http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Sun, 21 Apr 2013 08:21:05 +0000 http://www.hindawi.com/journals/jcer/2013/485317/ Quantitative analysis has been carried out in order to obtain more information about the structure of two glass systems, namely, (B2O3-MnO2-PbO) (BML glass system) and (B2O3-Na2CO3-P2O5) (BSP glass system). Their structural elucidation has been carried out by studying the ultrasonic velocities (longitudinal velocities and shear velocities ) and density of these glass samples. The present investigation has been interpreted by focusing more on elastic and mechanical properties of glass specimen through ultrasonic study and the elemental analysis study through spectroscopic studies. The scanning electron microscopic (SEM) study was also carried out with a view to throwing more light on their morphological aspects. The results are corroborated in the light of the role of borate (B2O3) glasses in the formation of glassy structural network. S. Thirumaran and N. Karthikeyan Copyright © 2013 S. Thirumaran and N. Karthikeyan. All rights reserved. Sun, 31 Mar 2013 15:24:56 +0000 http://www.hindawi.com/journals/jcer/2013/852867/ Ba0.5Sr0.5TiO3 thick films with B2O3–Li2O glass sintering aid were prepared by the screen printing method on Al2O3 substrates. A 200 MPa isostatic pressure was applied to the films before sintering. After being sintered at 950 °C, lower porosity and denser microstructure was obtained compared with the films without isostatic pressing. The dielectric constant and dielectric loss were 238 and 0.0028, respectively. A tunability of 61.7% was obtained for the isostatic pressed films, a 27.8% enhancement compared to unpressurized films. These results suggest that isostatic pressing is an effective way to prepare dielectric thick films with dense microstructure, low dielectric loss, and high tunability. Siwei Wang, Lingling Zhang, Jiwei Zhai, and Fanglin Chen Copyright © 2013 Siwei Wang et al. All rights reserved. Tue, 12 Mar 2013 15:26:10 +0000 http://www.hindawi.com/journals/jcer/2013/370603/ The grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field  V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc. The combined values give that the magnitude of the grain boundary resistivity  ohm-cm. The electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test. J. Wang, A. Du, Di Yang, R. Raj, and H. Conrad Copyright © 2013 J. Wang et al. All rights reserved. Wed, 06 Mar 2013 10:32:11 +0000 http://www.hindawi.com/journals/jcer/2013/906748/ The measured characteristics in C/X bands, including material properties of a dual segment cylindrical dielectric resonator antenna (CDRA) fabricated from glass-ceramic material based on B2O3–La2O3–MgO glass and La(Mg0.5Ti0.5)O3 ceramic, are reported. The sintering characteristic of the ceramic in presence of glass is determined from contact angle measurement and DTA. The return loss and input impedance versus frequency characteristics and radiation patterns of CDRA at its resonant frequency of 6.31 GHz are studied. The measured results for resonant frequency and return loss bandwidth of the CDRA are also compared with corresponding theoretical ones. Ravi Kumar Gangwar, S. P. Singh, Meenakshi Choudhary, D. Kumar, G. Lakshmi Narayana Rao, and K. C. James Raju Copyright © 2013 Ravi Kumar Gangwar et al. All rights reserved. Wed, 13 Feb 2013 18:58:54 +0000 http://www.hindawi.com/journals/jcer/2013/526434/ Nano-hematite (α-Fe2O3) and nano-cadmium ferrite (CdFe2O4) are prepared using template-assisted sol-gel method. The prepared samples are analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Mössbauer spectroscopy techniques for structural and microstructural studies. Nano-α-Fe2O3 with particle size ~60 nm is formed at 500°C, while nano-CdFe2O4 with smaller particle size (~40 nm) is formed at 600°C. It is found that with a simple sol-gel process we can prepare nano-CdFe2O4 with better conditions than other methods: pure phase at lower sintering temperature and time (economic point) and of course with a smaller particle size. So, based on the obtained experimental results, a proposed theoretical model is made to explain the link between the use of the sol-gel process and the formation of nano-CdFe2O4 as a pure phase at low temperature. This model is based on a simple magnetostatic interaction between the formed nuclei within the solution leading to the formation of the stable phase at low temperature. S. M. Ismail, Sh. Labib, and