Crystal and electronic structures of CaAl{sub 2}Si{sub 2}-type rare-earth copper zinc phosphides RECuZnP{sub 2} (RE=Pr, Nd, Gd-Tm, Lu)

Journal Article · Sat Jan 15 04:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.11.001· OSTI ID:21494177

Blanchard, Peter E.R.; Stoyko, Stanislav S; Cavell, Ronald G ^[1]; Mar, Arthur ^[1]

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1. Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

The quaternary rare-earth phosphides RECuZnP{sub 2} (RE=Pr, Nd, Gd-Tm, Lu) have been prepared by reaction of the elements at 900 {sup o}C, completing this versatile series which forms for nearly all RE metals. They adopt the trigonal CaAl{sub 2}Si{sub 2}-type structure (Pearson symbol hP5, space group P3-bar m1, Z=1), as confirmed by single-crystal X-ray diffraction analysis on ErCuZnP{sub 2} and powder X-ray diffraction analysis on the remaining members. The Cu and Zn atoms are assumed to be disordered over the single transition-metal site. Band structure calculations on a hypothetically ordered YCuZnP{sub 2} model suggest a semimetal, with a zero band gap between the valence and conduction bands. This electronic structure is supported by XPS valence band spectra for RECuZnP{sub 2} (RE=Gd-Er), in which the intensity drops off smoothly at the Fermi edge. The absence of a band gap permits the electron count to deviate from the precise value of 16 e{sup -} per formula unit, as demonstrated by the formation of a solid solution in GdCu{sub x}Zn{sub 2-x}P{sub 2} (1.0{<=}x{<=}1.3), while still retaining the CaAl{sub 2}Si{sub 2}-type structure. Because the Cu 2p XPS spectra indicate that the Cu atoms are always monovalent, the substitution of Cu for Zn leads to a decrease in electron count and a lowering of the Fermi level in the valence band. The magnetic susceptibility of RECuZnP{sub 2} (RE=Gd-Er), which obeys the Curie-Weiss law, confirms the presence of trivalent RE atoms. -- Graphical abstract: The absence of a band gap in the semimetallic quaternary rare-earth phosphides RECuZnP{sub 2} permits the formation of a solid solution such as GdCu{sub x}Zn{sub 2-x}P{sub 2} through hole-doping of the valence band. Display Omitted

• OSTI ID: 21494177
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 184; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COHERENT SCATTERING
COPPER COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
CURIE-WEISS LAW
DIFFRACTION
DISPERSIONS
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
FERMI LEVEL
HOMOGENEOUS MIXTURES
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MIXTURES
MONOCRYSTALS
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PHYSICAL PROPERTIES
PNICTIDES
RARE EARTH COMPOUNDS
SCATTERING
SEMIMETALS
SOLID SOLUTIONS
SOLUTIONS
SPACE GROUPS
SPECTRA
SPECTROSCOPY
SYMMETRY GROUPS
TRANSITION ELEMENT COMPOUNDS
TRIGONAL LATTICES
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
ZINC COMPOUNDS
ZINC PHOSPHIDES