Md. Imran Khan, Ahmad Mostafa, M. Aljarrah, E. Essadiqi, M. Medraj
The effect of cooling rate on microstructure and microsegregation of three commercially important magnesium alloys was investigated using Wedge (V-shaped) castings of AZ91D, AM60B, and AE44 alloys. Thermocouples were distributed to measure the cooling rate at six different locations of the wedge casts. Solute redistribution profiles were drawn based on the chemical composition analysis obtained by EDS/WDS analysis. Microstructural and morphological features such as dendrite arm spacing and secondary phase particle size were analyzed using both optical and scanning electron microscopes. Dendritic arm spacing and secondary phase particle size showed an increasing trend with decreasing cooling rate for the three alloys. Area percentage of secondary phase particles decreased with decreasing cooling rate for AE44 alloy. The trend was different for AZ91D and AM60B alloys, for both alloys, area percentage of β-Mg17Al12 increased with decreasing cooling rate up to location 4 and then decreased slightly. The tendency for microsegregation was more severe at slower cooling rates, possibly due to prolonged back diffusion. At slower cooling rate, the minimum concentration of aluminum at the dendritic core was lower compared to faster cooled locations. The segregation deviation parameter and the partition coefficient were calculated from the experimentally obtained data.
{"title":"Influence of Cooling Rate on Microsegregation Behavior of Magnesium Alloys","authors":"Md. Imran Khan, Ahmad Mostafa, M. Aljarrah, E. Essadiqi, M. Medraj","doi":"10.1155/2014/657647","DOIUrl":"https://doi.org/10.1155/2014/657647","url":null,"abstract":"The effect of cooling rate on microstructure and microsegregation of three commercially important magnesium alloys was investigated using Wedge (V-shaped) castings of AZ91D, AM60B, and AE44 alloys. Thermocouples were distributed to measure the cooling rate at six different locations of the wedge casts. Solute redistribution profiles were drawn based on the chemical composition analysis obtained by EDS/WDS analysis. Microstructural and morphological features such as dendrite arm spacing and secondary phase particle size were analyzed using both optical and scanning electron microscopes. Dendritic arm spacing and secondary phase particle size showed an increasing trend with decreasing cooling rate for the three alloys. Area percentage of secondary phase particles decreased with decreasing cooling rate for AE44 alloy. The trend was different for AZ91D and AM60B alloys, for both alloys, area percentage of β-Mg17Al12 increased with decreasing cooling rate up to location 4 and then decreased slightly. The tendency for microsegregation was more severe at slower cooling rates, possibly due to prolonged back diffusion. At slower cooling rate, the minimum concentration of aluminum at the dendritic core was lower compared to faster cooled locations. The segregation deviation parameter and the partition coefficient were calculated from the experimentally obtained data.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"22 1","pages":"1-18"},"PeriodicalIF":0.0,"publicationDate":"2014-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81842890","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}
The purpose of this study is to improve the performance properties of K-carrageenan (K-CRG) by utilizing nanosilica (NSI) as the reinforcing agent. The composite films were prepared by solution casting method. NSI was added up to 1.5% in the K-CRG matrix. The prepared films were characterized for mechanical (tensile strength, tensile modulus, and elongation at break), thermal (differential scanning calorimetry, thermogravimetric analysis), barrier (water vapour transmission rate), morphological (scanning electron microscopy), contact angle, and crystallinity properties. Tensile strength, tensile modulus, and crystallinity were found to have increased by 13.8, 15, and 48% whereas water vapour transmission rate was found to have decreased by 48% for 0.5% NSI loaded K-CRG composite films. NSI was found to have formed aggregates for concentrations above 0.5% as confirmed by scanning electron microscopy. Melting temperature, enthalpy of melting, and degradation temperature of K-CRG increased with increase in concentration of NSI in K-CRG. Contact angle also increased with increase in concentration of NSI in K-CRG, indicating the decrease in hydrophilicity of the films improving its water resistance properties. This knowledge of the composite film could make beneficial contributions to the food and pharmaceutical packaging applications.
