Microscopic studies on imperfections in selected YAB single crystals (original) (raw)
Related papers
Spectrochimica Acta Part B: Atomic Spectroscopy, 2004
Comparative analysis of yttrium aluminium borate (YAB) /YAl 3 (BO 3 ) 4 / optical single crystals was performed by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) methods for Cr, Dy, Er, Yb, Y, Al, B and Mo. The dopant element, Ce, could be determined only by the ICP-AES method at the required concentration level. The powdered crystal samples were fused with lithium metaborate (LiBO 2 ) at 950 8C in a platinum crucible and then dissolved in 6 mol l À1 HCl. Although this fusion-dissolution procedure proved to be simple and effective, the quantitative determination of B-as the matrix element in samples-was handicapped by the B content of the fusing reagent. For the FAAS method, with the use of nitrous oxide-acetylene flame, cesium chloride ionization buffer and lanthanum chloride releasing agent [0.1+0.2% (m/v), respectively] were applied. These agents enhanced the atomic absorption signals of Cr, Dy, Er, Mo, Yb and Y, whereas no change of sensitivity was resulted in for Al and B. A fairly good agreement was found between the results of the two alternative spectrochemical methods. The predicted stoichiometry of the crystals was also well approximated indicating the reliability of the crystal growth technology applied. D
Investigation of structural perfection and faceting in highly Er-doped Yb3Al5O12 crystals
Crystal Research and Technology, 2008
The undoped Yb 3 Al 5 O 12 (YbAG) single crystals and doped with 1.5, 10 and 30 at% erbium were grown by the Czochralski method. The YbAG crystals offer efficient emission of laser beam of 2.94 µm and 1.55 µm important for practical applications in communication and medicine. The crystals were investigated by various synchrotron X-ray diffraction methods including white beam topographic methods, monochromatic beam topography and recording of the rocking curves. The experiments were performed at E2 and F1 experimental stations in HASYLAB. The investigations proved a good crystallographic perfection of the crystals, in most cases revealing only segregation fringes and growth facets. The crystallographic identification of the facets was performed together with direct evaluation of growth front radius from the transmission section topographs. Relative lattice parameter changes connected with erbium segregation were found to be less than 2 × 10 -5 inside the segregation fringes and 8 × 10 -5 in the facets.
Characterisation of nonlinear conversion and crystal quality in Nd- and Yb-doped YAB
Optics Express, 2004
Variable crystal quality affects the laser performance of many self-frequency doubling crystals, particularly those of the yttrium aluminum borate family. In this report we characterize nonlinear frequency conversion in Yb:YAB and demonstrate a simple non-destructive technique for measuring crystal quality. By imaging the nonlinear conversion using a CCD camera we observe phase matching characteristics similar to that obtained in quasi-phase-matched crystals. These effects are attributed to stacking faults in the structure of the YAB crystal during crystal growth. We believe that such defects cause the large variability in self-doubled performance reported for Nd-or Yb-doped YAB and that our technique may be used as a nondestructive measurement of crystal quality.
Journal of Physics: Condensed Matter, 2003
For Ce 3+ , Er 3+ and Yb 3+ ions, electron paramagnetic resonance (EPR) spectra typical for S = 1/2 ions are measured for YAl 3 (BO 3 ) 4 (YAB) single crystal. The spectra show axial symmetry indicating that all three dopants replace Y 3+ at the given dopant concentration. Correspondingg-and hyperfineÃ-tensors are determined. The EPR linewidth of Ce broadens with increasing temperature due to an Orbach relaxation process. Fitting the curve with an exponential, the energy difference is found to be equal to 270 ± 16 cm −1 .
Crystal-field analysis of Er3+ ions in yttrium aluminium borate (YAB) single crystals
Journal of Alloys and Compounds, 2005
Crystal-field energy levels of Er 3+ ions doped in YAB single crystals were fitted to the parameters of semi empirical Hamiltonian including J-mixing. A simulation of the energy level scheme is carried out. The effective Hamiltonian includes elementary interactions such as columbic, spin-orbit, two-and three-body interactions. The crystal-field effect is introduced through the six non-zero crystal-field parameters allowed by D 3 symmetry site occupied by the rare earth. Very satisfactory correlations were obtained between calculated and experimental levels, with root mean square deviation (r.m.s.) of 15.5 cm −1 . These results are compared with those reported for Nd 3+ and Dy 3+ ions in the same host and with Er 3+ ions in other hosts. The concordance between the crystal-field strength parameters indicates the consistence of our analyses. The calculated wave functions of the system are used to predict the magnetic g-factors of the 4 I 15/2 ground state.
