Formation and thermo-assisted stabilization of luminescent silver clusters in photosensitive glasses

Abstract

Various photo-induced silver luminescent centres were obtained in photosensitive zinc and phosphate glasses containing silver ions after exposure to gamma or ultraviolet nanosecond pulsed-laser radiation. Gamma-irradiation of the glasses results mainly in the formation within the glass of electron-trapped and hole-trapped silver centres as evidenced by optical absorption, luminescence and electron spin resonance spectroscopies. For the highest irradiation doses silver clusters are obtained. Under ultraviolet nanosecond pulsed-laser exposure similar species are generated along the beam propagation direction as proven by the analogous optical and luminescence signatures. In this case for high irradiation doses few silver clusters are created. The evolution of the luminescence spectra with respect to the temperature and to the duration of the heat treatment after ultraviolet nanosecond pulsed-laser irradiation evidences the presence of potential barriers determining the stability limits of some species such as the Ag2+ hole-trapped centres or the Agmx+ clusters composed of silver ions and silver atoms. A heat treatment of several hundreds of degrees is identified as a the key parameter for tailoring the optical properties and controlling the formation of Agmx+ clusters in the photosensitive glasses.