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Title: LnSrScO4 (Ln=La, Ce, Pr, Nd and Sm) systems and structure correlations for A {sub 2} BO{sub 4} (K{sub 2}NiF{sub 4}) structure types

Abstract

The compounds LnSrScO{sub 4}, where Ln=La, Ce, Pr, Nd and Sm, have been synthesized. Rietveld profile analysis of powder X-ray diffraction data collected at room temperature reveal that the compounds possess a modified K{sub 2}NiF{sub 4}-type structure with orthorhombic cell symmetry formed by tilting of the ScO{sub 6} octahedra. Variable temperature (25-1200 deg. C) powder X-ray diffraction data show that at the highest temperatures the structures of LaSrScO{sub 4} and PrSrScO{sub 4} transform to the regular tetragonal K{sub 2}NiF{sub 4}-structure type but the degree of orthorhombicity (c/a) in the unit cells initially increases on heating for all materials, reaching a maximum near 300 deg. C. This structural behavior is analyzed in terms of relative ionic radii of the various lanthanides and scandium. A general structural model based on tolerance factors has been developed for the family of materials A {sub 2} BO{sub 4} with various A and B cation sizes. - Graphical abstract: Tilting of the octahedra in K{sub 2}NiF{sub 4} structure type oxides (A {sub 2} BO{sub 4}) may be controlled by the A-type cation size and by temperature.

Authors:
 [1];  [1];  [2]
  1. School of Chemistry, University of Southampton, University Road, Highfield, Southampton SO17 1BJ (United Kingdom)
  2. School of Chemistry, University of Southampton, University Road, Highfield, Southampton SO17 1BJ (United Kingdom), E-mail: mtw@soton.ac.uk
Publication Date:
OSTI Identifier:
21015657
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2006.10.023; PII: S0022-4596(06)00569-X; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BORATES; CERIUM COMPOUNDS; LANTHANUM COMPOUNDS; NEODYMIUM COMPOUNDS; ORTHORHOMBIC LATTICES; OXIDES; PHASE TRANSFORMATIONS; PRASEODYMIUM COMPOUNDS; SAMARIUM COMPOUNDS; SCANDIUM COMPOUNDS; STRONTIUM COMPOUNDS; STRUCTURAL MODELS; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; X-RAY DIFFRACTION

