摘要
采用基于柠檬酸体系的溶胶-凝胶法制备了Pr0.7(Sr1-xCax)0.3MnO3系列的多晶块材,同时还用脉冲激光沉积技术(PLD)在SrTiO3(100)衬底上外延生长了同一系列的薄膜,系统研究了它们的晶格结构和电输运行为.多晶和薄膜样品都具有正交晶格结构,电输运行为在居里温度TC以上的高温顺磁相都很好地符合了绝热小极化子模型.用绝热小极化子模型对两者的电阻率温度曲线进行拟合,多晶和薄膜样品的拟合结果在定性上是一致的.随着Ca掺杂量的增加,极化子跳迁能Ehop变大,ρ0先减小后增大.实验结果说明,只要多晶样品制备的质量好,缺陷、晶界的影响可以大大降低,多晶样品的电输运行为也能表现出本征的小极化子性质.
We have synthesized polycrystalline bars of Pr0.7（Sr1-xCax）0.3MnO3（x = 0,0.1,…, 1）with a sol-gel method using citrate as an agent, and grown epitaxial thin films of Pr0.7（Sr1-xCax）0.3MnO3 on （ 100）-oriented substrates of SrTiO3 （ STO ） by using pulsed laser deposition （ PLD ）. We systemically investigated their lattice structures and electronic transport property. Both polycrystalline and film samples have orthorhombic lattice structure, and their electronic transport behaviors nicely follow a adiabatic small polaron model in high temperature paramagnetic phase when T is larger than the Curie temperature Tc. All resistivity data have been fitted by the small polaron model. The fitted results of pelycrystalline samples qualitatively agree with that of corresponding film samples. With increasing contents of Ca, pelaron hopping energy Ehop increases monotoniccaly, and Po first decreases, then increases. The above results indicate that electronic transport property of high quality polycrystalline samples is less influenced by lattice defects and grain boundaries which are abundant in low quality samples, such that intrinsic small polaron transport behavior can appear in the former.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第7期4901-4907,共7页
Acta Physica Sinica
