Strontium titanate, SrTiO

Domen, K., Kudo, A., and Onishi, T., Mechanism of photocatalytic decomposition of water into hydrogen and oxygen over nickel (II) oxide-strontium titanate (SrTiOs), /. Catal, 102,92,1986. 

Lately, however, some surprising exceptions have been found to the general rule of low plasticity in ceramics. One is the perovskite oxide strontium titanate, SrTiOs. Recent studies on single crystals have revealed a transition from nonductile to ductile behavior in this material not only at temperatures above 1000°C, but again, below 600°C. Even more unexpectedly, it reached strains of 7 percent at room temperature with flow stresses comparable to those of copper and aluminum alloys. At both the high and low temperatures, the plasticity appears to be owing to a dislocation-based mechanism (Gumbsch et al., 2001). 

Lattice dynamics in bulk perovskite oxide ferroelectrics has been investigated for several decades using neutron scattering [71-77], far infrared spectroscopy [78-83], and Raman scattering. Raman spectroscopy is one of the most powerful analytical techniques for studying the lattice vibrations and other elementary excitations in solids providing important information about the stmcture, composition, strain, defects, and phase transitions. This technique was successfully applied to many ferroelectric materials, such as bulk perovskite oxides barium titanate (BaTiOs), strontium titanate (SrTiOs), lead titanate (PbTiOs) [84-88], and others. 

Figure 1 shows the two models which were calculated. The base structure was considered with another research group for improvement of the thermal conductivity, while three layered structure was adopted on the view point of shielding. The base structure was assumed to be a concentric cylinder of 60 cm height which was formed void, strontium titanate ( "SrTiOs, P 5.12g/cm 0 and boron nitride (BN, p 2.26g/cm3) from the inside. The weight of these two materials was made to be identical each other. 

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