The phase transition of the incommensurate phases beta-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb), crystal structures of alpha-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb) and Sc(PO{sub 3}){sub 3}

Journal Article · Wed Jul 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.02.036· OSTI ID:21370484

The incommensurately modulated room-temperature phases beta-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to alpha-Ln(PO{sub 3}){sub 3}(Ln=Y,Dy...Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (alpha-Dy(PO{sub 3}){sub 3},P2{sub 1}/c,Z=12,a=14.1422(6),b=20.0793(9),c=10.1018(4)A, beta=127.532(3){sup 0}). alpha-Tb(PO{sub 3}){sub 3} is isotypic with Gd(PO{sub 3}){sub 3}(alpha-Tb(PO{sub 3}){sub 3},I2/a,Z=16,a=25.875(6),b=13.460(3),c=10.044(2)A, beta=119.13(3){sup 0}). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO{sub 3}){sub 3} is isotypic with that of Lu(PO{sub 3}){sub 3} and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO{sub 4} tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed. - Abstract: Basic structure from which all crystal structures of the late lanthanoids' polyphosphates at room temperature and below can be derived.

• OSTI ID: 21370484
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 7 Vol. 182; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CATIONS
CHARGED PARTICLES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
IONS
MONOCLINIC LATTICES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHOSPHATES
PHOSPHORUS COMPOUNDS
RARE EARTH COMPOUNDS
SCANDIUM COMPOUNDS
SPECTROSCOPY
SYMMETRY
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION ELEMENT COMPOUNDS