Magnetic properties of solid solutions between BiCrO(3) and BiGaO(3) with perovskite structures

Magnetic properties of BiCr(1−x)Ga(x)O(3) perovskite-type solid solutions are reported, and a magnetic phase diagram is established. As-synthesized BiCrO(3) and BiCr(0.9)Ga(0.1)O(3) crystallize in a monoclinic (m) C2/c structure. The Néel temperature (T(N)) decreases from 111 K in BiCrO(3) to 98 K in BiCr(0.9)Ga(0.1)O(3), and spin-reorientation transition temperature increases from 72 K in BiCrO(3) to 83 K in BiCr(0.9)Ga(0.1)O(3). o-BiCr(0.9)Ga(0.1)O(3) with a PbZrO(3)-type orthorhombic structure is obtained by heating m-BiCr(0.9)Ga(0.1)O(3) up to 573 K in air; it shows similar magnetic properties with those of m-BiCr(0.9)Ga(0.1)O(3). T(N) of BiCr(0.8)Ga(0.2)O(3) is 81 K, and T(N) of BiCr(0.7)Ga(0.3)O(3) is 63 K. Samples with x = 0.4, 0.5, 0.6 and 0.7 crystallize in a polar R3c structure. Long-range antiferromagnetic order with weak ferromagnetism is observed below T(N) = 56 K in BiCr(0.6)Ga(0.4)O(3), T(N) = 36 K in BiCr(0.5)Ga(0.5)O(3) and T(N) = 18 K in BiCr(0.4)Ga(0.6)O(3). BiCr(0.3)Ga(0.7)O(3) shows a paramagnetic behaviour because the Cr concentration is below the percolation threshold of 31%.