Chemistry and Physics Faculty Articles

Document Type

Article

Publication Date

1-2-2015

Publication Title

Latin American Journal of Metallurgy and Materials

Keywords

Semiconductor alloys, X-Ray Diffraction, Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Optical Diffuse Reflectance UV/VIS/NIR Spectroscopy, Cu2GeTe4 and Cu2SnTe4

ISSN

0255-6952

Volume

35

Issue/No.

2

First Page

259

Last Page

268

Abstract

Polycrystalline samples (weight ~ 1g) of Cu 2 GeTe 4 and Cu 2 SnTe 4 alloys were prepared by the usual melt and anneal method and the products characterized by X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM) and Optical Diffuse Reflectance UV / VIS / NIR Spectroscopytechniques. It was found that: a) Cu 2 GeTe 4 and Cu 2 SnTe 4 crystallize in an orthorhombic structure (sg Imm2; N o44) with lattice parameters a = 5.9281 (4) Å, b = 4.2211 (6) Å, c = 12.645 (5) Å and a = 6.0375 (6) Å, b = 4.2706 (3) Å, c = 12.844 (1 ) Å, respectively; b) both alloys show two thermal transitions: 762 and 636K upon heating and; 700 and 578K upon cooling for Cu 2 GeTe 4 ; 702 and 636K upon heating and; 650 and 590K upon cooling for Cu 2 SnTe 4 ; c) both alloys present large deviations of stoichiometry for the cations Cu (~ 35%), Ge (7.2%) and Sn (26.4%) and minor deviation within the experimental error, for the anion Te; and, d) the measured optical band gaps were 0.63 and 0.53 eV for Cu 2 SnTe 4 and Cu 2 GeTe 4 , respectively.

Polycrystalline samples (weight ~ 1 g) of the Cu 2 GeTe 4 and Cu 2 SnTe 4 alloys were prepared by the melting and annealing method and the products characterized by the techniques of X-ray diffraction (XRD), Thermal Differential Analysis (ATD). ), Scanning Electron Microscopy (SEM) and UV / VIS / CIR diffuse optical reflectance spectroscopy. It was found that: a) Cu 2 GeTe 4 and Cu 2 SnTe 4 crystallize in an orthorhombic structure (ge Imm2; N o44) with network parameters a = 5.9281 (4) Å, b = 4.2211 (6) Å, c = 12.645 (5) Å and a = 6.0375 (6) Å, b = 4.2706 (3) Å, c = 12.844 (1) Å, respectively; b) both alloys show two thermal transitions: 762 and 636K when heating and; 700 and 578K after cooling for Cu 2 GeTe 4 ; 702 and 636K when heating and; 650 and 590K after cooling for Cu 2 SnTe 4 ; c) both alloys present important stoichiometric deviations in their cations: Cu (~ 35%), Ge (7.2%) and Sn (26.4%) and lower than the experimental error for the anion Te; and d) the optical energy gaps measured were 0.63 and 0.53 eV for Cu 2 SnTe 4 and Cu 2 GeTe 4, respectively.

ORCID ID

0000-0001-7825-8667

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