【作者】 石维；

【导师】 朱建国；

【作者基本信息】 四川大学 ， 凝聚态物理， 2007， 硕士

【摘要】 采用一步法制备了(1-x)Pb(Sc1/2Ta1/2)O3-xPbTiO3(PSTT)和xPb(Sc1/2Ta1/2)O3-y -PbTiO3-zPbZrO3(PSTZT)弛豫铁电陶瓷。利用XRD、SEM、阻抗分析仪、压电工作站等,对PSTT和PSTZT陶瓷的晶体结构、表面形貌、介电性能、压电性能、热释电性能和铁电性能等进行了深入的分析、研究和对比。本论文的研究工作主要包括:1、利用一步法在1250℃制备出了钙钛矿相较高的PSTT陶瓷,其钙钛矿相受PT掺入量的影响,在同一温度烧结条件下,PT掺入量增加会提高PSTT(x)的钙钛矿相含量;适当过量的PbO有助于钙钛矿相的生成。2、一步法制备的PSTT陶瓷可以获得2500～3000的相对室温介电常数,其室温介电损耗较小,在0.01～0.03之间;最高峰值介电常数接近20000;PSTT(x)晶体结构和压电性能参数表明,一步烧结法制备的PSTT陶瓷的准同型相界在PSTT(45)附近,该组分压电性能较高,其平均压电常数d33在450 pC/N以上,机电耦合系数k p=0.58。PSTT(45)热释电系数为3.4×10-8C/cm2·K。3、通过采用等静压成型工艺与常规成型工艺对比,发现等静压成型所制备的PSTT材料性能优于常规成型。等静压成型的压电常数d33为546pC/N,机电耦合系数k p= 0.62;而同样烧结条件下,常规成型工艺制备的PSTT样品的d 33 = 446pC/N; k p= 0.5798。4、采用一步法制备了三元复相结构的A系PSTZT50和PSTZT54陶瓷,得到钙钛矿相结构含量较高的PSTZT陶瓷样品。发现PSTZT50-78更接近该体系陶瓷的准同型相界,其压电常数d 33 = 323pC/N,机电耦合系数k p=0.52。而在PSTZT54系中随PZ成分的变化,并没观察到明显d33峰值,且相对起伏不大,维持在60pC/N附近。5、当PSTZT固溶体系的x>0.83,PZ成分效应明显,可以把Sc3+和Ta5+认为是掺杂离子,Sc3+和Ta5+掺杂离子可能取代PZT中B位的Ti4+和Zr4+。根据电荷守恒定律,这种取代的结果会在PSTZT中诱导大量氧空位和Pb空位,并且氧空位和Pb空位B位的PZT陶瓷体系中形成缺陷偶极子。这些缺陷偶极子便形成钉扎点阻碍PSTZT电畴壁的运动,因此PSTZT陶瓷电滞回线出现了“束腰”形状。更多还原

【Abstract】 In this thesis, relaxor ferroelectric ceramics (1-x)Pb(Sc1/2Ta1/2)O3-xPbTiO3 (PSTT) and xPb(Sc1/2Ta1/2)O3-yPbTiO3-zPbZrO3(PSTZT) with B-site ions was prepared by one-step sintering method. The properites of PSTT and PSTZT ceramics were analyzed, researched and compared deeply by XRD, SEM, etc., including crystalline, micostructure, dielectric, piezoelectric, pyroelectric and ferroelectric properties. In this paper, our work includes:1、PSTT ceramics with pure perovskite phase were obtained by one-step sintering method and sintered at 1250℃. The content of perovskite phase of PSTT ceamics was affected by PT content. At the same sintering temperature and time, the higher the PT content was, the purer the perovskite phase of PSTT ceramics was. Appropriate excess PbO is helpful to obtain the pure perovskite phase of PSTT ceramics.2、Reletive dielectric constant of PSTT ceramics prepared by one-step sintering method could achieved 2500~3000 at room temperature and 1kHz, and its dielectric loss at room temperature was lower, about 0.01 to 0.03. The highest peak dielectric constant was nearly to 20000. The crystalline and piezoelectric properties of PSTT(x) indicate that the MPB are close nearly to PSTT(45), because there was d33 of about more 450 pC/N and kp of about 0.58 at x=0.45. The pyroelectric coefficient of PSTT(45) was about 3.4×10-8C/cm2·K.3、Two different processing (isostantic processing and ordinary processing) were also used to prepare PSTT ceramics in this dissertation. The properties of PSTT ceramics prepared by using the isostantic processing were superior to those of PSTT ceramics prepared by using ordinary processing. It had been found that the best piezoelectric constant d33=546pC/N and elecromechanical coupling facor kp=0.62 of PSTT ceramics prepared by isostantic processing, however, the best d33 =446pC/N and kp=0.5798 of PSTT ceramics prepared by using ordinary processing.4、PSTZT ceramics with high content of perovskite phase were prepared by one-step-sintering-mothed. It was found that the MPB of the PSTZT50 system lies in the range of PZ=0.75~0.78. The best properties of the PSTZT50 ceramics were that d33=324 pC/N and kp=0.52 at PZ=0.78. But in PSTZT54 system, no apparent d33 peaks could be observed when PZ content changed and d33 value fluctuated without abrupt jump at about 60pC/N.5、Pinched hysteresis loops were founded in PSTZT ceramics when x =0.83～0.93. This is due to the pinned domain walls of the dipolar defects, and the Sc3+ and Ta5+ ions maybe substituted for the Ti4+ and Zr4+ ions in B site of PZT system. The results show the normal domain rotation is impeded by the slow response of defect dipoles, which leads to unsaturated loop, but the impurities pinning could be removed through rising temperature and decrease the freqency.更多还原