Structural and magnetoresistive properties of La0.7Ca0.3Mn0.96(Al1-xInx)(0.04)O-3

Structural, magnetic, and transport properties of ABO(3)-type La0.7Ca0.3Mn0 .96(Al1-xInx)(0.04)O-3 are investigated. Different structure deformation fr om that in the A-site doping, characterized by the synchronous variation of the lattice constants b with c/root 2 versus the content of In in the comp ounds, is observed. The metal-semiconductor transition shows a strong In co ntent dependence. The transition temperature decreases monotonously from 18 0.7 to 103.4 K as x varies from 0 to 1, with a corresponding maximum resist ivity ranging from 2.9 to 410.8 Omega cm. The magnetoresistive properties o f the materials are strongly affected by the size mismatch between A- and B - site ions, and a relation similar to that presented by Hwang et al. [Phys . Rev. Lett. 75, 914 (1995)] is observed though controlling of the toleranc e factor, is realized by B- site doping. (C) 1999 American Institute of Phy sics. [S0021-8979(99)00907-X].