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Design of Low-Dimensional Optical and Magnetic Chalcogenide Materials

Portrait of Dr. Abishek K. Iyer, speaker, young man with dark hair and beard, standing in front of a coffee shop window
Dr. Abishek K. Iyer
Kanatzidis Group, Non-linear Optics
Northwestern University
iSTEM Building 2, Room 1218
Materials Chemistry and Nanoscience Seminar

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 Na1xKxAsQ2. 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., Ba2MAsQ5 (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 La3Ga1.67S7, La3Ag0.6GaCh7 (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 M2-xM'xP2S6. Inorg Chem 2021, 60 (6), 3502-3513.

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