Heating of surfaces by optical beams is investigated theoretically and compared with experimental results in the context of infrared imaging with vanadium dioxide thin films. Using known solutions for the diffusion of point heat sources at the interface between two semi-infinite media, the theory is extended to beams of Gaussian and flat profiles, for steady-state and dynamic regimes. Parameters relevant to imaging, such as spatial resolution and response time, are linked to thermal diffusivity, beam dimensions, and intensity.

In this study, the effect of as-prepared annatase TiO 2 nanotubes on the sintering behavior and the piezoelectric properties of lead zirconate titanate (PZT) ceramics was investigated. Two types of PZT (with the use of TiO 2 nanotubes and commercial TiO 2) were prepared by a conventional oxide-mixing method. The density of samples using TiO 2 nanotubes tended to increase and the sintering temperature of these ceramics decreased. The electromechanical coupling factor (k p ) of PZT ceramics was improved significantly by the use of TiO 2 nanotubes.

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Vanadium dioxide (VO 2 ) undergoing phase transition is known alters the polarization state of light in reflection owing to large changes in complex refractive indices. While this effect is promising for optical modulation applications, the usual VO 2 films on dielectric substrates tend to offer limited tunability for polarization modulation. In this paper, we show that metallic under-layers greatly enhance the performance by widening the spectral range and include visible wavelengths, by increasing the polarization modulation amplitude, and by widening the range of workable incidence angles. The imaginary part of the refractive index in the metallic layer is found to increase the relative phase shifts between s-and p-components of polarization as well as increasing the reflectance.

Dielectric properties of xBaTiO 3 -(1-x)CoFe 2 O 4 composite materials have been investigated. Dielectric properties of BaTiO 3 , CoFe 2 O 4 and 0.5BaTiO 3 -0.5CoFe 2 O 4 samples show frequency dependence, which is classified as relaxor behavior with different relaxing degree. The relaxor behaviors were described using the modified Curier-Weiss and Vogel-Fulcher laws. Among three above samples, the BaTiO 3 sample has highest relaxing degree. Photoluminescence spectral indicated defects, which might in turn control relaxing degree.