Application of secondary ion mass spectrometry in studies of niobium segregation in niobium-doped titanium dioxide

Secondary ion mass spectrometry (SIMS) is a powerful technique in the study of materials that demonstrate compositional changes as a function of depth from the surface. This is due to the high chemical sensitivity of SIMS (sensitive to ppb) and potential for high depth resolution. However, as a semi-quantitative technique, the application of SIMS to quantitative studies can be problematic without knowledge of the appropriate calibration information, which must be obtained through the use of carefully prepared reference specimens. In the present work, SIMS is used in the investigation of surface segregation in niobium doped polycrystalline TiO"2. This material has demonstrated important photo-catalytic properties with implications for alternative energy generation and environmentally-friendly water purification, but requires investigation in relation to surface versus bulk processing. The present paper demonstrates the use of SIMS in the quantitatively assessment of segregation in TiO"2 and the development of a calibration curve.