An Explanation of the Photoinduced Giant Dielectric Constant of Lead Halide Perovskite Solar Cells.

A photoinduced giant dielectric constant of ~10(6) has been found in impedance spectroscopy measurements of lead halide perovskite solar cells. We report similar effects in measurements of a porous lead zirconate titanate (PZT) sample saturated with water. The principal effect of the illumination of the solar cell and of the introduction of water into the pore volume of the PZT sample is a significant increase in conductivity and dielectric loss.

Flexible piezoelectric transducer for ultrasonic inspection of non-planar components.

This paper presents the fabrication and characterisation of a flexible ultrasonic transducer using commercially available PZT-5A piezoelectric fibers which are lapped to form rectangular piezoelectric elements. The key feature in the device construction is the inclusion of gaps between the piezoelectric fibers to ensure good flexibility in the plane normal to the fiber direction. The spatial response of the transducer ultrasonic output was assessed using acoustographic imaging.

Anomalous power law dispersions in ac conductivity and permittivity shown to be characteristics of microstructural electrical networks.

The frequency dependent ac conductivity and permittivity of porous lead zirconate titanate ceramic with the pore volume filled with water are shown to match the simulated electrical response of a large network of randomly positioned resistors and capacitors. Anomalous power law dispersions in conductivity and permittivity are shown to be an electrical response characteristic of the microstructural network formed by the porous lead zirconate titanate pore structure. The anomalous power law dispersions of a wide range of materials are also suggested to be microstructural network characteristics.

Thermal imaging of composites.

Active thermal imaging techniques and their applications to composite materials are reviewed. The techniques included are transient thermography, scanning thermal microscopy and scanning thermal probe microscopy. The factors that affect the images produced by both pulsed and periodic forms of active heating are considered.