Pub Date : 2003-04-01DOI: 10.1179/096797803225001597
E. Salahi, J. Heinrich
Abstract In the present study, β tricalcium phosphate (β-TCP) was prepared by precipitation from aqueous solutions. Calcium nitrate tetrahydrate Ca(NO3)2.4H2O and diammonium hydrogen phosphate (NH4)2HPO4 salts with an initial Ca/P molar ratio of 1·5 were dissolved in distilled water and mixed at 20°C and pH 10. Phase evolution of the as received precipitate was studied by X-ray diffraction and infrared spectroscopy before and after calcination in a dry air atmosphere at temperatures in the range 200-1400°C for 1 h. Thermal behaviour was investigated by simultaneous thermal analysis (DTA-TG). Calcium and phosphorus contents of the as received precipitate were determined by the inductively coupled plasma technique, and a Ca/P molar ratio of 1·49 ± 0·01 was found. The densities of the as received precipitate and of powder calcined at 800°C were determined by picnometery to be 2·43 and 3·01 ± 0·05 g cm-3 respectively. The experimental data suggest the formation of an amorphous phase corresponding to a TCP-like composition, which is calcium deficient and contains a very small amount of HPO42- groups.
摘要本研究采用沉淀法从水溶液中制备了β磷酸三钙(β- tcp)。将四水硝酸钙Ca(NO3)2.4H2O和初始Ca/P摩尔比为1.5的磷酸氢二铵(NH4)2HPO4盐溶解于蒸馏水中，在20℃、pH 10条件下混合。通过x射线衍射和红外光谱研究了接收到的沉淀在干燥空气中在200-1400℃范围内煅烧1小时前后的相演变。通过同步热分析(DTA-TG)研究了热行为。采用电感耦合等离子体技术测定了接收沉淀物中钙、磷的含量，Ca/P摩尔比为1.49±0.01。经皮测，800℃煅烧后的沉淀和粉末的密度分别为2.43和3.01±0.05 g cm-3。实验数据表明，形成了一种非晶相，对应于tcp样成分，该成分缺钙，含有极少量的HPO42-基团。
{"title":"Synthesis and thermal behaviour of β tricalcium phosphate precipitated from aqueous solutions","authors":"E. Salahi, J. Heinrich","doi":"10.1179/096797803225001597","DOIUrl":"https://doi.org/10.1179/096797803225001597","url":null,"abstract":"Abstract In the present study, β tricalcium phosphate (β-TCP) was prepared by precipitation from aqueous solutions. Calcium nitrate tetrahydrate Ca(NO3)2.4H2O and diammonium hydrogen phosphate (NH4)2HPO4 salts with an initial Ca/P molar ratio of 1·5 were dissolved in distilled water and mixed at 20°C and pH 10. Phase evolution of the as received precipitate was studied by X-ray diffraction and infrared spectroscopy before and after calcination in a dry air atmosphere at temperatures in the range 200-1400°C for 1 h. Thermal behaviour was investigated by simultaneous thermal analysis (DTA-TG). Calcium and phosphorus contents of the as received precipitate were determined by the inductively coupled plasma technique, and a Ca/P molar ratio of 1·49 ± 0·01 was found. The densities of the as received precipitate and of powder calcined at 800°C were determined by picnometery to be 2·43 and 3·01 ± 0·05 g cm-3 respectively. The experimental data suggest the formation of an amorphous phase corresponding to a TCP-like composition, which is calcium deficient and contains a very small amount of HPO42- groups.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121778968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-04-01DOI: 10.1179/096797803225009283
J. Deng, Z. Zheng, Z. Ding, J. H. Wang
Abstract In the dry sand blasting process, the nozzle is the most critical component and is worn by repeated impact of abrasive particles. Erosion wear of the nozzle is influenced by various factors such as its mechanical properties and microstructure. In the present study, monolithic B4C, Al2O3/(W,Ti)C, WC/TiC/Co, and WC/Co composites, providing a reasonably wide range of mechanical properties and microstructure, were produced for use as nozzle materials. The erosion wear caused by abrasive particle impact was compared with that due to an abrasive air jet, by determining the cumulative mass loss and erosion rates of nozzles made from these materials. The effects of nozzle material mechanical properties and microstructure on erosion wear were investigated. Results showed that the hardness of the nozzle material plays an important role with respect to erosion wear in dry sand blasting. With their high hardness, the monolithic B4C nozzles exhibited lower erosion rates, while WC/TiC/Co and WC/Co cemented carbide nozzles with relatively low hardness showed higher erosion rates under the same test conditions. Analysis of eroded bore surfaces of the nozzles demonstrated that monolithic B4C nozzles exhibited a brittle fracture induced removal process, while WC/TiC/Co and WC/Co nozzles mainly showed a ploughing mode of material removal. Both material removal modes seemed to occur in the Al2O3/(W,Ti)C ceramic nozzles.
