Microstructural and magnetic properties of bulk La_1−xPr_xMnO_3+δ (x = 0.2, 0.3, 0.5)

Abstract

The magnetic, structural and microstructural properties of bulk La_{1− x} Pr _x MnO_3+δ have been studied as a function of Pr doping. Magnetization versus temperature measurements show that La_0.8Pr_0.2MnO_3+δ undergoes one magnetic transition, while La_0.7Pr_0.3MnO_3+δ and La_0.5Pr_0.5MnO_3+δ exhibit two magnetic transitions. X-ray diffraction and transmission electron microscopy studies indicate that all these compounds share an orthorhombic structure, which is derived from and also closely related to the ideal perovskite structure. Besides physical properties, the salient contrast between microstructures in these compounds is that there are high-density oriented microdomains in La_0.8Pr_0.2MnO_3+δ, whereas La_0.7Pr_0.3MnO_3+δ and La_0.5Pr_0.5MnO_3+δ are free of these microstructural characteristics. A possible mechanism of domain formation is discussed.

Acknowledgements

The author would like to thank Professor Z. D. Zhang of the Magnetism and Magnetic Materials Division of this laboratory for stimulating discussions. Financial support with Grant Nos. 50325101 and 2002CB613503 are gratefully acknowledged.