. It is evident that doping of glycine has a positive impact on characteristic features of BTCF, BTCC, ZTS, ZTC and BTCA crystals [ 5 – 9 ]. Potassium thiourea chloride (PTC) crystal is a promising NLO material having a tetragonal structure, good optical transparency, moderate hardness and high thermal stability  . It is noteworthy that till date no doping attempt has been made in case of PTC crystal as well as no investigations were accomplished to study the dielectric, third order nonlinear optical (TONLO) and surface characteristics of PTC crystal doped by an
S.M. Azhar, Mohd Anis, S.S. Hussaini, S. Kalainathan, M.D. Shirsat and G. Rabbani
F.A. Najar, G.B. Vakil and B. Want
hydrogen-containing atmospheres  . Crystalline materials in which the structural arrangement allows the motion of alkali ions along specific crystallographic axes has been a prime focus of investigations. In the present work, the anomalous dielectric behavior of LSMH crystals has been reported. It was observed that AC conductivity of the present crystal system is controlled by hopping mechanism. The growth aspect and the characterization studies, such as SXRD, UV-Vis, FT-IR, TGA/DTG, and microhardness of LSMH single crystals have been presented. Some numerical
M.N.V. Ramesh and K.V. Ramesh
density and Curie temperature of around 200 °C. Ramesh et al. [ 13 ] reported results of dielectric and impedance studies of BT-BKT20 with a Curie temperature of 185 °C at 1 KHz. As very few literature items were found on the effect of Zr substitution in BT-BKT20 lead free ceramics, an attempt was made to study the effect of Zr substitution on structural and dielectric properties of BT-BKT20 lead free ceramic materials. 2 Experimental Ceramic samples of Zr substituted with a composition 0.8Ba0.2(Bi 0.5 K 0.5 )Ti 1–x Zr x O 3 (0.01 ≤ x ≤ 0.06) have been
Sumit K. Roy, S. Chaudhuri, R.K. Kotnala, D.K. Singh, B.P. Singh, S.N. Singh, K.P. Chandra and K. Prasad
[ 23 ], (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 (Ti 1−5x/4 Nb x )O 3 [ 24 ] and (Bi 0.5 Na 0.5 ) 0.935 Ba 0.065 Ti (1−x) Nb x O 3 –0.01SrZrO 3 [ 25 ] ceramic solid solutions have been studied. Xu et al. [ 26 ] have studied the phase transitions, formation enthalpies and implications for general perovskite energetics with special reference to SrTiO 3 –NaNbO 3 solid solution, while magnetic and ferroelectric phase transitions studies in BiFeO 3 –NaNbO 3 system were carried out by Raevski et al. [ 27 ]. Besides, microstructural, Raman and dielectric properties of (1 – x
K. Selvarani, R. Mahalakshmi and B. Thanuja
Co-crystals of L-phenylalanine hydrochloride (LPAHCl) were grown by slow evaporation technique in the presence of manganese sulphate and cadmium chloride. Crystallinity of the grown crystals was confirmed by single crystal X-ray diffraction. Optical transmission spectra showed very high transmittance in the entire visible region. The cut-off wavelength was observed at 250 nm for both the crystals. The optical band gap energy was found to be 4.37 eV and 4.31 eV for the grown co-crystals of LPAHCl with MnSO4 and CdCl2, respectively. The second harmonic generation of the grown crystals was confirmed by Kurtz and Perry powder SHG method and compared with KDP. The frequency dependent dielectric properties of the co-crystals were studied at different temperatures.
M. Suresh, S. Asath Bahadur and S. Athimoolam
In the present work, a new organic second order NLO material: L-isoleucinium p-toluenesulfonate monohydrate (LIPT) is synthesized and reported for the first time. The LIPT is crystallized in a non-centrosymmetric monoclinic space group P21. Structural and hydrogen bond nature of the compound is analyzed using single crystal X-ray diffraction studies. The crystal exhibits very good optical properties such as wide optical transparency in the region of 210 nm to 1100 nm and the ultraviolet wavelength emission (λ = 283 nm). The second harmonic generation efficiency is found to be 1.7 times the standard KDP. Good thermal, mechanical properties and low dielectric constant at high frequency range show that the material may be a potential candidate for optoelectronic applications.