{"title":"Preparation and Characterization of K-Carrageenan/Nanosilica Biocomposite Film","authors":"Lokesh R. Rane, N. Savadekar, P. Kadam, S. Mhaske","doi":"10.1155/2014/736271","DOIUrl":"https://doi.org/10.1155/2014/736271","url":null,"abstract":"The purpose of this study is to improve the performance properties of K-carrageenan (K-CRG) by utilizing nanosilica (NSI) as the reinforcing agent. The composite films were prepared by solution casting method. NSI was added up to 1.5% in the K-CRG matrix. The prepared films were characterized for mechanical (tensile strength, tensile modulus, and elongation at break), thermal (differential scanning calorimetry, thermogravimetric analysis), barrier (water vapour transmission rate), morphological (scanning electron microscopy), contact angle, and crystallinity properties. Tensile strength, tensile modulus, and crystallinity were found to have increased by 13.8, 15, and 48% whereas water vapour transmission rate was found to have decreased by 48% for 0.5% NSI loaded K-CRG composite films. NSI was found to have formed aggregates for concentrations above 0.5% as confirmed by scanning electron microscopy. Melting temperature, enthalpy of melting, and degradation temperature of K-CRG increased with increase in concentration of NSI in K-CRG. Contact angle also increased with increase in concentration of NSI in K-CRG, indicating the decrease in hydrophilicity of the films improving its water resistance properties. This knowledge of the composite film could make beneficial contributions to the food and pharmaceutical packaging applications.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"7 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78594912","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}
Nonlinear optical single crystal of organic amino acid L-Serine (LS) was grown by slow evaporation technique. Solubility study of the compound was measured and metastable zone width was found. Single crystal X-ray diffraction study was carried out for the grown crystal. The linear and nonlinear optical properties of the crystal were confirmed by UV-Vis analysis and powder SHG tester. FT-IR spectrum was recorded and functional groups were analyzed. Vickers’ microhardness studies showed the mechanical strength of the grown crystal. Laser damage threshold value of the crystal was calculated. Photoconductivity studies reveal the conductivity of the crystal.
{"title":"Structural, Linear, and Nonlinear Optical and Mechanical Properties of New Organic L-Serine Crystal","authors":"K. Rajesh, P. Praveen Kumar","doi":"10.1155/2014/790957","DOIUrl":"https://doi.org/10.1155/2014/790957","url":null,"abstract":"Nonlinear optical single crystal of organic amino acid L-Serine (LS) was grown by slow evaporation technique. Solubility study of the compound was measured and metastable zone width was found. Single crystal X-ray diffraction study was carried out for the grown crystal. The linear and nonlinear optical properties of the crystal were confirmed by UV-Vis analysis and powder SHG tester. FT-IR spectrum was recorded and functional groups were analyzed. Vickers’ microhardness studies showed the mechanical strength of the grown crystal. Laser damage threshold value of the crystal was calculated. Photoconductivity studies reveal the conductivity of the crystal.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"84 6 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83572123","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}
Thermal spraying is a well-established surface modification technology which has been widely used in industrial applications. As the coating properties were mainly determined by the flattening nature of each splat, much attention has been increasingly paid to the study on the splat formation process of thermal sprayed particles. This paper is concerned with the development in the research of the splat formation process of the individual splat deposited by thermal spraying during the past few decades, including the experimental and numerical simulations up to today; some classical splashing models were also reviewed. As a simulation of the actual thermal spray process, the development of the flattening behavior of free falling droplet has been mentioned as well. On the basis of the current investigation, some recommendations for the future work have been advised.
{"title":"Recent Developments in the Research of Splat Formation Process in Thermal Spraying","authors":"Kun Yang, Min Liu, K. Zhou, C. Deng","doi":"10.1155/2013/260758","DOIUrl":"https://doi.org/10.1155/2013/260758","url":null,"abstract":"Thermal spraying is a well-established surface modification technology which has been widely used in industrial applications. As the coating properties were mainly determined by the flattening nature of each splat, much attention has been increasingly paid to the study on the splat formation process of thermal sprayed particles. This paper is concerned with the development in the research of the splat formation process of the individual splat deposited by thermal spraying during the past few decades, including the experimental and numerical simulations up to today; some classical splashing models were also reviewed. As a simulation of the actual thermal spray process, the development of the flattening behavior of free falling droplet has been mentioned as well. On the basis of the current investigation, some recommendations for the future work have been advised.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"28 1","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2013-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77108800","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}
A novel low cost polymer composite using brown grass flower broom reinforcement is prepared. The prepared polymer composite has the lowest porosity, homogeneous surface structure, and the greatest interface bonding. From the physico-mechanical characterization such as: hardness measurement, density measurement, void fraction or porosity measurement, and flexural strength measurement, it is found that the prepared composite is of light weight and high strength. Again, from dielectric behaviour of this polymer composite, it is found that this material has an efficiency that is considered as a high valued marketable product. As the composite is made using bio-materials from local resources, its cost is less compared to other polymer composites available today.
