Frustrated Orders in the Perovskite (Bi_0.5Sr_0.5)CrO₃

A new perovskite, (Bi 0.5 Sr 0.5 )CrO 3, has been prepared at 1000 °C and ambient pressure, although BiCrO 3 and SrCrO 3 are both high pressure phases. The crystal structure is rhombohedral ( R 3̅ c, a = 5.4652(5) and c = 13.3502(2) Å at 300 K). Well-defined local Bi 3+ displacements are evident despite an absence of long-range Bi/Sr cation order, but the degree of ferroelectric order is unclear. Long range G-type antiferromagnetic order occurs below 30 K; however, the low value of the ordered magnetic moment (1.2 μ B ), a high frustration index, and low temperature divergence of zero field and field cooled susceptibilities show that a substantial glassy component is also present.