Synthesis and characterization of the ternary compounds Cu2GeSe3 and Cu2GeTe3

This work reports the synthesis and characterization of the ternary compounds Cu2GeSe3 and Cu2GeTe3. Both samples were synthesized by using the direct fusion technique. The chemical analysis (EDX) confirmed the 2:13 stoichiometric ratio for both compounds. The thermal differential analysis (ATD) showed the existence of a single phase for Cu2GeSe3 that melts at 765 degreesC, and a principal phase for Cu2GeTe3 that melts at 504 degreesC. In the last compound, a second transition at 357 degreesC is also observed but with a peak area of less than 5% of total area, approximately. The X-ray powder diffraction analysis indicated that both compounds crystallize in the orthorhombic space group Imm2, with unit cell parameters: a = 11.8616(3) Angstrom, b = 3,9525(1) Angstrom, c = 5.4879(1) Angstrom, V = 257.29(1) Angstrom(3) for Cu2GeSe3, and a = 12.6406(6) Angstrom, b = 4.2115(2) Angstrom, c = 5.9261(2) Angstrom, V= 315.48(2) Angstrom(3) for Cu2GeTe3.