Erbium luminescence in (Y, Er, Yb)3Al5O12 powders

In this work, the Stokes and anti-Stokes luminescence (upconversion) of erbium in powders of yttrium-aluminum garnet with various concentrations of erbium, as well as co-doped with erbium and ytterbium, synthesized by the sol-gel method using multistage thermal processing, was investigated. It was established that the phase composition of the resulting powders corresponds to the crystal structure of garnet. For all powders, high-intensity Stokes luminescence with a maximum at 1.53 μm was observed due to the I13/24→I15/24 electronic transition, and anti-Stokes luminescence was observed with the most intense band in the region of 0.65–0.69 μm, associated with the F9/24→I15/24 transition of Er3+ ions. The highest intensity of the Stokes luminescence is observed for the maximum substitution of yttrium by erbium considered here, which corresponds to the Yb1.5Er1.5Al5O12 stoichiometry. The highest intensity of the anti-Stokes luminescence is for the lowest erbium concentration and for codoping with ytterbium with Y2.71Er0.29Al5O12 and Y2Er0.5Yb0.5Al5O12 stoichiometries, respectively

Optical properties of multilayer BaTiO3/SiO2 film structures formed by the sol–gel method

Multi-layer film structures BaTiO3/SiO2 with a thickness of ~1 μm containing up to 14 pairs of layers were synthesized by the sol–gel method with sequential heat treatment. It is shown that the synthesized structures are X-ray amorphous. The formation of bands in the transmission and reflection spectra caused by interference effects is demonstrated. A more regular structure exhibits a photon band gap (opacity band) in the visible range with main minimum at 636 nm and corresponding maximum in the reflection spectra. Dispersion characteristics of barium titanate films with different concentrations of initial sols were studied and an increase in the refractive index with an increase in the concentration of sol was demonstrated. For a sol with a concentration of 60 mg/ml, the refractive index in the spectral range of 390–1600 nm is 1.88–1.81. The prospects of sol–gel technology for the formation of BaTiO3/SiO2 structures for nanophotonics and solar radiation converters are discussed

Europium luminescence from amorphous yttrium alumina films on fused silica substrates

In this work, we investigate photoluminescence of sol-gel derived films corresponding to yttrium alumina garnet Y3Al5O12 doped with trivalent europium. The films with three concentrations of europium 0,02; 0,025; 0,03 M with the thickness 210-220 nm were deposited on fused silica substrates by the corresponding sols’ spinning followed by drying and high temperature annealing at 1000 °С for 30 min. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive Х-ray (EDX) analysis as well as ellipsometry, photoluminescence (PL) and photoluminescence excitation spectroscopy (PLE). All of the fabricated samples were amorphous and revealed room-temperature luminescence bands within the range of 550 – 750 nm corresponding to 5D0 → 7Fj (j=0,..,4) transitions of trivalent europium ions with the most intensive bands at 610 – 630 nm and 680 – 710 nm. The intensity of europium luminescence increases with europium concentration. The photoluminescence excitation spectra measured at the emission wavelength 710 nm exhibit strong bands at 220 nm, which could be associated with absorption of exciting light within Eu3+ - O2-bands. Practical application of the obtained films transforming ultraviolet irradiation into visible is discussed

ЗОЛЬ-ГЕЛЬ СИНТЕЗ И ПРОПУСКАНИЕ МНОГОСЛОЙНЫХ ПОКРЫТИЙ BaTiO3/SiO2

SOL-GEL METHOD, BARIUM TITANATE, FILTER.В работе изложены результаты формирования золь-гель методом многослойных покрытий, отличающихся показателем преломления BaTiO3/SiO2, на кварцевых и кремниевых подложках. Показано, что многослойные покрытия после термообработки при температуре 450 ºС формируют полосу непрозрачности на спектре пропускания с минимумом 693 нм для 14 пар слоев BaTiO3/SiO2, уменьшая пропускание до 35 %, при этом пропускание в ИК-диапазоне 1000-2000 нм ослабляется до 70-75 %. Пленки являются рентгеноаморфными после термообработки при температурах 450 и 600 ºС. Обсуждается перспектива применения разрабатываемых фильтров для оптики и нанофотоники

Sol-gel synthesis and transmission of BaTiO₃/SiO₂ multilayer coatings

SOL-GEL METHOD, BARIUM TITANATE, FILTER

Sol-gel synthesis and transmission of BaTiO3/SiO2 multilayer coatings

В работе изложены результаты формирования золь-гель методом многослойных покрытий, отличающихся показателем преломления BaTiO3/SiO2, на кварцевых и кремниевых подложках. Показано, что многослойные покрытия после термообработки при температуре 450 єС формируют полосу непрозрачности на спектре пропускания с минимумом 693 нм для 14 пар слоев BaTiO3/SiO2, уменьшая пропускание до 35 %, при этом пропускание в ИК-диапазоне 1000–2000 нм ослабляется до 70–75 %. Пленки являются рентгеноаморфными после термообработки при температурах 450 и 600 єС. Обсуждается перспектива применения разрабатываемых фильтров для оптики и нанофотоники. The paper presents a method for the formation of multilayer coatings differing in the refractive index of BaTiO3 / SiO2 on quartz and silicon substrates. It is shown that multilayer coatings after heat treatment at 450oC create a dip in the optical transmission spectrum at 693 nm for 14 pairs of BaTiO3 / SiO2 layers, reducing the transmission to 35 %, while the transmission in the IR range of 1000–2000 nm is attenuated to 70–75 %. The films are amorphous for X-ray diffraction analysis after heat treatment at 450 and 600 °C. The prospects of using the developed filters for optics and nanophotonics are discussed