Determination of growth conditions and structure of SrAl0.5Ta0.5O3 : LaAlO3 : CaAl0.5Ta0.5O3 crystals

Autor: R. Kikalejshvili-Domukhovska, R. Aleksiyko, M. Berkowski, P. Byszewski, Jan Fink-Finowicki, R. Diduszko
Rok vydání: 2005
Předmět:
Zdroj: Crystal Research and Technology. 40:380-385
ISSN: 1521-4079
0232-1300
DOI: 10.1002/crat.200410354
Popis: (SrAl 0 . 5 Ta 0 . 5 O 3 ) 1 - x - y (LaAlO 3 ) x (CaAl 0 . 5 Ta 0 . 5 O 3 ) y perovskite crystals of general formula ABO 3 (where A = Sr 1 - x - y La x Ca y and B = Al 1 / 2 + x / 2 Ta 1 / 2 - x / 2 ) were grown by the Czochralski and floating zone methods in wide a composition range. The experiments allowed us to determine regions on the composition diagram where solid solution crystals exist. The structure of the crystals at room temperatures was investigated by X-ray measurements. Structure of the crystals at constant radius of B-ions depends on the volume of a primitive perovskite unit cell. Thus, the structure undergoes transition from the cubic lattice of Fm3m + Pm3m space group symmetry through tetragonal (P4/mbm) to orthorhombic (Pbnm) with decreasing the primitive perovskite unit cell volume. One expects that with changing the temperature the crystals undergo second order structural phase transitions but no heat effects by differential scanning calorimetry were observed. There were no twins detected in the crystals with the cubic and tetragonal structures. The range of the lattice parameters variation and the high melting point indicate that these crystals may be used as substrates for HTSc, manganites or GaN epitaxial layers because of their high thermal and chemical stability.
Databáze: OpenAIRE
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