Single crystals of Gd<sub>1-x</sub>R<sub>x</sub>Ca<sub>4</sub>O(BO<sub>3</sub>)<sub>3</sub> (R<sup>3+</sup> = Sc<sup>3+</sup> or Lu<sup>3+</sup>) with large size and good quality have been grown by Czochralski method. The optical birefringence of Gd<sub>1-x</sub>Sc<sub>x</sub>Ca<sub>4</sub>O(BO<sub>3</sub>)<sub>3</sub> and Gd<sub>1-x</sub>Lu<sub>x</sub>Ca<sub>4</sub>O(BO<sub>3</sub>)<sub>3</sub> crystals can be controlled by changing the compositional parameter x. The chemical compositions of the grown crystals were determined and X-ray diffraction measurements have been carried out to characterize the structural changes with compositional parameter x. According to our assumptions, the obtained results demonstrate that two of the grown crystals convert the near-infrared radiation of 800nm into blue-violet light (400nm) by type-I noncritical phase-matching (NCPM) second-harmonic generation (SHG) processes along Y axis.
In this paper we present new results concerning the optical and morphologic properties of YVO<sub>4</sub>:Eu red nanophosphor
prepared by a precipitation method and subsequently annealed in air at various temperatures. We monitored the morphologic changes induced by the thermal treatments using the optical spectroscopy (reflectance and luminescence spectra), XRD and electron microscopy. The annealing leads to an increase of the particle size and improvement of the order of the crystalline lattice of YVO<sub>4</sub>. The annealing at 800°C produces the sample with the highest luminescence intensity.