Structural, magnetic, and dielectric properties of solid solutions between BiMnO3 and YMnO3

Bi 1− x Y x MnO 3 (0.1≤ x ≤0.9) solid solutions were prepared by the high-pressure high-temperature method at 6 GPa and 1573 K. They crystallize in the GdFeO 3 -type perovskite structure with the Pnma symmetry. Crystal structures of Bi 0.9 Y 0.1 MnO 3 and Bi 0.5 Y 0.5 MnO 3 are studied by synchrotron X-ray powder diffraction at room temperature. Only one Neel temperature, T N , is found in samples with 0.1≤ x ≤0.9 in comparison with two Neel temperatures observed in YMnO 3 ( T N =29 and 39 K). Samples with 0.5≤ x ≤0.9 have almost constant T N =44 K, while T N starts to increase linearly for other compositions: T N =46 K for x =0.3, T N =58 K for x =0.2, and T N =68 K for x =0.1. Field-induced transitions from canted-antiferromagnetic states to antiferromagnetic states are detected at about 30 kOe for x =0.2 and 70 kOe for x =0.1. Dielectric constant increases below T N in samples with 0.5≤ x ≤1, while it decreases below T N in samples with 0.1≤ x ≤0.3. Our data suggest that a magnetic structure changes near x =0.4. By extrapolation, we could estimate lattice parameters ( a =5.9221 A, b =7.5738 A, and c =5.4157 A) and T N =79 K for a hypothetical Pnma modification of BiMnO 3 .