钛酸铅晶体中3种Cu^(2+)离子中心的电子顺磁共振研究

Investigations of spin Hamitonian parameters for bivalent copper ion in lead titanate crystal

电子顺磁共振谱(EPR)参量对杂质离子局域结构极为敏感,对EPR参量的理论研究可以用来确定材料的离子占位和缺陷结构等。在晶体场理论基础上,采用高阶微扰方法,通过分析电子顺磁共振谱参量,确定了压电铁电材料PbTiO3晶体中3种Cu2+离子中心的局域结构。目前,对PbTiO3:Cu2+的EPR谱研究一般认为Cu2+离子在PbTiO3中只占据Ti4+位置。理论研究表明,除了传统认为的Cu2+离子占据Ti4+位置外,杂质Cu2+离子还可同时占据Pb2+位置,并给出了相应的缺陷结构。

Electron paramagnetic resonance （EPR） parameters are sensitive to the local structure of the impurity ions. Theoretical studies on the EPR parameters can be used to ascertain the ion location and defect structure of the impurity ions. Based on the analysis of EPR parameters, by the aid of the high-order perturbation method, the local structures of the three centers for Cu^2＋ ion in PbTiO3 are obtained. At present, it is widely accepted that the impurity transition ion would substitute for Ti site. This paper suggests that Cu^2＋ ion can substitute for both Ti^4＋ and Pb^2＋ sites. And the defect structures of the three impurity centers are also obtained.