{"title":"Erosion wear of ceramic and cemented carbide nozzles in dry sand blasting process","authors":"J. Deng, Z. Zheng, Z. Ding, J. H. Wang","doi":"10.1179/096797803225009283","DOIUrl":"https://doi.org/10.1179/096797803225009283","url":null,"abstract":"Abstract In the dry sand blasting process, the nozzle is the most critical component and is worn by repeated impact of abrasive particles. Erosion wear of the nozzle is influenced by various factors such as its mechanical properties and microstructure. In the present study, monolithic B4C, Al2O3/(W,Ti)C, WC/TiC/Co, and WC/Co composites, providing a reasonably wide range of mechanical properties and microstructure, were produced for use as nozzle materials. The erosion wear caused by abrasive particle impact was compared with that due to an abrasive air jet, by determining the cumulative mass loss and erosion rates of nozzles made from these materials. The effects of nozzle material mechanical properties and microstructure on erosion wear were investigated. Results showed that the hardness of the nozzle material plays an important role with respect to erosion wear in dry sand blasting. With their high hardness, the monolithic B4C nozzles exhibited lower erosion rates, while WC/TiC/Co and WC/Co cemented carbide nozzles with relatively low hardness showed higher erosion rates under the same test conditions. Analysis of eroded bore surfaces of the nozzles demonstrated that monolithic B4C nozzles exhibited a brittle fracture induced removal process, while WC/TiC/Co and WC/Co nozzles mainly showed a ploughing mode of material removal. Both material removal modes seemed to occur in the Al2O3/(W,Ti)C ceramic nozzles.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124862221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009256
B. Li, Longtu Li, X. Wang
Abstract Nanostructured SrBi2Ta2O9 powders have been prepared by sol-gel processing and the resulting precursors characterised after calcination by DTA-TG and XRD. The results show that pure powders can be obtained above 600°C with a particle size of 60 nm, as determined by TEM . Pressed pellets sintered in air increased in density with increasing sintering temperature, reaching a maximum of 8·42 g cm - 3 after 2 h at 1250°C. In order to improve densification, Bi2O3 contents between 3 and 10 wt-% were added to pure SrBi2Ta2O9. The results show that these additions tend to increase density, but that decomposition by volatilisation of Bi2O3 at high temperature is retarded to a degree depending on the Bi2O3 content. This behaviour is attributed to the increased density resulting from Bi2O3 addition, which reduces volatilisation, and hence decomposition, at higher temperatures.