S. S. Attallah Copyright © 2013 S. M. Ismail et al. All rights reserved. Sun, 10 Feb 2013 13:16:29 +0000 http://www.hindawi.com/journals/jcer/2013/721606/ Gamma ray exposure buildup factor for some ceramics such as boron nitride (BN), magnesium diboride (MgB2), silicon carbide (SiC), titanium carbide (TiC) and ferrite (Fe3O4) has been computed using five parametric geometric progression (G.P.) fitting method in the energy range of 0.015 to 15.0 MeV, up to the penetration of 40 mean free path (mfp). The variation of exposure buildup factors for all the selected ceramics with incident photon energy, penetration depth, and chemical composition has been studied. Tejbir Singh, Gurpreet Kaur, and Parjit S. Singh Copyright © 2013 Tejbir Singh et al. All rights reserved. Thu, 17 Jan 2013 07:24:11 +0000 http://www.hindawi.com/journals/jcer/2013/134169/ Industrial residues such as sludge from water treatment plants (Swtp) from centrifuged method; electrical porcelain residues (Pw); silica fume (Sf1 and Sf2); tire-rubber waste were evaluated in order to be used in concrete structures of electrical energy and environmental sectors, such as utility poles, crossarms, and reef balls technology. The results showed the necessity for evaluating different recycling concentrations in concrete, concomitantly to physicochemical tests allowing to diagnose natural and accelerated aging. Kleber Franke Portella, Alex Joukoski, João Bosco Moreira do Carmo, Camila Freitas, Carlos Vicente Gomes Filho, and Cinthya Hoppen Copyright © 2013 Kleber Franke Portella et al. All rights reserved. Wed, 02 Jan 2013 10:41:34 +0000 http://www.hindawi.com/journals/jcer/2013/734015/ Some recorded behaviours differences between chalcopyrite ternary oxide ceramics and telluride and sulphides are investigated in the framework of the recently proposed Lattice Compatibility Theory (LCT). Alterations have been evaluated in terms of Urbach tailing and atomic valence shell electrons orbital eigenvalues, which were calculated through several approximations. The aim of the study was mainly an attempt to explain the intriguing problem of difficulties of elaborating chalcopyrite ternary oxide ceramics (I-III-O2) at relatively low temperatures under conditions which allowed crystallization of ternary telluride and sulphides. K. Boubaker Copyright © 2013 K. Boubaker. All rights reserved. Mon, 31 Dec 2012 08:57:45 +0000 http://www.hindawi.com/journals/jcer/2013/261914/ An effort has been made to synthesize polycrystalline (abbreviated as BLNT) system with compositions x = 0, 0.02, and 0.04 by novel semiwet technique. Preparation of A-site oxides of BLNT for composition x = 0 was optimized using two precursor solutions such as ethylene glycol and citric acid. The XRD patterns revealed that the sample prepared by ethylene glycol precursor solution has single phase perovskite structure with a rhombohedral symmetry at RT as compared to the sample prepared by citric acid. Ethylene glycol precursor has been found to play a significant role in the crystallization, phase transitions, and electrical properties. The studies on structure, phase transitions, and dielectric properties for all the samples have been carried out over the temperature range from RT to 450°C at 100 kHz frequency. It has been observed that two phase transitions (i) ferroelectric to antiferroelectric and (ii) antiferroelectric to paraelectric occur in all the samples. All samples exhibit a modified Curie-Weiss law above Tc. A linear fitting of the modified Curie-Weiss law to the experimental data shows diffuse-type transition. The dielectric as well as ferroelectric properties of BLNT ceramics have been found to be improved with the substitution of La elements. Vijayeta Pal, R. K. Dwivedi, and O. P. Thakur Copyright © 2013 Vijayeta Pal et al. All rights reserved. Sun, 30 Dec 2012 16:10:08 +0000 http://www.hindawi.com/journals/jcer/2013/901375/ NiCuZn ferrite with composition of (NCu0.10Zn0.60F) (where , 0.02, 0.04, 0.06, 0.08, and 0.10) was prepared by the conventional ceramic double sintering technique. The formation of single phase was confirmed by X-ray diffraction. The microstructural features were also studied by electronic microscopy and are reported. Initial permeability measurements on these samples were carried out in the temperature range of 30 to 300°C. The effect of external applied stress on the open magnetic circuit type coil with these ferrite cores was studied by applying uniaxial compressive