Growth of pyrochlore Bi2Ti2O7 epitaxial films and their electrical characterization

Epitaxial growth condition of Bi2Ti2O7 films on the substrates having rutile-structure was investigated. TiO2 single crystals and the conductive epitaxial IrO(2)layers having same rutile- structure were used as substrates for film deposition. Strongly (111)-oriented Bi2Ti2O7 films were confirmed to be deposited on (110) TiO2 substrates by XRD theta-2theta scans, but obvious orientations were not detected on (100), (001) and (110) TiO2 substrates. The epitaxial growths of Bi2Ti2O7 films were confirmed on (100), (001) and (110) TiO2 substrates, where two variants were observed on (100) and (110) TiO2 substrates. The epitaxial relationships were confirmed as follows; (14 14 19)Bi2Ti2O7//(100)TiO2, (112)Bi2Ti2O7//(101)TiO2, and (111)Bi2Ti2O7//(110)TiO2. Same epitaxial growth was confirmed only on (110)IrO2//(110)TiO2 substrate, but not on (101)IrO2//(012)Al2O3 and (100)IrO2//(100)TiO2 substrates. The dielectric constant and loss tangent at 1 kHz were 130 and 2%, respectively for the 130 nm-thick epitaxial Bi2Ti2O7 film grown on (110)IrO2//(110)TiO2 substrate.