Yuko Satoh

Photoluminescence spectroscopy of highly oriented Y2O3:Tb crystalline whiskers

Abstract The crystalline state of terbium-containing yttria is one of the important candidates for uses to ultraviolet- and electron-excited green phosphors. To increase the intensity of green emission, structural design of the polycrystalline Y2O3:Tb was carried out using a chemical-vapor-deposition technique operated under atmospheric pressure. The green luminescence intensity was strongly dependent upon the concentration of Tb. The intensity of the photoluminescence at 542 nm obtained from ȥ100Ɂ oriented Y2O3:Tb whiskers was higher than that obtained from the uniform Y2O3:Tb polycrystalline film with random orientation.

Luminescence Properties of Y2O3:Tb3+ Whiskers Fabricated by Chemical Vapor Deposition

Luminescence properties of highly -oriented Y2O3:Tb3+ whiskers obtained by chemical vapor deposition on Si substrate have been investigated over a wide temperature range for different dopant concentrations. A considerable thermally stimulated increase of the green Tb3+ emission intensity was found in the temperature range of 98–433 K under 325 nm laser excitation. At temperatures higher than 433 K, the emission exhibits temperature quenching with the activation energy of ~0.98 eV. This behavior is discussed on the basis of the results of the time-decay measurements of the emission in the temperature range of 300–773 K. The thermally stimulated intensity increase is attributed to the thermal broadening of the photoluminescence excitation spectrum, whereas the temperature quenching is tentatively ascribed to the thermal activation of electrons from the excited 4f75d configuration to the conduction band. The decay time of the green Tb3+ emission exhibits shortening with increasing dopant concentration, which is considered in terms of the energy transfer processes between the Tb3+ ions.

Photoluminescence Properties of Y2O3:Eu Whiskers with Preferential Orientation

Highly oriented Y2O3 whiskers were obtained using a chemical vapor deposition technique under atmospheric pressure. Optimum growth conditions for obtaining the rapid growth rate of the crystal were determined. The whisker of Y2O3 oriented preferentially in the direction of the cubic structure under rapid growth conditions. Photoluminescence properties of highly oriented Y2O3:Eu whiskers were also examined. The luminescence intensity obtained from Y2O3:Eu whiskers was higher than that obtained from the continuous polycrystalline film of Y2O3:Eu with random orientation.