Phase and microstructural development of sol-gel-derived strontium barium niobate thin films

Microstructural changes in sol-gel-derived SrxBa1-xNb2O6 (SBN) thin films were monitored as a function of Ba-to-Sr ratio (from x = 0 to x = 1), choice of substrate (Si or MgO), and processing variations. Sols were created using Ba, Sr, and Nb alkoxides dissolved in acetic acid. The relatively high decomposition temperature for the organics led to a tendency to form defects, but careful control of thermal process parameters could be used to produce a uniform film microstructure. An unexpected phase, interpreted as a hexagonal (pseudo-orthorhombic) variant of hexagonal BaNb2O6, was encountered in Ba-rich sol-gel-derived SBN powders and thin films annealed at 750 degrees C. Increased (001) orientation was observed for SBN thin films deposited on (100) MgO when fast thermal processing was used.