High-Pressure Synthesis and Properties of Solid Solutions between BiMnO3 and BiScO3

Solid solutions BiMn 1 - x Sc x O 3 (0 ≤ x ≤ 1) were prepared at 6 GPa and 1383−1443 K. Selected area and convergent beam electron diffraction showed that BiMn 0.9 Sc 0.1 O 3 crystallizes in the centrosymmetric space group C 2/ c at room temperature. The structure parameters of BiMn 0.9 Sc 0.1 O 3 were refined by the Rietveld method from laboratory X-ray diffraction data ( Z = 8; a = 9.6029(3) Å, b = 5.60988(14) Å, c = 9.7690(3) Å, β = 108.775(2°) at 293 K). The Mn−O bond lengths suggest that the orbital order present in BiMnO 3 at 300 K disappears in BiMn 0.9 Sc 0.1 O 3 . Therefore, the monoclinic-to-monoclinic phase transition observed in BiMnO 3 at 474 K and associated with the orbital melting was not detected in BiMn 1 - x Sc x O 3 for x ≥ 0.05 down to 133 K. BiMn 1 - x Sc x O 3 were characterized by dc and ac magnetization, specific heat, and differential scanning calorimetry measurements. The long-range ferromagnetic order seems to survive for x = 0−0.2. For x ≥ 0.4, the samples showed spin-glass-like features. The Weiss temperature deduced from the fitting of magnetic susceptibilities was positive for all the compositions with x < 1 and decreased monotonically with increasing x . The temperature of the magnetic transitions decreased and the temperature of the structural monoclinic-to-orthorhombic phase transition increased (from 768 K for x = 0 to 840 K for x = 0.3) with increasing x .