Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated MEMS devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not very well controlled during deposition. The residual stress, for example, tends to vary significantly for different deposition conditions; experiments were carried out to study the polysilicon and silicon nitride deposited by Low Pressure Chemical Vapor Deposition (LPCVD) method at wide range of process conditions. High temperature annealing effects on stress in case polysilicon are also reported. The reduced residual stress levels can significantly improve device performance, reliability, and yield as MEMS devices become smaller.
{"title":"Synthesis and Characterization of LPCVD Polysilicon and Silicon Nitride Thin Films for MEMS Applications","authors":"N. Sharma, M. Hooda, S. Sharma","doi":"10.1155/2014/954618","DOIUrl":"https://doi.org/10.1155/2014/954618","url":null,"abstract":"Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated MEMS devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not very well controlled during deposition. The residual stress, for example, tends to vary significantly for different deposition conditions; experiments were carried out to study the polysilicon and silicon nitride deposited by Low Pressure Chemical Vapor Deposition (LPCVD) method at wide range of process conditions. High temperature annealing effects on stress in case polysilicon are also reported. The reduced residual stress levels can significantly improve device performance, reliability, and yield as MEMS devices become smaller.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"25 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82276004","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 his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.
Georges Guiochon在讲授充填层渗透率的教科书中，在阐述达西渗透率方程时，使用了流动相速度作为流体速度项。虽然从热力学的角度来看，这个速度框架很有意义，但它只对渗透率在单一理论边界条件下有效。然而，在他最近的著作中，Guiochon抛弃了他长期以来用Darcy方程来讨论渗透率的模式，转而采用了著名的Kozeny-Blake方程。本文考察了他关于Kozeny-Blake方程常数的教学，并根据他的教学中使用的速度系，确定并定义了一个新的相关系数。该系数将压降和流体速度作为颗粒孔隙度的函数联系起来。我们表明，在他们的实验方案中，Guiochon等人没有遵守严格的渗透率物质平衡，这造成了颗粒孔隙度的不匹配，并导致关于Kozeny-Blake方程中渗透率系数值的错误结论。通过对实验数据进行校正，使之更准确地反映颗粒孔隙度，并与Guiochon和Giddings的实验结果进行了协调，得到了渗透率参考图。该参考图表表明，Guiochon的实验数据，在适当地对颗粒孔隙度和其他相关差异进行归一化后，证实了Giddings在1965年推导的Kozeny-Blake方程中的常数为267。
{"title":"A Reconciliation of Packed Column Permeability Data: Column Permeability as a Function of Particle Porosity","authors":"H. Quinn","doi":"10.1155/2014/636507","DOIUrl":"https://doi.org/10.1155/2014/636507","url":null,"abstract":"In his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"48 1","pages":"1-22"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82169794","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}
We report experimental observations with optical microscopy of the usual so-called polygonal texture. We have made simulations of the Dupin cyclides in one small region of the sample.
我们报告用光学显微镜对通常所谓的多边形纹理的实验观察。我们在样本的一个小区域模拟了杜宾周期。
{"title":"The Construction of the Dupin Cyclides in a Smectic A Polygonal Texture","authors":"Claire Meyer, Brice Jonckheere, Coline Penaud","doi":"10.1155/2014/145375","DOIUrl":"https://doi.org/10.1155/2014/145375","url":null,"abstract":"We report experimental observations with optical microscopy of the usual so-called polygonal texture. We have made simulations of the Dupin cyclides in one small region of the sample.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"3 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81654677","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}
Study of thermal and optical parameters of glass has been undertaken. Crystallization and glass transition kinetics has been investigated under nonisothermal conditions by DSC technique. Phase separation has been observed in the material and is investigated by taking the XRD of annealed bulk samples. The material possesses good glass forming ability, high value of glass transition temperature about 420 K, and glass stability. Optical band gap and other optical constants such as refractive index and extinction coefficient have been determined. The isoelectronic substitution of Ge with Sn in the glassy system reduces the optical band gap and enhances the thermal properties.
