PRESSURE-TEMPERATURE SENSORS - SOLUTION DEPOSITION OF RARE-EARTH-DOPED GARNET-FILMS

An aqueous route to the deposition of multicomponent metal oxide films is based upon the complexation of precursor metal nitrate salts by gl ycine, or other organic complexant, followed by spin-coating the homog eneous solution onto pre-treated silica substrates. Glycine serves to frustrate the formation of cation oxides, thus precipitation. Upon deh ydration, a glassy matrix results through which metal cations and nitr ate anions are homogeneously dispersed. Subsequent heating of coated s ubstrates initiates an oxidation-reduction reaction, which removes the organic matrix and residual nitrate leaving behind a film of the desi red oxide composition. Using this method, Sm:YAG (Sm: Y3Al(5)O(12)-gar net) films about 150 nm thick have been deposited. The respective phas es have been confirmed by powder X-ray diffraction measurements and fl uorescence spectroscopy. Analogous studies using powders generated by the same technique provided the parameters for optimizing processing c onditions to generate phase pure YAG films. The fluorescence emission wavelength and related lifetime of certain electronic transitions aris ing from metal cation dopants vary as a function of pressure and tempe rature suggesting their use as optical sensors. This work suggests the possible application of these films as pressure-temperature sensors i n a planar waveguide configuration or as a coating material for optica l fibers.