【作者】 张华；

【导师】 李月明； 廖润华； 王竹梅；

【作者基本信息】 景德镇陶瓷学院 ， 材料学， 2010， 硕士

【摘要】 采用传统固相法制备了(Ca_1-xSr_x)_1-y(Li_1/2Sm_1/2)_yTiO₃（CSLST-y-x）基微波介质陶瓷,选用低熔点玻璃和氧化物为烧结助剂,研究各种烧结助剂对该微波介质陶瓷体系烧结性能、晶相组成、显微结构及微波介电性能的影响,并揭示低温烧结的内在机理。研究发现在y = 0.7～0.8,x=0～1/10范围内,CSLST-y-x体系均形成了单一的斜方钙钛矿结构,置换离子Sr²⁺的掺杂不会改变陶瓷体系的晶体结构,但能使烧结温度降低近200℃;y = 0.7,0.75,0.8时,陶瓷的最佳烧结温度分别为1 250,1 200,1 175℃;在烧结温度范围内,陶瓷的介电常数εr,品质因素Qf,谐振频率温度系数τf随y增大而减小;CSLST-0.7-1/16陶瓷在1 250℃保温5h具有良好的微波介电性能:εr= 118.3,Qf= 2989 GHz,τf= 47.49 ppm/℃;CSLST-0.75-1/16陶瓷在1200℃下保温5h陶瓷具有优良的微波介电性能:εr= 97.2,Qf= 2 490 GHz,τf= 14.74 ppm/℃。选用低熔点玻璃Li2O-B2O3-SiO2-CaO-Al2O3（LBSCA）、复合氧化物B2O3-CuO（BC）和B2O3-CuO-Li₂CO₃（BCL）为烧结助剂,对CSLST-y-1/16陶瓷进行了低温烧结性能研究。结果表明:烧结助剂的加入,不会改变CSLST-y-1/16陶瓷体系的主晶相,但陶瓷微波介电性能降低。（1）添加5.0～15.0 wt% LBSCA低熔点玻璃,可将CSLST-0.75-1/16陶瓷的烧结温度降低近300℃;随LBSCA添加量的增加,陶瓷的εr、Qf和τf值均下降;LBSCA添加量为5.0 wt%时,可在1 000℃烧结,陶瓷具有优良的微波介电性能:εr = 84.7,Qf = 2 446 GHz,τf = -12.48 ppm/℃;（2）添加2.0～14.0 wt% BC,CSLST-0.75-1/16陶瓷的烧结温度由1 200℃降低到1 000℃;BC添加量为5wt%时,1 000℃烧结时,具有较佳的微波介电性能:εr = 80.3,Qf = 1 380 GHz,τf = -32.89 ppm/℃;（3）添加BCL复合助剂可使CSLST-0.7-1/16陶瓷的烧结温度从1 250℃降低到950℃,当BC添加量为5wt%时,Li₂CO₃添加量为0.5 wt%时CSLST-0.7-1/16陶瓷具有优良的微波介电性能:εr =84.7,Qf = 1 929 GHz,τf =28.76 ppm/℃。通过对CSLST-y-x陶瓷体系及其低温烧结的研究,获得了一种可低温烧结且性能优良的微波介质陶瓷。更多还原

【Abstract】 (Ca_1-xSr_x)_1-y(Li_1/2Sm_1/2)_yTiO₃（CSLST-y-x） microwave dielectric ceramics were prepared by solid sate reaction technique in this dissertation. Using low melting point glass and oxide as sintering additives, the effects of different sintering aids on sintering characteristics, phase compositions, microstructures and dielectric properties of microwave ceramics were also studied. The low-temperature sintering properties and mechanisms of CSLST-y-x microwave dielectric ceramics were researched.The results show that a pure orthorhombic perovskite structure forms within the y range of 0.7-0.8 mol and x range of 0-1/10 mol; the best sintering temperatures of CSLST-y-x are 1 250, 1 200 and 1 175℃in the y range of 0.7, 0.75 and 0.8, respectively; the sintering temperatures of the Sr²⁺ modified the ceramics are efficiently decreased by nearly 200℃; the dielectric constantεr, the product of quality factor and resonance frequency （Qf ） value and the temperature coefficient of resonant frequencyτf decrease with the increasing of y content; the CSLST-0.7-1/16 ceramic sintered at 1 250℃for 5 h exhibits excellent microwave dielectric properties:εr= 118.3, Qf=2 989 GHz,τf= 47.49 ppm/℃; the CSLST-0.75-1/16 ceramic sintered at 1 200℃for 5 h exhibits excellent microwave dielectric properties:εr=97.2, Qf=2490 GHz,τf=14.74 ppm/℃.The low-temperature sintering of CSLST-y-1/16 microwave dielectric ceramics were researched by using Li2O-B2O3-SiO2-CaO-Al2O3（LBSCA）、B2O3-CuO （BC） and B2O3-CuO-Li₂CO₃ （BCL） as sintering additives. The results indicate that the major phase of additives-doped CSLST-y-1/16 ceramics is orthorhombic perovskite and dielectric properties of microwave ceramics are decreased. （1） The sintering temperature of CSLST-0.75-1/16 ceramics is reduced by 300℃using 5-15 wt% LBSCA as sintering additives. The sample of CSLST-0.75-1/16 with 5.0 wt% LBSCA sintered at 1 000℃for 5 h has excellent dielectric properties:εr = 84.7,Qf = 2 446 GHz,τf = -12.48 ppm/℃. （2） 2-14 wt% BC additives can effectively decrease the sintering temperature of CSLST-0.75-1/16 from 1 200℃to 1 000℃. The sample of CSLST-0.75-1/16 with 5 wt% BC sintered at 1 000℃for 5 h still has excellent dielectric properties:εr = 80.3, Qf = 1 380 GHz,τf = -32.89 ppm/℃. （3） BCL additives can effectively decrease the sintering temperature of CSLST-0.7-1/16 from 1 250℃to 1 000℃, The sample of CSLST-0.7-1/16 with 5 wt% BC and 0.5 wt% Li₂CO₃ can be sintered at 900℃for 5 h and still show excellent dielectric performance:εr = 84.7, Qf = 1 929 GHz,τf = 28.76 ppm/℃.A series of low-temprature sintering microwave dielectric ceramics with excellent dielectric properties would be achieved, based on the research of the microwave dielectric properties and the low-temperature sintering of CSLST-y-x ceramics.更多还原