{"title":"Effect of Sn Addition on Thermal and Optical Properties of Glass","authors":"V. Modgil, V. S. Rangra","doi":"10.1155/2014/318262","DOIUrl":"https://doi.org/10.1155/2014/318262","url":null,"abstract":"Study of thermal and optical parameters of glass has been undertaken. Crystallization and glass transition kinetics has been investigated under nonisothermal conditions by DSC technique. Phase separation has been observed in the material and is investigated by taking the XRD of annealed bulk samples. The material possesses good glass forming ability, high value of glass transition temperature about 420 K, and glass stability. Optical band gap and other optical constants such as refractive index and extinction coefficient have been determined. The isoelectronic substitution of Ge with Sn in the glassy system reduces the optical band gap and enhances the thermal properties.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"49 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90279665","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. Al-Kahlout, N. Dahoudi, I. Grobelsek, M. Jilavi, P. Oliveira
Stable crystalline aluminum doped zinc oxide (AZO) nanopowders were synthesized using hydrothermal treatment processing. Three different aluminum precursors have been used. The Al-precursors were found to affect the morphology of the obtained nanopowders. AZO nanoparticles based on zinc acetate and aluminum nitrate have been prepared with different Al/Zn molar ratios. XRD investigations revealed that all the obtained powders have single phase zincite structure with purity of about 99%. The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. The incorporation of Al in ZnO was confirmed by UV-Vis spectroscopy revealing a blue shift due to Burstein-Moss effect.
{"title":"Synthesis and Characterization of Aluminum Doped Zinc Oxide Nanostructures via Hydrothermal Route","authors":"A. Al-Kahlout, N. Dahoudi, I. Grobelsek, M. Jilavi, P. Oliveira","doi":"10.1155/2014/235638","DOIUrl":"https://doi.org/10.1155/2014/235638","url":null,"abstract":"Stable crystalline aluminum doped zinc oxide (AZO) nanopowders were synthesized using hydrothermal treatment processing. Three different aluminum precursors have been used. The Al-precursors were found to affect the morphology of the obtained nanopowders. AZO nanoparticles based on zinc acetate and aluminum nitrate have been prepared with different Al/Zn molar ratios. XRD investigations revealed that all the obtained powders have single phase zincite structure with purity of about 99%. The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. The incorporation of Al in ZnO was confirmed by UV-Vis spectroscopy revealing a blue shift due to Burstein-Moss effect.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"12 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82443711","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}
Habibur Rahman Sobuz, Noor Md. Sadiqul Hasan, N. Tamanna, M. S. Islam
Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS) is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed stone, and OPS as a substitution for coarse aggregate. The corresponding w/c ratios were used: 0.45, 0.6, and 0.75, respectively, for the defined mix proportions. Test results indicate that compressive strength of concrete decreased as the percentage of the OPS increased in each mix ratio. Other properties of OPS concrete, namely, modulus of rupture, modulus of elasticity, splitting tensile strength, and density, were also determined and compared to the corresponding properties of conventional concrete. Economic analysis also indicates possible cost reduction of up to 15% due to the use of OPS as coarse aggregate. Finally, it is concluded that the use of OPS has great potential in the production of structural lightweight concrete.
{"title":"Structural Lightweight Concrete Production by Using Oil Palm Shell","authors":"Habibur Rahman Sobuz, Noor Md. Sadiqul Hasan, N. Tamanna, M. S. Islam","doi":"10.1155/2014/870247","DOIUrl":"https://doi.org/10.1155/2014/870247","url":null,"abstract":"Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS) is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed stone, and OPS as a substitution for coarse aggregate. The corresponding w/c ratios were used: 0.45, 0.6, and 0.75, respectively, for the defined mix proportions. Test results indicate that compressive strength of concrete decreased as the percentage of the OPS increased in each mix ratio. Other properties of OPS concrete, namely, modulus of rupture, modulus of elasticity, splitting tensile strength, and density, were also determined and compared to the corresponding properties of conventional concrete. Economic analysis also indicates possible cost reduction of up to 15% due to the use of OPS as coarse aggregate. Finally, it is concluded that the use of OPS has great potential in the production of structural lightweight concrete.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"144 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2014-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77520739","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}
I. Arukalam, I. O. Madu, N. T. Ijomah, C. Ewulonu, G. N. Onyeagoro
The corrosion inhibition of mild steel in 1.0 M H2SO4 solution by ethyl hydroxyethyl cellulose has been studied in relation to the concentration of the additive using weight loss measurement, EIS, polarization, and quantum chemical calculation techniques. The results indicate that EHEC inhibited corrosion reaction in the acid medium and inhibition efficiency increased with EHEC concentration. Further increase in inhibition efficiency is observed in the presence of iodide ions, due to synergistic effect. Impedance results reveal that EHEC is adsorbed on the corroding metal surface. Adsorption followed a modified Langmuir isotherm, with very high negative values of the free energy of adsorption . The polarization data indicate that the inhibitor was of mixed type, with predominant effect on the cathodic partial reaction. The frontier molecular orbitals, HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) as well as local reactivity of the EHEC molecule, were analyzed theoretically using the density functional theory to explain the adsorption characteristics at a molecular level. The theoretical predictions showed good agreement with experimental results.
