Optical spectroscopy of zinc metaphosphate glasses activated by Ce3+ and Tb3+ ions Caldiño, U. ; Speghini, A. ; Bettinelli, M. Abstract Publication: Journal of Physics Condensed Matter Pub Date: April 2006 DOI: 10.1088/0953-8984/18/13/017 Bibcode: 2006JPCM...18.3499C