The double role played by the Gd2O3 in the gadolinium–aluminum–borate–bismuthate quaternary glass forming tendency. GdBO3 crystalline phase

Ca3Lu(AlO)3(BO3)4 : Sm3+: a novel red-emitting phosphor with high colour purity for NUV-based warm white LEDs

In the present work, we described the synthesis of a novel phosphor Ca₃Lu(AlO)₃(BO₃)₄ (CLAB) activated with Sm³⁺via high temperature solid-state reaction. X-ray diffraction (XRD), FTIR spectra, diffuse reflection spectra, photoluminescence (PL) spectra and fluorescence decay curves were used to characterize the as-synthesized samples. The morphology and chemical composition were measured by field emission scanning electron microscope (FE-SEM) and X-ray energy diffraction spectroscopy (EDAX). The structure refinements from XRD data revealed the isostructural arrangement of CLAB : Sm³⁺ to gaudefroyite with a hexagonal P6₃/m space group in which the AlO₆ octahedral chains are interconnected by BO₃ triangles in the ab plane to form a Kagome-type lattice (star-shaped), leaving trigonal and apatite-like-tunnels. Under 404 nm excitation, the as-synthesized phosphor shows an intensely red emission peaked at 614 nm with CIE coordinates of (0.615, 0.380) and high colour purity up to 98.53%. The quantum yield of the phosphor was found to be 15.5% with a desired doping concentration of 5 mol% Sm³⁺ ions. The red emission intensity of CLAB : 0.05Sm³⁺ at 425 K is 86.6% of that at 300 K. All these good properties make the phosphor of CLAB : Sm³⁺ exhibit a great potential for application in UV-based warm white LEDs used in displays.

Ca₃Lu(AlO)₃(BO₃)₄ : Sm³⁺: a novel red-emitting phosphor with high colour purity up to 98.53% and excellent thermal stability (the red emission intensity of CLAB : 0.05Sm³⁺ at 425 K is 86.6% of that at 300 K) for NUV-based warm white LEDs.

Effect of aluminum oxide codoping on copper-lead-germanate glasses

Glasses from xCuO⋅(100-x)[7GeO(2)⋅3PbO(2)⋅0.05Al(2)O(3)] system where x=0, 1, 5, 10, 20 and 30 mol% CuO were studied by FT-IR, UV-VIS and ESR spectroscopy in order to obtain information about the structural correlations and the relationship between structure and optical properties in these materials. The analyses of these IR spectra reveal that the accommodation of the network with the excess of oxygen ions is possible by the depolymerization of the germanate network in shorter chains, especially ortho- and/or pyrogermanate structural units. UV-VIS absorption spectrum of the sample with x=1% CuO begins with a rising absorption band situated at about 250 nm. This band can be assigned to the GeOGe wrong bonds such as the Ge(+2) centers. Optical study is performed to calculate the refractive index and optical band gap using UV-VIS spectra in the wavelength range 250-1,000 nm. The increase in optical band is explained on the basis of the average bond energy of the system and the number of non-bridging oxygen ions. ESR spectra of CuO substituted samples are characterized by broad peaks probably because of the formation of Cu(+2)-Ge(+2) exchange pairs which are weakly coupled though the oxygen atom.