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Title: Nickel deficiency in RENi{sub 2-x}P{sub 2} (RE=La, Ce, Pr). Combined crystallographic and physical property studies

Large single crystals from RENi{sub 2-x}P{sub 2} (RE=La, Ce, Pr) were synthesized from the pure elements using Sn as a metal flux, and their structures were established by X-ray crystallography. The title compounds were confirmed to crystallize in the body-centered tetragonal ThCr{sub 2}Si{sub 2} structure type (space group I4/mmm (No. 139); Pearson's symbol tI10), but with a significant homogeneity range with respect to the transition metal. Systematic synthetic work, coupled with accurate structure refinements indicated strong correlation between the degree of Ni-deficiency and the reaction conditions. According to the temperature dependent dc magnetization measurements, LaNi{sub 2-x}P{sub 2} (x=0.30(1)), as expected, is Pauli-like paramagnetic in the studied temperature regime, while the Ce-analog CeNi{sub 2-x}P{sub 2} (x=0.28(1)) shows the characteristics of a mixed valent Ce{sup 3+}/Ce{sup 4+} system with a possible Kondo temperature scale on the order of 1000 K. For three different PrNi{sub 2-x}P{sub 2} (x<=0.5) samples, the temperature and field dependence of the magnetization indicated typical local moment 4f-magnetism and a stable Pr{sup 3+} ground state, with subtle variations of T{sub C} as a function of the concentration of Ni defects. Field-dependent heat capacity data for CeNi{sub 2-x}P{sub 2} (x=0.28(1)) and PrNi{sub 2-x}P{sub 2} (x=0.53(1)) are discussed as well. -more » Graphical abstract: The non-stoichiometric RENi{sub 2-x}P{sub 2} phases (RE=La, Ce, Pr), whose average structure belongs to the ThCr{sub 2}Si{sub 2} type, are shown to exist with a wide range of defects on the transition metal site. The changes in the Ni-underoccupancy affect the magnetism of the synthesized materials.« less
Authors:
 [1] ;  [1] ; ; ; ;  [2]
  1. Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States)
  2. Materials Physics and Applications Division (MPA-10), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
Publication Date:
OSTI Identifier:
21370438
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 182; Journal Issue: 6; Other Information: DOI: 10.1016/j.jssc.2009.03.014; PII: S0022-4596(09)00126-1; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERIUM IONS; CERIUM PHOSPHIDES; CRYSTAL DEFECTS; CRYSTALLOGRAPHY; GROUND STATES; LANTHANUM PHOSPHIDES; MAGNETIZATION; MONOCRYSTALS; NICKEL PHOSPHIDES; PARAMAGNETISM; PRASEODYMIUM IONS; PRASEODYMIUM PHOSPHIDES; SPACE GROUPS; SPECIFIC HEAT; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; TETRAGONAL LATTICES; X RADIATION; X-RAY DIFFRACTION CERIUM COMPOUNDS; CHARGED PARTICLES; COHERENT SCATTERING; CRYSTAL LATTICES; CRYSTAL STRUCTURE; CRYSTALS; DIFFRACTION; ELECTROMAGNETIC RADIATION; ENERGY LEVELS; IONIZING RADIATIONS; IONS; LANTHANUM COMPOUNDS; MAGNETISM; NICKEL COMPOUNDS; PHOSPHIDES; PHOSPHORUS COMPOUNDS; PHYSICAL PROPERTIES; PNICTIDES; PRASEODYMIUM COMPOUNDS; RADIATIONS; RARE EARTH COMPOUNDS; SCATTERING; SYMMETRY GROUPS; TEMPERATURE RANGE; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPOUNDS