http://nopr.niscair.res.in/handle/123456789/4066 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/4096 Title: Dielectric relaxation studies of ternary liquid mixtures of aniline and substituted anilines with acrylonitrile in the microwave region <br/> <br/>Authors: Kalaivani, T; Krishnan, S <br/> <br/>Abstract: Dielectric behaviour of three amines and their mixtures: N-methyl aniline + acrylonitrile, aniline+ acrylonitrile and N, N-dimethyl aniline + acrylonitrile at microwave frequency 9.36GHz has been studied at temperature 303K. Different dielectric quantities like dielectric constant (ε^׳), dielectric loss (ε^״), static dielectric constant (ε_o), and dielectric constant at optical frequency (ε_∞) have been determined. The relaxation time (τ) has been calculated by both Higasi’s method and Cole-Cole method. The molar free energy of activation (Δ<i style="">F</i>_τ) and (Δ<i style="">F</i>_η) have also been calculated. The complex systems studied show the maximum relaxation time values at 1:1 complex ratio by both Higasi’s method and Cole-Cole plot method. <br/> <br/>Page(s): 383-385 http://nopr.niscair.res.in/handle/123456789/4095 Title: Structural and luminescence properties of sol-gel derived Cu doped ZnO films <br/> <br/>Authors: Das, K; Ray, S; Chaudhuri, S; Maity, A B <br/> <br/>Abstract: Well crystallized Cu doped (1, 3 and 5 molar %) ZnO films have been deposited on quartz substrates by sol-gel technique. The microstructural, optical and photoluminescence properties of the films have been studied. It has been observed that the band gap (3.38 eV) of ZnO films did not vary up to 5 molar % of Cu doping. The preferred orientation along (002) was observed for all the films. The X-ray diffraction (XRD) measurement confirmed the decrease of degree of orientation of (002) plane with increasing molar % of Cu in the films. The atomic force microscopy (AFM) measurements have also been performed to examine the surface morphologies of the films. It has been observed that the surface roughness of 1 molar % Cu doped film is smaller (~ 6 nm) than those of 3 and 5 molar % of Cu. The photoluminescence of the films shows prominent peaks between 2.27 to 3.11 eV due to excitonic as well as defect related transitions. A possible mechanism of carrier transitions between shallow and deep impurity levels in the photoluminescence has also been studied. <br/> <br/>Page(s): 377-382 http://nopr.niscair.res.in/handle/123456789/4094 Title: Polarization-tilt coupling for surface stabilized ferroelectric liquid crystal <br/> <br/>Authors: Bhattacharyya, Surjya Sarathi; Mukherjee, A; Chaudhuri, B K; Wu, S L <br/> <br/>Abstract: A ferroelectric liquid crystal (FLC) material in surface stabilized geometry has been characterized by polarized optical microscopic technique and detailed study of temperature dependent spontaneous polarization (<i style="">P_S</i>) and tilt angle ( θ) have been carried out. The tilt angle ( θ) has been measured in a newly developed electro-optic method. The coupling coefficient between molecular polarization (<i style="">P_S</i>) and tilt ( θ) has been determined in accordance with extended Landau theory. <br/> <br/>Page(s): 372-376 http://nopr.niscair.res.in/handle/123456789/4093 Title: Growth and characterization of NLO crystal <br/> <br/>Authors: Kumari, R Ananda <br/> <br/>Abstract: Pure ammonium dihydrogen orthophosphate (ADP) crystals and ADP crystals doped with nitrite tri-acetic acid and ethylene diamine tetra acetic acid (EDTA) have been grown by slow evaporation technique. Grown crystals have been characterized using X-ray diffraction and energy dispersive X-ray spectroscopy (EDAX). Second harmonic generation (SHG) efficiency measurements are carried out by Kurtz method. It has been found that the ADP crystals containing nitrite tri acetic acid and EDTA have resulted appreciable increase in SHG efficiency as compared to pure ADP crystals. Dielectric constant and dielectric loss are measured as a function of frequency. Study confirms the contribution of space charge polarization. <br/> <br/>Page(s): 369-371