CuMnGeS and CuMnGeS: two polar thiogermanates exhibiting second harmonic generation in the infrared and structures derived from hexagonal diamond

Jennifer R. Glenn, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Jeong Bin Cho, Department of Physics, Sogang University, Seoul, 04017, South Korea. jjcoupling@sogang.ac.kr.
Yiqun Wang, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208-3108, USA.
Andrew J. Craig, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Jian-Han Zhang, School of Resources and Chemical Engineering, Sangming University, Sanming, 365004, P.R. China.
Marvene Cribbs, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Stanislav S. Stoyko, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Kate E. Rosello, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Christopher Barton, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Allyson Bonnoni, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.
Pedro Grima-Gallardo, Centro de Estudios de Semiconductores, Departamento de Físcia, Facultad de Ciencias, Universidad de Los Andes, Mérida, 5101, Venezuela.
Joseph H. MacNeil, Department of Chemistry, Chatham University, Pittsburgh, PA 15232, USA.
James M. Rondinelli, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208-3108, USA.
Joon I. Jang, Department of Physics, Sogang University, Seoul, 04017, South Korea. jjcoupling@sogang.ac.kr.
Jennifer A. Aitken, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA. aitkenj@duq.edu.

Abstract

The new, quaternary diamond-like semiconductor (DLS) CuMnGeS was prepared at high-temperature from a stoichiometric reaction of the elements under vacuum. Single crystal X-ray diffraction data were used to solve and refine the structure in the polar space group CuMnGeS features [GeS] units and adopts the CuSiS structure type that can be considered a derivative of the hexagonal diamond structure. The DLS CuMnGeS with the wurtz-stannite structure was similarly prepared at a lower temperature. The achievement of relatively phase-pure samples, confirmed by X-ray powder diffraction data, was nontrival as differential thermal analysis shows an incongruent melting behaviour for both compounds at relatively high temperature. The dark red CuMnGeS and CuMnGeS compounds exhibit direct optical bandgaps of 2.21 and 1.98 eV, respectively. The infrared (IR) spectra indicate potentially wide windows of optical transparency up to 25 μm for both materials. Using the Kurtz-Perry powder method, the second-order nonlinear optical susceptibility, , values for CuMnGeS and CuMnGeS were estimated to be 16.9 ± 2.0 pm V and 2.33 ± 0.86 pm V, respectively, by comparing with an optical-quality standard reference material, AgGaSe (AGSe). CuMnGeS was found to be phase matchable at = 3100 nm, whereas CuMnGeS was determined to be non-phase matchable at = 1600 nm. The weak SHG response of CuMnGeS precluded phase-matching studies at longer wavelengths. The laser-induced damage threshold (LIDT) for CuMnGeS was estimated to be ∼0.1 GW cm at = 1064 nm (pulse width: = 30 ps), while the LIDT for CuMnGeS could not be ascertained due to its weak response. The significant variance in NLO properties can be reasoned using the results from electronic structure calculations.