Crescimento de cristais de Bi2TeO5
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Data
2010-07-30
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Universidade Federal de Goiás
Resumo
Bi2TeO5 (bismuth tellurite) crystals are photorefractive materials appropriate for permanent holographic recording. They are capable to retain a hologram for a long time, several years in the dark, without further fix processes. Just some
groups around the world have grown bismuth tellurite single crystals even with their interesting properties. It may be caused by the relatively difficulty for grow this crystal, mainly due to the high vapor pressure of tellurium oxide and the easy
crystal cleavage. The present work was dedicated to study the crystal growth process of Bi2TeO5 by Czochralski method in a low thermal gradient system. Tellurium oxide excess was used in the starting composition to compensate its lost
during crystal growth, and also this starting material was previously synthesized by solid state reaction before fusion. We have performed tests with 1Bi2O3 : 1,03TeO2 and 1Bi2O3 : 1,10TeO2 liquid phase compositions. Also, we tried to use a double crucible configuration, with pure tellurium oxide between the walls. Pulling and rotate rates are critical parameters. Pulling and rotate rates of 0,1 to 0,4 mm/h and
10 to 15 rpm, respectively, were appropriated parameters for our growth system. Good size and crystalline quality crystals have been grown. We have obtained samples of sufficient quality to perform preliminary optical measurements and
structural characterization.
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Citação
FABRIS, Zanine Vargas. Crystal growth Bi2TeO5. 2010. 63 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de Goiás, Goiânia, 2010.