Ce2Ni2Cd—A New Intermediate-Valent Cerium Compound

• Published in: Journal of solid state chemistry 2000-02, Vol.150 (1), p.139-144
• Main Authors: Niepmann, Dirk, Pöttgen, Rainer, Künnen, Bernd, Kotzyba, Gunter
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity phenomena in semiconductors and insulators; crystal structure; Electronic transport in condensed matter; Exact sciences and technology; intermediate valency; intermetallic cerium compounds; Low-field transport and mobility; piezoresistance; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Physics; Saturation moments and magnetic susceptibilities; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1999.8567

Ce2Ni2Cd was synthesized by reacting the elements in a sealed tantalum tube using a high-frequency furnace with a water-cooled sample chamber. The structure was refined from single-crystal X-ray data: ordered U3Si2 type, P4/mbm, a=755.67(8) pm, c=375.14(6) pm, wR2=0.0408, 232 F2 values, and 13 parameters. A refinement of the occupancy parameters showed defects on the nickel site, resulting in a composition of Ce2Ni1.88(1)Cd for the crystal investigated. The structure may be described as an intergrowth of CsCl and AlB2 related slabs of compositions CeCd and CeNi2. Magnetic susceptibility measurements indicate intermediate-valent behavior of the cerium atoms. The susceptibility data can be fit to a modified Curie–Weiss expression with ΘP=−5.2(2) K, μexp=0.79(3) μB/Ce, and a temperature-independent contribution χ0=67.5(7)×10−9 m3/mol. Temperature-dependent resistivity measurements indicate metallic behavior with a specific resistivity of 140±20 μΩ cm at room temperature. Below 50 K the specific resistivity reveals a T2 dependence with ρ0=84.4(1) μΩ cm and A=0.0056(1) (μΩ cm)/K2.