X-Ray and Ultraviolet Luminescence of Li3Ta1−xNbxO4 Prepared by Flux Synthesis and Characterization of a New High Efficiency X-Ray Phosphor

• Published in: Journal of solid state chemistry Vol. 145; no. 1; pp. 110 - 115
• Main Authors: Miao, C.R., Torardi, C.C.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01-06-1999; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other solid inorganic materials; Photoluminescence; Physics; Ultraviolet radiation; Inorganic compounds; Lithium tantalates; Transition element compounds; Lithium niobates; Photoluminescence; X radiation; Experimental study
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1999.8229

The phase development and luminescence properties, under both X-ray and ultraviolet excitation, of the lithium orthotantalate–lithium orthoniobate system, Li3Ta1−xNbxO4 for x=0 to 1, were examined. Using a flux synthesis technique, it was found that the levels of Nb-doping in monoclinic Li3TaO4 and of Ta-doping in cubic Li3NbO4 are higher than previously reported. Under 30 kVp molybdenum X-ray excitation, Li3Ta1−xNb4O4 is an efficient blue-emitting phosphor with broadband emission, peaking in the range of 390 to 435 nm. For x=0 to 0.1, the overall luminescence efficiency is comparable to, or better than, a commercial calcium tungstate, CaWO4, Hi-Plus material. The composition Li3Ta0.995Nb0.005O4 demonstrates an overall luminescence efficiency that makes this phosphor 45% brighter than CaWO4 Hi-Plus, thereby making it a potentially attractive candidate for use in medical diagnostic imaging systems. Under ultraviolet excitation, broadband blue emission is also observed. For all the Li3Ta1−xNbxO4 (x>0) solid solutions, the emission peak maximums agree well with those seen under X-ray excitation and are the result of Nb5+ emission.