: begin with 1 ℃/minute from room temperature, be warming up to 2 hours binder removals of 600 ℃ of constant temperature, be warmed up to 900 ℃ of constant temperature with 5 ℃/minute speed then and carried out pre-burning in 1 hour, cool to room temperature then with the furnace; At last with block 1200～1350 ℃ of following sintering 2 hours, obtain required microwave dielectric material.

Adopt X-ray diffractometer (Rigaku D the max2550 type, 40kv 200mA) carries out material phase analysis to sintered sample; Network analyzer (AgilentN5230A) and relevant necessary instrument are tested its microwave dielectric property.Test result is as follows: table 2

Table 2. (1-x) Li ₂TiO ₃-xMgO (x=0～0.981) material microwave dielectric properties

Embodiment two: according to Li _2+xTi _1-4xNb _3xO ₃(x=0～0.10) chemical equation converses the quality of required each raw material, then accurate each analytical pure raw material: Li of weighing ₂CO ₃(99.9%), TiO ₂(97%), Nb ₂O ₅(99.9%), as table 3:

Table 3.Li _2+xTi _1-4xNb _3xO ₃Allocation sheet (unit: g):

x	Li 2CO 3	TiO 2	Nb 2O 5
				0.00	53.9165	58.3932	0.0000
0.02	53.5367	52.8151	5.7205
				0.04	53.1695	47.4222	11.2511
0.06	52.8143	42.2054	16.6011
				0.07	39.4808	29.7453	14.4084
0.08	52.4705	37.1562	21.7793
				0.10	52.1376	32.2666	26.7937

Material preparation process and testing method are with embodiment one.Result such as table 4:

Table 4.Li _2+xTi _1-4xNb _3xO ₃(x=0～0.10) material microwave dielectric properties

Embodiment three: according to Li _2+xTiO ₃(x=-0.85～0.20) chemical equation converses the quality of required each raw material, then accurate each analytical pure raw material: Li of weighing ₂CO ₃(99.9%), TiO ₂(97%), as table 5:

Table 5.Li _2+xTiO ₃(x=-0.85～0.20) allocation sheet (unit: g)

x	Li 2CO 3	TiO 2
			-0.85	19.3763	36.4957
-0.55	24.4309	36.4957
			-0.25	29.4856	36.4957
0.01	33.8663	36.4957
			0.02	34.0348	36.4957
0.03	34.2033	36.4957
			0.04	34.3718	36.4957
0.05	34.5403	36.4957
			0.06	34.7088	36.4957
0.07	34.8773	36.4957
			0.08	35.0458	36.4957
0.12	35.7197	36.4957
			0.16	36.3937	36.4957
0.20	37.0676	36.4957

Material preparation process and testing method are with embodiment one.Result such as table 6:

Table 6.Li _2+xTiO ₃(x=-0.85～0.20) material microwave dielectric properties

Embodiment four: according to Li ₃Mg ₂NbO ₆Chemical equation converses the quality of required each raw material, then accurate each analytical pure raw material: Li of weighing ₂CO ₃(99.9%), MgO (98.5%), Nb ₂O ₅(99.9%), as table 7:

Table 7.Li ₃Mg ₂NbO ₆Allocation sheet (unit: g)

Li 2CO 3	MgO	Nb 2O 5
			25.7682	19.0070	30.8988

Material preparation process and testing method are with embodiment one.Result such as table 8:

Table 8.Li ₃Mg ₂NbO ₆The material microwave dielectric properties

Sintering temperature (℃)	Quality factor q * f (GHz)	DIELECTRIC CONSTANT r	Temperature factor τ f(ppm/℃)
				1250	79642.6	16.7	-23.13
1350	81871.5	16.1

Claims (2)

1, a kind of novel high-Q microwave dielectric ceramic material is characterized in that having following four kinds of chemical formulas:

(1), (1-x) Li ₂TiO ₃-xMgO, wherein x is 0～0.981;

(2), Li _2+xTi _1-4xNb _3xO ₃, wherein x is 0～0.1;

(3), Li _2+xTiO ₃, x=-0.85～0.20 wherein;

(4)、Li ₃Mg ₂NbO ₆。

2, the preparation method of a kind of novel high-Q microwave dielectric ceramic material of claim 1 is characterized in that having following technological process and step:

A. according to above-mentioned each chemical formula, converse the quality of each raw material; Raw material adopts the pure raw material of chemical analysis, i.e. 99.9% Li ₂CO ₃, 97% TiO ₂, 98.5～99.9% MgO, 99.9% Nb ₂O ₅

B. then according to respectively raw material, zirconium oxide balls, the dehydrated alcohol of regulation are packed in resin ball grinder ball milling 24 hours of 1: 2: 0.75 part by weight, after mixing, with it 100 ℃ of oven dry down;

C. calcined 3 hours down at 900～1100 ℃ then, will calcine good powder subsequently and cross 40 mesh sieves;

D. respectively powder, zirconium oxide balls, dehydrated alcohol are packed into according to 1: 2: 0.6 part by weight then and carry out the ball milling 24 hours second time in the resin ball grinder,, and cross 40 mesh sieves subsequently at 100 ℃ of oven dry slurries down;

E. the concentration that adds 7wt% in the powder that obtains is that the polyvinyl alcohol solution of 10wt% carries out granulation, and crosses 40 mesh sieves;

F. the mould of the powder material after the granulation being packed into is dry-pressing formed under the pressure of 150MPa; Then the block of moulding is calcined by following program: the heat-up rate that begins with 1 ℃/minute from room temperature heats, be warming up to 2 hours binder removals of 600 ℃ of constant temperature, be warmed up to 900 ℃ of constant temperature with 5 ℃/minute speed then and carried out pre-burning in 1 hour, cool to room temperature subsequently with the furnace; At last with block 1200～1350 ℃ of following sintering 2 hours, finally obtain the high-Q microwave dielectric ceramic material of required rock salt structure.