Doped Y3Al5O12 Research Articles

Auditory and vestibular impairment of Slitrk6-Deficient mice

A diode pumped Tm3+ doped YAlO3 (Tm:YAP ) self-Q-switched near 2 μm laser was studied with a compact linear cavity. Stable self-Q-switched laser pulses were obtained at the central wavelength of 1988 nm with the maximum average output power of 1.68 W, corresponding to the slope efficiency of 31.7%. The pulse repetition rate and single pulse energy were 65.16 kHz and 25.7 μJ, respectively. To the best of our knowledge, this is the first demonstration of a diode pumped all-solid-state self-Q-switched laser at the 2 μm region.

Comparative Study of Synthesis and Characterization of YAG:Yb<SUP>3+</SUP> Nanoparticles Using Different Precipitator by Co-Precipitation Method

Irregular club-shape nanoparticles of Yb3+ doped Y3Al5O12 were synthesized by the co-precipitation method using different precipitator, such as ammonium hydrogen carbonate, hexamethylene tetramine and urea. The reaction mechanism of different precipitator and the effect on the particle size and dispersion of Y3Al5O12:Yb3+ powders were investigated, and the influence of ammonium sulfate as the dispersant in the reaction system was also discussed. The results show that the large and agglomerated Y3Al5O12:Yb3+ powders were obtained from urea compared to that uniform particle size and dispersion one from ammonium hydrogen carbonate and hexamethylene tetramine. Moreover, ammonium sulfate is beneficial to enhance the dispersion of the particles for ammonium hydrogen carbonate and to form the club-shape morphology of Y3Al5O12:Yb3+ crystals for hexamethylene tetramine. The photoluminescence property investigation shows that the near-infrared emission intensity of the powders increased with the calcining temperature as well as the particle size and dispersion of as-prepared particles for all the precipitators.

Optical Properties of Cr(III) doped YAG Nanoceramics

The Cr3+ doped Y3Al5O12 ceramics composed of nanosized grains were fabricated by the low temperature high pressure sintering technique. The photo - and cathodoluminescence spectra of Cr3+:Y3Al5O12 nanoceramics were measured. The effect of applied pressure on luminescence properties of Cr3+ doped Y3Al5O12 nanoceramics was investigated.

Influence of combustion reagent and microwave drying method on the characteristics of nano-sized Nd3+:YAG powders synthesized by the gel combustion method

Nanosized Nd3+ doped Y3Al5O12 (Nd3+:YAG) powders have been synthesized by the gel combustion method using different combustion reagent such as citric acid, ethylene diamine tetraacetic acid (EDTA), glycine, glycol and the combination of citric acid and EDTA with different ratio. The pure YAG phase was obtained at relatively low temperature around 950 °C for citric acid or EDTA and 1,050 °C for glycine or glycol as combustion reagent, respectively by the gel combustion method. It was found that citric acid and EDTA are the better combustion reagents and yield rather homogeneous and well dispersed club-shape Nd3+:YAG samples, and the particle size synthesized by EDTA is larger than that by citric acid. Moreover, the particle size of Nd:YAG was enlarged when the ratio of EDTA was increased in the combination reagent, and the better dispersion of YAG was obtained when the ratio of citric acid to EDTA was 1:1 compared to that of other ratios and pure one as combustion reagent. On the other hand, the results showed that the microwave assisted in drying process of gel to xerogel produced more smaller Nd3+:YAG particles in size, and more homogeneous dispersion of the Nd3+:YAG particles than that of the traditional dry method.

Synthesis and Characterization of YAG:Ce3+ Nanophosphor prepared by Flame Spray Pyrolysis

Among the various types of synthesis techniques for phosphors, flame spray pyrolysis (FSP) is a powerful method which is capable of producing particles with good crystallinity and high luminescence efficiency. In this work, we have studied the possibility of producing yellow light emitting Ce3+ doped Y3Al5O12 (YAG:Ce3+) nanophosphor particles using FSP. The challenges in forming YAG arises is because of its complex stoichiometry and existence of numerous crystalline states. 3 M of urea was added to increase the flame temperature. The as-prepared nanoparticles were annealed in the temperature range 800° to 1100° for 1 hour. As-prepared phosphor particles were found to be YAlO3 which transformed to YAG when annealed above 900°. PL intensity of the phosphors increased with increase in annealing temperature above 900°. These results indicate the possibility of the fabrication of high quality YAG:Ce3+ nanophosphor particles via a simple process.