采用失重测量、EIS、极化和量子化学计算等方法研究了乙基羟乙基纤维素在1.0 M H2SO4溶液中对低碳钢的缓蚀作用与添加剂浓度的关系。结果表明，肠出血性大肠杆菌对酸性介质中的腐蚀反应有抑制作用，且抑制效果随肠出血性大肠杆菌浓度的增加而增加。在碘离子存在时，由于协同作用，抑制效率进一步提高。阻抗结果表明，EHEC吸附在腐蚀金属表面。吸附遵循改进的Langmuir等温线，吸附自由能的负值非常高。极化数据表明，缓蚀剂为混合型，对阴极部分反应的影响较大。利用密度泛函理论，从理论上分析了EHEC分子的前沿分子轨道HOMO(最高占据分子轨道)和LUMO(最低未占据分子轨道)以及局部反应性，在分子水平上解释了EHEC分子的吸附特性。理论预测与实验结果吻合较好。
{"title":"Acid Corrosion Inhibition and Adsorption Behaviour of Ethyl Hydroxyethyl Cellulose on Mild Steel Corrosion","authors":"I. Arukalam, I. O. Madu, N. T. Ijomah, C. Ewulonu, G. N. Onyeagoro","doi":"10.1155/2014/101709","DOIUrl":"https://doi.org/10.1155/2014/101709","url":null,"abstract":"The corrosion inhibition of mild steel in 1.0 M H2SO4 solution by ethyl hydroxyethyl cellulose has been studied in relation to the concentration of the additive using weight loss measurement, EIS, polarization, and quantum chemical calculation techniques. The results indicate that EHEC inhibited corrosion reaction in the acid medium and inhibition efficiency increased with EHEC concentration. Further increase in inhibition efficiency is observed in the presence of iodide ions, due to synergistic effect. Impedance results reveal that EHEC is adsorbed on the corroding metal surface. Adsorption followed a modified Langmuir isotherm, with very high negative values of the free energy of adsorption . The polarization data indicate that the inhibitor was of mixed type, with predominant effect on the cathodic partial reaction. The frontier molecular orbitals, HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) as well as local reactivity of the EHEC molecule, were analyzed theoretically using the density functional theory to explain the adsorption characteristics at a molecular level. The theoretical predictions showed good agreement with experimental results.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"37 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2014-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84924672","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}
J. A. Adekoya, E. O. Dare, M. Mesubi, N. Revaprasadu
The synthesis of new seed mediated AgNi allied bimetallic nanocomposites was successfully carried out by the successive reduction of the metal ions in diethylene glycol, ethylene glycol, glycerol, and pentaerythritol solutions, with concomitant precipitation of Ag/Ni bimetal sols. The optical measurement revealed the existence of distinct band edge with surface plasmon resonance (SPR) in the region of 400–425 nm and excitonic emission with maximum peak at 382 nm which were reminiscent of cluster-in-cluster surface enriched bimetallic silver-nickel sols. The morphological characterization by transmission electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction analyses complimented by surface scan using X-ray photoelectron spectroscopy strongly supported the formation of intimately alloyed face-centered silver/nickel nanoclusters.