stress parallel to the magnetizing direction and the change in the inductance was measured. The variation of inductance (ΔL/L)% increases up to certain applied compressive stress and there after it decreases, showing different stress sensitivities for different compositions of ferrites studied in the present work. The variation of ratio of inductance (ΔL/L)% with external applied compressive stress was examined. These results show that the Ni0.42Cu0.10Zn0.60Fe1.76O3.76 and Ni0.44Cu0.10Zn0.60Fe1.72O3.72 samples are found to be suitable for inductive stress sensor applications. M. Penchal Reddy, W. Madhuri, M. Venkata Ramana, I. G. Kim, D. S. Yoo, N. Ramamanohar Reddy, K. V. Siva Kumar, D. V. Subbaiah, and R. Ramakrishna Reddy Copyright © 2013 M. Penchal Reddy et al. All rights reserved. Wed, 05 Dec 2012 16:21:50 +0000 http://www.hindawi.com/journals/jcer/2013/879758/ Ferroelectric (PbxSr1−x)TiO3 (PST) perovskite phase has been crystallized in borosilicate glassy matrix with a suitable choice of composition and heat treatment schedule. La2O3 is a donor dopant for PST and can make it semiconducting. Dispersion of semiconducting perovskite phase in insulating glassy matrix in glass-ceramic samples may lead to the formation of space charge polarization around crystal-glass interface, leading to a high value of effective dielectric constant, . Therefore, with the aim of the developing glass ceramics with high dielectric constant, glasses in the system 64[(PbxSr1−x)O·TiO2]-25[2SiO2·B2O3]-5[K2O]-5[BaO]-1[La2O3] have been prepared (). It is found that the addition of La2O3 strongly affected the crystallization and dielectric behavior of glass-ceramic with PST perovskite phase. All glass ceramic samples show a diffuse broad Curie peak in their versus T plots. Curie peak temperature, , depends on compositions of the glass-ceramic samples as well as frequency of measurements. C. R. Gautam, Devendra Kumar, Om Parkash, and O. P. Thakur Copyright © 2013 C. R. Gautam et al. All rights reserved. Thu, 27 Sep 2012 10:22:18 +0000 http://www.hindawi.com/journals/jcer/2013/214974/ Investigations were carried out, on the effect of addition of kaolinite (2Al2O3·3SiO2·2H2O) and talc (Mg3Si4O10(OH)2) in terms of bulk density, XRD phases, microstructure, as well as thermal and mechanical properties of the aluminium titanate (AT) ceramics. AT ceramics with additives have shown enhanced sinterability at 1550°C, achieving close to 99% of TD (theoretical density) in comparison to 87% TD, exhibited with pure AT samples sintered at 1600°C, and found to be in agreement with the microstructural observations. XRD phase analysis of samples with maximum densities resulted in pure AT phase with a shift in unit cell parameters suggesting the formation of solid solutions. TG-DSC study indicated a clear shift in AT formation temperature with talc addition. Sintered specimens exhibited significant reduction in linear thermal expansion values by 63% (0.4210−6/C, (30–1000°C)) with talc addition. Thermal hysteresis of talc-doped AT specimens showed a substantial increase in hysteresis area corresponding to enhanced microcrack densities which in turn was responsible to maintain the low expansion values. Microstructural evaluation revealed a sizable decrease in crack lengths and 200% increase in flexural strength with talc addition. Results are encouraging providing a stable formulation with substantially enhanced thermomechanical properties. R. Papitha, M. Buchi Suresh, Dibakar Das, and Roy Johnson Copyright © 2013 R. Papitha et al. All rights reserved. Thu, 19 Jul 2012 11:44:01 +0000 http://www.hindawi.com/journals/jcer/2013/323018/ Computational material methods were used to predict and investigate electrical and structural properties of cerium oxide (CeO2). Density functional theory was used to obtain the optimized crystal structure and simulate the material’s electronic and elastic responses. Oxygen to oxygen nearest neighbor distance is 2.628 Å, while oxygen to cerium distance is calculated to be 2.276 Å. The conduction band has a prominent set of bands, which exists between 6 and 17 eV. An indirect energy gap (6.04 eV) exists between the valence and conduction bands. The independent elastic constants allow a mechanical assessment on the suitability of cubic cerium oxide as a substrate for advanced electronic devices. The calculated results of phonon dispersion curves are also given. Jon C. Goldsby Copyright © 2013 Jon C. Goldsby. All rights reserved.