Département de chimie moléculaire

A new family of highly emissive white phosphors is presented. These phosphors are based on original glassy Y aluminoborates (g-YAB) compns., obtained at low temps. without any melting, from nontoxic and low cost precursors through the generic polymeric precursor method. Their luminescence (PL) arises from structural defects, whose energy levels are widely extended within the large bandgap of these materials. One of the main objectives of this work, is to enhance the point defect concns. by accurately controlling the powder annealing (temp. and atm.) to generate intense and broadband PL. These g-YAB powders exhibit good thermal and chem. stabilities and tunable PL properties, from bluish to warm white emissions, by simply adjusting the annealing temps. The internal quantum yields of g-YAB powders were detd. using near UV excitations, which reached values {\textgreater}90{%}. The relative amts. of point defects were quantified by ESR and their distribution within the bandgap was detd. by thermally stimulated luminescence, and this defect d. was directly correlated to the PL properties. Based on these promising lighting properties, a prototype was firstly developed to est. the lighting performances of this new g-YAB phosphors family. [on SciFinder(R)]