Y. Hou

Synthesis and photocatalytic property of bismuth titanate Bi4Ti3O12

This study prepared layered perovskite Bi4Ti3O12 crystals by CSD method, and examined the photocatalystic property of Bi4Ti3O12 crystals for photo-degradation of methyl orange. The crystal particulate of Bi4Ti3O12 crystals was observed to be in spherical shapes with diameters of 10–90 nm from TEM images. The Bi4Ti3O12 catalyst shows high photocatalystic activities to photodegrade 10 ppm methyl orange solution in 4 h under UV irradiation.

Bi3.25La0.75Ti3O12 thin films prepared on Si (100) by metalorganic decomposition method

Bi3.25La0.75Ti3O12 (BLT) thin films have been grown on n-type Si (100) substrates by metalorganic decomposition method. The structural properties of the films were examined by x-ray diffraction. The BLT films exhibit good insulating property with room temperature resistivities in the range of 1012–1013 Ω cm. The current–voltage characteristics show ohmic conductivity in the lower voltage range and space-charge-limited conductivity in the higher voltage range. The capacitance–voltage characteristic hysteresis curves show that the metal-ferroelectric-semiconductor structure has memory effect. The fixed charge density and the surface state density were also calculated. The results obtained indicate that the present BLT films are suitable for making ferroelectric field effect transistor memories.

Effect of thermal annealing on structural properties, morphologies and electrical properties of TiO2 thin films grown by MOCVD

TiO2 thin films, were deposited on Si(100) and Si(111) substrates by metalorganic chemical vapor deposition at 500 °C, and have been annealed for 2 min, 30 min and 10 hours at the temperature from 600 °C to 900 °C, in oxygen and air flow, respectively. XRD and atomic force microscopy characterized the structural properties and surface morphologies of the films. As-deposited films show anatase polycrystalline structure with a surface morphology of regular rectangled grains with distinct boundaries. Rutile phase formed for films annealed above 600 °C, and pure rutile polycrystalline films with (110) orientation can be obtained after annealing under adequate conditions. Rutile annealed films exhibit a surface morphology of equiaxed grains without distinct boundaries. The effects of substrate orientation, annealing time and atmosphere on the structure and surface morphology of films have also been studied. Capacitance-Voltage measurements have been performed for films deposited on Si(100) before and after annealing. The dielectric properties of TiO2 films were greatly improved by thermal annealing above 600 °C in oxygen.

Pb(Zr,Ti)O3 thin films prepared on PbTiO3Si(100) by chemical solution decomposition technique

Abstract Pb(Zr0.5Ti0.5)O3 (PZT) thin films on PbTiO3/Si(100) substrates were prepared from lead acetate trihydrate [Pb(CH3COO)2.3H2O], zirconium nitrate pentahydrate [Zr(NO3)4.5H2O] and titanium butoxide [Ti(OC4H9)4] by using chemical solution decomposition (CSD) technique. Using a modified precursor solution and rapid thermal annealing (RTA) process, it was possible to obtain highly (110) oriented PZT thin films with high perovskite content at a low annealing temperature of 500°C. The influences of annealing temperature and time on leakage current density were investigated. The dielectric constant and dissipation factor at a frequency of 50KHz were 234 and 0.026, respectively.

Dielectric Properties of Bi2Ti2O7 Thin Films With (111) Orientation

Bismuth titanate thin films have been prepared on silicon by metalorganic decompositionMOD) technique with bismuth nitrate and titanium butoxide as source materials. The growth procedure of the Bi 2 Ti 2 O 7 thin films is discussed in this paper. The surface morphology of the Bi 2 Ti 2 O 7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi 2 Ti 2 O 7 thin films vs. frequency, in the temperature range of 100-800 °C, were studied. The dielectric constant and the dielectric loss for Bi 2 Ti 2 O 7 are 118 and 0.07 respectively at 100KHz. For the Bi 2 Ti 2 O 7 films with 0.4µm in thickness annealed at 580 °C for 40 minutes, their leakage current density is 4.06×10 −7 A/cm 2 at an applied voltage of 15V. The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi 2 Ti 2 O 7 ceramic films. Capacitance vs. temperature was measured from 27-800 at 1KHz, 100KHz, 100KHz and 1MHz.

Dielectric and ferroelectric properties of Bi2Ti2O7 thin films with (111) orientation

Abstract Transparent and crack-free Bi2Ti2O7 thin films with strong (111) orientation were successfully prepared on n-Si(100) by chemical solution deposition (CSD) using bismuth nitrate and titanium butoxide as starting materials. The growth procedure of the Bi2Ti2O7 thin films is discussed in this paper. The surface morphology of the Bi2Ti2O7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi2Ti2O7 thin films vs. frequency in the temperature range of 100–800°C were studied. The dielectric constant and the dielectric loss for Bi2Ti2O7 are 118 and 0.07 respectively at 100 KHz. For the Bi2Ti2O7 films with 0.4 μrn in thickness annealed at 580°C for 40 minutes, their leakage current density is 4.06×10−7 A/cm2 at an voltage of 15 V. The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi7Ti2O7 ceramic films. Capacitance vs. temperature was measured from 27°800°C at 1KHz. 10KHz, 100KHz and 1MHz.