Pub Date : 2012-08-31DOI: 10.5923/J.MATERIALS.20110102.12
L. Nnanna, I. Anozie, C. Akoma, I. M. Mejeha, K. Okeoma, K. I. Mejeh
The effect of Euphorbia hirta and Dialum guineense leave extracts on the corrosion of aluminium in 0.25M NaOH was investigated using gravimetric technique. It was shown that the presence of Euphorbia hirta and Dialum guineense leave extracts inhibited the corrosion of aluminium in the test solutions and that the inhibition efficiency depended on the concentration of the plant extract as well as on the time of exposure of the aluminium samples in 0.25M NaOH solu- tions containing the extracts. Dialum guineense extract shows the best inhibition capability for aluminium corrosion in so- dium hydroxide, probably, this is due to the planer orientation of the adsorbed extract molecules. Inhibition efficiency of the inhibitors tested increases with decreasing sodium hydroxide concentrations. The experimental data complied to both Langmuir and Temkin adsorption isotherms and the value and sign of the apparent activation energy of adsorption obtained suggests that inhibitor molecules have mixed inhibition mechanism.
{"title":"Corrosion Control of Aluminium Alloy in Alkaline Solution Using Some Leave Extracts","authors":"L. Nnanna, I. Anozie, C. Akoma, I. M. Mejeha, K. Okeoma, K. I. Mejeh","doi":"10.5923/J.MATERIALS.20110102.12","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20110102.12","url":null,"abstract":"The effect of Euphorbia hirta and Dialum guineense leave extracts on the corrosion of aluminium in 0.25M NaOH was investigated using gravimetric technique. It was shown that the presence of Euphorbia hirta and Dialum guineense leave extracts inhibited the corrosion of aluminium in the test solutions and that the inhibition efficiency depended on the concentration of the plant extract as well as on the time of exposure of the aluminium samples in 0.25M NaOH solu- tions containing the extracts. Dialum guineense extract shows the best inhibition capability for aluminium corrosion in so- dium hydroxide, probably, this is due to the planer orientation of the adsorbed extract molecules. Inhibition efficiency of the inhibitors tested increases with decreasing sodium hydroxide concentrations. The experimental data complied to both Langmuir and Temkin adsorption isotherms and the value and sign of the apparent activation energy of adsorption obtained suggests that inhibitor molecules have mixed inhibition mechanism.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76234079","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20110102.18
O. Ajide, A. Makinde
The enormous financial loss and the problems of plants shut down, lost production, product loss, product contaminations and loss of customer confidence as a result of corrosion is a serious challenge to the oil and gas industry. The objective of this paper is to investigate the microstructural characteristics of selected corroded materials from Nigeria oil and gas environments. A chemical analysis of the selected corroded materials was carried out with the aid of spectro-metal analyzer. Also, the microstructures of these corroded materials were examined under optical microscope. The results obtained were compared with the chemical compositions and microstructures of the standard alloy of the as received materials .Significant variations were noticed both in the chemical compositions and the ferrite/pearlite ratio within the microstructure. It is concluded that corrosion has added some undesirable features to the material samples and altered the microstructure characteristics which will remarkably alters their mechanical properties.
