摘要
铁电体是重要的物理器件材料之一,它们的自发极化性能在许多器件中得到广泛的应用。而铁电体中的顺电-铁电和铁电-铁电相变是一类重要的结构相变,研究这些相变,一方面可以获得产生铁电性微观机构的重要信息,另一方面对研制新的铁电材料及改进性能也有指导意义。低温铁电相变及共与晶体结构的关系是其中一个重要的分支。由于体系的复杂性及技术上难度的局限,迄今为止只有英国的Megaw等开展了这方面的研究。
Li_(0.025)Na_(0.975)NbO_3 undergoes a ferroelectric-ferroelectric phase transition at 180K (on cooling) or 260 K (on heating). The structure determinations of both phases have been carried out by single crystal diffraction analysis. The ferroelectric room-temperature phase is orthorhombic, with space group Pc2_1b; the cell parameters are a=5.508(3), b=15.521(6), c=5.568(2). The structure is same with Li_(0.02)Na_(0.98)NbO_3. The ferroelectric low-temperature phase is also orthorhomhie, a=5.497(7), b=7.913(18),c=5.565(10),V=242.1~3, Z=4. Thereis disordernal position distribution of 0(2)atoms iuthe low-temperature phase. Its'apparent space group' is P 2/n 2/n 2/n. The relation of the ferroelectric properties to the low-temperature phase structure is discussed.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1989年第1期7-9,共3页
Acta Physico-Chimica Sinica
基金
北京大学结构化学开放实验室009号课题
