Journal of Ceramics http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Preparation of Stable ZrB2-SiC-B4C Aqueous Suspension for Composite Based Coating: Effect of Solid Content and Dispersant on Stability Sun, 07 Sep 2014 12:18:44 +0000 http://www.hindawi.com/journals/jceram/2014/370851/ ZrB2-SiC-B4C aqueous suspension has been prepared using poly(ethyleneimine) as a dispersant. Since increasing the solid content of suspension leads to high compaction and consequently low porosities through final coat, the effect of solid content has been studied. The dispersant and solid content were changed in the range of 0.3–1.5 wt.% and 45–55 vol.%, respectively, to assess the optimal conditions effect on stability and characteristics of suspension. Results of zeta potential measurements and rheological analysis at pH 7.8 showed that the composite suspension including 45 vol.% solid content and 1.5 wt.% dispersant was in stable state. Mehri Mashadi, Mohsen Mohammadijoo, Alireza Honarkar, and Zeinab Naderi Khorshidi Copyright © 2014 Mehri Mashadi et al. All rights reserved. Increasing Bending Strength of Porcelain Stoneware via Pseudoboehmite Additions Mon, 28 Apr 2014 11:19:59 +0000 http://www.hindawi.com/journals/jceram/2014/270689/ Pseudoboehmite nanoparticles synthesized through the desulfation of Al2(SO4)3 were used to investigate the reinforcement of commercial porcelain stoneware. Fractured specimens investigated by SEM suggest that the added pseudoboehmite precursor generated a nanometric primary mullite phase dispersed in the porcelain glassy phase that limited and stopped the intergranular crack propagation. The porcelain modulus of rupture increased twice the value of the modulus of rupture (108 MPa) as compared with that samples without pseudoboehmite additions. Pseudoboehmite also led to increased densification of porcelain stoneware bodies up to 1250°C as shown by thermodilatometry data. Omar Aguilar-García, Rafael Lara-Hernández, Azucena Arellano-Lara, José L. Gil-Vázquez, and Jaime Aguilar-García Copyright © 2014 Omar Aguilar-García et al. All rights reserved. Durability Modeling of Environmental Barrier Coating (EBC) Using Finite Element Based Progressive Failure Analysis Wed, 09 Apr 2014 08:32:31 +0000 http://www.hindawi.com/journals/jceram/2014/874034/ The necessity for a protecting guard for the popular ceramic matrix composites (CMCs) is getting a lot of attention from engine manufacturers and aerospace companies. The CMC has a weight advantage over standard metallic materials and more performance benefits. However, these materials undergo degradation that typically includes coating interface oxidation as opposed to moisture induced matrix which is generally seen at a higher temperature. Additionally, other factors such as residual stresses, coating process related flaws, and casting conditions may influence the degradation of their mechanical properties. These durability considerations are being addressed by introducing highly specialized form of environmental barrier coating (EBC) that is being developed and explored in particular for high temperature applications greater than 1100°C. As a result, a novel computational simulation approach is presented to predict life for EBC/CMC specimen using the finite element method augmented with progressive failure analysis (PFA) that included durability, damage tracking, and material degradation model. The life assessment is carried out using both micromechanics and macromechanics properties. The macromechanics properties yielded a more conservative life for the CMC specimen as compared to that obtained from the micromechanics with fiber and matrix properties as input. Ali Abdul-Aziz, Frank Abdi, Ramakrishna T. Bhatt, and Joseph E. Grady Copyright © 2014 Ali Abdul-Aziz et al. All rights reserved. Structural Evolution of Silicon Carbide Nanopowders during the Sintering Process Thu, 20 Mar 2014 17:41:26 +0000 http://www.hindawi.com/journals/jceram/2014/723627/ Processes of sintering of silicon carbide nanopowder were investigated. Values of density ( g/cm3) and strength ( MPa) were