{"title":"Microstructural Analysis of Selected Corroded Materials from Nigeria Oil and Gas Industry","authors":"O. Ajide, A. Makinde","doi":"10.5923/J.MATERIALS.20110102.18","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20110102.18","url":null,"abstract":"The enormous financial loss and the problems of plants shut down, lost production, product loss, product contaminations and loss of customer confidence as a result of corrosion is a serious challenge to the oil and gas industry. The objective of this paper is to investigate the microstructural characteristics of selected corroded materials from Nigeria oil and gas environments. A chemical analysis of the selected corroded materials was carried out with the aid of spectro-metal analyzer. Also, the microstructures of these corroded materials were examined under optical microscope. The results obtained were compared with the chemical compositions and microstructures of the standard alloy of the as received materials .Significant variations were noticed both in the chemical compositions and the ferrite/pearlite ratio within the microstructure. It is concluded that corrosion has added some undesirable features to the material samples and altered the microstructure characteristics which will remarkably alters their mechanical properties.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79759693","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20110102.21
D. Vlasov, L. Apresyan, T. V. Vlasova, V. Kryshtob
In plasticized poly(vinylchloride) (PVC) films, representing system of two chemically non-interacting insula- tors, PVC and plasticizer, at monotonous increase of concentration of one of the insulators (plasticizer) sharp transition insulator-semiconductor to a "high" conductive state is found out, which is accompanied by similar transition back to state with low conductivity at further increase of plasticizer concentration. The observed concentration range with a "high" (semiconductor) level of electric conductivity permits us to measure the resistance-thickness dependence for relatively wide films thickness set (20-200 µm), which is close to simple exponential. A phenomenological model that allows to interpret the observed phenomena as "direct" and "inverse" percolation transitions in two-phase medium with charge-transfer by nano-scale kinetic segments of macromolecules mainly along the borders between PVC-clusters and plasticizer is proposed.
{"title":"On Anomalies of Electrical Conductivity in Antistatic Plasticized Poly(Vinyl Chloride) Films","authors":"D. Vlasov, L. Apresyan, T. V. Vlasova, V. Kryshtob","doi":"10.5923/J.MATERIALS.20110102.21","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20110102.21","url":null,"abstract":"In plasticized poly(vinylchloride) (PVC) films, representing system of two chemically non-interacting insula- tors, PVC and plasticizer, at monotonous increase of concentration of one of the insulators (plasticizer) sharp transition insulator-semiconductor to a \"high\" conductive state is found out, which is accompanied by similar transition back to state with low conductivity at further increase of plasticizer concentration. The observed concentration range with a \"high\" (semiconductor) level of electric conductivity permits us to measure the resistance-thickness dependence for relatively wide films thickness set (20-200 µm), which is close to simple exponential. A phenomenological model that allows to interpret the observed phenomena as \"direct\" and \"inverse\" percolation transitions in two-phase medium with charge-transfer by nano-scale kinetic segments of macromolecules mainly along the borders between PVC-clusters and plasticizer is proposed.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86707713","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120203.01
M. Bedre, R. Deshpande, Basavaraja Salimath, V. Abbaraju
Polyaniline (Pani) and Polyaniline-Co3O4 nanocomposites (PCO) were prepared by employing interfacial po- lymerization using ammonium persulphate as an oxidizing agent. The formations of regular nanocomposite materials were studied by Fourier transform infrared (FTIR) spectroscopy and XRD techniques. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were conducted to characterize the morphology. Thermo-gravimetric (TG) and differential thermal analysis (DTA) were carried out study the thermal stability of the resulting composites. The nano- composites were weakly ferromagnetic at room temperature. Formation of conducting emeraldine salt form was concluded by electrical conductivity.
