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Dielectric properties of model BaTiO3/polymer composites were measured over a broad frequency and temperature range. A series of BaTiO3/monomer suspensions were photocured into thin wafers. The wafers were equipped with aluminum electrodes, and the dielectric permittivity of the composites was investigated at frequencies from 100 Hz to 10 GHz and at temperatures from -140 to +150 °C. It has been found that for the same BaTiO3 loading dielectric characteristics of the composites strongly depend of the type of polymer. Polar polymers increase dielectric constant of the composites at low frequencies but have little effect at gigahertz frequencies. Dielectric losses of the composites show a maximum at some intermediate frequency within megahertz to gigahertz range that reflects the relaxation behavior of the polymer matrix. The magnitude of the losses increases with increasing polarity of the polymer component. At constant frequency and temperature, the composites follow a linear relationship between logarithm of their dielectric constant and volume fraction of the ferroelectric filler. Practical implications of such composites behavior are discussed.

A study of the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, is reported. When films of trans- (CH)x are exposed to chlorine, bromine, or iodine vapor, uptake of halogen occurs; and the conductivity increases markedly, over eleven orders of magnitude in the case of iodine. The behavior of the halogenated polyacetylene is like that of a series of semiconductors with activation energies which vary with halogen content. The results are discussed in terms of a model of the doping process based on charge transfer.

A series of experiments are reported which demonstrate that donors or acceptors can dope polyacetylene to n type or p type, respectively, and that the two kinds of dopants can compensate one another. The formation of a rectifying p-n junction is demonstrated. These results suggest the possibility of utilizing doped polyacetylene in a variety of potential semiconductor device applications.

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