{"title":"Processing and Properties of Natural Fiber-Reinforced Polymer Composite","authors":"J. P. Dhal, S. Mishra","doi":"10.1155/2013/297213","DOIUrl":"https://doi.org/10.1155/2013/297213","url":null,"abstract":"A novel low cost polymer composite using brown grass flower broom reinforcement is prepared. The prepared polymer composite has the lowest porosity, homogeneous surface structure, and the greatest interface bonding. From the physico-mechanical characterization such as: hardness measurement, density measurement, void fraction or porosity measurement, and flexural strength measurement, it is found that the prepared composite is of light weight and high strength. Again, from dielectric behaviour of this polymer composite, it is found that this material has an efficiency that is considered as a high valued marketable product. As the composite is made using bio-materials from local resources, its cost is less compared to other polymer composites available today.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"29 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84290173","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}
Selected silicone membranes are investigated in order to find attractive multifunctional materials as liquid confining flexible agents with good heat resistance as well as low affinity towards the chemical specimens commonly used in dye sensitized solar cells (DSSC). In fact, the leakage and/or volatilization of liquid components inside DSSC remains one of the most critical obstacles in the progress of this technology from laboratory scale to large area applications. Dynamic mechanical spectroscopic, differential scanning calorimetric, and thermogravimetric analyses on dry membranes were performed in order to investigate their mechanical properties and their thermal stability. By a further comparative study between the equilibrium uptake and the adsorption-desorption process of a nitrile based solution, useful indications about the ability of these networks to encapsulate the liquid mixture were inferred. Moreover, a rough evaluation of porosity was also carried out, giving results which are in agreement with surface morphology observed by scanning electron microscopy and atomic force microscopy. In the light of the results obtained by the different experimental techniques the confinement capability of these membranes towards the liquid components inside a DSSC is discussed.
{"title":"RTV Silicone Membranes as Agents to Confine the Liquid Components in Dye Sensitized Solar Cells","authors":"A. Bartolotta, G. Calogero, C. Crupi, G. Marco","doi":"10.1155/2013/597616","DOIUrl":"https://doi.org/10.1155/2013/597616","url":null,"abstract":"Selected silicone membranes are investigated in order to find attractive multifunctional materials as liquid confining flexible agents with good heat resistance as well as low affinity towards the chemical specimens commonly used in dye sensitized solar cells (DSSC). In fact, the leakage and/or volatilization of liquid components inside DSSC remains one of the most critical obstacles in the progress of this technology from laboratory scale to large area applications. Dynamic mechanical spectroscopic, differential scanning calorimetric, and thermogravimetric analyses on dry membranes were performed in order to investigate their mechanical properties and their thermal stability. By a further comparative study between the equilibrium uptake and the adsorption-desorption process of a nitrile based solution, useful indications about the ability of these networks to encapsulate the liquid mixture were inferred. Moreover, a rough evaluation of porosity was also carried out, giving results which are in agreement with surface morphology observed by scanning electron microscopy and atomic force microscopy. In the light of the results obtained by the different experimental techniques the confinement capability of these membranes towards the liquid components inside a DSSC is discussed.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"11 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2013-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85270717","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}
In situ, observation of twinning and detwinning in magnesium single crystals during tension-compression cyclic loading was made using optical microscopy. A quantitative analysis of plastic strain indicates that twinning and detwinning experience two stages, low and high work hardening de-twinning, and pure re-twinning and fresh twinning combined with retwinning. Slip is always activated. For the first time, inverse slip accompanying with pure retwinning and high work hardening detwinning was experimentally identified, which provides insights in better understanding of the activity of twining, detwinning, and slips.