{"title":"Preparation and Characterization of Polyaniline-Co 3 O 4 Nanocomposites via Interfacial Polymerization","authors":"M. Bedre, R. Deshpande, Basavaraja Salimath, V. Abbaraju","doi":"10.5923/J.MATERIALS.20120203.01","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120203.01","url":null,"abstract":"Polyaniline (Pani) and Polyaniline-Co3O4 nanocomposites (PCO) were prepared by employing interfacial po- lymerization using ammonium persulphate as an oxidizing agent. The formations of regular nanocomposite materials were studied by Fourier transform infrared (FTIR) spectroscopy and XRD techniques. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were conducted to characterize the morphology. Thermo-gravimetric (TG) and differential thermal analysis (DTA) were carried out study the thermal stability of the resulting composites. The nano- composites were weakly ferromagnetic at room temperature. Formation of conducting emeraldine salt form was concluded by electrical conductivity.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87505564","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120204.03
B. Tilak
Polycrystalline ceramics (Na0.5 Bi0.5)1-xBax ZryTi1-yO3, (BNBZT) (for x=0.10, 0.12; y=0.04), has been synthe- sized by conventional solid-state sintering. X-ray diffraction analysis indicates the formation of a single phase with tetragonal symmetry with pure perovskite structure. Scanning electron micrograph of the studied materials shows a distribution of grains. A broad dielectric peak with maximum permittivity has been observed near 1200 (for x=0.10, y=0.04) and 1600 (for x=0.12, y=0.04) respectively in the temperature range, RT-600℃. This result indicates that these materials may have great potential for a variety of high temperature applications. These ceramics show diffuse phase transition and the transition temperature shifting toward higher temperature with increasing frequency, which represents the relaxor behvaiour. The relaxor materials obey modified Curie-Weiss law and Vogel-Fulcher relationship. The values of the diffuseness parameter γ=2 for x = 0.10 and 1.67 for x = 0.12, obtained from the fit of a modified Curie-Weiss law established the relaxor type nature. For a more detailed interpretation of the ac data, the complex impedance (Z*) and electric modulus (M*) as a function of frequency f (i.e., 45 Hz-5 MHz) has been simultaneously analysed. Impedance study reveals that there exists a temperature dependent electrical relaxation phenomenon in the materials. Modulus represents hopping of ions and localized motion in studied compositions. Conductivity obey's Jonscher law
{"title":"Ferroelectric Relaxor Behavior and Spectroscopic Properties of Ba 2+ and Zr 4+ Modified Sodium Bismuth Titanate","authors":"B. Tilak","doi":"10.5923/J.MATERIALS.20120204.03","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120204.03","url":null,"abstract":"Polycrystalline ceramics (Na0.5 Bi0.5)1-xBax ZryTi1-yO3, (BNBZT) (for x=0.10, 0.12; y=0.04), has been synthe- sized by conventional solid-state sintering. X-ray diffraction analysis indicates the formation of a single phase with tetragonal symmetry with pure perovskite structure. Scanning electron micrograph of the studied materials shows a distribution of grains. A broad dielectric peak with maximum permittivity has been observed near 1200 (for x=0.10, y=0.04) and 1600 (for x=0.12, y=0.04) respectively in the temperature range, RT-600℃. This result indicates that these materials may have great potential for a variety of high temperature applications. These ceramics show diffuse phase transition and the transition temperature shifting toward higher temperature with increasing frequency, which represents the relaxor behvaiour. The relaxor materials obey modified Curie-Weiss law and Vogel-Fulcher relationship. The values of the diffuseness parameter γ=2 for x = 0.10 and 1.67 for x = 0.12, obtained from the fit of a modified Curie-Weiss law established the relaxor type nature. For a more detailed interpretation of the ac data, the complex impedance (Z*) and electric modulus (M*) as a function of frequency f (i.e., 45 Hz-5 MHz) has been simultaneously analysed. Impedance study reveals that there exists a temperature dependent electrical relaxation phenomenon in the materials. Modulus represents hopping of ions and localized motion in studied compositions. Conductivity obey's Jonscher law","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85429136","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120203.09
P. Venkatesan, J. Santhanalakshmi
Colloidal bimetallic gold core palladium shell nanoparticles were prepared by wet chemical method, in which Au(III) and Pd(II) ions in an aqueous solution in the presence of a cationic surfactant, Cetyltrimethylammonium bromide (CTAB). The structure and composition of the metallic nanoparticles were characterized by UV-Vis, HRTEM, SEM-EDX, XRD, XPS and FTIR. The catalytic activities of nanoparticles are tested on the surface chemical characterization study of Cetyltrimethylammonium bromide supported Au-Pd bimetallic nanoparticle catalyst, hereafter named Au-Pdnp, is reported. Such a catalyst was developed for the Suzuki coupling reaction and found excellent catalytic activity. Here we describe the catalytic performance and the FTIR studies provide proof of the mode of binding that occurs in the Palladium nanoparticle surface for the first time and also confirms the mechanism of the Suzuki reaction.
