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The phase diagram of the Pb(Mg 1/3 Nb 2/3 )O 3 and PbTiO 3 solid solution (PMN-xPT) depicts a boundary between cubic and rhombohedral phases for x 0.32. X-ray powder measurements reported by Dkhil et al show a rhombohedrally split (222) Bragg peak for PMN-10% PT at 80 K that is consistent with this phase boundary. Remarkably, our neutron data taken on a single crystal of the same compound with comparable q-resolution reveal a single resolutionlimited (111) peak down to 50 K, and thus no rhombohedral distortion. Given the marked difference in penetration depths between x-rays and neutrons in these lead-oxide relaxor materials, our results suggest that the bulk structure, which is nearly cubic, differs from that of the outer layer in PMN-10% PT, a situation that has also recently been observed in PZN by Xu et al.

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Using a new composite flux and an improved growth process, large and high-quality ferroelectric SrBi2Ta2O9 (SBT) single crystals (up to 25 × 20 mm2 area) were successfully grown from high-temperature solutions. The effects of chemical, thermodynamic, and kinetic parameters on the growth results were systematically studied. The optimum system for the growth of SBT crystals has been identified. B2O3 additive was shown to play an important role in improving the effectiveness of the Bi2O3 solvent. The grown SBT single crystals exhibit a dominant (001)-orientation and large single-domain areas. The dielectric and ferroelectric properties measured in relation to crystal orientations have confirmed the absence of any polarization component normal to the (Bi2O2)2+ sheets of the structure, indicating a high anisotropy in the properties.

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