Raman scattering, electronic, and ferroelectric properties of Nd modified Bi4Ti3O12 nanotube arrays
ABSTRACT Neodymium-modified bismuth titanate, Bi 4- x Nd x Ti 3 O 12 (BNdT), nanotube arrays were fabricated by sol-gel method utilizing experimentally prepared porous anodic aluminum oxide (AAO) templates with pore diameters of about 200 nm and 100 nm, respectively. The as-prepared nanotube arrays exhibit orthorhombic perovskite polycrystalline structure of BNdT, which have outer diameters of about 200 and 100 nm, corresponding to the pores diameters of the AAO templates employed, and with wall thicknesses of about 9.7 nm and 12 nm, respectively. The phonon vibration modes corresponding to the Bi atoms in the Bi 2 O 2 layers weaken and broaden with increasing Nd content. The changes of Raman internal modes originated from the vibrations of atoms inside the TiO 6 octahedral indicate the increase in octahedron tilting and structural distortion. The leakage current and polarization-electric field response curves of BNdT nanotube arrays were measured, and the hysteresis loop illustrates a good ferroelectric property of as-prepared BNdT nanotube array at room temperature. The dielectric constant and dissipation factor were measured in the frequency region from 1 kHz to 1 MHz indicating polarization relaxation phenomenon.
SourceAvailable from: Hui-Yuan Sun[Show abstract] [Hide abstract]
ABSTRACT: A simple method of fabricating Co-containing anodic aluminum oxide films for multifunctional anti-counterfeit technology is reported. The films display highly saturated colors after being synthesized by an ac electrodeposition method. Tunable color in the films is obtained by adjusting anodization time, and can be adjusted across the entire visible range. Magnetic measurements indicate that such colored composite films show excellent magnetic properties. The resulted short (310 nm in length) and wide (50 nm in diameter) Co nanowires present only hexagonal close-packed phase, with the coercivity and squareness ratio as high as 1.2 x 10(5) A/m and 0.803, respectively. The magnetization reversal mechanism is in good agreement with coherent rotation model. The color and magnetic properties remain the same over a wide temperature range. The Co-containing anodic aluminum oxide films with structural color and perpendicular magnetic recording properties have friability-resistant feature and could be used in many areas including decoration, display and multifunctional anti-counterfeiting applications.Dyes and Pigments 12/2014; 111:185–189. DOI:10.1016/j.dyepig.2014.06.012 · 3.47 Impact Factor
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ABSTRACT: Ho-doped Bi4Ti3O12 ferroelectric thin films with the composition of Bi3.6Ho0.4Ti3O12 (BHT) were integrated with the epitaxial (0001)-oriented Al-doped ZnO (AZO) semiconductor thin films grown on c-sapphire substrates by pulsed laser deposition using a pure phase BHT ceramic target. The structure characterizations indicated that the BHT film grown on AZO (0001) was a single phase structure of Bi-layered Aurivillius phase bismuth titanate and showed (100)-preferred orientation. The BHT/AZO heterostructure was with a smooth interface and a uniform microstructure. All samples with various thickness were transparent and the average transmittance of (500 nm)BHT/(300 nm)AZO was higher than 89% in the range of 400–800 nm.Materials Letters 07/2012; 79:173–176. DOI:10.1016/j.matlet.2012.04.032 · 2.27 Impact Factor
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ABSTRACT: Raman scattering enhancement has been observed from highly ordered ferroelectric Bi3.25La0.75Ti3O12 nanotube (BLT-NT) arrays prepared by a template-assisted method. Scattering enhancement factor which is the ratio of average Raman intensity per molecule for nanostructure and film is evaluated to be about 92, 257, and 623 corresponding to the outer diameters of 50, 100, and 200 nm, respectively. The phenomena can be attributed to unique surface, microstructure, grain size, and tensile stress in the curved nanotube walls. These results indicate that BLT-NT arrays are suitable for fabricating multifunctional devices due to remaining good ferroelectricity.Applied Physics Letters 08/2012; 101(8). DOI:10.1063/1.4747218 · 3.52 Impact Factor