Lamellar and filament-like crystals of misfit-layer compounds containing (Sm, Ta, S) and (Pb, Bi, Nb, S) elements

Journal Article · Sun May 15 04:00:00 EDT 2005 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2005.02.021· OSTI ID:20725932

Ohno, Youichi ^[1]

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1. Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Tochigi (Japan)

This paper presents the preparation and characterization of filament-like crystals as well as lamellar crystals for misfit-layer compounds containing (Sm, Ta, S) and (Pb, Bi, Nb, S) elements. They were grown by chemical-vapor transport reaction. The crystal structure and morphologies are investigated by transmission and reflection X-ray diffraction (XRD) and scanning electron microscopy (SEM). Filament-like crystals of (SmS){sub 1.19}TaS{sub 2} and {l_brace}(Nb{sub 1-y-z}Pb{sub y}Bi{sub z}S){sub 1.5}{r_brace}{sub 1+x}NbS{sub 2} are grown abundantly. They belong to a large family of 1Q/1H and 1.5Q/1H types of misfit-layer compounds. They have an asymmetric layered structure, constructed of Q (SmS and Nb{sub 1-y-z}Pb{sub y}Bi{sub z}S) and H (NbS{sub 2}) layers alternately stacked along the c axis. The lattice parameters of {l_brace}(Nb{sub 1-y-z}Pb{sub y}Bi{sub z}S){sub 1.5}{r_brace}{sub 1+x}NbS{sub 2} are scarcely dependent on the amounts of Pb and Bi in raw materials, excluding a slight distortion in a crystal structure from the orthorhombic to the monoclinic. A comparison with the XRD results of the lamellar crystals of (Pb{sub 1-y'}Bi{sub y'}S){sub 1+x'}(NbS{sub 2}){sub n} (n=1 and 2) shows that Bi is in a higher oxidation state than Pb. However, both elements are contained only slightly in the filament-like crystals. The preliminary two-probe measurements of the temperature-dependent resistance have been made. The results indicate that there are two distinct types with positive and negative temperature coefficients.

• OSTI ID: 20725932
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 5 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BISMUTH COMPOUNDS
CRYSTALS
FILAMENTS
LATTICE PARAMETERS
LAYERS
LEAD COMPOUNDS
MONOCLINIC LATTICES
NANOTUBES
NIOBIUM COMPOUNDS
RAW MATERIALS
SAMARIUM COMPOUNDS
SCANNING ELECTRON MICROSCOPY
SULFUR COMPOUNDS
TANTALUM COMPOUNDS
TEMPERATURE COEFFICIENT
TEMPERATURE DEPENDENCE
VALENCE
X-RAY DIFFRACTION