{"title":"Inverse Slip Accompanying Twinning and Detwinning during Cyclic Loading of Magnesium Single Crystal","authors":"Qin Yu, Jian Wang, Yanyao Jiang","doi":"10.1155/2013/903786","DOIUrl":"https://doi.org/10.1155/2013/903786","url":null,"abstract":"In situ, observation of twinning and detwinning in magnesium single crystals during tension-compression cyclic loading was made using optical microscopy. A quantitative analysis of plastic strain indicates that twinning and detwinning experience two stages, low and high work hardening de-twinning, and pure re-twinning and fresh twinning combined with retwinning. Slip is always activated. For the first time, inverse slip accompanying with pure retwinning and high work hardening detwinning was experimentally identified, which provides insights in better understanding of the activity of twining, detwinning, and slips.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"31 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2013-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85857057","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}
Structural and thermal properties of binary () alloys obtained by melt spinning and copper mold casting methods were investigated. The fully amorphous samples in a bulk form cannot be obtained in the binary Ni-Zr alloys over a wide composition range, though they have and values close to or even higher than those of the binary Cu-Zr bulk metallic glasses (BMGs). The low thermal stability of the supercooled liquid against crystallization and the formation of the equilibrium crystalline phases with a high growth rate are responsible for their low glass-forming abilities (GFAs). Relatively low thermal conductivities of Ni-based alloys are also considered to be another factor to limit their GFAs. The GFA of the binary Ni65.5Zr34.5 alloy alloyed with 4% or 5% Al was enhanced, and a fully glassy rod with a diameter of 0.5 mm was formed.
{"title":"Glass Formation in Ni-Zr-(Al) Alloy Systems","authors":"Lan Huang, Song Li","doi":"10.1155/2013/575640","DOIUrl":"https://doi.org/10.1155/2013/575640","url":null,"abstract":"Structural and thermal properties of binary () alloys obtained by melt spinning and copper mold casting methods were investigated. The fully amorphous samples in a bulk form cannot be obtained in the binary Ni-Zr alloys over a wide composition range, though they have and values close to or even higher than those of the binary Cu-Zr bulk metallic glasses (BMGs). The low thermal stability of the supercooled liquid against crystallization and the formation of the equilibrium crystalline phases with a high growth rate are responsible for their low glass-forming abilities (GFAs). Relatively low thermal conductivities of Ni-based alloys are also considered to be another factor to limit their GFAs. The GFA of the binary Ni65.5Zr34.5 alloy alloyed with 4% or 5% Al was enhanced, and a fully glassy rod with a diameter of 0.5 mm was formed.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"3 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2013-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87718836","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}
X-ray reflectometry is a powerful tool for investigations on rough surface and interface structures of multilayered thin film materials. The X-ray reflectivity has been calculated based on the Parratt formalism, accounting for the effect of roughness by the theory of Nevot-Croce conventionally. However, in previous studies, the calculations of the X-ray reflectivity often show a strange effect where interference effects would increase at a rough surface. And estimated surface and interface roughnesses from the X-ray reflectivity measurements did not correspond to the TEM image observation results. The strange result had its origin in a used equation due to a serious mistake in which the Fresnel transmission coefficient in the reflectivity equation is increased at a rough interface because of a lack of consideration of diffuse scattering. In this review, a new accurate formalism that corrects this mistake is presented. The new accurate formalism derives an accurate analysis of the X-ray reflectivity from a multilayer surface of thin film materials, taking into account the effect of roughness-induced diffuse scattering. The calculated reflectivity by this accurate reflectivity equation should enable the structure of buried interfaces to be analyzed more accurately.
