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Photorefraction In Batio3, Stephen Ducharme
Photorefraction In Batio3, Stephen Ducharme
Stephen Ducharme Publications
This thesis summarizes the results of experimental investigations of the photorefractive properties of melt-grown BaTiO3 single crystals. Three basic photorefractive material properties are studied: (1) the effective density of photorefractive charges, (2) the photoconductivity of the photorefractive charges, and (3) the relative contributions of electron and hole photoconduction. Volume holographic measurement techniques are used: two-beam energy coupling, four-wave mixing, and erasure of volume holograms. The photorefractive properties were altered experimentally by chemically reducing or oxidizing a BaTiO3 crystal. I have extended the “hopping conduction” model of photorefractive transport to include simultaneous electron and hole photoconduction. The extension of …
Altering The Photorefractive Properties Of Batio3 By Reduction And Oxidation At 650 °C, Stephen Ducharme, Jack Feinberg
Altering The Photorefractive Properties Of Batio3 By Reduction And Oxidation At 650 °C, Stephen Ducharme, Jack Feinberg
Stephen Ducharme Publications
The photorefractive Properties of a nominally pure single crystal of BaTiO3 were altered by treating the crystal at 650 °C in oxygen at different partial pressures. Treatment altered the effective density of photorefractive charge carriers in the crystal and couls convert an inactive crystal into an active one. Treatment at low oxygen pressure (reduction) decreased the temperature of the tetragonal-to-cubic phase transition of the crystal and also decreased the measured optical band gap, implying that oxygen vacancies had been introduced into the bulk crystal. These oxygen vacancies are associated with negative photorefractive charge sonors. Either hole transport or electron transport …