Since Sr0.6Ba0.4Nb2O6 (SBN) is ferroelectric with a tungsten–bronze structure, numerous needlelike ferroelectric domains appear in a SBN single crystal when it is cooled through its transition temperature in the absence of a poling field. If the domains were illuminated by 1.06 μm radiation from a Nd:YAG laser, second-harmonic diffuse light was generated from these domains. This interesting effect, which can clearly be seen with the naked eye, will be used to generate all the primary colors using suitable lasers.

Transparent and stoichiometric lead-magnesium-niobate crystals were grown by the Bridgman method. Crystals of centimeter size were obtained without material loss by employing self-seeded and seeded techniques using sealed platinum crucibles. The fastest growth direction was found to be pseudocubic 〈111〉. As-grown crystals showed a broad absorption band centered near λ=600 nm and an OH absorption near λ=2830 nm. The electrostrictive coefficient Q11 was determined to be 1.15×10−2 m4 C−2 from the measured strain and polarization.

The infrared OH− absorptions in Bridgman grown Sr0.61Ba0.39Nb2O6 crystals have been investigated by Fourier transform infrared spectroscopy. Crystals exhibited typical O–H stretching vibrations near ν=3500 cm−1 (λ≈2.87 μm). The polarization dependent absorption measurements revealed that a greater density of O–H bonds are polarized in the a−b plane with a smaller amount of bonds along the c axis. Protons (H+), which prefer a specific site at room temperature, tended to occupy different sites as the temperature increased. As-grown crystals contained protons on the order of 1017 cm−3, and the proton concentration increased by approximately 1 order of magnitude after heat treatment in a humid atmosphere.

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The movement and growth of macroscopic ferroelectric domains in a crystal under an electric field (poling voltage) have been studied using laser scattering tomography, a technique heretofore used mainly for studying microscopic defects in crystals. This technique involves scanning successive planes in a crystal with a laser beam and collecting the scattered light in a computer. The data collected can then be visualized as two- or three-dimensional static images or as a video to study structural changes as a function of time. An important feature of this method is that these images can be viewed along any axis in the crystal. Using this technique, we were able to generate images of domain wall nucleation and growth as a function of electric field strength and time. It also allowed for the observation of domain wall movement along any crystallographic direction including down the poling axis which is covered with opaque metallic electrodes. Details of the technique and its use during the poling of a strontium barium niobate crystal are discussed.