铌铁酸锶-钛酸铅铁电固溶体的合成与性能研究

Preparation and electrical properties of (1-x)Sr(Fe_(1/2)Nb_(1/2))O_3-xPbTiO_3 ferroelectric solid-solution ceramics

通过铌铁矿预合成法制备了(1-x)Sr(Fe1/2Nb1/2)O3-xPbTiO3(SFN-PT)铁电陶瓷。XRD测量表明,合成的SFN-PT陶瓷为纯钙钛矿结构。随着PbTiO3(PT)摩尔分数的增加,SFN-PT陶瓷的晶体结构从三方相向四方相转变,其介电响应也从弥散的宽峰变得比较尖锐,并伴随着介电常数峰值温度(Tm)的升高。少量的MnO2或Li2CO3掺杂能有效地降低SFN-PT陶瓷的介电损耗。SFN-PT陶瓷呈现典型的P-E电滞回线,但是剩余极化强度较小,少量的MnO2或Li2CO3掺杂能明显地降低矫顽场、增大剩余极化强度。SFN-PT陶瓷的压电应变常量d33较小,随着组分的不同,d值在10～22pC/N之间变化。

（1 - x）Sr（Fe1/2Nb1/2 ）O3-xPbTiO3 （SFN-PT） ferroelectric ceramics were prepared by the conventional solid-state reaction method via the columbite precursor technique. XRD measurement confmned that the synthesized SFN-PT ceramics are of pure perovskite structure. With the increase of the mole fraction of PbTiO3 （PT）, the crystal structure of the synthesized SFN-PT ceramics changes from a rhombohedral structure to a tetragonal one. Dielectric response also changes from diffused and broad dielectric peaks to relatively sharp and almost frequency independent ones accompanied by an increase of the temperature of dielectric maximum （ Tm ）. A small content of MnO2 or Li2 CO3 doping can greatly decrease the dielectric loss of the SFN-PT ceramics. Furthermore, the abnormal increase of dielectric constant and loss tangent in the paraelectric region is accordingly suppressed. Typical P-E hysteresis loops are observed in the SFN-PT ceramics although the remanent polarization （PY） is small. MnO2 and Li2CO3 doping can greatly decrease coercive field （ E0 ） of the SFN-PT ceramics accompanied by large increase of PT. The piezoelectric constant d33 of the SFN-PT ceramics is small which changes from 10 pC/N to 22 pC/N.