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Abstract: Praseodymium-aluminum (PrAlO3) perovskite crystals have been grown by the Czochralski method for the first time, to our knowledge. An almost periodic microtwin structure has been observed in the as-grown crystals, and a three-dimensional texturing of the polished surfaces has been observed. Optical absorption and emission spectra have been investigated at room temperature for crystals containing only Pr3+ ions as well as for crystals containing a mixture of Pr3+/Pr4+ ions. The observed broad emission band for the as-grown crystals could lead to a future potential application as a tunable laser for the whole visible range. [Copyright &y& Elsevier]

A new candidate single crystal (La,Sr)(Al,Ta)O3 (LSAT) as a substrate for GaN epitaxial growth was found. Mixed-perovskite (1 1 1) oriented crystals were successfully grown by conventional Czochralski method. Excellent lattice matching with gallium nitride makes this material specially promising. Determination of the lattice parameters and the phase identification obtained crystals by X-ray diffraction analysis was carried out. Thermal expansion, thermal conductivity and electrical conductivity were measured. GaN epitaxial layers have been grown on (1 1 1) LSAT substrate and the results are presented. [Copyright &y& Elsevier]

Czochralski growth of Ca4GdO(BO3)3 (GdCOB) single crystals, pure and doped with several rare earth ions (Nd3+, Pr3+, Tm3+, and Sm3+), has been carried out. As-grown single crystals free from inclusions, bubbles and cracks were 20 mm in diameter and up to 60 mm in length. Optical absorption spectra of 6 at% thulium and samarium doped calcium gadolinium oxoborate were measured and presented. It was found that introduction of Pr3+ and Tm3+ ions leads to an increase of second-order photoinduced effects in GdCOB. The second harmonic generation shows an increase of at least 35% under the influence of photoinducing nitrogen laser (λ=377 nm) power. [Copyright &y& Elsevier]