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The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.

The twin structure of NdGaO3and YAlO3: Dy crystals was examined using white beam synchrotron X-ray topography. The relation of the orthorhombic lattice basis vectors has been obtained for every domain pair in the crystals with GdFeO3-type structure. A new computer program has been used to generate Laue simulation patterns and to calculate the image shifts in topographs. The proposed approach allow for the analysis of both, sample images for specified reflections and Laue patterns as a whole. Topography was used to map domain patterns, to show misorientations and to detect symmetric aspects of ferroelastic twins. Information on twin laws and the twin distribution was obtained simultaneously.

Experimental results on the growth and characterization of single crystals of mixed perovskite (La,Sr)(Al,Ta)O3(LSAT), a promising material to prepare substrates for GaN epitaxial layers, growth by the Czochralski method, are reported. The single crystals obtained along <111> orientation up to 20 mm in diameter and 50 mm in length were free of inclusions and macroscopic defects. The optical transmission was measured in the region 200 nm – 3000 nm. For the of <111> oriented LSAT single crystals, its measured unit cell parameter (a= 7.730 Å) matches well to the GaN lattice. The chemical composition was checked by electron microprobe analysis. It was found that it is close to the stoichiometric one. With Lang transmission topography growth striations and dislocations were examined. Data on Vickers microhardness, thermal expansion coefficient, etch pit density and temperature dependence of electrical conductivity and capacitance are reported.

Single crystals of lithium tantalate (LiTaO3) doped with Pr, Nd + Yb and Tm were grown by the Czochralski method. A thermal system with 50 mm diameter iridium crucible and two different afterheaters (active and passive) was checked with respect to temperature distribution in a pulling region. The obtained crystals were up to 20 mm in diameter and up 50 mm in length. Crystals were poled, and the Curie temperature was determined for specimens cut of from different parts of single crystals. The polarized absorption spectra, time resolved emission spectra and emission lifetime of Pr3+doped LiTaO3crystals were measured. An intense emission from the 3P0level was observed. Optical properties of the Yb3+ions excited by energy transfer from Nd3+ ions have been researched for LiTaO3:Nd, Yb crystals.

Yttrium‐aluminum garnets, strontium and barium lanthanum gallates, lithium niobate and tantalate as‐grown crystals and doped by diffusion with rare‐earth (Nd, Dy, Er, Tm, Ho, Pr, Ce) and metal transition elements (Mn, Cr) were investigated optically and using Electron Spin Resonance method before and after gamma, electron and proton irradiation.

Single crystals of lithium niobate doped with 0.03 and 0.1 at.% of Cu or Fe ions were grown by the Czochralski technique. Optical absorption spectra in visible and infrared regions before and after gamma irradiation with doses up to 105Gy were measured and positions of both dopants in LiNbO3lattice were analyzed according to changes in optical absorption in the range of OH‐group absorption. Some properties of crystals doped with Cu during the growth processes were compared to those for specimens doped by thermodiffusion. It was observed that doping with Cu results in an increase of crystal resistance to radiation.

Conclusions: Optical properties of the Sm3+ ion in YAG crystals have been investigated, in particular:

We report an efficient room-temperature operation of a resonantly pumped Er^3+:GdVO_4 laser at 1598.5?nm. The maximum continuous wave (CW) output power of 3.5?W with slope efficiency of 56% was achieved with resonant pumping by an Er-fiber laser at 1538.6?nm. With pumping by a commercial laser diode bar stack, a quasi-CW (QCW) output of 7.7?W and maximum slope efficiency of ∼53% versus absorbed pump power were obtained. This is believed to be the first resonantly (in-band) pumped, room-temperature Er^3+:GdVO_4 laser.

Nearly quantum-defect-limited laser operation of a resonantly pumped Er^3+:YVO_4 at 1593.5?nm is demonstrated. Maximum slope efficiency of ∼85% and true CW power of ∼13?W at 1593.5?nm were achieved with a beam propagation factor of M_2∼1.05. This slope efficiency is, to the best of our knowledge, the highest efficiency ever reported for a crystalline Er-doped laser.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.