Growth of ferroelectric lead germanate single crystal by the vertical Bridgman method

Bridgman growth of ferroelectric lead germanate crystal (Pb5Ge3O11) had been investigated for the first time. Pt crucible of circle divide 25 mm x 200 mm with a seed well of circle divide 10 mm x 60 mm was used, and PGO seed was grown by spontaneous nucleation, in advance. The growth parameters were optimized as the furnace temperature was set to 830 degreesC, temperature gradient in crystal-melt interface was less than 25 degreesC/cm and growth rate was less than 0.5 mm/h. PGO crystals with 25 mm in diameter and 60 mm in length were grown successfully from its stoichiometric melt. DSC curve indicated that the congruent melting temperature was about 744.6 degreesC. The transmittance spectra was measured and the absorption edge of PGO crystal was about 430 nm. (C) 2003 Elsevier B.V. All rights reserved.