CN101863658A - Preparation method of barium-strontium titanate ceramic - Google Patents

Abstract

The invention discloses a preparation method of a barium-strontium titanate ceramic for solving the technical problem that the barium-strontium titanate ceramic prepared by existing technique according to existing formula is high in electric loss, poor in temperature stability and high in sintering temperature. The technical scheme is as follows: analytically pure BaCO3, SrCO3, TiO2 and MgO are mixed according to a stoichiometric ratio of BaxSr1-x(MgyTi)O3, wherein x=0.5-0.7, and y=0.01-0.07; the mixed materials are subjected to a ball milling and sieved and then shaped under an isostatic pressure, the shaped product is thermally insulated for 3-5 hours at 1180-1260 degrees centigrade and then sintered into ceramic. By optimizing the formula of a magnesium-doped barium-strontium titanate ceramic, the dielectric loss of the ceramic is kept low at a temperature 0-50 degrees centigrade different from room temperature, in addition, as an unglazed ware is sintered after subjected to an isostatic pressing, the sintering temperature is reduced to about 1200 degrees centigrade from 1400 degrees centigrade required in background technology.

Description

The preparation method of barium-strontium titanate ceramic

Technical field

The present invention relates to a kind of preparation method's of pottery, particularly a kind of barium-strontium titanate ceramic preparation method.

Background technology

The development of ferroelectric phase shifter, it is little to press near the dielectric loss of a kind of room temperature, the tuning material that specific inductivity and tuning rate are moderate, the deemed appropriate candidate target of strontium-barium titanate series sosoloid.The dielectric loss of pure strontium-barium titanate is bigger, and behind overdoping, dielectric loss obviously descends, but its temperature stability descends simultaneously.

Document " B.Su and T.W.Button; Microstructure and dielectric properties of Mg-dopedbarium strontium titanate ceramics; JOURNAL OF APPLIED PHYSICS; 95 (3); 2004; 1382-1385 " discloses a kind of preparation method of pottery, by at Ba _0.8Sr _0.2TiO ₃Mix certain density magnesium in the pottery and reduced ceramic dielectric loss, but dielectric loss increases sharply with the temperature rising near room temperature, and the sintering temperature of pottery is higher, is 1400 ℃.

Summary of the invention

In order to overcome the high deficiency of preparation method's sintering temperature of existing barium-strontium titanate ceramic, the invention provides a kind of preparation method of barium-strontium titanate ceramic.This method is by adjusting the prescription of magnesium strontium titanate doping titanate ceramics, and near the dielectric loss that can make pottery temperature range of 0～50 ℃ room temperature all keeps lower; And, can reduce the sintering temperature of pottery by optimizing technology.

The technical solution adopted for the present invention to solve the technical problems: a kind of preparation method of barium-strontium titanate ceramic is characterized in comprising the steps:

(a) with analytical pure BaCO ₃, SrCO ₃, TiO ₂, MgO is according to stoichiometric ratio Ba _xSr _1-x(Mg _yTi) O ₃Weighing and batching, x=0.5～0.7 wherein, y=0.01～0.07;

(b) material that will prepare is put into ball grinder, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 4～8 hours;

(c) with ball milling material oven dry back briquetting, pre-burning is 1～4 hour under 1000～1100 ℃ of temperature, takes out to grind, and ball milling is 8～12 hours again, sieves then;

(d) to be pressed into diameter in advance be 12mm to the powder after will sieving, and thickness is the disk of 1～1.5mm, then at the hydrostatic pressure compacted under of 200MPa;

(e) disk after the moulding is incubated 3～5 hours down at 1180～1260 ℃, sinters porcelain into.

Useful result of the present invention is: because by optimizing the prescription of magnesium strontium titanate doping titanate ceramics, make near the dielectric loss of pottery 0～50 ℃ temperature range room temperature keep lower, biscuit process waits sintering behind the static pressure in addition, and sintering temperature is reduced to about 1200 ℃ by 1400 ℃ of background technology.

