Color center formation in vacuum sintered Nd3xY3−3xAl5O12 transparent ceramics

Abstract

Color center formation was studied in vacuum sintered Nd3xY3−3xAl5O12 transparent ceramics. The primary color centers were F- and F+-centers as evidenced by optical absorption in the 250–400 nm wavelength range and the presence of an electron spin resonance (ESR) line at g=1.9977. Annealing in air at 1600 °C for 10 h reduced the number of color centers to below the detection limit of ESR. Color center formation is controlled by oxidation and reduction of Fe2+/3+ impurities.

Strong visible and near infrared luminescence in undoped YAG single crystals

“…Copyright 2011 Author(s (YAG) are widely used as host materials for transition and rare earth elements for laser, optoelectronic and scintillation applications. [1][2][3][4][5][6][7] They are the most important solid state laser host materials and the most promising scintillation materials. In addition to their technological importance, they possess many interesting optical properties.…”

“…16 However according to the current measurements, undoped YAG has multiple strong luminescence peaks, not only the 300 nm emission, which has been the focus of all the previous investigations on YAG crystals. [6][7][8][9][10][11][12][13][14][15][16] The UV emission in YAG has been suggested to result from self trapped excitons and antisite defects Y Al 3+ , 16 which have low formation energy as predicted by first principals calculations. 17 We attribute the new observed PL emission bands at 700 and 800 nm to Fe 3+ impurities for the following reasons: 1) Fe 3+ in either tetrahedral or octahedral sites has a broad emission in many materials between 700 nm 1000 nm; 18 and according to EPR studies, 19 Fe ion substitutes for the Al ion at both octahedral and tetrahedral sites in the YAG structure.…”

Direct thermal diffusion bonding of Nd:YAG/YAG composite transparent ceramics by vacuum sintering

“…The oxygen vacancies can produce strong light absorption through the formation of color centers associated with the generation of free electrons, i.e., F − and F + -center. It has been shown experimentally that the primary color centers in transparent vacuum sintered Nd:YAG were F and F + centers as evidenced by optical absorption in the 250-1100 nm wavelength range [30]. Just as most of rare-earth ions doped single crystals [31,32], the bonded ceramics after vacuum sintering are preferred to anneal in air to compensate oxygen vacancies, which caused the in-line transmittance of sample S3 which is higher than that of without annealing sample S2.…”

Effect of air annealing on the color center in Yb:Y3Al5O12 transparent ceramics with MgO as sintering additive

“…They hypothesized that SiO 2 doping, which is necessary for sintering Nd:YAG ceramics to transparent, causes color center formation. While in a recent study, Stevenson et al did not observe any Si-induced color centers using spectrophotometry in Nd:YAG ceramics [10]. They considered that color center formation was controlled by oxidation and reduction of Fe 2+/3+ impurities.…”