Application of Broad-Band Dielectric Spectroscopy for Investigations of Liquid Crystal - Porous Media Microcomposites
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origin as was found earlier for bulk alkylcyanobiphenyls. However this mode in pores like other modes observed at lower frequencies is not Debye like. CONCLUSION Application of broad band dielectric spectroscopy is powerful method for investigations of dielectric properties of liquid crystal - porous media microcomposites. This method makes it possible to obtain complete information about different aspects of dielectric behavior of two component heterogeneous systems. The separation of modes of different physical origin such as modes due to molecular rotation, surface polarization modes as well as dispersion due to conductivity can be performed. Detailed qualitative and quantitative information characterizing these modes can be obtained. The spatial confinement has a strong influence on the dielectric properties of LC. Slow relaxational process which does not exist in the bulk phase was observed. All observed relaxational modes, even bulk like modes are characterized by spectrum of relaxation times and are not described by Debye equation. The dielectrically active modes were not completely frozen even at temperatures at least 20 'C below the bulk crystallization temperature. These investigations should be extended to the temperature range which is much below
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the bulk crystallization temperature of the liquid crystal. ACKNOWLEDGEMENTS This work was supported by US Air Force grant F49620-95-1-0520 and NSF grant OSR9452893. REFERENCES 1. R. Hilfer, Phys. Rev. B 44, p. 60 (1991). 2. F.M.Aliev, M.N.Breganov, Soy. Phys. JETP 68, p. 70 (1989). 3. J. Schuller, Yu.B. Mel'nichenko, R. Richert, and E.W. Fischer, Phys. Rev. Lett. 73, p.
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