Crystallographic Features and Tetragonal Phase Stability of PbVO₃, a New Member of PbTiO₃ Family.

Abstract

Structure D 2000Crystallographic Features and Tetragonal Phase Stability of PbVO 3 , a New Member of PbTiO3 Family. -The crystallographic properties of the title compound are characterized by synchrotron powder XRD between 12 and 570 K. At 300 K, PbVO3 crystallizes in the tetragonal space group P4mm with Z = 1 and is isotypic with PbTiO3. The tetragonal phase is stable over the whole temperature range studied. Under applied pressure, a tetragonal-to-cubic phase transition accompanied by an insulator-to-metal transition starts at ≈2 GPa at room temperature. -(BELIK*, A. A.; AZUMA, M.; SAITO, T.; SHIMAKAWA, Y.; TAKANO, M.; Chem. Mater. 17 (2005) 2, 269-273; Inst. Chem. Res., Kyoto Univ., Uji, Kyoto 611, Japan; Eng.) -W. Pewestorf

Emerging Multiferroic Memories

“…One can create a Type I multiferroic, for instance, by engineering the functionality on a site-by-site basis in model systems such as the perovskites (ABO 3 ) where one can make use of the stereochemical activity of an A-site cation with a lone pair (i.e., 6s electrons in Bi or Pb) to induce a structural distortion and ferroelectricity while inducing magnetism with the B-site cation. This is the case in the multiferroics BiFeO 3 [17], BiMnO 3 [18,19], and PbVO 3 [20][21][22][23]. From the microscopic view, it can be understood that the orientation of the lonepairs in the materials can give rise to local dipoles that can order thereby creating a net polarization as has been demonstrated with ab initio models ( Fig.…”

A new cubic perovskite in PbGeO3 at high pressures

“…, which exhibit prominent ionic character, the Pb 2+ cation shows strong polarization due to its 6s 2 lone-pair electrons, and usually forms covalent bonds with oxygen atom at ambient conditions (Trinquire and Hoffmann 1984;Häussermann et al 2001). The Pb-based oxide perovskites, such as PbTiO 3 and PbVO 3 (Sani et al 2002;Belik et al 2005), also crystallize in the distorted tetragonal perovskite structure (P4mm) at ambient conditions for the polarized character of the Pb 2+ cation. The normal compressibility of the PbGeO 3 cubic perovskite Phase II indicates that the polarized character of Pb 2+ cation is completely suppressed when Pb 2+ combines with Ge 4+ to form the oxide perovskite at high pressures.…”

“…Many novel phase transitions in perovskite compounds have been thus discovered. For instance, the cubic PbCrO 3 perovskite (Phase I) transforms reversibly to another cubic perovskite (Phase II) with a 9.8% volume collapse at the pressure of ∼1.6 GPa (Xiao et al 2010); the multiferroic material of PbVO 3 , which crystallizes in the polarized tetragonal perovskite (P4mm) structure at ambient conditions, changes reversibly to a cubic perovskite with >10% volume collapse at about 2 GPa (Belik et al 2005); BiCoO 3 has the same polarized structure as PbVO 3 at ambient conditions but transforms to the orthorhombic perovskite (Pnma) with a 13% volume reduction at 3-4 GPa, which is induced by the high-spin to low-spin electronic transition in Co 3+ cation and the complete suppression of the polarized character in the Bi 3+ cation (Oka et al 2010). Silicate perovskites are the primary mineral components in the Earth's lower mantle (Kesson et al 1998;Wood 2000).…”

Ion-Exchange Reactions for Two-Dimensional Quantum Antiferromagnetism

“…Both a-and c-axes show a linear increase with the ionic radius of A 2+ , except Pb. A deviation from the linear relation for A = Pb is due to the steric effect of the 6s 2 lone pair in Pb [57]. There is no B-site dependence because of the similar ionic radii.…”