摘要采用溶胶-凝胶法制备了SrBi2Ta2O9纳米粉体，并通过DTA-TG和XRD对所制备的前驱体进行了表征。结果表明:在600℃以上可制得纯粉末，TEM测定其粒径为60 nm;在空气中烧结的压球密度随烧结温度的升高而增大，在1250℃下烧结2 h后达到最大值8.42 g cm - 3。为了提高致密性，在纯SrBi2Ta2O9中添加3 ~ 10 wt-%的Bi2O3。结果表明，Bi2O3的添加会增加密度，但Bi2O3在高温下的挥发分解会受到一定程度的阻碍，这取决于Bi2O3的含量。这种行为是由于Bi2O3的加入增加了密度，减少了挥发，从而在更高的温度下分解。
{"title":"Preparation and sintering behaviour of nanostructured SrBi2Ta2O9 ceramics","authors":"B. Li, Longtu Li, X. Wang","doi":"10.1179/096797803225009256","DOIUrl":"https://doi.org/10.1179/096797803225009256","url":null,"abstract":"Abstract Nanostructured SrBi2Ta2O9 powders have been prepared by sol-gel processing and the resulting precursors characterised after calcination by DTA-TG and XRD. The results show that pure powders can be obtained above 600°C with a particle size of 60 nm, as determined by TEM . Pressed pellets sintered in air increased in density with increasing sintering temperature, reaching a maximum of 8·42 g cm - 3 after 2 h at 1250°C. In order to improve densification, Bi2O3 contents between 3 and 10 wt-% were added to pure SrBi2Ta2O9. The results show that these additions tend to increase density, but that decomposition by volatilisation of Bi2O3 at high temperature is retarded to a degree depending on the Bi2O3 content. This behaviour is attributed to the increased density resulting from Bi2O3 addition, which reduces volatilisation, and hence decomposition, at higher temperatures.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116704009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009193
Hai Jun Zhang, X. Yao, M. Wu, L. Zhang
Abstract A series of Z type hexaferrite samples with composition Ba3CoxZn2 -xFe24O41 (x varying from 0·0 to 2·0 in steps of 0·4) were prepared by a citrate sol-gel process. Samples were characterised by TG-DSC, X-ray diffraction, and scanning electron microscopy. Complex permittivity and permeability, and dielectric and magnetic losses were studied as a function of measurement frequency, composition, and annealing temperature. The dependence of natural resonant frequency on annealing temperature as well as on cobalt content was investigated in the range 100 MHz to 6 GHz. Reflection loss has been calculated as a function of frequency according to transmission line theory.
{"title":"Complex permittivity andpermeability of Zn–Co substituted Z type hexaferrite prepared by citrate sol–gel process","authors":"Hai Jun Zhang, X. Yao, M. Wu, L. Zhang","doi":"10.1179/096797803225009193","DOIUrl":"https://doi.org/10.1179/096797803225009193","url":null,"abstract":"Abstract A series of Z type hexaferrite samples with composition Ba3CoxZn2 -xFe24O41 (x varying from 0·0 to 2·0 in steps of 0·4) were prepared by a citrate sol-gel process. Samples were characterised by TG-DSC, X-ray diffraction, and scanning electron microscopy. Complex permittivity and permeability, and dielectric and magnetic losses were studied as a function of measurement frequency, composition, and annealing temperature. The dependence of natural resonant frequency on annealing temperature as well as on cobalt content was investigated in the range 100 MHz to 6 GHz. Reflection loss has been calculated as a function of frequency according to transmission line theory.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121764553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009201
R. Dwivedi, D. Kumar, O. Parkash
Abstract T he structure and dielectric behaviour of the valence compensated system Sr1 -xLaxTi1 -x CrxO3 (x • 0·50) have been studied. Complex plane and spectroscopic studies of the impedance and modulus functions have been made in the temperature range 100-550 K to separate out the various contributions to the overall polarisation/electrical behaviour. The immittance data of various compositions in the system can be modelled by an equivalent circuit containing three parallel RC elements connected in series. These three elements correspond to the grain (bulk), grain boundaries, and electrode/specimen interface. It has been observed that the resistance of grain boundaries in all samples except x = 0·05 is higher than that of the grains. At low temperatures the contribution of electrode polarisation to total observed resistance is small in comparison with that of the grains and grain boundaries, and becomes significant only at high temperatures. Debye type relaxation owing to reorientation of dipoles is observed within the grains at low temperatures. With increasing temperature, Maxwell-Wagner type polarisation is observed at grain/grain boundary interfaces. The relaxation observed at high temperatures and low frequencies corresponds to electrode/specimen interface polarisation.
