The complex dielectric permittivity of 4-(2-hexyloxyethoxy) 4 -cyanobiphenyl (6O2OCB) enclosed in porous samples of ZrO 2 has been studied in the frequency range 10 −1 -10 6 Hz and over a wide temperature range. For the substance in the nearly spherical pores of ZrO 2 no phase transition has been found, while for the substance in the bulk a monotropic system of phases, with smectic and crystalline phases, was determined. The relaxation spectra observed for the liquid phase of 6O2OCB in porous material are rather complex and they have been separated into three parts using sums of Havriliak-Negami equations. Two lower-frequency relaxations have been ascribed to collective and ionic motions. Our interest is in the high-frequency relaxation connected with the reorientations of molecules around the short axes. That process was the only one found in the pure 6O2OCB substance. In both cases the temperature changes of that relaxation were found to conform with the Vogel-Fulcher-Tammann formula for the average relaxation time. The relaxation times of molecules in pores are smaller than in the bulk. In pores the substance survives in the isotropic liquid phase to lower temperatures before the glass transition occurs. For the substance enclosed in pores the thermal hystereses of the dielectric permittivity and the relaxation times were found and discussed.

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