Microscopic studies on imperfections in selected YAB single crystals

Abstract

The as-grown surface and inner structures of undoped and Nd 3+ -, Cr 3+ -, V ) flux by spontaneous crystallization or top seeded solution growth (TSSG) technique, were investigated using optical and scanning electron microscopic and analytic chemical methods. Fine and rough growth hillocks of dislocational origin, growth layers, traces of inner planar defects and foreign phase crystalline debris were found and analyzed on the as-grown faces of crystals. Irregular grains and regular block structures and foreign phase inclusions were observed and studied in the interior of the crystals. The chemical compositions measured by energy dispersive X-ray spectrometry on perfect and imperfect micro regions are compared with those obtained by flame atomic absorption spectrometry on bulk crystals.

High resolution spectroscopy to investigate impurity traces in YAB single crystals

“…dislocation, twinning, etc. [9]). In principle such effects are not expected to affect the HMFW of the CF absorption peaks due to transition metals as Cr…”

“…A variety of methods, as flame atomic absorption spectrometry (FAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), energy dispersive X-ray spectroscopy (EDS), joined with optical and scanning electron microscopies, was already applied to verify the YAB crystals stoichiometry, the doped sample actual composition, the presence of unwanted impurities, and to analyze the grown-in extended defects [8,9] [10]. The crystals were X-ray oriented, cut, and polished for spectroscopic analysis.…”

Atomic spectrometry update. Environmental analysis

“…Behrens and co-workers have developed a GC combustion IRMS system for the high precision measurement of delta 13 C in atmospheric methane extracted from ice core samples 60 . Swiss researchers optimised an automated gas sampling and IRMS system for air analysis 61 .…”

“…60 Swiss researchers optimised an automated gas sampling and IRMS system for air analysis. 61 Tuzson et al 62 describe a compact and cryogen-free, quantum cascade, laser-based absorption spectrometer designed for in situ, continuous and high precision isotope ratio measurements of atmospheric CO 2 .…”

“…Resano et al 318 devised a protocol to obtain accurate PGE concentrations with RSDs below 10% and LODs around 10 ng g À1 when analysing platiniferous ores. This involved sampling 40-75 g of ore, grinding the NiS buttons, preparing a pellet of the powder using a polyethylene wax binder, ablating a line profile for 2-3 minutes per sample, using ammonia in a DRC to cope with all the spectral interferences and preparing matrix-matched calibration standards, combined with monitoring 61 Ni as an internal standard. The key factor in an improved protocol 214 for the analysis of soils and sediments by LA-ICP-MS was the reduction of the particle size to less than 1 mm.…”