FERROELECTRIC DOMAINS AND GROWTH STRIAE IN BARIUM SODIUM NIOBATE SINGLE CRYSTALS

The relationship between the ferroelectric domain structure and growth striae is examined in barium sodium niobate (Ba2NaNb5O15) single crystals. Growth striae stabilise a particular form of domain structure and are further shown to be caused by temperature fluctuations occurring in the melts from which such crystals are grown. These fluctuations and the associated striae can be eliminated by reducing the melt level in the crucible used to contain the molten material. Evidence is presented to show that this effect cannot simply be regarded as a reduction in the Rayleigh Number of the melt system, as convective effects occurring in the gas ambient above the melt also exert an influence. © 1969 Chapman and Hall.