Dual role of the six-coordinated molybdenum and lead ions in novel of photochromic properties of the molybdenum-lead-borate glasses

Abstract

Transparent glasses were prepared by conventional melting-quenching method in the xMoO(3).(100-x)[3B(2)O(3).PbO] system where 0<or=x<or=15 mol%. By increasing the MoO(3) content up to 20 mol% the PbMoO(4) crystalline phase appears. These systems exhibit a photochromic effect which can be induced through laser exposures (lambda=633 nm) directly on the bulk sample. Structural investigations by FTIR spectroscopy show that the photosensitive effect is due to a reduction of Mo(6+) to Mo(4+) and/or Mo(5+) promoted by the oxidation of Pb(2+) and some structural changes of the borate network.