Synthesis and properties of the Co{sub 7}Se{sub 8-x}S{sub x} and Ni{sub 7}Se{sub 8-x}S{sub x} solid solutions

We report the synthesis and elementary properties of the Co{sub 7}Se{sub 8-x}S{sub x} (x=0-8) and Ni{sub 7}Se{sub 8-x}S{sub x} (x=0-7) solid solutions. Both systems form a NiAs-type structure with metal vacancies. In general, the lattice parameters decrease with increasing x, but in the Ni{sub 7}Se{...

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Published inJournal of solid state chemistry Vol. 178; no. 5
Main Authors Miller, Virginia Lea, Lee, Wei-li, Lawes, Gavin, Ong, Nai-Phuan, Cava, Robert J.
Format Journal Article
LanguageEnglish
Published United States 15.05.2005
Subjects
COBALT COMPOUNDS
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
LATTICE PARAMETERS
MAGNETIC SUSCEPTIBILITY
NICKEL COMPOUNDS
PARAMAGNETISM
SELENIDES
SOLID SOLUTIONS
SOMMERFELD CONSTANT
SPECIFIC HEAT
SULFIDES
SYNTHESIS
VACANCIES
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Summary:We report the synthesis and elementary properties of the Co{sub 7}Se{sub 8-x}S{sub x} (x=0-8) and Ni{sub 7}Se{sub 8-x}S{sub x} (x=0-7) solid solutions. Both systems form a NiAs-type structure with metal vacancies. In general, the lattice parameters decrease with increasing x, but in the Ni{sub 7}Se{sub 8-x}S{sub x} system c increases on going from x=5 to 7. Magnetic susceptibility measurements show that all samples exhibit temperature-independent paramagnetism from 25-250K. Samples within the Co{sub 7}Se{sub 8-x}S{sub x} system, as well as Ni{sub 7}Se{sub 8} and Ni{sub 7}SeS{sub 7}, were found to be poor metals with resistivities of {approx}0.20 and {approx}0.06m{omega}cm at 300K, respectively. The Sommerfeld constant ({gamma}) was determined from specific heat measurements to be {approx}13mJ/mol{sub Co}K{sup 2} and {approx}7mJ/mol{sub Ni}K{sup 2} for Co{sub 7}Se{sub 8-x}S{sub x} and Ni{sub 7}Se{sub 8-x}S{sub x}, respectively.
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2004.11.013