Three series of quaternary rare-earth transition-metal pnictides with CaAl{sub 2}Si{sub 2}-type structures: RECuZnAs{sub 2}, REAgZnP{sub 2}, and REAgZnAs{sub 2}

Journal Article · Thu May 01 00:00:00 EDT 2014 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.03.009· OSTI ID:22334232

Stoyko, Stanislav S.; Ramachandran, Krishna K.; Blanchard, Peter E.R. ^[1]; Rosmus, Kimberly A.; Aitken, Jennifer A. ^[2]; Mar, Arthur ^[1]

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1. Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)
2. Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States)

Three series of quaternary rare-earth transition-metal pnictides REMM′Pn{sub 2} (M=Cu, Ag; M′=Zn; Pn=P, As) have been prepared by reaction of the elements at 800 °C, with crystal growth promoted through the addition of iodine. The extent of RE substitution is broad in these series: RECuZnAs{sub 2} (RE=Y, La-Nd, Sm, Gd–Lu), REAgZnP{sub 2} (RE=La–Nd, Sm, Gd–Dy), and REAgZnAs{sub 2} (RE=La-Nd, Sm, Gd-Dy). Powder and single-crystal X-ray diffraction analysis revealed that they adopt the trigonal CaAl{sub 2}Si{sub 2}-type structure (space group P3{sup ¯}m1, Z=1), in which Cu or Ag atoms are disordered with Zn atoms over the unique tetrahedrally coordinated transition-metal site. Magnetic measurements indicated Curie–Weiss behavior for several members of the RECuZnAs{sub 2} and REAgZnP{sub 2} series. Core-line X-ray photoelectron spectra (XPS) collected on some RECuZnAs{sub 2} members corroborate the charge assignment deduced by the Zintl concept for these compounds, (RE{sup 3+})(M{sup 1+})(Zn{sup 2+})(Pn{sup 3−}){sub 2}. Optical diffuse reflectance spectra and valence band XPS spectra established that these compounds are small band-gap semiconductors (up to ∼0.8 eV in REAgZnP{sub 2}) or semimetals (RECuZnAs{sub 2}). Band structure calculations also support this electronic structure and indicate that the band gap can be narrowed through appropriate chemical substitution (RE=smaller atoms, M=Cu, and Pn=As). - Graphical abstract: Cu or Ag atoms are disordered with Zn atoms over the tetrahedral site within relatively rigid [M{sub 2}Pn{sub 2}] slabs in three series of quaternary pnictides adopting the CaAl{sub 2}Si{sub 2}-type structure. - Highlights: • Three series (comprising 25 compounds) of pnictides REMM'Pn{sub 2} were prepared. • Cu or Ag atoms are disordered with Zn atoms within relatively rigid [M{sub 2}Pn{sub 2}] slabs. • They are semimetals or small band-gap semiconductors. • RECuZnAs{sub 2} and REAgZnP{sub 2} are generally paramagnetic.

• OSTI ID: 22334232
• Journal Information: Journal of Solid State Chemistry, Vol. 213; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
ATOMS
CRYSTAL GROWTH
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
IODINE
MAGNETIC PROPERTIES
MONOCRYSTALS
PARAMAGNETISM
PNICTIDES
RARE EARTHS
RHENIUM IONS
SEMIMETALS
SPACE GROUPS
SPECTRA
TRANSITION ELEMENTS
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
ZINC IONS