Thermal conductivity/diffusivity of Nd3+ doped GdVO4, YVO4, LuVO4, and Y3Al5O12 by temperature wave analysis

Thermal diffusivity and thermal conductivity of single crystals of Nd3+ doped GdVO4, YVO4, LuVO4, and Y3Al5O12 are precisely measured over a wide range of doping concentration from 0.5to15at.% by temperature wave analysis. Thermal diffusivity serves as the most sensitive parameter to detect the effect of doping on thermal properties, where Nd3+ doped GdVO4 exhibits a decrease in thermal diffusivity (it has changed about 20% in their values in the c axis) but an increase in heat capacity (only 1.7%). It has long been understood that the thermal conductivity of YVO4 is inferior to that of Y3Al5O12; however, the thermal conductivity of YVO4 in the c axis shows the highest value in all four crystals compared at 1at.% of Nd3+ doping concentration. Thermal conductivity exhibits a decrease (∝ε−1∕2, ε: mass variance) with an increase of doping concentration, that is characteristic of Klemens’ point defect model for the phonon scattering. In the numerical fitting, the anisotropic decrease of thermal conductivity in different crystal axes, [100], [001], and [110], is reflected as the different phonon velocities. The simulated and the experimental thermal conductivity show the various decreasing curvatures indicating that the effect of mass difference of the host and the doping cations serves as an important factor, as with the crystallographic anisotropy, on the thermal conductivity of the doped single crystals.

Thermoluminescence properties of undoped and Tb3+ and Ce3+ doped YAG nanophosphor under UV-, X- and β-ray irradiation

The thermoluminescence (TL) properties of undoped, Ce3+ and Tb3+ doped Y3Al5O12 (YAG) nanocrystals under UV-, X- and β-rays irradiation is reported. The TL signal of undoped and doped samples indicates a high sensitivity to UV-, X- and β-ray irradiation. The introduction of the doping ions induces changes in the trapping processes and the TL efficiency. The results show that both undoped and doped YAG nanocrystalline phosphor present good TL efficiency as well as good dose response which qualify them as a potential UV-, X- and β-ray dosimeter. A linear response under X-ray irradiation is observed for low doses level in the 0.02–1.02μGy range and for relatively high doses level of β-ray irradiation in the range from 10 to 600Gy.

Fluorescent and Magnetic Resonance Imaging by Rare Earth Doped Nanoparticles with Garnet Structure

ABSTRACTYb3+ doped Y3Al5O12 (YAG:Yb3+) nanoparticles are prepared from yttrium acetate tetrahydrate, ytterbium acetate tetrahydrate and aluminum isopropoxide in 1,4-butanediol by autoclave treatment at 300 °C for 2 h. Moreover, Gd-YAG:Yb3+ nanoparticles are prepared from the mixture of YAG:Yb3+ colloidal solution and gadolinium acetate tetrahydrate by the same autoclave treatment as YAG:Yb3+. Properties of structure, near infrared photoluminescence and magnetic resonance contrast enhancement are characterized for as-prepared and calcined YAG:Yb3+ and Gd-YAG:Yb3+ nanoparticles.

Long (1 1 1)-oriented Y3Al5O12:Nd3+ single crystal fibers grown by modified micro-pulling down technology for optical characterization and laser generation

Long (111)-oriented 0.2at% Nd3+ doped Y3Al5O12 (YAG:Nd) single crystal fibers were grown by modified pulling down technology. The crystal fibers with uniform diameter ranging from 0.5mm to 1.5mm and about 970mm long were obtained under optimal stationary stable growth conditions. The characterization of their optical properties (propagation and transmission) shows that the fibers were optically powerful with optical performance similar to rods cut from bulk single crystal grown by the conventional Czochralski technique. In a diode pumped configuration, we obtained a cw power of 10W at 1064nm, with a M2 quality factor of 5, for an incident pump power of 60W at 808nm. In Q-switched regime, 12ns pulses with an energy of 4.4mJ at 1kHz have been produced.

Thermoluminescence and optically stimulated luminescence properties of nanocrystalline Er3+ and Yb3+ doped Y3Al5O12 exposed to β-rays

The thermoluminescence (TL) and optically stimulated luminescence (OSL) characterization of Er3+ and Yb3+ doped Y3Al5O12 nanocrystalline samples prepared by the precipitation process and exposed to β-rays are discussed. The TL as well as the OSL were two orders of magnitude higher in Er3+ doped than in Yb3+ specimens. The charge trapping and the radiative thermally stimulated recombination processes in Y3Al5O12 : Er3+ involve four trapping states at 166, 243, 342 and 424 °C, but just two trapping levels at 219 and 413 °C for Y3Al5O12 : Yb3+ at a heating rate of 10 °C s−1. The photostimulation with 470 nm light causes in both phosphors a radiative recombination of the optically free charge carriers belonging to the same trapping states. The TL and the OSL as a function of radiation dose behaviour were linear in the 10–100 Gy dose range. The results provide evidence of the potential uses of these materials in radiation storage and dosimeter devices.

Thermoluminescence characterization of Tb3+ and Ce3+ doped nanocrystalline Y3Al5O12 exposed to X- and β-ray irradiation

Abstract The thermoluminescence (TL) characterization of undoped, as well as Ce3+ and Tb3+ doped Y3Al5O12 (YAG) nanocrystals, exposed to X- and β-radiation was performed. The samples were prepared by precipitation process and the crystalline structure was obtained after annealing at 1150 °C. The TL signal of the undoped samples indicates a high sensitivity to X- and β-ray irradiation. The introduction of the dopants ions induced changes in the TL glow curve structure and the kinetic properties modifying the radiative recombination efficiency. The TL results suggest that both undoped and doped YAG nanocrystalline phosphor present a good potential for X- and β-ray irradiation dosimeter applications.

