Design of Low-Dimensional Optical and Magnetic Chalcogenide Materials

Chalcogenides are compounds of the group-16 elements or chalcogens (Q), consisting of O, S, Se, and Te. Because O differs significantly in electronegativity (3.5 for O compared to 2.5 for S, 2.4 for Se, and 2.1 for Te), oxides are typically distinguished from the rest of the chalcogenides, which exhibit strongly covalent character. Metal chalcogenides have found applications in wide ranging areas as optical materials, magnetic materials, catalysis and as solid-state battery materials. My research has focused on the design of noncentrosymmetric chalcogenides for as nonlinear optical (NLO) materials in the infra-red (IR) region and the synthesis of 2D metal thiophosphates (M2P2S6) for magnetism.  Currently there are only three commercially used IR NLO materials AgGaS₂, AgGaSe₂ and ZnGeP₂. All these materials suffer from significant performance challenges from laser damage to crystal growth. First, I will discuss the development (new materials and crystal growth) of chalcoarsenates as a promising class because of their high powder second harmonic generation (SHG) coefficients,^1-2 followed by exploration of noncentrosymmetric rare-earth containing chalcogenides.^3-4 Next, I will discuss the synthesis of a promising class of 2D chalcophosphates (M₂P₂S₆) using P₂S₅ flux. The biggest bottleneck for these materials was the reaction times (> 3 months) and the use of P₂S₅ flux has enabled the search of new magnetic compounds in this family.⁵ 

1.    Iyer, A. K.; Cho, J. B.; Byun, H. R.; Waters, M. J.; Hao, S.; Oxley, B. M.; Gopalan, V.; Wolverton, C.; Rondinelli, J. M.; Jang, J. I.; Kanatzidis, M. G., Structure Tuning, Strong Second Harmonic Generation Response, and High Optical Stability of the Polar Semiconductors Na₁–_xK_xAsQ₂. Journal of the American Chemical Society 2021, 143 (43), 18204-18215.

2.    Iyer, A. K.; Cho, J. B.; Waters, M. J.; Cho, J. S.; Oxley, B. M.; Rondinelli, J. M.; Jang, J. I.; Kanatzidis, M. G., Ba₂MA_sQ₅ (Q = S and Se) Family of Polar Structures with Large Second Harmonic Generation and Phase Matchability. Chemistry of Materials 2022, 34 (11), 5283-5293.

3.    Iyer, A. K.; Rudyk, B. W.; Lin, X.; Singh, H.; Sharma, A. Z.; Wiebe, C. R.; Mar, A., Noncentrosymmetric rare-earth copper gallium chalcogenides RE₃CuGaCh₇ (RE=La–Nd; Ch=S, Se): An unexpected combination. Journal of Solid State Chemistry 2015, 229, 150-159.

4.    Iyer, A. K.; Yin, W.; Rudyk, B. W.; Lin, X.; Nilges, T.; Mar, A., Metal ion displacements in noncentrosymmetric chalcogenides La₃Ga_1.67S₇, La₃Ag_0.6GaCh₇ (Ch=S, Se), and La₃MGaSe₇ (M=Zn, Cd). Journal of Solid State Chemistry 2016, 243, 221-231.

5.    Chica, D. G.; Iyer, A. K.; Cheng, M.; Ryan, K. M.; Krantz, P.; Laing, C.; Dos Reis, R.; Chandrasekhar, V.; Dravid, V. P.; Kanatzidis, M. G., P₂S₅ Reactive Flux Method for the Rapid Synthesis of Mono- and Bimetallic 2D Thiophosphates M_2-xM'xP₂S₆. Inorg Chem 2021, 60 (6), 3502-3513.