{"title":"Grain and grain boundary relaxation in Sr1 -xLaxTi1 -xCrxO3 ceramics: impedance and modulus spectroscopy","authors":"R. Dwivedi, D. Kumar, O. Parkash","doi":"10.1179/096797803225009201","DOIUrl":"https://doi.org/10.1179/096797803225009201","url":null,"abstract":"Abstract T he structure and dielectric behaviour of the valence compensated system Sr1 -xLaxTi1 -x CrxO3 (x • 0·50) have been studied. Complex plane and spectroscopic studies of the impedance and modulus functions have been made in the temperature range 100-550 K to separate out the various contributions to the overall polarisation/electrical behaviour. The immittance data of various compositions in the system can be modelled by an equivalent circuit containing three parallel RC elements connected in series. These three elements correspond to the grain (bulk), grain boundaries, and electrode/specimen interface. It has been observed that the resistance of grain boundaries in all samples except x = 0·05 is higher than that of the grains. At low temperatures the contribution of electrode polarisation to total observed resistance is small in comparison with that of the grains and grain boundaries, and becomes significant only at high temperatures. Debye type relaxation owing to reorientation of dipoles is observed within the grains at low temperatures. With increasing temperature, Maxwell-Wagner type polarisation is observed at grain/grain boundary interfaces. The relaxation observed at high temperatures and low frequencies corresponds to electrode/specimen interface polarisation.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129898372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009247
K. K. Patankar, S. L. Kadam, V. Mathe, C. Kanamadi, V. P. Kothawale, B. K. Chougule
Abstract Dielectric and magnetoelectric properties are reported in magnetoelectric (ME) composites containing lead doped barium titanate as the electrical component and a mixed Ni-Co ferrite as the magnetic component. Changes were observed in dielectric properties as well as in the ME effect as the molar ratio of the components was varied. A maximum value of ME conversion factor of 0·42 mV cm - 1 Oe - 1 (52·78 VA - 1) was observed in the composite containing 15 mol-% ferrite. Larger ME effects were observed in composites with higher contents of ferroelectric phase. This conclusion differs from earlier theoretical studies which predict a large ME interaction in composites with a 1:1 molar ratio of participating phases. Apart from the technological importance of the ME effect, some anomalies in magnetic phase transition induced by electric fields are also of scientific interest. The variation in dielectric properties with temperature resulted in two maxima, corresponding to the ferroelectric and ferrimagnetic Curie temperatures. This behaviour is unlike anything previously observed in other ME composites.
