A series of novel KLaSr3−x (PO4)3F:xEu2+ phosphors were synthesized for the first time. The crystal structure, photoluminescence properties, concentration quenching, decay analysis, and the temperature dependent luminescence properties were investigated in detail. The unit cell parameters for KLaSr3(PO4)3F were estimated to be a = 9.8997 Å, c = 7.4075 Å, and V = 628.7 Å3. The photoluminescence excitation spectrum of KLaSr3(PO4)3F:Eu2+ shows a broad band from 225 nm to 450 nm with a maximum at about 320 nm. KLaSr3−x (PO4)3F:xEu2+ phosphors exhibit a wide emission band ranging from 425 to 550 nm. KLaSr3(PO4)3F:Eu2+ phosphors exhibit good thermal stability up to 423 K. KLaSr3(PO4)3F:Eu2+ was fabricated with commercial green (Ba,Sr)SiO4:Eu2+ and red CaAlSiN3:Eu2+ phosphors to obtain a white-light-emitting diode. All the results demonstrate that KLaSr3(PO4)3F:Eu2+ are promising blue phosphors for white-light ultraviolet light-emitting diode applications.

ZrO2:Eu3+ hollow spheres were successfully fabricated with the resin microspheres as the template. The sample characterizations were carried out by means of x-ray diffraction (XRD), scanning electron microscope (SEM), and photoluminescence spectra. XRD results revealed that Eu3+-doped samples were pure t-ZrO2 phase after being calcined at 873 K. SEM results exhibited that this Eu3+ doped ZrO2 was hollow spheres; the diameter and thickness of which were about 450 and 50 nm, respectively. Upon excitation at 394 nm, the orange-red emission bands at the wave length longer than 570 nm were from 5D0 → 7FJ (J = 1, 2) transitions. The asymmetry ratio of (5D0 → 7F2)/(5D0 → 7F1) intensity is about 1.61, 1.26, 1.42, 1.42, 1.40, and 1.38 for the Eu3+ concentration 0.4, 0.7, 1.0, 1.5, 2.0, and 2.5 mol%, respectively. These values suggest that the asymmetry ratio of Eu3+ ions is independent of the doping concentration. The optimal doping concentration of Eu3+ ions in ZrO2 is 1.5 mol%. According to Dexter's theory, the critical distance between Eu3+ ions for energy transfer was determined to be 16 Å.

Translucent, polycrystalline YAG:Ce disks with 0.1, 0.5, and 1 mol% concentrations of cerium as well as different resulting thicknesses of 0.5 and 0.8 mm were prepared by reaction sintering of yttria, alumina, and cerium oxide under vacuum at a temperature of 1800 °C. The obtained samples displayed a microstructure with a Y3Al5O12 main phase interrupted by an intended scattering phase of alumina. Furthermore, the total forward transmittance was between 75 and 78% with the typical absorption bands of cerium at wavelengths of 330 and 460 nm. Phosphor conversion light-emitting diodes (LEDs) with 0.88 W power dissipation have been prepared from these YAG:Ce ceramic disks as converters and blue 455 nm LED chips for excitation. Their color coordinates in the CIE (Commission Internationale de l’Eclairage) diagram determined by spectral photometry depend on the concentration of the Ce dopant and the ceramic converter thickness. The highest luminous flux of 276 lm with an efficiency of 76.6 lm/W was measured for a converter with 0.5 mol% dopant concentration and 0.8 mm thickness emitting a yellowish white light.

Crystal structures of Li(Ta0.89Ti0.11)O2.945 and (Li0.977Eu0.023)(Ta0.89Ti0.11)O2.968 were investigated by laboratory X-ray powder diffraction. Both title compounds were trigonal with space group R3c and Z = 6. The hexagonal unit-cell dimensions were a = 0.514 82 9(2) nm, c = 1.377 61 2(4) nm, and V = 0.316 21 6(2) nm3 for the former compound and a = 0.517 71 2(2) nm, c = 1.373 50 0(6) nm, and V = 0.318 81 2(3) nm3 for the latter. The initial structural models, being isostructural with LiTaO3, were refined by the Rietveld method. The maximum-entropy method-based pattern fitting (MPF) method was subsequently used to confirm the validity of the structural models, in which conventional structure bias caused by assuming intensity partitioning was minimized. Atomic arrangements of the final structural models were in excellent agreement with the three-dimensional electron-density distributions determined by MPF.

A method for preparing rare-earth element-doped yttrium oxide phosphor photonic band gap crystals (PBG) is described, which obviates the necessity for multiple infilling of the opal-like template. The method utilizes (i) the re-dissolving and the concentration of previously precipitated spherical phosphor particles made by homogeneous precipitation methods into a viscous precursor phosphor solution, and (ii) formation of an opal-like template of polystyrene or silica spheres. A procedure is outlined that permits the precursor solution to be drawn into the template in a controlled manner that can be easily monitored using an optical microscope. Attenuation of the strong, red cathodoluminescent emission is observed in Y2O3:Eu3+ phosphor PBG crystals that are engineered to have a stopband overlapping the emission bands in the red region. This attenuation results from Bragg diffraction of the light emitted within the PBG phosphor crystals.

We have investigated the effects of oxygen incorporation on cathodoluminescence (CL) and photoluminescence (PL) from sputtered amorphous films of AlN:Eu3+. Ordinarily, these materials must be activated at elevated temperatures (~1000K) before appreciable luminescence can be observed. We have shown that oxygen doping is an effective alternative to thermal activation. Studies of CL intensity versus oxygen contamination indicate that luminescence turns on if the oxygen content of the sputtering plasma exceeds a few percent. Significantly, oxygen appears to have a greater impact (>600-fold) on luminescence than does thermal activation (100-fold). The oxygen dependence of PL intensity varies slightly from that of CL intensity. A possible explanation for this observation is proposed. The results suggest that low temperature alternatives to the customary thermal activation process may be available. Such alternatives would eliminate materials constraints and would permit the facile integration of plastic components or substrates with rare-earth-doped III-N luminescent devices.