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The pyroelectric coefficient of 0-3 composites of ferroelectric ceramic particles in a polymer matrix can be increased drastically by introducing a specified dc conductivity as explained by predictions based on the Poon-Shin model. The influence of doping with lithium chlorate on the dielectric permittivity of polyurethane has been studied to identify proper process parameters for the doping of composites. After appropriate doping the pyroelectric coefficient of 0-3 PZT/polyurethane composite is increased by more than a factor of ten at frequencies around 50 Hz. [ABSTRACT FROM AUTHOR]

Ba0.65Sr0.35(Ti0.95Sn0.05)O3 (BSTS) ferroelectric thin films are prepared by means of the sol-gel method on the Pt/Ti/SiO2/Si substrate. The results of the atomic force microscopy and X-ray diffraction analysis indicate that the grain sizes of BST thin films does not cause the change with the doped Sn. Compared with Ba0.65Sr0.35TiO3 (BST) thin films, BSTS thin films possess a lower dielectric constant and loss tangent, which is propitious to the improvement of the figures of merits of pyroelectric materials. The polarization at E = 0 and the field at P = 0 of BSTS thin films are 1.35 μ C/cm2 and 12.89 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

To obtain an optimum coupling of the pyroelectric activity of ferroelectric inclusions to the electrodes of a 0–3 composite film, the dielectric constants of matrix material and inclusions would have to be comparable. While there is no way to substantially raise the real part of the dielectric constant of the polymer matrix, the imaginary part can be increased by an appropriate doping. The results from theoretical modelling predict a significant increase of the pyroelectric coefficient and especially the pyroelectric signal power. Experimental investigations on composites of lead titanate particles in polyurethane doped with potassium bromide show the improvement and give hints to further optimization of its pyroelectric performance. [ABSTRACT FROM AUTHOR]

To improve the coupling of the pyroelectric activity of the ferroelectric particles to the electrodes of a composite film we propose the use of a matrix material which is not a perfect insulator but shows some electric conduction. Theoretical modelling results show that the pyroelectric coefficient of these composites is drastically enhanced. Furthermore, the noise figure of merit can be optimized by a proper selection of the electric conductivity of the polymer matrix. For the practical application in a sensor, these new composites have the additional advantage that the gate voltage of the first field effect transistor can be supplied through the resistance of the pyroelectric sensor element. [ABSTRACT FROM AUTHOR]

A simplified photopyroelectric (PPE) configuration that allows the simultaneous determination of the temperature dependent thermal and pyroelectric parameters of pyroelectric materials is described. The thermal parameters (thermal diffusivity, conductivity, effusivity and volumic specific heat) are obtained from the analysis of the phase of the complex photopyroelectric (PPE) signal generated from the pyroelectric sample itself and measured for two different modulation frequencies. The pyroelectric coefficient is obtained from the amplitude of the signal. Experimental results on thermal and pyroelectric parameters of LiTaO 3 single crystal in the 25°C-70°C temperature range are reported. [ABSTRACT FROM AUTHOR]