Synthesis, Structure, Magnetic and Optical Properties of Ternary Thio-Germanates: Ln₄(GeS₄)₃ (Ln = Ce, Nd)


Single crystals of two ternary thio-germanates containing rare-earth metals, Ln4(GeS4)3 (Ln = Ce (I), Nd (II)), have been isolated from the reaction of anhydrous rare-earth trichloride (LnCl 3) and ternary sodium thio-germanate (Na2GeS3) in evacuated quartz ampoules. We have determined the crystal structure of the compounds, which are isostructural to La4(GeS4) 3 and crystallize in trigonal system in the space group R3c with the cell dimensions: I, a = b = 19.375(3)Å, c = 8.028(2) Å, Z = 6; II, a = b = 19.250(3) Å, c = 7.949(2) Å, Z = 6. The structure is built with the complex network of two independent tricapped trigonal prisms of CeS9, in which Ge atoms occupy tetrahedral holes of sulfur atoms. The bulk synthesis of the two compounds has also been achieved by the stoichiometric combination of the elements. The magnetic and optical properties of the compounds have been investigated. The magnetic moments of 2.32 and 3.49 ?B for I and II, respectively, are in good agreement with the theoretical magnetic moments of Ce and Nd in the +3 oxidation state. The optical band gap of I is found to be located around 2.3 eV, while the optical band gap of II lies around 2.62 eV. In addition, Raman spectroscopic characterizations have also been performed for I, II, and La4(GeS4)3.



Keywords and Phrases

Crystal structure; Lanthanides; Magnetic property; Optical property; Thiogermanates

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Article - Journal

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© 2008 Wiley-VCH Verlag, All rights reserved.

Publication Date

01 Apr 2008