LiNbO3 and LiTaO3 pyroelectric crystals are characterized by a large band gap and a polar crystal structure resulting in a spontaneous polarization. In contrast to near surface space charge zone formation in semiconducting pyroelectrics like ZnO or GaN, the bound polarization charges at the surface of large band gap pyroelectrics are preferentially neutralized by external screening charges attracted from surrounding media. When the pyroelectric crystal is subjected to a temperature change an electric potential develops due to an imbalance of temperature dependent bound polarization charges and screening charges. In wet conditions this electric potential is available for reduction and oxidation reactions via charge transfer to physisorbed molecular species. In this context, we have investigated the impact of cyclically thermal excited pyroelectric LiNbO3 and LiTaO3 on the redox behavior of noble metal salts, organic dyes and nicotineamide cofactors in aqueous solutions. The reaction efficiencies strongly depend on the total surface of the pyroelectric particulate material in direct contact with the medium. Moreover successful bactericidal tests with Escherichia coli have been performed offering potential applications in environmental technology.
LiNbO3 and LiTaO3 pyroelectric crystals are characterized by a large band gap and a polar crystal structure resulting in a spontaneous polarization. In contrast to near surface space charge zone formation in semiconducting pyroelectrics like ZnO or GaN, the bound polarization charges at the surface of large band gap pyroelectrics are preferentially neutralized by external screening charges attracted from surrounding media. When the pyroelectric crystal is subjected to a temperature change an electric potential develops due to an imbalance of temperature dependent bound polarization charges and screening charges. In wet conditions this electric potential is available for reduction and oxidation reactions via charge transfer to physisorbed molecular species. In this context, we have investigated the impact of cyclically thermal excited pyroelectric LiNbO3 and LiTaO3 on the redox behavior of noble metal salts, organic dyes and nicotineamide cofactors in aqueous solutions. The reaction efficiencies strongly depend on the total surface of the pyroelectric particulate material in direct contact with the medium. Moreover successful bactericidal tests with Escherichia coli have been performed offering potential applications in environmental technology.
