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Determination and Rietveld refinement of the crystal structure of Li0.50Ni0.25TiO(PO4) from powder X-ray and neutron diffraction

Published online by Cambridge University Press:  06 March 2012

B. Manoun ,
A. El Jazouli ,
P. Gravereau ,
J. P. Chaminade  and
F. Bouree
B. Manoun
Affiliation:
LCMS, UFR Science des Matériaux Solides, Faculté des Sciences Ben M’Sik (UH2M), Avenue Idriss El Harti, BP 7955, Casablanca, Morocco
A. El Jazouli*
Affiliation:
LCMS, UFR Science des Matériaux Solides, Faculté des Sciences Ben M’Sik (UH2M), Avenue Idriss El Harti, BP 7955, Casablanca, Morocco
P. Gravereau
Affiliation:
Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), 87, Av. du Dr A. Schweitzer-33608 Pessac Cedex, France
J. P. Chaminade
Affiliation:
Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), 87, Av. du Dr A. Schweitzer-33608 Pessac Cedex, France
F. Bouree
Affiliation:
Laboratoire Léon Brillouin (CEA-CNRS), CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
*
a)Author to whom correspondence should be addressed; electronic mail: [email protected]
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Abstract

The structure of the oxyphosphate Li0.50Ni0.25TiO(PO4) has been determined from conventional X-ray and neutron powder diffraction data. The parameters of the monoclinic cell (space group P21/c, Z=4), obtained from X-ray results, are: a=6.3954(6) Å, b=7.2599(6) Å, c=7.3700(5) Å, and β=90.266(6)°; those resulting from neutron study are: a=6.3906(7) Å, b=7.2568(7) Å, c=7.3673(9) Å, and β=90.234(7)°. Refinement by the Rietveld method using whole profile, leads to satisfactory reliability factors: cRwp=0.128, cRp=0.100, and RB=0.038 for X-ray and cRwp=0.110, cRp=0.120, and RB=0.060 for neutrons. The structure of Li0.50Ni0.25TiO(PO4) can be described as a TiOPO4 framework constituted by chains of tilted corner-sharing TiO6 octahedra running parallel to the c axis and cross linked by phosphate tetrahedra. In this framework, there are octahedral cavities occupied by Li and Ni atoms: Li occupies the totality of the 2a sites and Ni occupies statistically half of the 2b sites. Ti atoms are displaced from the center of octahedra units in alternating long (2.242 Å) and short (1.711 Å) Ti–O bonds along chains.

Keywords

Li0.50Ni0.25TiO(PO4)titanyl oxyphosphatestructure determinationRietveld refinementpowder diffractionX-raysneutrons
Type
Technical Articles
Information
Powder Diffraction , Volume 17 , Issue 4 , December 2002 , pp. 290 - 294
Copyright
Copyright © Cambridge University Press 2002

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