Below in conjunction with drawings and Examples the present invention is elaborated.

Description of drawings

Fig. 1 is the X ray diffracting spectrum of the barium-strontium titanate ceramic of different magnesium doping contents.

Fig. 2 is under the 1kHz, the variation relation curve of the barium-strontium titanate ceramic dielectric constant with temperature of different magnesium doping contents.

Fig. 3 is under the 1kHz, and the barium-strontium titanate ceramic dielectric loss of different magnesium doping contents is with the variation of temperature relation curve.

Embodiment

Following examples are with reference to Fig. 1～3.

Embodiment 1, weighing 11.214g BaCO ₃, 5.593g SrCO ₃, 7.567g TiO ₂, 0.0384g MgO puts into ball grinder with the material that weighs up, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 4 hours; With the material oven dry back briquetting that mixes, pre-burning is 4 hours under 1000 ℃ of temperature, and good material grinds to take out calcining, and ball milling is 8 hours again, sieves then; It is 12mm that powder after sieving is pressed into diameter in advance, and thickness is the disk of 1mm, then final molding under the hydrostatic pressure of 200MPa; Disk after the moulding is incubated 5 hours down at 1180 ℃; Sinter into after the porcelain, sanding and polishing, the silver coating slurry under 550 ℃, is incubated 30 minutes and burns till silver electrode then.Full-automatic X-ray diffractometer (D/Max2550VB+/PC) with Japan company of science is tested ceramic structure, carries out the test of temperature spectrum with the pottery of Agilent impedance instrument (4294A) after to quilt silver.(a) is the X ray diffracting spectrum of the barium-strontium titanate ceramic of doping 1mol%Mg among Fig. 1, and as can be seen from Figure 1, prepared pottery does not have other dephasigns.As can be seen, its specific inductivity and dielectric loss are respectively 3226 and 0.00674 in the time of 25 ℃ from Fig. 2 and Fig. 3, and its tuning rate is 21.1% when extra electric field is 17kV/cm.

Embodiment 2, weighing 11.214g BaCO ₃, 5.593g SrCO ₃, 7.567g TiO ₂, 0.1151g MgO puts into ball grinder with the material that weighs up, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 6 hours; With the material oven dry back briquetting that mixes, pre-burning is 3 hours under 1040 ℃ of temperature, and good material grinds to take out calcining, and ball milling is 9 hours again, sieves then; It is 12mm that powder after sieving is pressed into diameter in advance, and thickness is the disk of 1.2mm, then final molding under the hydrostatic pressure of 200MPa; Disk after the moulding is incubated 4 hours down at 1200 ℃; Sinter into after the porcelain, sanding and polishing, the silver coating slurry under 550 ℃, is incubated 30 minutes and burns till silver electrode then.Full-automatic X-ray diffractometer (D/Max2550VB+/PC) with Japan company of science is tested ceramic structure, carries out the test of temperature spectrum with the pottery of Agilent impedance instrument (4294A) after to quilt silver.(b) is the X ray diffracting spectrum of the barium-strontium titanate ceramic of doping 3mol%Mg among Fig. 1, and as can be seen from Figure 1, prepared pottery does not have other dephasigns.As can be seen, its specific inductivity and dielectric loss are respectively 2411 and 0.00133 in the time of 25 ℃ from Fig. 2 and Fig. 3, and when extra electric field was 17kV/cm, its tuning rate was 17.2%.And near 0～50 ℃, it is more stable that the dielectric loss of material all keeps.

