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The diffuse dielectric anomaly by the dielectric relaxation found at the high-temperature region of 400-700 °C was investigated in perovskite-type ferroelectric oxides such as BaTiO[sub 3], (Pb,La)TiO[sub 3], and (Pb,La)(Zr, Ti)O[sub 3] ceramics. We observed that the diffuse dielectric anomaly in perovskite oxides was strongly affected by oxygen-related processing parameters. We have modified the Debye relaxation equation by introducing the mobile dipole of the thermal motion of oxygen vacancies in order to explain the temperature-dependent behavior of the diffuse dielectric anomaly. A relationship between the dielectric polarization/relaxation and the electrical conduction by the thermal motion of oxygen vacancies was microscopically suggested to explain the origin of the diffuse dielectric anomaly found at 400-700 °C in perovskite-type ferroelectric oxides. [ABSTRACT FROM AUTHOR]

We investigated the retention properties of BLT capacitors fabricated by a chemical solution deposition with Pt electrodes. BLT capacitors showed an opposite-state retention loss much better than that of PZT capacitor. On the other hand, BLT capacitors showed a large polarization loss of the same-state retention within 1 hour baking, while the corresponding loss of PZT was negligible. The hysteresis loops after different baking time showed a negligible imprint and a large relaxation of polarization. These behaviors were explained by a high resistance against imprint and a polarization relaxation possibly due to damaged interfacial layers developed by etching process of the BLT capacitors. [ABSTRACT FROM AUTHOR]

We investigated the time-dependent current-voltage curves of the forming process in unipolar resistance switching. We applied triggered-voltage triangular-waveform (pulse-waveform) signals with varied sweep rate (amplitude) to Pt/SrTiOx/Pt capacitors. By investigating their temperature dependences, we found that the forming process was driven by two different mechanisms, depending on the sweep rate (amplitude): a purely electrical dielectric breakdown and a thermally assisted dielectric breakdown. For the latter process, we observed precursory changes in the current I(t) before the forming process. By fitting the time-dependent precursory changes with I(t)=Io-A exp(-t/τ), we suggest that the thermally activated migration of oxygen vacancies/ions could help the thermally assisted dielectric breakdown. [ABSTRACT FROM AUTHOR]

Epitaxial c-axis-oriented Bi3.15Nd0.85Ti3O12 (BNT) thin films with thickness ranging from 150 to 350 nm were deposited on conductive SrRuO3 (SRO) on (001) SrTiO3 substrates by pulsed laser deposition. The top Pt electrode was deposited by sputtering to construct a capacitor Pt/BNT/SRO. The authors have evaluated the effective thickness (ti) and dielectric constant ([variant_greek_epsilon]i) of interfacial layers at the Pt/BNT and BNT/SRO interfaces based on the optical refractive index of the BNT layer and the capacitance frequency as well as the current-voltage characteristics of the capacitors. Using a series capacitor model, they have found that the dielectric constant of bulk BNT and the ti/[variant_greek_epsilon]i ratio are 586 and 1.46 nm, respectively. Knowing the optical dielectric constant ([variant_greek_epsilon]opt) and the product of [variant_greek_epsilon]optti of BNT thin films, the authors have estimated that the effective thickness and dielectric constant of the interfacial layers are 20.1 nm and 13.7, respectively. [ABSTRACT FROM AUTHOR]

The principal and innovative concept of this research is the replacement of piezoresistors in the current piezoresistive pressure sensors with carbon fibers. The piezoresistive characteristics of carbon fibers can play the same role as piezoresistors in current pressure sensors. The main structure of pressure sensors was built by back side etching on a silicon-on-insulator wafer to create a square diaphragm. Dielectrophoresis was used for the alignment and deposition of carbon fiber across the gap between two electrodes. The fabricated pressure sensors clearly showed linear response to applied pressure, so the feasibility of carbon-fiber-based pressure sensors was demonstrated. [ABSTRACT FROM AUTHOR]

Epitaxial (001)-oriented Bi3.25La0.75Ti3O12 (BLT) thin films were grown by pulsed-laser deposition on (001) LaAIO3 single-crystal substrates. The dielectric properties of the BLT films are highly anisotropic along different crystal directions. The dielectric constants are 358 and 160 along [100] and [110], respectively. Dielectric nonlinearity is also detected along these crystal directions. On the other hand, a much smaller dielectric constant and no detectable dielectric nonlinearity in a field range of 0–200 kV/cm are observed for a film along [001] where c-axis oriented SrRuO3 is used as the bottom electrode. [ABSTRACT FROM AUTHOR]