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A study was carried out on the luminescence excitation spectra and photoluminescence (PL) spectra as well as the luminescence kinetics of low-density polyethylene composites with different contents of CaGa2S4:Eu2+ phosphor filler. The phospholuminescence was attributed to the 4f65d → 4f7 transition of the Eu3+ ion and was greatest when the filler concentration was 7 vol.%. The dependence of the PL intensity on the excitation power density up to 0.3 W/cm2 was found to be linear, indicating that these phosphors can be used as visible radiation sources in various lighting systems. [ABSTRACT FROM AUTHOR]

Dielectric permittivity, electrical conductivity, and photoluminescence properties of high-density polyethylene with the additive of CaGa2S4:Eu+2 are studied. It was shown that dielectric permittivity and electric conductance increase with increasing filler concentration at all temperatures. In this case, conductivity has a hopping mechanism described by the Josher theory. The corresponding exponent parameter and activation energy slightly decrease with increasing filler concentration. The experimental data of dielectric permittivity are compared with the Maxwell–Garnett theory. It is also shown that the position of maximum of photoluminescence does not change with an increase in the concentration of Eu2+ ions and equals to about 550 nm. In this case, its intensity is maximal at the concentration of the filler is 5 mol. %. [ABSTRACT FROM AUTHOR]

Influence of ferroelectric BaTiO3particles on dielectric and electro-optic properties of liquid crystals (LC) 5CB and H37 has been investigated. It has been shown that the presence of particles decreases the clearing temperature, increases dielectric permittivity and losses, changes the Freedericksz transition voltage and switching times. A rise time of the BaTiO3-5CB colloid improved while a decay time worsened in comparison with the pure 5CB at all applied voltages. The inverse trends were observed for the H37 matrix. Experimental results are explained by appearance of local electric fields near the polarized ferroelectric particles at application of external electric field. [ABSTRACT FROM AUTHOR]

We have studied the optical transmission of a small aluminum oxide particles – liquid crystal (4-methoxybenzylidene-4′-butylaniline) system. We have observed that at room temperature, in the spectrum we observe a transmission band with maximum at 1896 cm–1, which is shifted toward shorter wavelengths on application of a voltage and depends on temperature. The experimental results are explained by the optical homogeneity of the system in a narrow frequency interval when the refractive indices of the particle material and the matrix are close, and also by reorientation of the liquid crystal molecules when a voltage is applied. [ABSTRACT FROM AUTHOR]

The crystals of TlInS2 are investigated by the methods of optical absorption and second‐harmonic generation. It is found that after a crystal is cooled for the first time an additional band appears in the absorption spectrum and the intensity of the second harmonic is greatest at temperatures 170–201 K. The characteristic features of the spectra and their dependence on the process of thermal cycling are explained by the formation of clusters and regions of an incommensurate phase in a commensurate one. [ABSTRACT FROM AUTHOR]

Auger electron spectroscopy and Raman spectroscopy were used to study a GaSe-SiO[sub 2] structure before and after irradiation with 4.0-MeV electrons at a dose of 3.0 × 10[sup 15] cm[sup -2]. It was shown that after the irradiation the thickness of the transition region in the GaSe-SiO[sub 2] structure decreases, while the oxide film becomes more homogenous. One of the possible causes of these changes may be radiation-stimulated gettering of Ga atoms by the GaSe-SiO[sub 2] interface that serves as a sink. [ABSTRACT FROM AUTHOR]