Time-resolved optical absorption in YAlO3 crystals

The present work is devoted to the investigation of transient absorption (TA) induced by a pulsed electron beam (E=250keV) in pure and doped YAlO3 (YAP) single crystals. The nature of centers responsible for TA is discussed.

Preparation, photo- and thermo-luminescence characterization of Tb3+ and Ce3+ doped nanocrystalline Y3Al5O12 exposed to UV-irradiation

Abstract The photoluminescence (PL) and thermoluminescence (TL) characterization of undoped and cerium and terbium doped nanocrystalline Y3Al5O12 prepared by precipitation process is reported. The crystalline structure of the samples was obtained at 900 °C. The PL results show the typical emission bands centered at 490, 543 and 590 nm for Tb3+ and 530 nm for Ce3+ excited with light of 325 and 345 nm, respectively. The TL signal, obtained after exposure to UV-irradiation, indicates a high TL sensitivity of the samples and that the presence of the dopant ions induces changes in the trapping process and the radiative recombination efficiency. The high efficiency of the PL and TL suggests a good potential of this phosphor as UV-irradiation dosimeter as well as for photonics application.

Crystal growth of vanadium doped YAlO3, LaGaO3, and CaYAlO4 crystals and spectroscopic studies of vanadium valence states

V 4+ doped YAlO3, LaGaO3, and CaYAlO4 crystals (3d1 ion in octahedral coordination) have been grown and characterized as potential broadband laser materials using optical and electron paramagnetic resonance techniques. The effect of charge compensation on the vanadium valence state and spectroscopic properties of the materials are discussed.

Influence of impurity ions on the radiation induced optical absorption in YAlO3 and LiNbO3 crystals

A study of the influence of gamma irradiation (60Co source, 105—106 Gy absorbed doses) on the optical properties of doped YAlO3 and LiNbO3 crystals was performed. The role of Nd, Er, Tm, Ho, Ce, Mn and Ca ions in YAlO3 crystals and Nd, Er, Tm, Yb, Dy, Pr, Fe, Cr and Mg ions in LiNbO3 crystals in the radiation induced optical absorption is discussed.

Off-axis extra lines in powder pattern electron paramagnetic resonance of Cr3+ in YAlO3

Powder sample electron paramagnetic resonance (EPR) spectrum of Cr3+ ions in YAlO3 crystals contains off-axis extra lines, which do not belong to the principal X, Y,and Z components of the fine structure. Orientation dependence of the EPR spectrum of Cr3+ doped YAlO3 single crystal confirms the existence of extra turning points corresponding to directions lying off the X, Y, and Z axes, consistent with theoretical predictions. This results in five EPR lines due to the transition between the central Kramers doublet in the powder system. The observed powder pattern EPR has been used in identification of Cr3+ as an impurity ion in undoped YAlO3 crystals.

Emission and excitation spectra of Er3+, Ho3+, Pr3+, Tm3+, and Cr3+ doped YAG, YAlO3, and LiSrAlF6 crystals in the UV and VUV

Emission and excitation spectra of Er3+, Ho3+, Pr3+, Tm3+, and Cr3+ doped YAG, YAlO3, and LiSrAlF6 crystals in the UV and VUV

High resolution spectroscopy of Cr4+ doped Y3Al5O12

High resolution absorption and emission spectra of Cr4+ doped Y3Al5O12 are presented. Angular overlap model calculations for the determination of the energy level scheme of the Cr4+ : YAG system are presented. Group-theoretical considerations according to the crystal structure and the symmetry of the tetrahedrally co-ordinated Cr4+ lattice site are presented to explain the observed dependence of the emission spectra on the direction of polarization.

Stimulated emission and excited-state absorption at room temperature on the 550 nm-laser transition in Er3+ doped YAlO3

A pump- and probe-beam technique is used for measuring time-resolved and cw-pumped excited-state absorption (ESA) and stimulated-emission (SE) spectra of Er3+ : YAlO3 with high resolution. In combination with absorption and fluorescence spectra, detailed information on the wavelengths and cross-sections of ESA and SE at the 550 nm laser transition is provided.

Identification of trace impurities in pure and doped YAlO3 and Y3Al5O12 crystals by their fluorescence and by the EMA method

Trace uncontrolled impurities as Ce3+, Cr3+, Eu3+ and Nd3+ were detected in YAlO3 and YAlO3: Cr crystals from their fluorescence by high sensitive photon counting detection. The concentrations of Ce, Cr, Eu, Nd and some other impurities (Tm, Ho, Mn, Mg, Fe) were also determined by electron beam excited X-ray microanalysis (abbr. EMA) in YAlO3 and Y3Al5O12 crystals (pure or doped). Both the methods (fluorescence detection and EMA) are compared, fluorescence properties of some trace impurities were determined and their influence on local distribution and transfer processes (Ce3+→Nd3+, Cr3+→ Nd3+) in these crystals are discussed.