{"title":"Synthesis of Gold-Palladium Bimetallic Nanoparticles and Surface Catalytic Activity in Suzuki Coupling Reactions Using in FTIR Spectroscopy","authors":"P. Venkatesan, J. Santhanalakshmi","doi":"10.5923/J.MATERIALS.20120203.09","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120203.09","url":null,"abstract":"Colloidal bimetallic gold core palladium shell nanoparticles were prepared by wet chemical method, in which Au(III) and Pd(II) ions in an aqueous solution in the presence of a cationic surfactant, Cetyltrimethylammonium bromide (CTAB). The structure and composition of the metallic nanoparticles were characterized by UV-Vis, HRTEM, SEM-EDX, XRD, XPS and FTIR. The catalytic activities of nanoparticles are tested on the surface chemical characterization study of Cetyltrimethylammonium bromide supported Au-Pd bimetallic nanoparticle catalyst, hereafter named Au-Pdnp, is reported. Such a catalyst was developed for the Suzuki coupling reaction and found excellent catalytic activity. Here we describe the catalytic performance and the FTIR studies provide proof of the mode of binding that occurs in the Palladium nanoparticle surface for the first time and also confirms the mechanism of the Suzuki reaction.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79473980","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20110102.25
M. Deshpande, M. N. Parmar, Nilesh N. Pandya, Sandip V. Bhatt, S. Chaki
Absorption spectrum of copper (Cu) doped WSe2 (% of Cu = 0.0, 0.5, 1.0) single crystals were obtained in the range 700 nm to 1450 nm. The energy gap and phonon energies were determined for the crystals from the spectrum using two and three dimensional models. This study reflects that indirect transition is dominant in these crystals. On the basis of three dimensional models it was not possible for us to decide whether the indirect inter-band transition is forbidden or allowed type. Hence, different plots were made for two dimensional models, which showed that indirect forbidden transition holds accu- rately for this sample whereas indirect allowed type transition is not valid. The phonon energies calculated for these samples corresponds to the energies associated with optical phonons. The obtained results are discussed in details in this paper.
在700 ~ 1450 nm范围内获得了铜(Cu)掺杂WSe2 (% of Cu = 0.0, 0.5, 1.0)单晶的吸收光谱。利用二维和三维模型从光谱中确定了晶体的能隙和声子能量。本研究反映了这些晶体以间接转变为主。在三维模型的基础上，我们无法确定间接带间跃迁是禁止型还是允许型。因此，对二维模型进行了不同的绘制，结果表明间接禁止型转换对该样本有效，而间接允许型转换无效。为这些样品计算的声子能量与光学声子的能量相对应。本文对所得结果进行了详细的讨论。
{"title":"Band Gap Determination of Copper Doped Tungsten Diselenide Single Crystals by Optical Absorption Method","authors":"M. Deshpande, M. N. Parmar, Nilesh N. Pandya, Sandip V. Bhatt, S. Chaki","doi":"10.5923/J.MATERIALS.20110102.25","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20110102.25","url":null,"abstract":"Absorption spectrum of copper (Cu) doped WSe2 (% of Cu = 0.0, 0.5, 1.0) single crystals were obtained in the range 700 nm to 1450 nm. The energy gap and phonon energies were determined for the crystals from the spectrum using two and three dimensional models. This study reflects that indirect transition is dominant in these crystals. On the basis of three dimensional models it was not possible for us to decide whether the indirect inter-band transition is forbidden or allowed type. Hence, different plots were made for two dimensional models, which showed that indirect forbidden transition holds accu- rately for this sample whereas indirect allowed type transition is not valid. The phonon energies calculated for these samples corresponds to the energies associated with optical phonons. The obtained results are discussed in details in this paper.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81618776","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120202.04
K. Ch.Varada Rajulu, Tilak B, K. Sambasiva Rao
Solid state reaction route is used by adopting calcination, dry pressing and sintering for the preparation of polycrystalline Bi0.5(Na0.7K0.2Li0.1)0.5 TiO3(BNKLT) material. Studies of dielectric and conductivity parameters of the ma- terial were studied as a function of frequency(45Hz to 5MHz) and temperature(RT-600℃). At higher temperatures the conductivity curves were found to be merging, due to the effect of release of space charge.The conductivity parameters such as ion-hopping rate (ωp), fitting parameters (n(T), A(T)) and the charge carrier concentration(K ' ) terms have been calculated using Almond and West formalism.A strong dispersion in both the components of complex dielectric constant, appear to be a common feature in ferroelectrics associated with good ionic conductivity and is referred to as the low frequency dielectric dispersion(LFDD).This offered an opportunity to obtain a good candidate for replacing the lead based ceramics.
