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Title: PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}: Crystal structure and electronic properties

Abstract

The praseodymium cobalt aluminides, PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}, were prepared by reaction of the elemental components in an arc-melting furnace, followed by heat treatment at 900 deg. C for several days. Their chemical composition was checked by scanning electron microscopy and energy dispersive spectroscopy, and their crystal structure was refined from single crystal X-ray diffraction data. PrCo{sub 2}Al{sub 8} adopts the CaCo{sub 2}Al{sub 8} type of structure, crystallizing with the orthorhombic space group Pbam, with four formula units in a cell of dimensions at room temperature: a=12.4623(3)A, b=14.3700(4)A, c=4.0117(1)A. Pr{sub 2}Co{sub 6}Al{sub 19} crystallizes in the monoclinic space group C2/m, with four formula units in a cell of dimensions at room temperature: a=17.6031(4)A, b=12.1052(4)A, c=8.2399(2)A and {beta}=103.903(1){sup o}. Its structure belongs to the U{sub 2}Co{sub 6}Al{sub 19} type. The crystal structures of both compounds studied can be viewed as three-dimensional structures resulting from the packing of Al polyhedra centred by the transition elements. Along the c-axis, the coordination polyhedra around the Pr atoms pack by face sharing to form strands, which are separated one from another by an extended Co-Al network. Magnetic measurements have revealed that PrCo{sub 2}Al{sub 8} orders antiferromagnetically at T{sub N}=5K, with amore » clear metamagnetic transition occurring at a critical field H{sub c}=0.9(1)T. The temperature dependence of the susceptibility of Pr{sub 2}Co{sub 6}Al{sub 19} does not provide any evidence for long-range magnetic ordering in the temperature domain 1.7-300K. At low temperatures (T<10K), the susceptibility saturates in a manner characteristic of a non-magnetic singlet ground state. At high temperatures, the magnetic susceptibility of each compound follows a Curie-Weiss law, with the effective magnetic moment per Pr atom of 3.48(5){mu}{sub B} and 3.41(2){mu}{sub B} for PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}, respectively. These values are close to the theoretical value of 3.58{mu}{sub B} expected for a free Pr{sup 3+} ion and exclude any contribution due to the Co atoms. Both compounds exhibit in the temperature range 5-300K metallic-like electrical conductivity, and their Seebeck coefficient is of the order of several {mu}V/K. several {mu}V/K.« less

Authors:
 [1];  [2];  [3]
  1. Laboratoire de Chimie du Solide et Inorganique Moleculaire, Universite de Rennes1, LCSIM, UMR CNRS 6511, 263 avenue du General Leclerc, 35042 Rennes (France). E-mail: tougait@univ-rennes1.fr
  2. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)
  3. Laboratoire de Chimie du Solide et Inorganique Moleculaire, Universite de Rennes1, LCSIM, UMR CNRS 6511, 263 avenue du General Leclerc, 35042 Rennes (France)
Publication Date:
OSTI Identifier:
20784808
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 178; Journal Issue: 12; Other Information: DOI: 10.1016/j.jssc.2005.09.019; PII: S0022-4596(05)00416-0; Copyright (c) 2005 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; ALUMINIUM COMPOUNDS; CHEMICAL COMPOSITION; COBALT COMPOUNDS; CURIE-WEISS LAW; ELECTRIC CONDUCTIVITY; ELECTRONIC STRUCTURE; INTERMETALLIC COMPOUNDS; MAGNETIC SUSCEPTIBILITY; MONOCLINIC LATTICES; MONOCRYSTALS; ORTHORHOMBIC LATTICES; PRASEODYMIUM COMPOUNDS; PRASEODYMIUM IONS; SCANNING ELECTRON MICROSCOPY; SPACE GROUPS; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0273-0400 K; X-RAY DIFFRACTION

Citation Formats

Tougait, O., Kaczorowski, D., and Noel, H. PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}: Crystal structure and electronic properties. United States: N. p., 2005. Web. doi:10.1016/j.jssc.2005.09.019.
Tougait, O., Kaczorowski, D., & Noel, H. PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}: Crystal structure and electronic properties. United States. doi:10.1016/j.jssc.2005.09.019.
Tougait, O., Kaczorowski, D., and Noel, H. Thu . "PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}: Crystal structure and electronic properties". United States. doi:10.1016/j.jssc.2005.09.019.
@article{osti_20784808,
title = {PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}: Crystal structure and electronic properties},
author = {Tougait, O. and Kaczorowski, D. and Noel, H.},
abstractNote = {The praseodymium cobalt aluminides, PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}, were prepared by reaction of the elemental components in an arc-melting furnace, followed by heat treatment at 900 deg. C for several days. Their chemical composition was checked by scanning electron microscopy and energy dispersive spectroscopy, and their crystal structure was refined from single crystal X-ray diffraction data. PrCo{sub 2}Al{sub 8} adopts the CaCo{sub 2}Al{sub 8} type of structure, crystallizing with the orthorhombic space group Pbam, with four formula units in a cell of dimensions at room temperature: a=12.4623(3)A, b=14.3700(4)A, c=4.0117(1)A. Pr{sub 2}Co{sub 6}Al{sub 19} crystallizes in the monoclinic space group C2/m, with four formula units in a cell of dimensions at room temperature: a=17.6031(4)A, b=12.1052(4)A, c=8.2399(2)A and {beta}=103.903(1){sup o}. Its structure belongs to the U{sub 2}Co{sub 6}Al{sub 19} type. The crystal structures of both compounds studied can be viewed as three-dimensional structures resulting from the packing of Al polyhedra centred by the transition elements. Along the c-axis, the coordination polyhedra around the Pr atoms pack by face sharing to form strands, which are separated one from another by an extended Co-Al network. Magnetic measurements have revealed that PrCo{sub 2}Al{sub 8} orders antiferromagnetically at T{sub N}=5K, with a clear metamagnetic transition occurring at a critical field H{sub c}=0.9(1)T. The temperature dependence of the susceptibility of Pr{sub 2}Co{sub 6}Al{sub 19} does not provide any evidence for long-range magnetic ordering in the temperature domain 1.7-300K. At low temperatures (T<10K), the susceptibility saturates in a manner characteristic of a non-magnetic singlet ground state. At high temperatures, the magnetic susceptibility of each compound follows a Curie-Weiss law, with the effective magnetic moment per Pr atom of 3.48(5){mu}{sub B} and 3.41(2){mu}{sub B} for PrCo{sub 2}Al{sub 8} and Pr{sub 2}Co{sub 6}Al{sub 19}, respectively. These values are close to the theoretical value of 3.58{mu}{sub B} expected for a free Pr{sup 3+} ion and exclude any contribution due to the Co atoms. Both compounds exhibit in the temperature range 5-300K metallic-like electrical conductivity, and their Seebeck coefficient is of the order of several {mu}V/K. several {mu}V/K.},
doi = {10.1016/j.jssc.2005.09.019},
journal = {Journal of Solid State Chemistry},
number = 12,
volume = 178,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}