Introduction: Tin dioxide, is one of the many transparent conducting oxides, aroused the interest of researchers due to its wide range of applications. SnO₂ exists in a variety of polymorphs with different atomic structures, and Sn-O connectivity [1]. However, there are no comprehensive studies on the physical and chemical properties of SnO₂ polymorphs.

Methods and Results: For the first time, we investigated the structural stability, and ground state properties of eleven polymorphs in the sequence of experimental phases determined by density functional theory (DFT). Among the eleven phases Pnmb (62) structure is dynamically and mechanically unstable and Fm m and I4_1/amd are dynamically unstable, where the remaining eight phases satisfied all stability criteria. We calculated the elastic anisotropic and the directional dependent elastic modulus of all polymorphs. Electronic properties of the involved phases were calculated by employing the hybrid functional of Heyd, Scuseria, and Erhzerhof (HSE06) and the value scattered from 3.35 to 1.86 eV. The bonding nature of the global minimum rutile phase is analyzed from charge-density, charge-transfer, electron-localization-function given in figure 1.

Conclusion: Although many phases are available on SnO₂, rutile is of course promising candidate for many applications [2].

Figure 1: Calculated charge density (a), charge transfer (b), and electron localization function (c) plots for SnO₂ in rutile structure.

References:

1. Abello, L., Bochu, B., Gaskov, A., et al. “Structural characterization of nanocrystalline SnO2 by X-ray and Raman spectroscopy,” Journal of Solid State Chemistry, V. 135, No. 1, 1998, pp. 78–85.

2. Haines, J., and Léger, J. “X-ray diffraction study of the phase transitions and structural evolution of tin dioxide at high pressure: Relationships between structure types and implications for other rutile-type dioxides,” Physical Review B - Condensed Matter and Materials Physics, V. 55, No. 17, 1997, pp. 11144–54.

Keywords: Tin dioxide polymorphs, Electronic structure_, Structural stability.