Embodiment 3, weighing 11.214g BaCO ₃, 5.593g SrCO ₃, 7.567g TiO ₂, 0.1918g MgO puts into ball grinder with the material that weighs up, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 5 hours; With the material oven dry back briquetting that mixes, pre-burning is 2 hours under 1080 ℃ of temperature, and good material grinds to take out calcining, and ball milling is 10 hours again, sieves then; It is 12mm that powder after sieving is pressed into diameter in advance, and thickness is the disk of 1.3mm, then final molding under the hydrostatic pressure of 200MPa; Disk after the moulding is incubated 4 hours down at 1220 ℃; Sinter into after the porcelain, sanding and polishing, the silver coating slurry under 550 ℃, is incubated 30 minutes and burns till silver electrode then.Full-automatic X-ray diffractometer (D/Max2550VB+/PC) with Japan company of science is tested ceramic structure, carries out the test of temperature spectrum with the pottery of Agilent impedance instrument (4294A) after to quilt silver.(c) is the X ray diffracting spectrum of the barium-strontium titanate ceramic of doping 5mol.%Mg among Fig. 1, and as can be seen from Figure 1, prepared pottery does not have other dephasigns.As can be seen, its specific inductivity and dielectric loss are respectively 2089 and 0.00155 in the time of 25 ℃ from Fig. 2 and Fig. 3, and when extra electric field was 17kV/cm, its tuning rate was 15.8%.And near 0～50 ℃, it is more stable that the dielectric loss of material all keeps.

Embodiment 4, weighing 11.214g BaCO ₃, 5.593g SrCO ₃, 7.567g TiO ₂, 0.2685g MgO puts into ball grinder with the material that weighs up, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 8 hours; With the material oven dry back briquetting that mixes, pre-burning is 1 hour under 1100 ℃ of temperature, and good material grinds to take out calcining, and ball milling is 12 hours again, sieves then; It is 12mm that powder after sieving is pressed into diameter in advance, and thickness is the disk of 1.5mm, then final molding under the hydrostatic pressure of 200MPa; Disk after the moulding is incubated 3 hours down at 1260 ℃; Sinter into after the porcelain, sanding and polishing, the silver coating slurry under 550 ℃, is incubated 30 minutes and burns till silver electrode then.Full-automatic X-ray diffractometer (D/Max2550VB+/PC) with Japan company of science is tested ceramic structure, carries out the test of temperature spectrum with the pottery of Agilent impedance instrument (4294A) after to quilt silver.(d) is the X ray diffracting spectrum of the barium-strontium titanate ceramic of doping 7mol%Mg among Fig. 1, and as can be seen from the figure, prepared pottery does not have other dephasigns.As can be seen, its specific inductivity and dielectric loss are respectively 1946 and 0.0019 in the time of 25 ℃ from Fig. 2 and Fig. 3, and when extra electric field was 17kV/cm, its tuning rate was 15.2%.And near 0～50 ℃, it is more stable that the dielectric loss of material all keeps.

The present invention is to have prepared magnesium strontium titanate doping titanate ceramics about 1200 ℃ by traditional ceramic preparation technology in sintering temperature, it is lower that near the scope of dielectric loss broad room temperature of pottery keeps, specific inductivity and tuning rate are moderate, can satisfy the service requirements of microwave phase shifter.

Claims (1)

1. the preparation method of a barium-strontium titanate ceramic is characterized in that comprising the steps:

(a) with analytical pure BaCO ₃, SrCO ₃, TiO ₂, MgO is according to stoichiometric ratio Ba _xSr _1-x(Mg _yTi) O ₃Weighing and batching, x=0.5～0.7 wherein, y=0.01～0.07;

(b) material that will prepare is put into ball grinder, and in zirconia ball: material: alcohol is 3: 1: 1 ratio batch mixing ball milling, and the ball milling time is 4～8 hours;

(c) with ball milling material oven dry back briquetting, pre-burning is 1～4 hour under 1000～1100 ℃ of temperature, takes out to grind, and ball milling is 8～12 hours again, sieves then;

(d) to be pressed into diameter in advance be 12mm to the powder after will sieving, and thickness is the disk of 1～1.5mm, then at the hydrostatic pressure compacted under of 200MPa;

(e) disk after the moulding is incubated 3～5 hours down at 1180～1260 ℃, sinters porcelain into.

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