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

Abstract

Solid solutions BiMn 1-x Sc x O 3 (0 e x e 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 C2/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 g 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 g 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.

Ferroelectric-ferromagnetic correlations in BiMnO3 perovskite within Landau theory: comparison with experiment

“…A detailed structural study of BiMnO 3 suggests [13,14] that the material has a highly distorted perovskite structure (centrosymmetric space group C2/c) which is incompatible with the existence of ferroelectricity. In spite of this, there is an experimental evidence of ferroelectric order in a BiMnO 3 polycristaline samples [13,15,16].…”

“…In spite of this, there is an experimental evidence of ferroelectric order in a BiMnO 3 polycristaline samples [13,15,16]. The discussion concerning the origin of the ferroelectricity in this compound is still controversial.…”

“…∆C p (T ) is taken as the difference between the total specific heat of BiMnO 3 and that BiScO 3 [13]. In this manner, ∆C p (T ) represents only the magnetic part of the specific heat.…”

“…After a Fourier transform we can write g( r, r ) as: the mean-field part of the specific heat; thick solid line: experimental data [13] was taken as and finally:…”

Effects of doping on structural, physical, and chemical properties of multiferroic BiMnO₃ and BiCrO₃

“…10,11 It is interesting that at 0.0 ≤ x ≤ 0.5, the phase diagrams are very similar 9,10 Note that the a parameter for M = Sc with x ≥ 0.05 is given using the right-hand axis. to each other independent of the non-magnetic or magnetic substitution in the Mn-sublattice.…”