1 Section of Chemistry, The Faculty of Engineering and Science, Aalborg University, VBN2 Department of Chemistry and Bioscience, The Faculty of Engineering and Science, Aalborg University, VBN3 Inorganic Amorphous Materials, The Faculty of Engineering and Science, Aalborg University, VBN4 The Faculty of Engineering and Science, Aalborg University, VBN5 Qilu University of Technology6 Ocean University of China7 Ocean University of China
We study the impact of the Nd-doping on the grain formation, the crystal structure, and the fluorescence of the Yttrium Aluminum Garnet (YAG). The results show that Nd-doping leads to the YAG lattice expansion and distortion, and hence to an increase in defect concentration. This is attributed to substitution of larger Nd3+ ions for smaller Y3+ ions. As a result, the fluorescence intensity of Nd:YAG increases and reaches a maximum at 3 at% Nd. Above 3 at% Nd, the lattice distortion becomes more evident, and the Nd3+ ions segregate on the surface of grains and thus the fluorescence intensity decreases. Above 8 at% Nd, a large fraction of Nd3+ ions cannot enter the YAG lattice, but reside on the surface of grains instead, leading to formation of disordered clad layers. Above 10 at% Nd, a high degree of disorder in the structure is induced by the Nd3+ segregation both in the interior and boundary of grains. Above 15 at% Nd, Schottky and Frenkel defects appear due to the lattice distortion. In general, at Nd . 3 at% the Nd3+ segregation and concentration quenching cause the attenuation of the fluorescence of Nd:YAG.