A New Family of Self-Activated Phosphors

Abstract

A series of compounds were discovered which have the generalized formula R22+R4+R25+Og.Examination of single crystals of Pb~ZrP209 showed it to have hexagonal symmetry with aH ~ 10.08fl~ and CH ~ 23.29A. Five of the seven compounds studied (Ba2ZrP,209, Sr2ZrP209, Pb2TiP209, Ba2ZrAs2Og, and PbuZrAs2Og) were isostructural with PbuZrP2Og, and the seventh, Sr2ZrAs2Og, had optical properties closely related to the group. With the exception of Pb2TiP2Og, all of the compounds exhibited a broad band blue fluorescence, with an intensity maximum near 4800A, when excited by 25377~ radiation. By contrast, Pb2TiP.209 showed a weak orange fluorescence, more easily excited by 3650A radiation. Emission, absorption, and excitation data are presented.

Electronic Structures and Luminescence Properties of YNbO4 and YNbO4:Bi

“…The band gaps of YNbO and YNbO :Bi were determined by Grisafe and Fritsch (4) to be 4.3 and 3.6 eV from di!use re#ectance spectra, respectively. Similar results were obtained by Blasse and Bril (12) and Harrison and Blasse (13).…”

“…The valence band (VB) consists of mainly the O 2p orbital and the conduction band (CB) of the Nb 4d orbital. The band gap is estimated as 4.3 eV, which agrees well with our experimental result (4.4 eV) and others (4.3 eV) (4,12,13). The PDOS of Y is away from the region we are interested in; thus, we do not give any attention to them in the present report.…”

“…[13,14,15,16] decrease. Two angles of O [14]}Bi}O [20] and O [15]}Bi}O [18] are getting close to 1803.…”

“…In consideration of the angles, the orbital overlap between Bi and O [14,15,18,20] may increase. The distances of Bi}O [18,20] are longer than those of Bi}O [14,15] and the distance of Bi}O [13] is the shortest. Therefore, the charge transfer between Bi and O [13,14,15,16] may occur more easily than that between Bi and the other oxygen in view of distances and angles.…”

Synthesis, Characterization and Properties of Zirconium Oxide (ZrO2)-Doped Titanium Oxide (TiO2) Thin Films Obtained via Sol-Gel Process

“…Zirconium oxide (ZrO2) has good dielectric and optical properties [41,42] it has a high refraction index [43]. Additionally, it has a very good transparency on a broad spectral field [44], a great chemical stability and a threshold of resistance to high laser flow. All these properties led to miscellaneous applications such as optical filters, laser mirrors [45] or barriers layers from the heat [46].…”