D. Ehrentraut

Flux growth of baryte-type BaSO4 from chloridic alkaline metal solvents

The growth of BaSO4 from high-temperature fluxes of both chloridic alkaline metal and alkaline-earth metal solvents has been investigated. Two binary alkaline-metal solvent systems containing LiCl and the additive ternary system with CsCl–KCl–NaCl where optimized with respect to solute concentration and growth temperature. It is found that the solution of BaSO4 in these solvents increases with decreasing average radius of the solvent cation. In addition, the solubility of BaSO4 is increased in the LiCl-containing fluxes by a chemical reaction between solute and solvent. Binary solvents of LiCl–KCl and LiCl–CsCl delivered prismatic crystals of 2 cm size, whereas the CsCl–KCl–NaCl flux prefers the growth of short-prismatic crystals. The crystals grown under optimized conditions were crack free, colorless, and transparent.

On the potential of BaSO/sub 4/:Mn/sup 6+/ for broadly tunable laser emission in the near infrared spectral region

High-quality layers of BaSO4:Mn6+ were grown by liquid-phase epitaxy. Spectroscopic investigation and numerical calculation using the measured spectroscopic parameters show that lasing at the long-wavelength side should be possible under 532-nm excitation.

Flux growth and liquid-phase epitaxy of Mn/sup 6+/ -doped molybdates and tungstates

We performed a systematic investigation of Mn/sup 6+/ in (Ca/Sr/Ba)(Mo/W)O/sub 4/ compounds which can be divided into three parts. Crystal-growth experiments in order to estimate the best conditions for liquid-phase epitaxy (LPE) of thin films doped with Mn/sup 6+/, whose spectroscopic properties are then studied. Since Mn/sup 6+/ tends to be reduced to Mn/sup 5+/ at temperatures T>600/spl deg/C, we used NaCl-KCl-CsCl as a solvent for the flux and LPE experiments. Due to the low solidification temperature of the solvent (480/spl deg/C), the maximum growth temperature could be kept below 600/spl deg/C. The dependencies of the crystal dimensions versus solute concentration for all six (Ca/Sr/Ba)(Mo/W)O/sub 4/ compounds were constructed from the results of the flux experiments.

Liquid phase epitaxy, spectroscopic investigation, and broadband emission of BaSO/sub 4/:Mn/sup 6+/ layers

Summary from only given. We report on the first epitaxial growth of Mn/sup 6+/-doped BaSO/sub 4/ layers. Growth techniques such as the melt growth that work at higher temperatures fail, because BaSO/sub 4/ has a phase transition at 1090 C and a melting point does not exist due to the thermal decomposition. Therefore, we grew undoped BaSO/sub 4/ on the flux-grown BaSO/sub 4/ crystals by use of liquid phase epitaxy (LPE). The Mn/sup 6+/-doped BaSO/sub 4/ layers were investigated spectroscopically by absorption, emission, and luminescence-excitation measurements at room temperature.