Citation Formats

Patel, Rina, Simon, Charles, and Weller, Mark T. LnSrScO4 (Ln=La, Ce, Pr, Nd and Sm) systems and structure correlations for A {sub 2} BO{sub 4} (K{sub 2}NiF{sub 4}) structure types. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.10.023.
Patel, Rina, Simon, Charles, & Weller, Mark T. LnSrScO4 (Ln=La, Ce, Pr, Nd and Sm) systems and structure correlations for A {sub 2} BO{sub 4} (K{sub 2}NiF{sub 4}) structure types. United States. doi:10.1016/j.jssc.2006.10.023.
Patel, Rina, Simon, Charles, and Weller, Mark T. Mon . "LnSrScO4 (Ln=La, Ce, Pr, Nd and Sm) systems and structure correlations for A {sub 2} BO{sub 4} (K{sub 2}NiF{sub 4}) structure types". United States. doi:10.1016/j.jssc.2006.10.023.
@article{osti_21015657,
title = {LnSrScO4 (Ln=La, Ce, Pr, Nd and Sm) systems and structure correlations for A {sub 2} BO{sub 4} (K{sub 2}NiF{sub 4}) structure types},
author = {Patel, Rina and Simon, Charles and Weller, Mark T.},
abstractNote = {The compounds LnSrScO{sub 4}, where Ln=La, Ce, Pr, Nd and Sm, have been synthesized. Rietveld profile analysis of powder X-ray diffraction data collected at room temperature reveal that the compounds possess a modified K{sub 2}NiF{sub 4}-type structure with orthorhombic cell symmetry formed by tilting of the ScO{sub 6} octahedra. Variable temperature (25-1200 deg. C) powder X-ray diffraction data show that at the highest temperatures the structures of LaSrScO{sub 4} and PrSrScO{sub 4} transform to the regular tetragonal K{sub 2}NiF{sub 4}-structure type but the degree of orthorhombicity (c/a) in the unit cells initially increases on heating for all materials, reaching a maximum near 300 deg. C. This structural behavior is analyzed in terms of relative ionic radii of the various lanthanides and scandium. A general structural model based on tolerance factors has been developed for the family of materials A {sub 2} BO{sub 4} with various A and B cation sizes. - Graphical abstract: Tilting of the octahedra in K{sub 2}NiF{sub 4} structure type oxides (A {sub 2} BO{sub 4}) may be controlled by the A-type cation size and by temperature.},
doi = {10.1016/j.jssc.2006.10.023},
journal = {Journal of Solid State Chemistry},
number = 1,
volume = 180,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • The chemical preparation of rare earth nitridosilicates of the formula types, Ln{sub 3}Si{sub 6}N{sub 11} and LnSi{sub 3}N{sub 5} is reported. The samarium example (Sm{sub 3}Si{sub 6}N{sub 11}) was characterized by X-ray crystallography. The LnSi{sub 3}N{sub 5} compounds were found to be isostructural with the previously determined LaSi{sub 3}N{sub 5}.
  • Ln{sub 2}YbCuQ{sub 5} (Ln = La, Ce, Pr, Nd, Sm; Q = S, Se) have been prepared by direct reaction of the elements in Sb{sub 2}Q{sub 3} (Q = S, Se) fluxes at 900 °C. All compounds have been characterized by single-crystal X-ray diffraction methods and they are isotypic. The structure of Ln{sub 2}YbCuQ{sub 5} consists of one-dimensional {sup 1}{sub {infinity}} [YbCuQ{sub 5}]{sup 6-} ribbons extending along the b axis that are connected by larger Ln{sup 3+} ions. Each ribbon is constructed from two single chains of [YbQ{sub 6}] octahedra with one double chain of [CuQ{sub 5}] trigonal bipyramids inmore » the middle. All three chains connect with each other via edge-sharing. There are two crystallographically unique Ln atoms, one octahedral Yb site, and two disordered Cu positions inside of distorted Q{sub 5} trigonal bipyramids. Both Ln atoms are surrounded by eight Q atoms in bicapped trigonal prisms. The magnetic properties of Ln{sub 2}YbCuQ{sub 5} have been characterized using magnetic susceptibility and heat capacity measurements, while their optical properties have been explored using UV-vis-NIR diffuse reflectance spectroscopy. Cesub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, and Pr{sub 2}YbCuS{sub 5} are Curie-Weiss paramagnets. La{sub 2}YbCuSe{sub 5} and Nd{sub 2}YbCuS{sub 5} show evidence for short-range antiferromagnetic ordering at low temperatures. Sm{sub 2}YbCuS{sub 5} shows magnetic ordering at 5.9 K, followed by negative magnetization at low external fields. The band gaps of La{sub 2}YbCuSe{sub 5}, Ce{sub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, Pr{sub 2}YbCuS{sub 5}, Nd{sub 2}YbCuS{sub 5},and Sm{sub 2}YbCuS{sub 5} are 1.15 eV, 1.05 eV, 1.45 eV, 1.37 eV, 1.25 eV, 1.35 eV, and 1.28 eV respectively.« less
  • The new title compounds were prepared by reaction of the elemental components at high temperatures. They crystallize with a rhombohedral cell in space group R 3m. The structure was determined for Pr/sub 2/Mn/sub 17/C/sub 3-x/ (x = 1.23), which has the lattice constants a = 8.8714 (7) A and c = 12.783 (2) A with Z = 3 formula units in the hexagonal setting of the cell. The structure refinement from single-crystal X-ray data resulted in a residual of R = 0.023 for 25 variable parameters and 414 unique structure factors. The Pr and Mn positions correspond to those ofmore » the Th and Zn positions in Th/sub 2/Zn/sub 17/. The carbon atoms fill voids of nearly octahedral shape formed by a rectangle of Mn atoms (Mn-C distances 1.94 and 1.95 A) and two Pr atoms at 2.57 A. The idealized composition with all octahedral voids filled is Pr/sub 2/Mn/sub 17/C/sub 3/. The refinement of the occupancy parameter for this position resulted in a value of 59 +/- 3% for the crystal used for the structure determination. The discussion reviews the correspondence of binary intermetallic and ternary complex carbide phases. 28 references, 2 figures, 5 tables.« less
  • The crystal structures of Nd{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O and Eu{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O were determined by the conventional single-crystal X-ray diffraction technique. In addition, unit cell dimensions were measured for La{sub 2} (CrO{sub 4}){sub 3}{center dot}7H{sub 2}O and Sm{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O. All these compounds are isostructural. Crystals are monoclinic, space group P2{sub 1}/c. For Nd{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O, a=8.052(4){angstrom}, b=19.143(4){angstrom}, c=13.326(6){angstrom}, {beta}=128.15(4){degree}, Z=4, D{sub x}=3.14 Mg{center dot}m{sup {minus}3}, T=296(1); and for Eu{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O, a=7.965(3){angstrom}, b=18.985(4){angstrom}, c=13.185(4){angstrom}, {beta}=128.00(2){degree}, Z=4, D{sub x}=3.29 Mg{center dot}m{sup {minus}3}, T=296(1). Ln atoms aremore » nine-coordinated so that the coordination polyhedron is a tricapped trigonal prism for Ln1 and a monocapped square antiprism for Ln2. Structures form a three-dimensional network. Unit cell dimensions for La{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O are a=8.181(6){angstrom}, b=19.294(6){angstrom}, c=13.436(8){angstrom}, {beta}=128.09(6){degree} and those for Sm{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O are a=7.975(9){angstrom}, b=19.00(1){angstrom}, c=13.18(3){angstrom} and {beta}=127.5(2){degree}. Thermal behavior was investigated and IR spectra were recorded for Ln{sub 2}(CrO{sub 4}){sub 3}{center dot}7H{sub 2}O (Ln=La, Pr, Nd, Sm, Eu, Gd).« less
  • The orthorhombic crystal structures of the series of Ln{sub 4-x}In{sub 5-y}S{sub 13} (Ln=La, Ce, Pr and Nd; x=0.08-0.12, y=0.21-0.24) compounds were investigated by means of X-ray crystal diffraction. The crystals of La{sub 3}In{sub 1.67}S{sub 7} and Gd{sub 3}InS{sub 6} were also obtained unexpectedly from the La-In-S and Gd-In-S systems and no respective Gd{sub 4-x}In{sub 5-y}S{sub 13} was obtained. In the structures of the orthorhombic Ln{sub 4-x}In{sub 5-y}S{sub 13} series and hexagonal La{sub 3}In{sub 1.67}S{sub 7} indium atoms occupy disordered positions in the octahedral and trigonal antiprismatic arrangement of the sulphur atoms. The crystal structure of the La{sub 4}Ag{sub 2}In{sub 4}S{submore » 13} is also given and discussed as an example of quaternary sulphide related to a ternary La-In sulphide. - Graphical abstract: In the series of the Ln{sub 4-x}In{sub 5-y}S{sub 13} (Ln=La, Ce, Pr and Nd; x=0.08-0.12, y=0.21-0.24) compounds the indium atoms occupy disordered position in the octahedral arrangement of the sulphur atoms. The tetrahedral position is ordered.« less