{"title":"Electricalconductivity and Dielectric Properties of Bi 0.5 (Na 0.7 K 0.2 Li 0.1 ) 0.5 TiO 3 Ceramic Material","authors":"K. Ch.Varada Rajulu, Tilak B, K. Sambasiva Rao","doi":"10.5923/J.MATERIALS.20120202.04","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120202.04","url":null,"abstract":"Solid state reaction route is used by adopting calcination, dry pressing and sintering for the preparation of polycrystalline Bi0.5(Na0.7K0.2Li0.1)0.5 TiO3(BNKLT) material. Studies of dielectric and conductivity parameters of the ma- terial were studied as a function of frequency(45Hz to 5MHz) and temperature(RT-600℃). At higher temperatures the conductivity curves were found to be merging, due to the effect of release of space charge.The conductivity parameters such as ion-hopping rate (ωp), fitting parameters (n(T), A(T)) and the charge carrier concentration(K ' ) terms have been calculated using Almond and West formalism.A strong dispersion in both the components of complex dielectric constant, appear to be a common feature in ferroelectrics associated with good ionic conductivity and is referred to as the low frequency dielectric dispersion(LFDD).This offered an opportunity to obtain a good candidate for replacing the lead based ceramics.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84197056","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120202.06
A. Kartavykh
The reported contradictory data on microstructure formation of the refractory intermetallic Ti-46Al-8Nb (at.%) alloy and on the high-temperature phase transformations proceeding within the Ti-Al-Nb phase diagram are ana- lysed and clarified experimentally. To determine the primary solidifying phase, a set of experiments is performed on melt- ing of the alloy specimens with low oxygen contamination in a high purity argon atmosphere using crucibles made of oxy- gen-free ceramics (99.99% AlN), and subsequent rapid solidification. Volumetrically-isothermal cooling from 1943 K at rates of 5, 10, and 20 K/s and following quench of mini-ingots from 1763 K are used. Specimens were studied by scanning electron microscopy (SEM) in backscattered electron (BSE) mode. SEM-BSE micrographs demonstrate contrasting shadow regions of non-uniform niobium segregation, which are fixed by quench and decorate the primary polycrystalline microstructure formed within the temperature range between 1843 (liquidus) and 1773 K (solidus). The primary crystalliz- ing phase is proven to be represented by β(Ti) dendrites, which have clearly pronounced fourfold (bcc-lattice) symmetry being formed with secondary dendrite arms development. The solidification path is shown to be described with single- phase scheme L→L+β(Ti)→β(Ti); no peritectic β(Ti)→α(Ti) bcc-hcp phase transformation revealed within the mushy state of alloy.