obtained. Within the theory of dispersed systems, the temperature evolution of the materials structure was considered. The relationship between sintering temperature, characteristics of crystal structure and physical properties, in particular, density, and strength of aforementioned ceramics was established. It was concluded that it is necessary to suppress the anomalous diffusion at temperatures above 2080°C. Galina Volkova, Oleksandr Doroshkevych, Artem Shylo, Tetyana Zelenyak, Valeriy Burkhovetskiy, Igor Danilenko, and Tetyana Konstantinova Copyright © 2014 Galina Volkova et al. All rights reserved. Provenance Study of Archaeological Ceramics from Syria Using XRF Multivariate Statistical Analysis and Thermoluminescence Dating Tue, 11 Mar 2014 14:50:21 +0000 http://www.hindawi.com/journals/jceram/2014/681017/ Thermoluminescence (TL) dating and multivariate statistical methods based on radioisotope X-ray fluorescence analysis have been utilized to date and classify Syrian archaeological ceramics fragment from Tel Jamous site. 54 samples were analyzed by radioisotope X-ray fluorescence; 51 of them come from Tel Jamous archaeological site in Sahel Akkar region, Syria, which fairly represent ceramics belonging to the Middle Bronze Age (2150 to 1600 B.C.) and the remaining three samples come from Mar-Takla archaeological site fairly representative of the Byzantine ceramics. We have selected four fragments from Tel Jamous site to determinate their age using thermoluminescence (TL) method; the results revealed that the date assigned by archaeologists was good. An annular 109Cd radioactive source was used to irradiate the samples in order to determine their chemical composition and the results were treated statistically using two methods, cluster and factor analysis. This treatment revealed two main groups; the first one contains only the three samples M52, M53, and M54 from Mar-Takla site, and the second one contains samples that belong to Tel Jamous site (local). Elias Hanna Bakraji, Rana Abboud, and Haissm Issa Copyright © 2014 Elias Hanna Bakraji et al. All rights reserved. Mechanical Behavior of Yttria-Stabilized Zirconia Aqueous Cast Tapes and Laminates Sun, 09 Mar 2014 09:31:56 +0000 http://www.hindawi.com/journals/jceram/2014/713916/ Aqueous tape casting was used to produce yttria-stabilized zirconia films for electrolyte-supported solid oxide fuel cell (SOFC). Tape casting slurries were prepared varying the binder content between 20 and 25 wt%. A commercial acrylic emulsion served as binder. Rheological measurements of the two slurries were performed. Both slurries showed a shear-thinning behavior. Tapes with 25 wt% binder exhibited adequate flexibility and a smooth and homogeneous surface, free of cracks and other defects. Suitable conditions of lamination were found and a theoretical density of 54% in the laminates was achieved. Laminated tapes showed higher tensile strength compared to single sheets. Tape orientation has a significant influence on the mechanical properties. Tensile strength, elongation to strain, and Young’s modulus measured in samples produced in the direction of casting showed higher property values. V. Moreno, R. M. Bernardino, and D. Hotza Copyright © 2014 V. Moreno et al. All rights reserved. Alumina-Based Ceramics for Armor Application: Mechanical Characterization and Ballistic Testing Thu, 09 Jan 2014 13:10:52 +0000 http://www.hindawi.com/journals/jceram/2014/618154/ The aim of this work is to present results of mechanical characterization and ballistic test of alumina-based armor plates. Three compositions (92, 96, and 99 wt% Al2O3) were tested for 10 mm thick plates processed in an industrial plant. Samples were pressed at 110 MPa and sintered at 1600°C for 6 h. Relative density, Vickers hardness, and four-point flexural strength measurements of samples after sintering were performed. Results showed that the strength values ranged from 210 to 300 MPa depending on the porosity, with lower standard deviation for the 92 wt% Al2O3 sample. Plates (120 mm × 120 mm × 12 mm) of this composition were selected for