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Nano-size effects on the dielectric properties in the quantum paraelectric SrTiO 3 were studied. Nanocrystalline SrTiO 3 powders were prepared by the sol-gel method, and the particle sizes were controlled by varying firing temperatures. The sizes were determined to be from 12 to 44 nm using Scherrer's formula. The classical paraelectric to quantum paraelectric phase transition temperatures were suggested to be increased for the smaller particle size samples. These results could be explained with the aid of transverse Ising model.

Size effects of quantum paraelectric SrTiO 3 particles were studied by Raman scattering. The particles were synthesized by a sol-gel method. The particle sizes were controlled by the firing temperatures and determined by the X-ray analysis to range from 12 to 44 nm in diameter. The soft mode frequencies of the smaller particles were higher than those of the larger particles in the low temperature. The soft mode behavior was conforming with dielectric results of the Lyddane-Sachs-Teller relation.

SrBi/sub 2/Ta/sub 2/O/sub 9/ (SBT) thin films With various orientations: [001] oriented, partially [115]&[001] oriented, partially [115]&[200] oriented, and [116] oriented films were grown by rf magnetron sputtering deposition method. The orientations of the films were controlled varying the substrate orientation and the deposition temperature. Their structural properties were investigated by the X-ray diffraction /spl theta/-2/spl theta/ scan. Surface morphologies were examined by atomic force microscope. Longer grains were observed in partially oriented and [116] oriented films than those in [001] oriented film. The remanent polarizations were about 3-5 and 10 /spl mu/C/cm/sup 2/ in partially oriented films and [116] oriented films, respectively. The activation fields were calculated by measuring the switching currents of the samples. The remanent polarizations and the activation fields of various films were explained in conjunction with the inclination of SBT grains to the film surface.

Publisher Summary Silica fume and fly ash are used to replace 10% of cement by weight. They are used either separately or in combination with quarry dust in the concrete mixes. Quarry dust is incorporated to replace 20% and 40% of sand in the respective mixes. Superplasticizer and air entraining admixture are used as chemical admixtures to control the flowability of fresh concrete. This chapter focuses on the physical properties of fresh concrete mixes that are monitored batch by batch. The properties of fresh mixes are determined in respect of slump, slump flow, V-funnel flow, air content, mix temperature, and unit weight. It is observed that the properties, particularly, the flow and the entrained air content are influenced by the presence of mineral and chemical admixtures. In presence of superplasticizer, silica fume provides better flow properties than fly ash. Besides, the incorporation of quarry dust improves the flowability of fresh mixes. The outcome of the study given in the chapter suggests the use of quarry dust as partial replacement of sand to augment the flowability of high performance concrete.