Abstract: Tin dioxide (SnO₂) is an n-type semiconductor material with tetragonal rutile crystal structure under normal conditions and displays many interesting physical and chemical properties. Another form of SnO₂ with an orthorhombic crystal structure is known to be stable only at high pressures and temperatures. However, there are limited reports on effects of Mn-doped tetragonal phase SnO₂ on micro/nanostructured characteristics. In this article, micro/nanostructures of Mn-doped tetragonal phase SnO₂  have been successfully prepared with a chemical co-precipitation method. The micro/nanostructural evolution of Mn-doped tetragonal phase SnO₂ under different heat treatment temperatures is evaluated with X-ray diffraction (XRD) and a high-resolution transmission electron microscopy (HRTEM). It is surprisingly found that the orthorhombic phase SnO₂  is formed in Mn-doped tetragonal phase SnO₂ . The obvious diffraction peaks and clear lattice fringes confirm that the orthorhombic phase SnO₂  nanocrystals evidently exist in Mn-doped SnO₂ samples. Experimental results indicate that the XRD peak intensities and crystal planes of the orthorhombic phase SnO₂  decrease with increasing of heat treatment temperatures. Formation of orthorhombic phase SnO₂ is attributed to the lattice distortion of tetragonal phase SnO₂ due to the Mn-doped tetragonal phase SnO₂.

Key words: lattice distortion, micro-nanostructure, orthorhombic, tetragonal, tin dioxide (SnO₂)