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991.
Homogeneous (LiCl)
x
(P2O5)1 − x
glasses were synthesised using a melt-quenching method for x = 0.1–0.6 in the interval of 0.05. The amorphous structure of the samples was evident by the X-ray diffraction spectrum.
The short range structures of the binary phosphate samples were examined by Fourier transform infrared spectroscopy, whilst
the density of the samples was measured as supportive data for the investigations. The results of refractive indices as measured
using an ellipsometer reveal the homogeneity of samples and was found to depend on the glass composition. The electrical properties
of the glasses were investigated by ac impedance spectroscopy from 10 mHz to 1 MHz for temperatures ranging from room temperature
to 573 K. An estimation of the bulk resistivity was obtained by taking the intercepts on the real axis at low frequencies
of the complex impedance plot. The dc conductivities derived from the reciprocal of resistivity values were found to obey
the Arrhenius relationship, and its activation energy shows a decreasing trend with the increase in LiCl content in the glass.
Lastly, an equivalent circuits consisting of real and complex capacitors is proposed to describe the dielectric response of
the glass. 相似文献
992.
993.
994.
The dielectric function of MgO-doped lithium niobate (LN:Mg) has been calculated, which depends on the angular frequency and Mg concentration. On the basis of our experimental data and the defect structure models, the substitution of Li ions by Mg ions will strongly influence the dielectric properties of LN:Mg. 相似文献
995.
Dongxian ZhuoAijuan Gu Guozheng Liang Jiang-tao HuLei Cao Li Yuan 《Polymer Degradation and Stability》2011,96(4):505-514
A novel kind of modified bismaleimide/cyanate ester (BCE) resins by copolymerizing with hyperbranched polysiloxane including high content of phenyl (HBPSi) was first reported. The effect of HBPSi on the curing mechanism, and that on the dielectric properties and flame retardancy of cured networks were systemically investigated. Results show that compared with BCE resin, HBPSi/BCE resin has obviously different cross-linked structure, and thus leading to simultaneously improved dielectric properties and flame retardancy. The reactions between HBPSi and the decomposition structure of BCE resin change the thermo-oxidative degradation mechanism of the first step in the thermo-oxidative degradation; in addition, the presence of HBPSi in BCE resin also significantly reduces the mass loss rate (MLR) and increases char yield at 800 °C under an air atmosphere. Therefore, the positive effect of HBPSi on improving the flame retardancy is attributed to the condensed phase mechanism. On the other hand, HBPSi/BCE resins exhibit improved dielectric properties (including decreased dielectric constant and loss) with increasing the content of HBPSi. More importantly, this investigation demonstrates that designing new polysiloxane with suitable chemical structure is important to develop high performance resins with attractive flame retardancy and dielectric properties. 相似文献
996.
《Physics letters. A》2020,384(28):126731
Ln0.8Lu0.2TiNbO6 (Ln = Ce, Pr, Nd & Sm) are synthesized through conventional solid state ceramic route. The XRD, FT Raman and FT IR studies revealed that the samples have aeschynite orthorhombic symmetry. The samples are sintered at 1230 ∘C. Using SEM technique, microstructure of the sintered samples is analyzed. The dielectric properties of all the samples in the radio as well as microwave frequencies are studied. UV spectra of the samples are recorded and the optical band gap is estimated from the Tauc's plots. The samples are found to be photoluminescent materials with emissions at violet and green regions. 相似文献
997.
We present the first successful dispersion analysis of a triclinic crystal in the infrared spectral region. The corresponding scheme involves the parallel evaluation of 12 polarized reflection spectra recorded from three mutual perpendicular faces of a cube-shaped crystal. The dispersion analysis was carried out on a CuSO4·5H2O single crystal. The determined oscillator parameters and the corresponding dielectric function tensor were used to model the spectra of polycrystalline CuSO4·5H2O. The good correspondence between modeled and experimental spectra of the polycrystalline species proves the correctness of the approach. 相似文献
998.
Bismuth ferrite (BFO) and La-substituted BFO with composition Bi1−xLaxFeO3 (x=0.05, 0.1 and 0.15) (BLFOx=0.05-0.15) ceramics were prepared using the solid state reaction route. A structural phase transition from rhombohedral phase to triclinic phase was observed for BLFOx=0.05-0.15 ceramics. Modulus spectroscopy reveals the deviation of dielectric behavior from ideal Debye characteristics and the dependence of conductivity on ion hopping in BFO and BLFOx=0.05-0.15 ceramics. The conductivity of the BFO ceramics decreases for La content of 5 mol%, followed by a subsequent increase with 10 and 15 mol% of lanthanum doping. The typical values of the activation energies at high temperature reveal the contribution of short range movement of doubly ionized oxygen vacancies to the conduction process in BFO and BLFOx=0.05 ceramics. Both short range and long range motion of oxygen vacancies are responsible for large conductivity in BLFOx=0.1 and 0.15 ceramics. 相似文献
999.
Pure and ZnCl2 doped anthracene (AN & ANZ) single crystals were grown by the slow evaporation method. In XRD studies a shift in peaks towards higher theta value and change in preferred orientation from (0 0 1) to (0 0 2) were observed as a result of doping. UV-vis spectra show a blueshift of various peaks in ANZ. Remarkable increases in dielectric constant and AC conductivity were observed along with a structure related phase transition at 40 °C in ANZ at atmospheric pressure itself. Good fluorescence properties with a strong green emission were observed in photoluminescence studies. 相似文献
1000.
Landau-Ginzburg equation is utilized to investigate the dielectric spectrum of an antiferroelectric liquid crystal (AFLC). Two collective modes, one associated with the in-phase motion at the low frequency side and the other related with the anti-phase motion at the high frequency side, are discussed in details utilizing the concept of bulk free energy of the material in terms of the pair interactions of two adjacent Smectic layers. The phenomenon of helix distortion related to the in-phase motion is observed theoretically based on the interlayer interactions of the AFLC system. The anti-phase mode related to the degree of the antiferroelectric ordering is also an important phenomenon depending on the layer-to-layer interactions. Finally we have theoretically obtained the critical field for helix unwinding with the model proposed by de Gennes. 相似文献