摘要研究了以掺铅钛酸钡为电组分，以Ni-Co混合铁氧体为磁性组分的磁电复合材料的介电性能和磁电性能。随着各组分摩尔比的变化，可以观察到介电性能和ME效应的变化。在含有15 mol-%铁氧体的复合材料中，ME转换因子最大值为0.42 mV cm - 1 Oe - 1(52·78 VA - 1)。铁电相含量越高，复合材料的ME效应越大。这一结论不同于早期的理论研究，后者预测在参与相的摩尔比为1:1的复合材料中有较大的ME相互作用。除了ME效应在技术上的重要性外，电场引起的磁相变中的一些异常也引起了科学的兴趣。介电性能随温度的变化产生两个最大值，对应于铁电和铁磁居里温度。这种行为不同于以前在其他ME复合材料中观察到的任何行为。
{"title":"Dielectric behaviour and magnetoelectric effect in Ni0·25Co0·75Fe2O4-Ba0·8Pb0·2TiO3 ceramic composites","authors":"K. K. Patankar, S. L. Kadam, V. Mathe, C. Kanamadi, V. P. Kothawale, B. K. Chougule","doi":"10.1179/096797803225009247","DOIUrl":"https://doi.org/10.1179/096797803225009247","url":null,"abstract":"Abstract Dielectric and magnetoelectric properties are reported in magnetoelectric (ME) composites containing lead doped barium titanate as the electrical component and a mixed Ni-Co ferrite as the magnetic component. Changes were observed in dielectric properties as well as in the ME effect as the molar ratio of the components was varied. A maximum value of ME conversion factor of 0·42 mV cm - 1 Oe - 1 (52·78 VA - 1) was observed in the composite containing 15 mol-% ferrite. Larger ME effects were observed in composites with higher contents of ferroelectric phase. This conclusion differs from earlier theoretical studies which predict a large ME interaction in composites with a 1:1 molar ratio of participating phases. Apart from the technological importance of the ME effect, some anomalies in magnetic phase transition induced by electric fields are also of scientific interest. The variation in dielectric properties with temperature resulted in two maxima, corresponding to the ferroelectric and ferrimagnetic Curie temperatures. This behaviour is unlike anything previously observed in other ME composites.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132556074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009184
H. K. Chen, C. I. Lin, C. Meng
Abstract The reaction between titanium pellet and nitrogen was investigated, under a regime in which both chemical reaction and gas pore diffusion were important, and on the basis of this study a physicochemical model was formulated to describe the reaction system. T he chemical reaction rate expressions, determined in the chemical reaction control region, were used to interpret the experimental data in the light of the model. T he expression for effective gas diffusivity De, which was used as a fitting parameter for calculation of the theoretical predictions, was determined to be 1·37 × 10 - 5 exp(-13000/RT) m2 s - 1. Deviation was found between the predictions of the model and the experimental data as the pellet thickness was increased. This is explained by the geometrical difference between the mathematical model, with flat surfaces only, and the actual pellet with both flat and circumferential surfaces. A geometrical factor g was introduced to compensate for this difference, the value of which was calculated to be 1/( 1 + 11·47L), where L is the half thickness of the sample.
{"title":"Mathematical model of reaction between titanium pellet and nitrogen","authors":"H. K. Chen, C. I. Lin, C. Meng","doi":"10.1179/096797803225009184","DOIUrl":"https://doi.org/10.1179/096797803225009184","url":null,"abstract":"Abstract The reaction between titanium pellet and nitrogen was investigated, under a regime in which both chemical reaction and gas pore diffusion were important, and on the basis of this study a physicochemical model was formulated to describe the reaction system. T he chemical reaction rate expressions, determined in the chemical reaction control region, were used to interpret the experimental data in the light of the model. T he expression for effective gas diffusivity De, which was used as a fitting parameter for calculation of the theoretical predictions, was determined to be 1·37 × 10 - 5 exp(-13000/RT) m2 s - 1. Deviation was found between the predictions of the model and the experimental data as the pellet thickness was increased. This is explained by the geometrical difference between the mathematical model, with flat surfaces only, and the actual pellet with both flat and circumferential surfaces. A geometrical factor g was introduced to compensate for this difference, the value of which was calculated to be 1/( 1 + 11·47L), where L is the half thickness of the sample.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133671485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009210
M. Šveda
Abstract High frost resistance is one of the signs of good quality in clay roofing tile products. The present paper deals with the question of whether the water absorption of clay roofing tiles affects frost resistance. The results show that clay roofing tiles with high water absorption can be just as frost proof as tiles with lower absorption. Median pore radius is found to be an important factor in determining frost resistance: increasing the median pore radius increases frost resistance.
