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Titolo:
Renormalization of the phase transition in lead phosphate, Pb-3(PO4)(2), by high pressure: structure
Autore:
Angel, RJ; Bismayer, U; Marshall, WG;
Indirizzi:
Univ Bayreuth, Bayer Geoinst, D-95440 Bayreuth, Germany Univ Bayreuth Bayreuth Germany D-95440 eoinst, D-95440 Bayreuth, Germany Univ Hamburg, Mineral Petrog Inst, D-20146 Hamburg, Germany Univ Hamburg Hamburg Germany D-20146 trog Inst, D-20146 Hamburg, Germany Rutherford Appleton Lab, ISIS Facil, Didcot OX11 0QX, Oxon, England Rutherford Appleton Lab Didcot Oxon England OX11 0QX 1 0QX, Oxon, England
Titolo Testata:
JOURNAL OF PHYSICS-CONDENSED MATTER
fascicolo: 22, volume: 13, anno: 2001,
pagine: 5353 - 5364
SICI:
0953-8984(20010604)13:22<5353:ROTPTI>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
PB3(PO4)2; PB3(P1-XASXO4)2; TRANSFORMATION; PARAMETERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
21
Recensione:
Indirizzi per estratti:
Indirizzo: Angel, RJ Virginia Polytech Inst & State Univ, Dept Geol Sci, Crystallog Lab, Blacksburg, VA 24060 USA Virginia Polytech Inst & State Univ Blacksburg VA USA 24060 USA
Citazione:
R.J. Angel et al., "Renormalization of the phase transition in lead phosphate, Pb-3(PO4)(2), by high pressure: structure", J PHYS-COND, 13(22), 2001, pp. 5353-5364

Abstract

The structure of the high-pressure phase of lead phosphate, Pb-3(PO4)(2), has been determined from neutron powder time-of-flight diffraction data. Rietveld refinement to data collected at a pressure of 1.93(1) GPa and room temperature yielded unit-cell parameters a = 5.4613(3) Angstrom c = 20.069(1) Angstrom, V = 518.41(4) Angstrom, The space group is R (3) over barm. Thestructure consists of PO4 tetrahedra together with ph atoms in two symmetrically distinct sites. Analysis of the anisotropic displacement parameters of the Pb and O atoms indicates that they are spatially disordered within the structure. A structural model including split sites for these atoms suggests that the local environments around the Pb atoms in the high-pressure phase are very similar to those found in the low-pressure phase. We concludethat the phase transition from C2/c to R (3) over barm symmetry occurs as a result of the disordering of the static displacements of the Pb2 atoms and not, to pressures of 1.93 GPa, as the result of the elimination of these displacements, The evolution of the structure of the monoclinic phase of lead phosphate with pressure was also followed. With increasing pressure there is an apparent decrease in the displacements of the Ph atoms from the symmetry points of the high-pressure phase, but that of Pb2 does not extrapolate to zero at the phase transition pressure.

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Documento generato il 07/07/20 alle ore 22:31:11