title: Anomalous perovskite PbRuO3 stabilized under high pressure.
abstract: Perovskite oxides ABO3 are important materials used as components in electronic devices. The highly compact crystal structure consists of a framework of corner-shared BO6 octahedra enclosing the A-site cations. Because of these structural features, forming a strong bond between A and B cations is highly unlikely and has not been reported in the literature. Here we report a pressure-induced first-order transition in PbRuO3 from a common orthorhombic phase (Pbnm) to an orthorhombic phase (Pbn21) at 32 GPa by using synchrotron X-ray diffraction. This transition has been further verified with resistivity measurements and Raman spectra under high pressure. In contrast to most well-studied perovskites under high pressure, the Pbn21 phase of PbRuO3 stabilized at high pressure is a polar perovskite. More interestingly, the Pbn21 phase has the most distorted octahedra and a shortest Pb-Ru bond length relative to the average Pb-Ru bond length that has ever been reported in a perovskite structure. We have also simulated the behavior of the PbRuO3 perovskite under high pressure by first principles calculations. The calculated critical pressure for the phase transition and evolution of lattice parameters under pressure match the experimental results quantitatively. Our calculations also reveal that the hybridization between a Ru:t2g orbital and an sp hybrid on Pb increases dramatically in the Pbnm phase under pressure. This pressure-induced change destabilizes the Pbnm phase to give a phase transition to the Pbn21 phase where electrons in the overlapping orbitals form bonding and antibonding states along the shortest Ru-Pb direction at P > Pc.
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712.
authors.forename: J-G
authors.initials: JG
authors.lastname: Cheng
authors.forename: K E
authors.initials: KE
authors.lastname: Kweon
authors.forename: J-S
authors.initials: JS
authors.lastname: Zhou
authors.forename: J A
authors.initials: JA
authors.lastname: Alonso
authors.forename: P-P
authors.initials: PP
authors.lastname: Kong
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: Changqing
authors.initials: C
authors.lastname: Jin
authors.forename: Junjie
authors.initials: J
authors.lastname: Wu
authors.forename: Jung-Fu
authors.initials: JF
authors.lastname: Lin
authors.forename: S A
authors.initials: SA
authors.lastname: Larregola
authors.forename: Wenge
authors.initials: W
authors.lastname: Yang
authors.forename: Guoyin
authors.initials: G
authors.lastname: Shen
authors.forename: A H
authors.initials: AH
authors.lastname: MacDonald
authors.forename: Arumugam
authors.initials: A
authors.lastname: Manthiram
authors.forename: G S
authors.initials: GS
authors.lastname: Hwang
authors.forename: John B
authors.initials: JB
authors.lastname: Goodenough
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D011312:Pressure; D017975:Ruthenium Compounds / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D017356:Synchrotrons; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D017975:Ruthenium Compounds; C059910:perovskite; D007854:Lead; D014025:Titanium