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.
{"title":"Dielectric Properties of La2O3 Doped Composite (PbxSr1−x)TiO3 Borosilicate Glass Ceramic","authors":"C. Gautam, D. Kumar, O. Parkash, O. P. Thakur","doi":"10.1155/2013/879758","DOIUrl":"https://doi.org/10.1155/2013/879758","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"53 1","pages":"1-9"},"PeriodicalIF":16.9,"publicationDate":"2013-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84684384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"Thermal Variation of Elastic Modulus on Nanocrystalline NiCuZn Ferrites","authors":"S. Murthy","doi":"10.1155/2013/451863","DOIUrl":"https://doi.org/10.1155/2013/451863","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"26 1","pages":"1-7"},"PeriodicalIF":16.9,"publicationDate":"2013-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83123793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shanming Ke, Peng Lin, Haitao Huang, H. Fan, Xierong Zeng
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.
{"title":"Mean-Field Approach to Dielectric Relaxation in Giant Dielectric Constant Perovskite Ceramics","authors":"Shanming Ke, Peng Lin, Haitao Huang, H. Fan, Xierong Zeng","doi":"10.1155/2013/795827","DOIUrl":"https://doi.org/10.1155/2013/795827","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"1 1","pages":"1-7"},"PeriodicalIF":16.9,"publicationDate":"2013-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90670867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"Mechanical Behaviour and Fracture Mechanics of Praseodymium Modified Lead Titanate Ceramics Prepared by Solid-State Reaction Route","authors":"Vishal Singh, Shivani Suri, K. Bamzai","doi":"10.1155/2013/280605","DOIUrl":"https://doi.org/10.1155/2013/280605","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"45 1","pages":"1-9"},"PeriodicalIF":16.9,"publicationDate":"2013-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75071148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"A Comprehensive Study on Gamma-Ray Exposure Build-Up Factors and Fast Neutron Removal Cross Sections of Fly-Ash Bricks","authors":"Vishwanath P. Singh, N. M. Badiger","doi":"10.1155/2013/967264","DOIUrl":"https://doi.org/10.1155/2013/967264","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"12 1","pages":"1-13"},"PeriodicalIF":16.9,"publicationDate":"2013-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74393515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. F. Solarte, N. Pellegri, O. Sanctis, M. Stachiotti
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
{"title":"Simple and rapid fabrication of Na0.5K0.5NbO3 thin films by a chelate route","authors":"A. F. Solarte, N. Pellegri, O. Sanctis, M. Stachiotti","doi":"10.1155/2013/850751","DOIUrl":"https://doi.org/10.1155/2013/850751","url":null,"abstract":"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","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"1 1","pages":"1-7"},"PeriodicalIF":16.9,"publicationDate":"2013-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77659485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"Structural Elucidation of Some Borate Glass Specimen by Employing Ultrasonic and Spectroscopic Studies","authors":"S. Thirumaran, N. Karthikeyan","doi":"10.1155/2013/485317","DOIUrl":"https://doi.org/10.1155/2013/485317","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"9 1","pages":"1-10"},"PeriodicalIF":16.9,"publicationDate":"2013-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85321332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"The Effect of Isostatic Pressing on the Dielectric Properties of Screen Printed Ba 0.5 Sr 0.5 TiO 3 Thick Films","authors":"Siwei Wang, Lingling Zhang, J. Zhai, F. Chen","doi":"10.1155/2013/852867","DOIUrl":"https://doi.org/10.1155/2013/852867","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"28 1","pages":"852867"},"PeriodicalIF":16.9,"publicationDate":"2013-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78037502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
{"title":"Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C","authors":"Jun Wang, A. Du, Di Yang, R. Raj, H. Conrad","doi":"10.1155/2013/370603","DOIUrl":"https://doi.org/10.1155/2013/370603","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"49 1","pages":"1-4"},"PeriodicalIF":16.9,"publicationDate":"2013-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73647569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Gangwar, S. P. Singh, M. Choudhary, DNagesh Kumar, G. Rao, K. Raju
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.
{"title":"Experimental Study on LTCC Glass-Ceramic Based Dual Segment Cylindrical Dielectric Resonator Antenna","authors":"R. Gangwar, S. P. Singh, M. Choudhary, DNagesh Kumar, G. Rao, K. Raju","doi":"10.1155/2013/906748","DOIUrl":"https://doi.org/10.1155/2013/906748","url":null,"abstract":"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.","PeriodicalId":14862,"journal":{"name":"Journal of Advanced Ceramics","volume":"115 1","pages":"1-8"},"PeriodicalIF":16.9,"publicationDate":"2013-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79022860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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