摘要
Room-temperature Raman scattering and x-ray difraction measurements together with first principles calculations were employed to invetigate the behavior of disordered Pb(In_(1/2)Nb_(1/2))O_(3)(PIN)under pressure up to 50GPa.Raman spectra show broad bands but a peak near the 380cm^(-1) increases its intensity with pressure.The linewidth of the band at 550cm^(-1) also increases with pressure,while two of the Raman peaks merge above 6GPa.Above 16 GPa,we observe additional splitting of the band at 50cm^(-1).The pressure evolution of the diffraction patterns for PIN shows obvious Bragg peaks splitting above 16GPa;consistent with a symmetry lowering transition.The transition at 0.5 GPa is identified as a pseudo-cubic to orthorhombic(Pbam)structural change whereas the transition at 16GPa is istructure and associated with changes in linear compresibility and octahedral titling,and the transition at 30 GPa is associated to an orthorhombic to monoclinic change.First-principles calculations indicate that the Pbam structure is ground state with antiferrodisdortion consistent with experiment.
基金
sponsored by the Carnegie/Department of Energy Alliance Center(CDAC,DE-FC03-03NA00144)
Use of the Advanced Photon Source was supported by the U.S.Department of Energy under Contract No.DE-AC02-06CH11357
HPCAT operations are supported by CIW,CDAC,UNLV,and LLNL through funding from DOENNSA and DOE-BES,with partial instrumentation funding by NSF.M.A.acknowledges ONR grants N00014-14-1-0561.S.P.acknowledges ONR grants N00014-12-1-1034
The computations were possible,thanks to the Arkansas High Performance Computer Center at University of Arkansas.S.P.also appreciates Russian Foundation for Basic Research Grant No.14-02-90438_Ucr_a.