I.S. Yahia, Mohd. Shkir, V. Ganesh, M.M. Abutalib, H.Y. Zahran and S. Alfaify
Herein, we report a successful development of nano-scale pure and Al and Mn co-doped PbI2 using facile microwaveassisted route. Structural study was done through X-ray diffraction analysis of grain size, dislocation density and lattice strain. The crystallite size was found to vary from 28 nm to 40 nm due to Al:Mn co-doping in PbI2. The presence of various vibrational modes was confirmed by FT-IR spectroscopy and red shifting was observed in peak positions compared to the bulk. Surface morphology, examined using a scanning electron microscope, confirmed the formation of single crystal nanosheets of a thickness in the range of 10 nm to 30 nm. The single crystal nanosheets were found to be transformed to large area nanosheets due to the doping. Enhancement in dielectric constant from ~7.5 to 11 was observed with increasing Al doping concentration. Linear attenuation coefficient was calculated and showed the enhancement of blocking gamma rays with increasing doping concentration. Its value was found to increase from 7.5 to 12.8 with the doping. The results suggest that the synthesized nanostructures can be used for detection and absorption of gamma rays emitted by 137Cs and 241Am sources.
Tanusree Mondal, Sayantani Das, T.P. Sinha and P.M. Sarun
This work aims to study the electrical conduction mechanism in the dielectric material BaZr0.1Ti0.9O3 (BZT) ceramics by applying AC signal in the frequency range of 102 Hz to 106 Hz. The phase purity and microstructure of the sample have been studied by X-ray diffraction refinement and field-emission scanning electron microscope (FE-SEM) analysis. The appearance of resonance peaks in the loss tangent at high temperature is due to inherent dielectric relaxation processes of this oxide. The temperature dependent Cole-Cole plot has been studied in details to determine both the grain and grain boundary contribution to the conductivity. Electrical modulus analysis reveals that the hopping of charge carriers is the most probable conduction mechanism in BZT ceramics. The obtained data of AC conductivity obey the universal double power law and have been discussed in terms of microstructural network characteristics. The behavior of frequency exponent n of AC conductivity as a function of temperature verify the applicability of the correlated barrier hopping (CBH) model. The AC conductivity data are used to estimate the minimum hopping length, density of states at Fermi level, thermal conductivity and apparent activation energy. The value of activation energy confirms that the oxygen vacancies play a vital role in the conduction mechanism.
W. Skierucha, A. Wilczek and A. Szypłowska
-503. Nunes A. C., Bohigas X., and Tejada J., 2006. Dielectric study of milk for frequencies between 1 and 20 GHz. J. Food Eng., 76, 250-255. Pavlik Z., Fiala L., and Cerny R., 2008. Determination of moisture content of hygroscopic building materials using time domain reflectometry. J. Appl. Sci., 8, 1732-1737. Pavlik Z., Jirickova M., Cerny R., Sobczuk H., and Suchorab Z., 2006. Determination of moisture diffusivity using the time domain reflectometry (TDR) method. J. Building Physics, 30, 59
Mohd Anis, S.S. Hussaini, M.D. Shirsat and G.G. Muley
device applications. As doping can largely influence the characteristic traits of the crystal system, various researchers have re-investigated the ZTC crystal using different amino acids. The positive impact of glycine on structural, UV-Vis, thermal and SHG efficiency of ZTC crystal has been reported in the literature [ 3 ]. The improved structural, linear-nonlinear optical and thermal studies of L-alanine doped ZTC crystal have been explored [ 4 ]. The influence of L-cysteine on optical transparency, SHG efficiency, photoluminescence, thermal and dielectric properties