Lead titanate ( PbTiO3) thin films were deposited on silicon substrates covered with platinum by reactive sputtering using a single multicomponent-type target at high temperatures (around 500° C). Small chips of metallic niobium were incorporated into the target for doping purposes. Samples analyzed in this study were fabricated in such a way that the molar concentration of niobium was kept at 0, 1, 2, 3, or 4%. X-ray diffraction (XRD) patterns showed that samples doped with niobium tended to exhibit epitaxial growth on top of a (111)-oriented platinum electrode. At 2 mol% niobium doping, the tetragonality ratio (c/a) exhibited a maximum value and the dielectric permittivity showed a local minimum. The dielectric loss and leakage current characteristics of Nb-doped films were considerably improved. Electric displacement-electric field (D-E) hysteresis loops were observed at all doping concentrations. Some promising acoustic surface wave characteristics were also observed. Samples with 1 or 2 mol%Nb seem to be very promising candidates for integrated devices.

This work describes a new type of piezoelectric motor that can be employed for both linear and rotary displacements. Although inspired on a classical "V-type" configuration, its long and thin stator tip can oscillate with relatively high amplitude and in several mode combinations. Two piezostacks are used to vibrate the stator accordingly. Movement in both directions can be achieved by driving each stack independently. The driving circuit is based on half-bridge inverter circuit. Parameters affecting speed control, as well as unbalance due to fabrication inaccuracy are analyzed.

The present work aims to model, simulate and propose a process for manufacturing a MEMS electrostatic device called Capacitive Micromachined Ultrasound Transducer (CMUT). The finite element method was used for modeling the operating conditions of the devices. Static analysis were made for three different materials Si, Cu, and SU-8. For Si and Cu membranes wider than 800µm in diameter, the CMUT collapsed. As for the SU-8, the collapse of CMUT occurred around 400µm in diameter and 10µm in thickness. Electrostatic and modal analysis were performed subsequently. The modal analysis were made to determine the natural mode shapes of the CMUT membrane. Simulation results gave an approximate idea of suitable dimensions of the devices. In this way, two microfabrication methods are proposed, one for Cu membrane and the other for the SU-8 membrane. Preliminary results allowed us to assert that the process for producing SU-8 CMUTs is very promising.

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An experiment is discussed which allows us to show that two-photon interference can be observed even when there is no intrinsic indistinguishability between different possibilities. This result follows from a conflict between the wave-like and the nonlocal properties of entangled photons.

Some electrical properties of niobium-doped highly (001)-oriented lead titanate thin films epitaxially grown on (100)Pt/(100)MgO substrates by reactive sputtering have been analyzed. The dielectric permittivity, which ranged from 160 to 200, had its minimum value corresponding to a niobium concentration of 1 mol%. Doped samples exhibited outstanding low dielectric losses, lower than 2.5%, compared to undoped ones. Current-voltage (I–V) leakage characteristics of doped samples were considerably better than those of the undoped samples. Such enhancement of resistivity is related to a decrease in the characteristic p-type semiconductive behavior of undoped PbTiO3 due to a reduction in lead vacancies which occurs in the presence of niobium. Doped samples exhibited electric displacement-electric field (D–E) hysteresis curves with high remanent polarization, around 30 µC/cm2, and high coercive field, around 150 kV/cm. In addition, voltage offsets in the hysteresis curves of doped samples could be lowered by applying a DC bias.

As technology advances AC system is also adhering to major advancements. In general, automobile airconditioning systems are designed to provide comfort for the driver and the passengers during a journey.

This work consists on the design, fabrication and characterization of a sensor to measure the concentration of a liquid solution with dielectric components. The sensor is of capacitive type, and it is processed using conventional microfabrication techniques. A thick interdigital structure made of nickel was electroplated on an alumina substrate. In this way, the interdigital structure forms the capacitor plates while the liquid solution is the dielectric material. The dielectric constant of the solution has an intermediate value when compared to the respective values of the pure components of the mixture. Such microsensors have been successfully applied to distinguish amongst different types of fuels commonly used in Brazilian automobiles (gasoline and ethanol).