Local structure and electron density distribution analysis of tin(II) sulfide using pair distribution function and maximum entropy method

Tin(II) sulfide (SnS) is a low symmetric orthorhombic double-layered dual bandgap semiconductor. It is low cost, toxic-free and highly abundant on Earth, with multifunctional optical, electronic, magnetic and light conversion applications when doped adequately with impurity. These physical properties can be understood only by the complete understanding of microstructural properties like average structure, electron density distribution inside the unit cell, bonding nature and local structure. In this work, the average and local structure, along with the electron density distribution of a nano crystallite sized single-phase sample of tin(II) sulfide is elucidated with the help of precise X-ray intensity data. The average structural information was extracted using Rietveld refinement analysis and the visual mapping of 3D, 2D and 1D electron density distribution inside the unit cell and its numerical contribution using maximum entropy method (MEM). The bonding between the first inter and intra bonding between Sn and S atoms is 2.65,105 angstrom and 3.2689 angstrom with mid bond electron density 0.907 e/angstrom(3) and 0.1688 e/angstrom(3) respectively. The inter-atomic correlations of 1st, 2nd and 3rd nearest neighbour atoms, their bond length, and the crystallite size are reported from pair distribution function (PDF) analysis using low Q-XRD data (Q similar to 6.5 angstrom(-1)). The PDF analysis shows that the first and second nearest Sn-S bonding distance is 2.6064 angstrom and 3.4402 angstrom, first is between the Sn and S atoms of the same layer and the other between the Sn and S atoms of the adjacent layers respectively.