Resumo

QUINTERO, Miguel et al. LATTICE PARAMETER VALUES AND PHASE TRANSITIONS FOR THE Cu2-II-IV-S4(Se4) (II=Mn, Fe, Co; IV=Si, Ge, Sn) MAGNETIC SEMICONDUCTOR COMPOUNDS. Rev. LatinAm. Metal. Mater. [online]. 2014, vol.34, n.1, pp.28-38. ISSN 0255-6952.

X-ray powder diffraction measurements, at 300 K, and differential thermal analysis (DTA) were made on sixteen polycrystalline samples of Cu2-II-IV-S4(Se4) (II: Mn, Fe, Co; IV: Si, Ge, Sn) magnetic semiconductor compounds. The diffraction patterns were analyzed to determine lattice parameter values. The results showed that ten have tetragonal stannite I42m structure, one has tetragonal pseudo-cubic P4 structure, four an orthorhombic wurtz-stannite Pmn21 and two an orthorhombic pseudo-cubic F222 structure. When the values of the effective parameter ae = (V/N)^1/3 are plotted against its molecular weight W, it was found that the tetragonal and orthorhombic materials lie on the same straight line. The peaks on the DTA measurements were used to determine the type of melting as well as the melting temperature. The resulting data together with the Lindemann relation were used to estimate values for the Debye temperature θD as well as for the sound velocity in the material vs.

Palavras-chave : Semiconducting; X-ray diffraction (XRD); differential thermal analysis (DTA). .

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