Influence of Ce ion Concentration on Fluorescence Properties of Ce:TAG‐Al₂O₃ Eutectic Mixed Crystals

Abstract

Combining a blue LED chip with phosphor, white light can be obtained. In traditional white LEDs, the phosphor was dispersed in resin in a form of particles. Particle‐resin composite has complex packaging and poor thermal stability. For high‐power white LEDs, this combination cannot provide long‐term stable work because of photo‐degradation of the organic epoxy resin under high irradiation and high temperatures. Here we develop resin‐free phosphor (Tb1‐nCen)3Al5O12‐Al2O3 eutectic mixed crystals (Ce:TAG‐Al2O3) to eliminate the photo‐degradation issue of the organic material. They were grown by optical floating zone method. X‐ray diffraction and scanning electron microscopy show that these materials have typical eutectic mixed crystal structure of sapphire and garnet phases, in which lamellar spacing is in an order of tens of microns. The doped Ce3+ ions do not influence basic structure of TAG crystal. Ce3+ ion replaces Tb3+ ion rather than Al3+ ion. Photoluminescence emission and excitation properties of the eutectic mixed crystals were investigated. They get to maximal value with 2.0% Ce3+, and have wide excitation band at 470 nm. Luminous efficiency of eutectic mixed crystal‐packaged LED is higher than that of particle‐resin composite packaged LED. These results show that Ce:TAG‐Al2O3 eutectic mixed crystals are promising phosphor for white LEDs.

Outstanding optical temperature sensitivity and dual‐mode temperature‐dependent photoluminescence in Ho3+‐doped (K,Na)NbO3–SrTiO3 transparent ceramics

“…The maximum S values of ~0.0089/K (for x = 0.005) and ~0.0096/K (for x = 0.01) are obtained at ~540 K. For comparison, the optical temperature sensing properties of the RE 3+ ‐doped materials, including ceramics, glasses, phosphors, and nanophosphors, are demonstrated in Figure . It is noteworthy that the x Ho‐KNNST transparent ceramics (especially x = 0.01) own rather high value of sensitivity, which is higher than other RE 3+ ‐doped ferroelectric ceramics and most of other RE 3+ ‐doped/codoped nonferroelectric materials, exhibiting great potential in the field of FIR‐based optical temperature sensors. The high optical transmittances, easy‐modulated up‐conversion PL, and outstanding optical temperature sensitivity enable the x Ho‐KNNST transparent ceramics to be superior multifunctional materials.…”

Boosting Upconversion Photoluminescence and Multielectrical Properties via Er-Doping-Modulated Vacancy Control in Ba0.85Ca0.15Ti0.9Zr0.1O3

“…The results are consistent with the XRD analysis. In addition, vacancies in the dielectric ceramics can influence T c ; for instance, T c decreases after the introduction of V c . , Hence, compared with the ceramics with y = 0, Ba, and Ca, the V c concentrations of ceramics with y = Ti and y = Zr are higher and the effect on reducing T c is dominant.…”

Hf 4+ Ion Concentration Dependence of Holographic Storage Properties in Hf:Fe:Cu:LiNbO3 Crystals

“…In the development of holographic volume storage, the storage media plays an important role in determining storage capacity and density. In the past few decades, more and more dielectric materials have been applied to holographic volume storage, such as Bi 12 SiO 20 , BaTiO 3 , and LiNbO 3 .…”