Pressure-induced structural change in orthorhombic perovskite GdMnO₃

Abstract

Structural stability of the perovskite-type GdMnO 3 has been investigated by the synchrotron angle-dispersive x-ray diffraction technique up to 63 GPa in a diamond anvil cell. GdMnO 3 stays in an orthorhombic structure but undergoes an isostructural phase transition with ∼5% volume reduction at 50 GPa. In the parent orthorhombic phase, the compressions along a, b and c axes exhibit a large anisotropic behavior. With increasing pressure, our results show that the distortion and tilts of the MnO 6 octahedra are reduced continuously and the orthorhombic structure evolves towards higher symmetry. By fitting the observed pressure-volume data using the third-order Birch-Murnaghan equation of state, we obtain the bulk modulus B 0 = 156(3) GPa with B 0 = 6.5(3) for the starting orthorhombic phase. Upon decompression, the starting orthorhombic phase is recovered.

Pressure Impact on the Stability and Distortion of the Crystal Structure of CeScO3

“…For the ideal cubic perovskite structure, these angles are 180° and a deviation of these angles from 180º increases the lattice distortion while lowering the symmetry as well as the unit-cell volume. The behavior of the tilting angles of CeScO3 resembles the results reported from CaSnO3 and CaTiO3 17,46 , but it is different from the behavior reported for magnetic GdMnO3 11 and YAl0.25Cr0.75O3. 63 On the other hand, in Fig.…”

“…45 An extension of the pressure limits of this study will be needed to search for the existence of a pressure-driven phase transition in CeScO3 and to elucidate if such transition will be a second-order orthorhombic-tetragonal transition or a first-order one. 11 The anisotropy in the axial compressibility of CeScO3 (βa : βb : βc = 1.23 : 1.38 :…”

Origin of the large ferroelectric polarization enhancement under high pressure for multiferroic DyMnO3 studied by polarized and unpolarized neutron diffraction

“…It should be noted that there is no purely structural distortion induced by pressure up to 8 GPa, reported in previous high-pressure x-ray experiment at room temperature in RMnO 3 (R =Gd, Dy, Tb). [26][27][28] The gigantic ferroelectric polarization along the a-axis in DyMnO 3 , ∼1.0 µC/cm 2 , which appears below T ∼ 30 K for the pressure region above 4.0 GPa, can be explained by the exchange striction mechanism for the E-type magnetic ordering for Mn spins. [4,29,30] However, the large polarization is significantly reduced below T Dy N to ∼0.3 µC/cm 2 in zero magnetic field.…”

Structural change from Pbnm to R3̅c phase with varying Fe/Mn content in (1-x) LaFeO3.xLaMnO3 solid solution leading to modifications in octahedral tilt and valence states

“…Various physical phenomena such as ferromagnetism, ferroelectricity, multiferroicity, magnetoresistance are associated with ABO3 perovskites [1][2][3][4][5][6][7] which exhibit an extraordinary range of structures, physical properties, and chemical bonding [8,9]. There are various types of solid-state structural transitions [10,11] depending on the choice of A and B cations [12,13]. A lattice is cubic for a tolerance factor, t = 1 [14,15] with B-O-B bond angle, φ = 180° [16].…”