Growth, structural and optical characterizations of LiLa{sub (1-x)}Eu{sub x}(WO{sub 4}){sub 2} single-crystalline fibers by the micro-pulling-down method

Highlights: Black-Right-Pointing-Pointer Transparent and uniform LiLa{sub (1-x)}Eu{sub x}(WO{sub 4}){sub 2} single-crystalline fibers were grown by the micro-pulling-down method. Black-Right-Pointing-Pointer Alkali and rare earth ionic radii influence the pulling rate on the growth. Black-Right-Pointing-Pointer Eu incorporation in LiLa(WO{sub 4}){sub 2} induces local distortions in the crystalline lattice. Black-Right-Pointing-Pointer LiLa{sub (1-x)}Eu{sub x}(WO{sub 4}){sub 2} single-crystalline fibers present intense red emission under 395 nm excitation. Black-Right-Pointing-Pointer Concentration quenching observed in the emission around 20 mol% of Eu doping. -- Abstract: Transparent and uniform LiLa{sub (1-x)}Eu{sub x}(WO{sub 4}){sub 2} single-crystalline fibers where x = 0.005, 0.01, 0.03, 0.05, 0.07, 0.1, 0.15, 0.2, 0.25 and 1.0, with an average of 20-40 mm length were obtained by the micro-pulling-down method aiming structural and optical characterization. The optimum pulling rate was found to depend on the difference between alkali and rare earth ionic radii. Rietveld analysis from X-ray diffraction data and excitation spectroscopy at room temperature were applied to investigate the lattice changes due to the Eu{sup 3+} incorporation in the host. LiLa{sub (1-x)}Eu{sub x}(WO{sub 4}){sub 2} crystal fibers present red emission due to the electric dipole {sup 5}D{sub 0} {yields} {sup 7}F{sub 2} transition under 395 nm excitation showing a concentration quenching around 20 mol% of doping. The excitation spectra of the {sup 7}F{sub 0} {yields} {sup 5}D{sub 0} transition show small changes in the Eu{sup 3+} surroundings as function of dopant concentration.