The mu-pulling down technique has permitted to grow single crystal fibers, of the gross chemical formula K3Sr2NdNb10O30, having a sufficient optical quality to carry out spectroscopic studies. The crystal structure has been determined and refined to reliability factors: (i) R-1 = 0.0384 (wR(2) = 0.0665) at room temperature; (ii) R-1 = 0.0334 (wR(2) = 0.0638) at 120 K. Difference in the cationic distribution over the 15- and 12-fold sites was noticed. IR fluorescence spectra investigated under different laser excitation wavelength at 300 K and 77 K show strong emissions at 0.9 and 1.06 mu m. Low temperature fluorescence behavior is compatible with Nd3+ ions located in both Sr2+ and K+ sites with 15- and 12-fold coordination, respectively. (C) 2012 Elsevier Ltd. All rights reserved.