Crystal structure and optical spectroscopy of CaGdAlO4 : Er single crystal

The structure of CaGdAlO4, single crystal doped with Er has been refined by the Rietveld method using X-ray powder data. The crystal structure belongs to the tetragonal K2NiF4 type structure (space group I4/mmm, Z=4, a=3.6585 5(6) Angstrom, c=11.9787(3) Angstrom). Green and blue upconversion emission s from Er3+ in CaGdAlO4 at 550 nm, 440 nm and 407 nm due to the S-4(3/2)--> I-4(15/2), F-4(3/2)-->I-4(15/2) and H-2(9/2)-->I-4(15/2) transitions, respe ctively, under near-infrared (800 nm) Light pumping have been observed. (C) 2000 Elsevier Science S.A. All rights reserved.