{"title":"Effect of water absorption on frost resistance of clay roofing tiles","authors":"M. Šveda","doi":"10.1179/096797803225009210","DOIUrl":"https://doi.org/10.1179/096797803225009210","url":null,"abstract":"Abstract High frost resistance is one of the signs of good quality in clay roofing tile products. The present paper deals with the question of whether the water absorption of clay roofing tiles affects frost resistance. The results show that clay roofing tiles with high water absorption can be just as frost proof as tiles with lower absorption. Median pore radius is found to be an important factor in determining frost resistance: increasing the median pore radius increases frost resistance.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131541855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009238
P. Rao, Swapankumar Ghosh, P. Koshy
Abstract Polycrystalline samples of Ba3RE3Ti5Ta5O30 (RE = Nd, Sm) were prepared by conventional solid state powder processing. The calcined compounds were pelletised and sintered at 1320, 1340, and 1360°C for 4 h. XRD structural and SEM microstructural characterisation showed the formation of single phase material with tetragonal crystal structure. Detailed studies of dielectric properties (ϵ, tanδ) as a function of frequency (100 Hz to 13 MHz) showed that the compounds had a dielectric constant around 120 and a loss factor of 6 × 10 - 3 at 1 MHz. At 1 MHz, the Nd and Sm compounds had dielectric constants of 123 and 117 respectively.
{"title":"Preparation and characterisation of Ba3RE3Ti5Ta5O30 ceramics","authors":"P. Rao, Swapankumar Ghosh, P. Koshy","doi":"10.1179/096797803225009238","DOIUrl":"https://doi.org/10.1179/096797803225009238","url":null,"abstract":"Abstract Polycrystalline samples of Ba3RE3Ti5Ta5O30 (RE = Nd, Sm) were prepared by conventional solid state powder processing. The calcined compounds were pelletised and sintered at 1320, 1340, and 1360°C for 4 h. XRD structural and SEM microstructural characterisation showed the formation of single phase material with tetragonal crystal structure. Detailed studies of dielectric properties (ϵ, tanδ) as a function of frequency (100 Hz to 13 MHz) showed that the compounds had a dielectric constant around 120 and a loss factor of 6 × 10 - 3 at 1 MHz. At 1 MHz, the Nd and Sm compounds had dielectric constants of 123 and 117 respectively.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125458367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-02-01DOI: 10.1179/096797803225009229
N. Amdouni, H. Zarrouk, C. Julien
Abstract The synthesis of Cr substituted lithium cobaltate LiCr0·3Co0·7O2 using four different low temperature methods is presented. These wet chemical routes involve the mixing of either acetates or nitrates of Co and Cr with a chelating agent in aqueous solution, namely citric acid for the sol-gel method, oxalic acid for the coprecipitation method, succinic acid for the pyrolysis method, or the complexing agent glycine for the combustion method. The synthesised products were characterised by T G-DTA, XRD, SEM, and FTIR. Structural analysis revealed the R 3-m space group for the solid solution. The electrochemical behaviour of LiCr0·3Co0·7O2 was evaluated in a lithium cell.
{"title":"Low temperature synthesis of LiCr0·3Co0·7O2 intercalation compounds using citrate, oxalate, succinate, and glycinate precursors","authors":"N. Amdouni, H. Zarrouk, C. Julien","doi":"10.1179/096797803225009229","DOIUrl":"https://doi.org/10.1179/096797803225009229","url":null,"abstract":"Abstract The synthesis of Cr substituted lithium cobaltate LiCr0·3Co0·7O2 using four different low temperature methods is presented. These wet chemical routes involve the mixing of either acetates or nitrates of Co and Cr with a chelating agent in aqueous solution, namely citric acid for the sol-gel method, oxalic acid for the coprecipitation method, succinic acid for the pyrolysis method, or the complexing agent glycine for the combustion method. The synthesised products were characterised by T G-DTA, XRD, SEM, and FTIR. Structural analysis revealed the R 3-m space group for the solid solution. The electrochemical behaviour of LiCr0·3Co0·7O2 was evaluated in a lithium cell.","PeriodicalId":350675,"journal":{"name":"British Ceramic Transactions","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126965866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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