{"title":"Synthesis and Characterization of Optically Active Fractal Seed Mediated Silver Nickel Bimetallic Nanoparticles","authors":"J. A. Adekoya, E. O. Dare, M. Mesubi, N. Revaprasadu","doi":"10.1155/2014/184216","DOIUrl":"https://doi.org/10.1155/2014/184216","url":null,"abstract":"The synthesis of new seed mediated AgNi allied bimetallic nanocomposites was successfully carried out by the successive reduction of the metal ions in diethylene glycol, ethylene glycol, glycerol, and pentaerythritol solutions, with concomitant precipitation of Ag/Ni bimetal sols. The optical measurement revealed the existence of distinct band edge with surface plasmon resonance (SPR) in the region of 400–425 nm and excitonic emission with maximum peak at 382 nm which were reminiscent of cluster-in-cluster surface enriched bimetallic silver-nickel sols. The morphological characterization by transmission electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction analyses complimented by surface scan using X-ray photoelectron spectroscopy strongly supported the formation of intimately alloyed face-centered silver/nickel nanoclusters.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"212 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2014-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75758813","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. Boulouz, A. Giani, B. Sorli, L. Koutti, A. Massaq, F. Pascal-Delannoy
The principal motivation of this work is the development and realization of smart cooling and sensors devices based on the elaborated and characterized semiconducting thermoelectric thin film materials. For the first time, the details design of our sensor and the principal results are published. Fabrication and characterization of Bi/Sb/Te (BST) semiconducting thin films have been successfully investigated. The best values of Seebeck coefficient (α(T)) at room temperature for Bi2Te3, and (Bi1−xSbx)2Te3 with x = 0.77 are found to be −220 µV/K and
{"title":"Fabrication of Thermoelectric Sensor and Cooling Devices Based on Elaborated Bismuth-Telluride Alloy Thin Films","authors":"A. Boulouz, A. Giani, B. Sorli, L. Koutti, A. Massaq, F. Pascal-Delannoy","doi":"10.1155/2014/430410","DOIUrl":"https://doi.org/10.1155/2014/430410","url":null,"abstract":"The principal motivation of this work is the development and realization of smart cooling and sensors devices based on the elaborated and characterized semiconducting thermoelectric thin film materials. For the first time, the details design of our sensor and the principal results are published. \u0000Fabrication and characterization of Bi/Sb/Te (BST) semiconducting thin films have been successfully investigated. The best values of Seebeck coefficient (α(T)) at room temperature for Bi2Te3, and (Bi1−xSbx)2Te3 with x = 0.77 are found to be −220 µV/K and","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"35 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78081474","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}
Magnesium oxide nanopowder is synthesized using magnesium nitrate hexahydrate and oxalic acid as precursors via the sol-gel method. In order to investigate the effect of magnesia nanopowders on the physical properties of sintered alumina, 0.1, 0.3, and 0.5 wt% of MgO are added to alumina. The prepared specimens were sintered at 1570°C for 4 hours under an inert atmosphere. The morphology and size of nanopowders were characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). Structural analysis was investigated by means of Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Outcomes show that by increasing the percentage of MgO, spinel phase (MgAl2O4) has been formed in the structure of alumina. During the sintering process, spinel phase diffused through the grain boundaries and pinned the grain boundaries which led to decrease in grain sizes. So, by decreasing the grain size, the physical properties of sintered alumina have improved.
{"title":"Investigating the Physical Properties of Sintered Alumina in the Presence of MgO Nanopowder","authors":"M. Dadkhah, A. Saboori, M. Jafari","doi":"10.1155/2014/496146","DOIUrl":"https://doi.org/10.1155/2014/496146","url":null,"abstract":"Magnesium oxide nanopowder is synthesized using magnesium nitrate hexahydrate and oxalic acid as precursors via the sol-gel method. In order to investigate the effect of magnesia nanopowders on the physical properties of sintered alumina, 0.1, 0.3, and 0.5 wt% of MgO are added to alumina. The prepared specimens were sintered at 1570°C for 4 hours under an inert atmosphere. The morphology and size of nanopowders were characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). Structural analysis was investigated by means of Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Outcomes show that by increasing the percentage of MgO, spinel phase (MgAl2O4) has been formed in the structure of alumina. During the sintering process, spinel phase diffused through the grain boundaries and pinned the grain boundaries which led to decrease in grain sizes. So, by decreasing the grain size, the physical properties of sintered alumina have improved.","PeriodicalId":17611,"journal":{"name":"Journal: Materials","volume":"43 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2014-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77130741","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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