ballistic testing according to AISI 1045, using a metallic plate as backing and witness plates in the case of penetration or deformation. Standard NIJ-0108.01 was followed in regard to the type of projectile to be used (7.62 × 51 AP, Level IV, 4068 J). Five alumina plates were used in the ballistic tests (one shot per plate). None of the five shots penetrated or even deformed the metal sheet, showing that the composition containing 92 wt% Al2O3 could be considered to be a potential ballistic ceramic, being able to withstand impacts with more than 4000 J of kinetic energy. M. V. Silva, D. Stainer, H. A. Al-Qureshi, O. R. K. Montedo, and D. Hotza Copyright © 2014 M. V. Silva et al. All rights reserved. Influence of the Dopants on the Mechanical Properties of Alumina-Based Ceramics Wed, 25 Dec 2013 07:54:54 +0000 http://www.hindawi.com/journals/jceram/2013/430408/ In the present study the mechanical properties of dense alumina-based ceramics obtained by two processing routes are investigated. The application of magnetic-pulsed compaction or hot pressing of the powder leads to a comparable combination of microhardness, elastic modulus, and fracture toughness. The insertion of Al into Al2O3 powder increases the microdistortions of the crystalline lattice, resulting in the sufficient decrease of indentation wear-resistance. The usage of ZrO2 or TiCN as dopants to alumina matrix improves slightly the mechanics of the composites with a noticeable decrease of the material lost by 30% compared to pure alumina at closely spaced arrays of indents. Regardless of the synthesis method, the ceramic grains were formed completely with the fracture travelling along the grain boundaries. Anton Sergeevich Kaygorodov, Vasily Ivanovich Krutikov, and Sergey Nikolaevich Paranin Copyright © 2013 Anton Sergeevich Kaygorodov et al. All rights reserved. Processing and Characterization of Yttria-Stabilized Zirconia Foams for High-Temperature Applications Thu, 19 Dec 2013 08:28:25 +0000 http://www.hindawi.com/journals/jceram/2013/785210/ In this work ceramic foams of 3 and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) were manufactured by the replication method using polystyrene-polyurethane foams with pore sizes in the 7–10 ppi range. A second coating was carried out on presintered foams in order to thicken struts and hinder microstructural defects. The produced ceramic foams were structurally and thermomechanically characterized. Samples recoated with 3YSZ presented the highest relative densities () which contributed to a better mechanical and thermal behavior. Ana María Herrera, Amir Antônio Martins de Oliveira Jr., Antonio Pedro Novaes de Oliveira, and Dachamir Hotza Copyright © 2013 Ana María Herrera et al. All rights reserved. Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation Mon, 16 Dec 2013 14:27:21 +0000 http://www.hindawi.com/journals/jceram/2013/350931/ High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm), while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm) to higher but approximately the same emissivities. Mohannad M. S. Al Bosta, Keng-Jeng Ma, and Hsi-Hsin Chien Copyright © 2013 Mohannad M. S. Al Bosta et al. All rights reserved. Thermal Variation of Elastic Modulus on Nanocrystalline NiCuZn Ferrites Tue, 08 Oct 2013 13:23:08 +0000 http://www.hindawi.com/journals/jceram/2013/451863/ The nanopowders of Ni0.38Cu0.12Zn0.5Fe2O4 with particle size, 20 nm have been synthesised using Microwave-Hydrothermal method and characterized. Then the ferrite samples were microwave sintered at different temperatures in an air atmosphere and characterized. The magnetic properties were measured at room temperature. The dielectric constant (), initial permeability () and quality factor () has been measured on sintered samples at 1 MHz. Thermal variation of initial permeability has been measured over temperature range of 300 K–600 K. A detailed study of elastic behaviour of NiCuZn ferrites has been under taken using a composite piezoelectric oscillator method over a temperature of 300 K–600 K. The room temperature elastic moduli is found to be