Synthesis and magnetic properties of the high-pressure scheelite-type GdCrO{sub 4} polymorph

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2012.04.044· OSTI ID:22149837

Climent-Pascual, E.; Gallardo-Amores, J. M.; Rabie, M. G. ^[1]; Doi, Y. ^[2]; Romero de Paz, J. ^[3]; Beuneu, B. ^[4]; Saez-Puche, R. ^[1]

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1. Departamento de Quimica Inorganica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2. Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)
3. CAI Tecnicas Fisicas, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
4. Laboratoire Leon Brillouin (CEA-CNRS), CEA/Saclay-91191 Gif-sur-Yvette cedex (France)

The scheelite-type polymorph of GdCrO{sub 4} has been obtained from the corresponding zircon-type compound under high pressure and temperature conditions, namely 4 GPa and 803 K. The crystal structure has been determined by X-ray powder diffraction. This GdCrO{sub 4} scheelite crystallizes in a tetragonal symmetry with space group I4{sub 1}/a (No. 88, Z=4), a=5.0501(1) A, c=11.4533(2) A and V=292.099(7) A{sup 3}. The thermal decomposition leads to the formation of the zircon-polymorph as intermediate phase at 773 K to end in the corresponding GdCrO{sub 3} distorted perovskite-structure at higher temperatures. Magnetic susceptibility and magnetization measurements suggest the existence of long-range antiferromagnetic interactions which have been also confirmed from specific heat measurements. Neutron powder diffraction data reveal the simultaneous antiferromagnetic Gd{sup 3+} and Cr{sup 5+} ordering in the scheelite-type GdCrO{sub 4} with a T{sub N}{approx}20 K. The magnetic propagation vector was found to be k=(0 0 0). Combined with group theory analysis, the best neutron powder diffraction fit was obtained with a collinear antiferromagnetic coupling in which the m{sub Cr{sup 5}{sup +}} and m{sub Gd{sup 3}{sup +}} magnetic moments are confined in the tetragonal basal plane according to the mixed representation {Gamma}{sub 6} Circled-Plus {Gamma}{sub 8}. Thermal decomposition of the GdCrO{sub 4} high pressure polymorph, from the scheelite-type through the zircon-type structure as intermediate to end in the GdCrO{sub 3} perovskite. Highlights: Black-Right-Pointing-Pointer New high pressure GdCrO{sub 4} polymorph crystallizing in the scheelite type structure. Black-Right-Pointing-Pointer It is an antiferromagnet with a metamagnetic transition at low magnetic fields. Black-Right-Pointing-Pointer We have determined its magnetic structure from powder neutron diffraction data. Black-Right-Pointing-Pointer Otherwise, the room pressure zircon-polymorph is a ferromagnet. Black-Right-Pointing-Pointer The paper will be a great contribution in the study of 3d-4f magnetic interactions.

• OSTI ID: 22149837
• Journal Information: Journal of Solid State Chemistry, Vol. 194; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTIFERROMAGNETISM
CHEMICAL PREPARATION
CHROMIUM IONS
GADOLINIUM IONS
GROUP THEORY
MAGNETIC FIELDS
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
NEUTRON DIFFRACTION
PEROVSKITE
PYROLYSIS
SPACE GROUPS
SPECIFIC HEAT
TETRAGONAL LATTICES
X-RAY DIFFRACTION
ZIRCON