Synthesis, thermal stability and structural transition of cubic SnS nanoparticles

Hegde, SS and Murahari, P and Fernandes, BJ and Venkatesh, R and Ramesh, K (2020) Synthesis, thermal stability and structural transition of cubic SnS nanoparticles. In: Journal of Alloys and Compounds, 820 .

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Abstract

Recently identified cubic polymorph of SnS (SnS-CUB) is a promising low-cost material for solar cell applications. We report on the thermal stability, structural and optical properties of SnS-CUB nanoparticles. The average crystallite size of cubic SnS nanoparticles synthesized by wet chemical method at 20 °C is about 34.9 nm and unit cell lattice parameter a = 11.59 à . We found that cubic phase remained structurally stable up to 400 °C even though sulfur is partially re-evaporated. The sample annealed at 450 °C contains both cubic and orthorhombic phases. When the annealing temperature is increased to 500 °C, the sample completely transforms to orthorhombic structure. Raman spectroscopy showed the formation of minor secondary phases Sn2S3 and SnO2 at temperatures �500 °C. Three distinct regions of weight loss are observed in thermogravimetric curve (TGA) of cubic SnS nanoparticles; around 300 °C, 600 °C and 800 °C. Weight loss of 10 observed near 600 °C was due to rapid re-evaporation of sulfur from SnS. Annealing at 500 °C decreases the direct optical bandgap value 1.68 eV�1.3 eV (direct), 1.0 eV (indirect) is also an indication of the structural transition of SnS-CUB to orthorhombic SnS. Cubic SnS nanoparticles were strongly absorbing light photons in the visible wavelength range of 400 nm�700 nm. The orthorhombic SnS with an indirect bandgap of 1 eV has extended the absorption edge to 1000 nm. By combining both cubic and orthorhombic SnS, the absorption can be extended to a wide wavelength range.

Item Type:	Journal Article
Publication:	Journal of Alloys and Compounds
Publisher:	Elsevier Ltd
Additional Information:	The copyright of this article belongs to Elsevier
Keywords:	Annealing; Crystallite size; Energy gap; Layered semiconductors; Nanoparticles; Optical properties; Sulfur; Synthesis (chemical); Thermodynamic stability; Thermogravimetric analysis, Annealing temperatures; Orthorhombic structures; Solar-cell applications; Structural and optical properties; Structural transitions; Thermogravimetric curve; Visible-wavelength range; Wet-chemical method, IV-VI semiconductors
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	09 Mar 2020 10:41
Last Modified:	09 Mar 2020 10:41
URI:	http://eprints.iisc.ac.in/id/eprint/64779

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