Journal of Physics: Conference Series, 2009
Phase formation has been studied in the complex system YbAl 3 (BO 3) 4-K 2 Mo 3 O 10-B 2 O 3-Yb 2 O 3 within the stability region of YbAl 3 (BO 3) 4 (YbAB). The obtained data were compared with those for YAl 3 (BO 3) 4 as another end member of the YbAB-YAB solid solutions. Visually transparent (Er,Yb):YAl 3 (BO 3) 4 single crystals with a typical size up to 10×10×15 mm 3 and crystalline layers were obtained from K 2 Mo 3 O 10 based fluxed melts. The 1.5 µm emission spectra of (Er,Yb):YAl 3 (BO 3) 4 thin films as well as bulk crystals were measured using CW Ti:sapphire laser tuned to 976 nm as a pump source.
Ba3Yb(BO3)3 single crystals: Growth and spectroscopic characterization
Journal of Materials Research, 2008
We obtained Ba3Yb(BO3)3 single crystals by the flux method with solutions of the BaB2O4–Na2O–Yb2O3 system. The evolution of the cell parameters with temperature shows a slope change at temperatures near 873 K, which may indicate a phase transition that is not observed by changes appearing in the x-ray powder patterns or by differential thermal analysis (DTA). The evolution of the diffraction patterns with the temperature shows incongruent melting at temperatures higher than 1473 K. DTA indicates that there is incongruent melting and this process is irreversible. Ba3Yb(BO3)3 has a wide transparency window from 247 to 3900 nm. We recorded optical absorption and emission spectra at room and low temperature, and we determined the splitting of Yb3+ ions. We used the reciprocity method to calculate the maximum emission cross section of 0.28 × 10−20 cm2 at 966 nm. The calculated lifetime of Yb3+ in Ba3Yb(BO3)3 is τrad = 2.62 ms, while the measured lifetime is τ = 3.80 ms.
Effect of Yb3+ content on purity and crystal growth of Ba2NaNb5O15
Journal of Crystal Growth, 2000
Growth by the micro-pulling-down technique ( -PD) of homogeneous and crack-free "ber single crystals with composition Ba Na \V Yb V Nb O (0(x(0.08) is reported. The e!ect of Yb> addition to barium sodium niobate (BNN, x"0), having the tungsten bronze-type structure, was examined by room temperature X-ray powder di!raction and di!erential thermal analysis coupled to thermogravimetry. In the region of the monophased "eld the structure is tetragonal from x"0.02 to 0.16. Volume change is mainly by variation of the a-axis length. Addition of Yb> to BNN could be e!ective for the production of high optical quality, crack-free, bulk crystals by the Czochralski technique.
The Journal of Physical Chemistry A, 2011
The atomistic structure, energetics, and electronic structure of single-substitutional Ce and La defects and double-substitutional Ce-La defects in Ce,La-codoped yttrium aluminum garnet (YAG) Y 3 Al 5 O 12 have been studied by means of first-principles periodic boundary conditions density functional theory calculations. Single substitution of Y by Ce or by La produces atomistic expansions around the impurities, which are significantly smaller than the ionic radii mismatches and the overall lattice distortions are found to be confined within their second coordination spheres. In double-substitutional defects, the impurities tend to be as close as possible. La-codoping Ce:YAG provokes an anisotropic expansion around Ce defects. The Ce impurity introduces 4f occupied states in the 5.0 eV computed gap of YAG, peaking 0.25 eV above the top of the valence band, and empty 4f, 5d, and 6s states starting at 3.8 eV in the gap and spreading over the conduction band. La-codoping produces very small effects on the electronic structure of Ce:YAG, the most visible one being the decrease in covalent bonding with one of the oxygen atoms, which shifts 0.05 Å away from Ce and gets 0.04 Å closer to La in the most stable Ce-La doublesubstitutional defect.
Growth, Morphology and Characterization of Yb : YVO4 Crystal
physica status solidi (a), 1999
An Yb : YVO 4 single crysal with good optical quality and large size has been grown by the Czochralski method. We have discussed the growth shape of Yb : YVO 4 single crystal which is composed of f100g and f101g simple forms. The data of thermal expansion and specific heat of the crystal have been measured. The thermal expansion coefficients along a-and c-axis directions are a 1 1X5 Â 10 À6 /K and a 3 8X2 Â 10 À6 /K, respectively. The specific heat is 30.4 cal/mol K at 320 K. The absorption and fluorescence spectra have been measured.