{"title":"Recent Developments in the X-Ray Reflectivity Analysis for Rough Surfaces and Interfaces of Multilayered Thin Film Materials","authors":"Y. Fujii","doi":"10.1155/2013/678361","DOIUrl":"https://doi.org/10.1155/2013/678361","url":null,"abstract":"X-ray reflectometry is a powerful tool for investigations on rough surface and interface structures of multilayered thin film materials. The X-ray reflectivity has been calculated based on the Parratt formalism, accounting for the effect of roughness by the theory of Nevot-Croce conventionally. However, in previous studies, the calculations of the X-ray reflectivity often show a strange effect where interference effects would increase at a rough surface. And estimated surface and interface roughnesses from the X-ray reflectivity measurements did not correspond to the TEM image observation results. The strange result had its origin in a used equation due to a serious mistake in which the Fresnel transmission coefficient in the reflectivity equation is increased at a rough interface because of a lack of consideration of diffuse scattering. In this review, a new accurate formalism that corrects this mistake is presented. The new accurate formalism derives an accurate analysis of the X-ray reflectivity from a multilayer surface of thin film materials, taking into account the effect of roughness-induced diffuse scattering. The calculated reflectivity by this accurate reflectivity equation should enable the structure of buried interfaces to be analyzed more accurately.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"77 1","pages":"1-20"},"PeriodicalIF":0.0,"publicationDate":"2013-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86825035","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}
Frequency and temperature dependence of a.c. electrical conductivity of layered mixed ionic alkali trititanates, Na1.89Li0.10K0.01Ti3O7, Na1.88Li0.10K0.02Ti3O7, Na1.86Li0.10K0.04Ti3O7, and Na1.85Li0.10K0.05Ti3O7, have been investigated over a wide temperature 350 K 725 K and frequency 10 kHz to 1 MHz range. For this, Arrhenius plots are used for a.c. electrical conductivity of these compounds. The obtained conductivity plots have been divided into four distinct regions and discussed the relevant theory. According to slop variation, the conduction mechanisms occurring are different in different temperature regions. At lower temperatures, the hopping electron disorders the surroundings by moving to its neighboring Ti atoms from their equilibrium positions, causing structural defect in the polycrystalline network named small polaron. At higher temperatures, associated/unassociated interlayer ionic conduction occurs along with the alkali ions hopping through the interlayer space and electron hopping (small polaron) conduction through Ti–Ti chains in these layered polar alkali titanates.
研究了三钛酸盐层状混合离子碱Na1.89Li0.10K0.01Ti3O7、Na1.88Li0.10K0.02Ti3O7、Na1.86Li0.10K0.04Ti3O7和Na1.85Li0.10K0.05Ti3O7在350 K - 725 K和频率10 kHz - 1 MHz范围内交流电导率的频率和温度依赖性。为此，用阿伦尼乌斯图来表示这些化合物的交流电导率。得到的电导率图被划分为四个不同的区域，并讨论了相关的理论。根据斜率变化，不同温度区域发生的传导机制不同。在较低的温度下，跳跃电子通过从其平衡位置移动到邻近的Ti原子而扰乱周围环境，导致称为小极化子的多晶网络中的结构缺陷。在较高温度下，这些层状极性碱钛酸盐中的缔合/非缔合层间离子导电伴随着碱离子在层间空间的跳跃和电子(小极化子)通过Ti-Ti链的跳跃而发生。
{"title":"A.C. Conductivity Investigations on Layered Ceramics","authors":"R. Singh, Shripal","doi":"10.1155/2013/617973","DOIUrl":"https://doi.org/10.1155/2013/617973","url":null,"abstract":"Frequency and temperature dependence of a.c. electrical conductivity of layered mixed ionic alkali trititanates, Na1.89Li0.10K0.01Ti3O7, Na1.88Li0.10K0.02Ti3O7, Na1.86Li0.10K0.04Ti3O7, and Na1.85Li0.10K0.05Ti3O7, have been investigated over a wide temperature 350 K 725 K and frequency 10 kHz to 1 MHz range. For this, Arrhenius plots are used for a.c. electrical conductivity of these compounds. The obtained conductivity plots have been divided into four distinct regions and discussed the relevant theory. According to slop variation, the conduction mechanisms occurring are different in different temperature regions. At lower temperatures, the hopping electron disorders the surroundings by moving to its neighboring Ti atoms from their equilibrium positions, causing structural defect in the polycrystalline network named small polaron. At higher temperatures, associated/unassociated interlayer ionic conduction occurs along with the alkali ions hopping through the interlayer space and electron hopping (small polaron) conduction through Ti–Ti chains in these layered polar alkali titanates.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"4 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2013-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89431394","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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