{"title":"On the Primary Phase Microstructure of Solidifying Ti-46Al-8Nb Refractory Intermetallic Alloy","authors":"A. Kartavykh","doi":"10.5923/J.MATERIALS.20120202.06","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120202.06","url":null,"abstract":"The reported contradictory data on microstructure formation of the refractory intermetallic Ti-46Al-8Nb (at.%) alloy and on the high-temperature phase transformations proceeding within the Ti-Al-Nb phase diagram are ana- lysed and clarified experimentally. To determine the primary solidifying phase, a set of experiments is performed on melt- ing of the alloy specimens with low oxygen contamination in a high purity argon atmosphere using crucibles made of oxy- gen-free ceramics (99.99% AlN), and subsequent rapid solidification. Volumetrically-isothermal cooling from 1943 K at rates of 5, 10, and 20 K/s and following quench of mini-ingots from 1763 K are used. Specimens were studied by scanning electron microscopy (SEM) in backscattered electron (BSE) mode. SEM-BSE micrographs demonstrate contrasting shadow regions of non-uniform niobium segregation, which are fixed by quench and decorate the primary polycrystalline microstructure formed within the temperature range between 1843 (liquidus) and 1773 K (solidus). The primary crystalliz- ing phase is proven to be represented by β(Ti) dendrites, which have clearly pronounced fourfold (bcc-lattice) symmetry being formed with secondary dendrite arms development. The solidification path is shown to be described with single- phase scheme L→L+β(Ti)→β(Ti); no peritectic β(Ti)→α(Ti) bcc-hcp phase transformation revealed within the mushy state of alloy.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90700578","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 : 2012-08-31DOI: 10.5923/J.MATERIALS.20120203.06
P. Mallick, N. Mishra
We present a brief review on the evolution of structure, microstructure, electrical and magnetic properties of NiO with transition metal (TM) doping. The fcc structure of NiO is not affected with TM doping whereas the some of the TM ion influences the microstructure. The antiferromagnetic property of NiO is strongly modified with some of the TM (Fe, Mn, V) doping and the same is not much affected with some other TM (Co, Cr, Zn and Cu) doping. Not only the dopants but also the form of the material decides the magnetic order in the host matrix. Powder NiO exhibits room tem- perature ferromagnetism with Fe doping, superparamagnetism with Mn doping. NiO thin films on the other hand exhibit ferromagnetism with Fe, Mn and V doping. The ferromagnetic ordering in these cases was improved with Li co-doping. The increased ferromagnetism in these cases may be due to increase of hole concentration due to Li doping. Giant dielectric response has been observed for (Li, Fe) and (Li, V) doped NiO ceramics.
{"title":"Evolution of Structure, Microstructure, Electrical and Magnetic Properties of Nickel Oxide (NiO) with Transition Metal ion Doping","authors":"P. Mallick, N. Mishra","doi":"10.5923/J.MATERIALS.20120203.06","DOIUrl":"https://doi.org/10.5923/J.MATERIALS.20120203.06","url":null,"abstract":"We present a brief review on the evolution of structure, microstructure, electrical and magnetic properties of NiO with transition metal (TM) doping. The fcc structure of NiO is not affected with TM doping whereas the some of the TM ion influences the microstructure. The antiferromagnetic property of NiO is strongly modified with some of the TM (Fe, Mn, V) doping and the same is not much affected with some other TM (Co, Cr, Zn and Cu) doping. Not only the dopants but also the form of the material decides the magnetic order in the host matrix. Powder NiO exhibits room tem- perature ferromagnetism with Fe doping, superparamagnetism with Mn doping. NiO thin films on the other hand exhibit ferromagnetism with Fe, Mn and V doping. The ferromagnetic ordering in these cases was improved with Li co-doping. The increased ferromagnetism in these cases may be due to increase of hole concentration due to Li doping. Giant dielectric response has been observed for (Li, Fe) and (Li, V) doped NiO ceramics.","PeriodicalId":7420,"journal":{"name":"American Journal of Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90119310","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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