Magnetic, thermal, and electrical properties of La1-xCaxCrO3 (0≤x≤0.5) -: art. no. 214435

A broad range of measurements of La1-xCaxCrO3 (0less than or equal toxless than or equal to0.5) are presented. LaCrO3 is an insulating antiferromagnet with Neel temperature T-N=293 K. Substitution of Ca2+ for La3+ decreases T-N with a slope of -210 K/x; this is more rapid than that of Sr substitution (dT(N)/dx=-90 K/x) reported by [Tezuka J. Solid State Chem. 141, 404 (1998)]. Since Sr doping affects the Cr-O-Cr bond angles more severely, it is suggested that Ca doping provides a reliable measure of the influence of d-orbital vacancies on T-N. Ca doping induces a small ferromagnetic moment that rises rapidly at small doping and falls with x above x=0.05. At x=0.40, the ferromagnetic moment vanishes, but returns at x=0.50. In addition, the electrical resistivity at x=0.40 is significantly larger than at x=0.30 and 0.50. These observations near x=0.4 may signify a change in the spin structure associated with the magnetic lattice and coupling between the charge carriers and magnetism. Heat capacity measurements on x=0 and 0.20 reveal no discernible electronic term and Debye temperatures near 700 K. Comparisons are made with perovskite manganese oxides.