slightly sample dependent and decreases with increasing the temperature, except near the Curie temperature, , where a small anomaly is observed. The internal friction at room temperature is also found to be more particle size dependent. The temperature variation of internal friction exhibits a broad maximum around 500 K, just below Curie temperature 530 K. The above observations were carried on in the demagnetized state; on the application of a 400 mT magnetic field allowed us to reach the saturated state of the sample at any of the measuring temperature. The anomaly observed in the thermal variation of elastic moduli and internal friction is explained with the help of temperature variation of magneto-crystalline anisotropy constant. S. R. Murthy Copyright © 2013 S. R. Murthy. All rights reserved. Mean-Field Approach to Dielectric Relaxation in Giant Dielectric Constant Perovskite Ceramics Wed, 25 Sep 2013 09:10:15 +0000 http://www.hindawi.com/journals/jceram/2013/795827/ The dielectric properties of CaCu3Ti4O3 (CCTO) and A2FeNbO6 (AFN, A = Ba, Sr, and Ca) giant dielectric constant ceramics were investigated in the frequency range from 1 Hz to 10 MHz. The relaxation properties can be perfectly described by a polaron model, indicating that the dielectric relaxation is intimately related to the hopping motion caused by localized charge carriers. Shanming Ke, Peng Lin, Haitao Huang, Huiqing Fan, and Xierong Zeng Copyright © 2013 Shanming Ke et al. All rights reserved. Mechanical Behaviour and Fracture Mechanics of Praseodymium Modified Lead Titanate Ceramics Prepared by Solid-State Reaction Route Thu, 29 Aug 2013 11:50:17 +0000 http://www.hindawi.com/journals/jceram/2013/280605/ The praseodymium modified lead titanate ceramics with composition where = 0.04, 0.06, 0.08, and 0.10 prepared by solid-state reaction technique were subjected to indentation induced hardness testing method. The indentations were induced in the applied load ranging from 0.245 N to 4.90 N. The microhardness varies nonlinearly with load and was best explained by the concept of Newtonian resistance pressure as proposed by Hays and Kendall’s law. Crack propagation, fracture toughness (), brittleness index (), and yield strength () were studied to understand the effect of Pr content on various mechanical parameters. The load independent values were found to increase with the increase in praseodymium content. Vishal Singh, Shivani Suri, and K. K. Bamzai Copyright © 2013 Vishal Singh et al. All rights reserved. A Comprehensive Study on Gamma-Ray Exposure Build-Up Factors and Fast Neutron Removal Cross Sections of Fly-Ash Bricks Wed, 21 Aug 2013 11:06:01 +0000 http://www.hindawi.com/journals/jceram/2013/967264/ Geometric progression (GP) method was utilized to investigate gamma-ray exposure build-up factors of fly-ash bricks for energies from 0.015 to 15 MeV up to 40 mfp penetration depth. The EBFs of the fly-ash bricks are dependent upon the photon energy, penetration depths, and the chemical compositions of the elements. Appreciable variations in exposure build-up factor (EBF) are noted for the fly-ash bricks. The EBFs were found to be small in low and high photon energy regions whereas very large in medium energy region. EBF of the bricks is inversely proportional to equivalent atomic number below 10 mfp for entire energy region of interest 0.015 to 15 MeV. The EBFs of fly-ash, brick of mud, and common brick were similar at 1.5 MeV photon energy. The EBF of the fly-ash bricks was found to be higher than that of the brick of mud, and common brick. The fast neutron removal cross sections of the fly-ash bricks, brick of mud, and common bricks were also calculated which were found to be in the same order. It is expected that this study should be very directly useful for shielding effectiveness of fly-ash brick materials and dose estimation. Vishwanath P. Singh and N. M. Badiger Copyright © 2013 Vishwanath P. Singh and N. M. Badiger. All rights reserved. Simple and Rapid Fabrication of Thin Films by a Chelate Route Wed, 12 Jun 2013 11:23:07 +0000 http://www.hindawi.com/journals/jceram/2013/850751/ Na0.5K0.5NbO3 (NKN) thin films were prepared by a chelate route which offers the advantage of a simple and rapid solution synthesis. The route is based on the use of acetoin as a chelating agent. The process was optimized by investigating the effects of alkaline volatilization on film properties. While we observed no evidence of stoichiometry problems due to potassium volatilization loss during the heat treatments, thin films synthesized with insufficient sodium excess presented a potassium-rich secondary phase, which has a significant influence on the ferroelectric properties. We show that the amount of spurious phase decreases with increasing Na+ concentration, in such a way that a 20 mol% Na+ excess is necessary to fully compensate the volatilization loss that occurred during the heat treatment. In this way, NKN thin films annealed at 650°C presented a well-crystallized perovskite structure, no secondary phases, well-defined ferroelectric hysteresis loops ( μC/cm2,  kV/cm), and low leakage current density ( A/cm2 at 80 kV/cm). A. Fernández Solarte, N. Pellegri, O. de Sanctis, and M. G. Stachiotti Copyright © 2013 A. Fernández Solarte et al. All rights reserved. Structural Elucidation of Some Borate Glass Specimen by Employing Ultrasonic and Spectroscopic Studies Sun, 21 Apr 2013 08:21:05 +0000 http://www.hindawi.com/journals/jceram/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. The Effect of Isostatic Pressing on the Dielectric Properties of Screen Printed Ba0.5Sr0.5TiO3 Thick Films Sun, 31 Mar 2013 15:24:56 +0000 http://www.hindawi.com/journals/jceram/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. Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C Tue, 12 Mar 2013 15:26:10 +0000 http://www.hindawi.com/journals/jceram/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. Experimental Study on LTCC Glass-Ceramic Based Dual Segment Cylindrical Dielectric Resonator Antenna Wed, 06 Mar 2013 10:32:11 +0000 http://www.hindawi.com/journals/jceram/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. Preparation and Characterization of Nano-Cadmium Ferrite Wed, 13 Feb 2013 18:58:54 +0000 http://www.hindawi.com/journals/jceram/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. Study of Gamma Ray Exposure Buildup Factor for Some Ceramics with Photon Energy, Penetration Depth and Chemical Composition Sun, 10 Feb 2013 13:16:29 +0000 http://www.hindawi.com/journals/jceram/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. The use of Waste Materials in Utility Poles, Crossarms, Paver, and Reef Balls Concrete Structures: Advantages and Care Thu, 17 Jan 2013 07:24:11 +0000 http://www.hindawi.com/journals/jceram/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. The Lattice Compatibility Theory: Arguments for Recorded I-III-O2 Ternary Oxide Ceramics Instability at Low Temperatures beside Ternary Telluride and Sulphide Ceramics Wed, 02 Jan 2013 10:41:34 +0000 http://www.hindawi.com/journals/jceram/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. Effect of Processing on Synthesis and Dielectric Behavior of Bismuth Sodium Titanate Ceramics Mon, 31 Dec 2012 08:57:45 +0000 http://www.hindawi.com/journals/jceram/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. Possibility of NiCuZn Ferrites Composition for Stress Sensor Applications Sun, 30 Dec 2012 16:10:08 +0000 http://www.hindawi.com/journals/jceram/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. Dielectric Properties of La2O3 Doped Composite (PbxSr1−x)TiO3 Borosilicate Glass Ceramic Wed, 05 Dec 2012 16:21:50 +0000 http://www.hindawi.com/journals/jceram/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. Mineral-Oxide-Doped Aluminum Titanate Ceramics with Improved Thermomechanical Properties Thu, 27 Sep 2012 10:22:18 +0000 http://www.hindawi.com/journals/jceram/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. Basic Elastic Properties Predictions of Cubic Cerium Oxide Using First-Principles Methods Thu, 19 Jul 2012 11:44:01 +0000 http://www.hindawi.com/journals/jceram/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.