Structural studies have been carried out on SnO2 multilayer thin film grown by the Rheotaxial Growth and Thermal Oxidation method on A120 3 substrates. A preliminary analysis of the X-ray diffraction patterns shows that, in addition to the Sn0 2 cassiterite phase, a strong contribution from an orthorhombic Sn02 phase is present.
In the case of the 3-layer film, the orthorhombic phase is structurally and microstructurally stable after an annealing up to 32 h at 400 'C. The cation coordination is similar to that found in cassiterite, but the chains of edge-sharing [SnO6]8- octahedra run in a zig-zag fashion along the  direction, each straight unit containing four octahedra. The relationship between the two phases is discussed on the basis of structural simulations including twinning planes in the crystal structure.