Tijana Stamenković, Nadežda Radmilović, M. Nikolic, Jelena Erčić, V. Lojpur
In this manuscript, down-conversion nanopowders of SrGd2O4 doped with different concentrations of either Dy3+ or Sm3+ ions were examined in detail. All samples were prepared via glycine-assisted combustion method, primarily burned at 500?C for 1.5 h and additionally calcined at 1000?C for 2 h, at ambient room temperature. The XRD analysis showed that all samples crystallize as single phase and the orthorhombic lattice SrGd2O4. TEM analysis determined high degree of crystallinity of samples with grain size of approximately 200 nm for Dy3+ doped and 150 nm for Sm3+ doped SrGd2O4. For both samples SAED confirmed that diffraction rings correspond to the hkl plane indices of SrGd2O4, while EDS confirmed presence of Dy in crystal structure. Results of luminescent characterization demonstrated all appropriate emission peaks related to either Dy3+ or Sm3+ dopant ions. Investigation of dopant concentration revealed that the lowest values of both dopants have the most prominent emission peaks, while coordinates obtained from the CIE diagram showed emission shifting with the change of concentration.
{"title":"Structural and luminescence properties of SrGd2O4 nanocrystalline phosphor doped with Dy3+ and Sm3+","authors":"Tijana Stamenković, Nadežda Radmilović, M. Nikolic, Jelena Erčić, V. Lojpur","doi":"10.2298/sos2203295s","DOIUrl":"https://doi.org/10.2298/sos2203295s","url":null,"abstract":"In this manuscript, down-conversion nanopowders of SrGd2O4 doped with different concentrations of either Dy3+ or Sm3+ ions were examined in detail. All samples were prepared via glycine-assisted combustion method, primarily burned at 500?C for 1.5 h and additionally calcined at 1000?C for 2 h, at ambient room temperature. The XRD analysis showed that all samples crystallize as single phase and the orthorhombic lattice SrGd2O4. TEM analysis determined high degree of crystallinity of samples with grain size of approximately 200 nm for Dy3+ doped and 150 nm for Sm3+ doped SrGd2O4. For both samples SAED confirmed that diffraction rings correspond to the hkl plane indices of SrGd2O4, while EDS confirmed presence of Dy in crystal structure. Results of luminescent characterization demonstrated all appropriate emission peaks related to either Dy3+ or Sm3+ dopant ions. Investigation of dopant concentration revealed that the lowest values of both dopants have the most prominent emission peaks, while coordinates obtained from the CIE diagram showed emission shifting with the change of concentration.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mina Popovic, Z. Veličković, J. Bogdanov, A. Marinković, M. Casas-Luna, Isaak Trajković, N. Obradović, V. Pavlović
In this study, the structure, morphology and composition of the synthesized magnetite/3D-printed wollastonite (3D_W/M) composite were characterized, and its adsorption performance with respect to As(V) and Cr(VI) were studied. Magnetite (MG) modified 3D printed wollastonite was obtained by two step procedure: modification of 3D_W with 3-aminoproylsilane (APTES) followed by controlled magnetite (MG) deposition to obtain 3D_W/M adsorbent. The structure/properties of 3D_W/M were confirmed by applying FTIR, XRD, TGD/DTA, and SEM analysis. The adsorption properties of hybrid adsorbents were carried out for As(V) and Cr(VI) removal - one relative to the initial pH value, the adsorbent mass, the temperature, and the adsorption time. Time-dependent adsorption study was best described by pseudo-second order equation, while Weber Morris analysis showed that intraparticle diffusion controled diffusional transport. Similar activation energy, 17.44 and 14.49 kJ?mol-1 for adsorption As(V) and Cr(VI) on 3D_W/M, respectively, indicated main contribution of physical adsorption. Determination of adsorption parameters was performed by applying different adsorption isotherm models, and the best fit was obtained using Freundlich model. The adsorption capacity of 24.16 and 29.6 mg g-1 for As(V) and Cr(VI) at 2?C, Co = 5.5 and 5.3 mg L-1, respectively, were obtained. Thermodynamic study indicated favourable process at a higher temperature. Preliminary fixed-bed column study and results fitting with Bohart-Adams, Yoon-Nelson, Thomas, and Modified dose-response model showed good agreement with results from the batch study.
{"title":"Removal of the As(V) and Sr(VI) from the water using magnetite/3D-printed wollastonite hybrid adsorbent","authors":"Mina Popovic, Z. Veličković, J. Bogdanov, A. Marinković, M. Casas-Luna, Isaak Trajković, N. Obradović, V. Pavlović","doi":"10.2298/sos2201105p","DOIUrl":"https://doi.org/10.2298/sos2201105p","url":null,"abstract":"In this study, the structure, morphology and composition of the synthesized magnetite/3D-printed wollastonite (3D_W/M) composite were characterized, and its adsorption performance with respect to As(V) and Cr(VI) were studied. Magnetite (MG) modified 3D printed wollastonite was obtained by two step procedure: modification of 3D_W with 3-aminoproylsilane (APTES) followed by controlled magnetite (MG) deposition to obtain 3D_W/M adsorbent. The structure/properties of 3D_W/M were confirmed by applying FTIR, XRD, TGD/DTA, and SEM analysis. The adsorption properties of hybrid adsorbents were carried out for As(V) and Cr(VI) removal - one relative to the initial pH value, the adsorbent mass, the temperature, and the adsorption time. Time-dependent adsorption study was best described by pseudo-second order equation, while Weber Morris analysis showed that intraparticle diffusion controled diffusional transport. Similar activation energy, 17.44 and 14.49 kJ?mol-1 for adsorption As(V) and Cr(VI) on 3D_W/M, respectively, indicated main contribution of physical adsorption. Determination of adsorption parameters was performed by applying different adsorption isotherm models, and the best fit was obtained using Freundlich model. The adsorption capacity of 24.16 and 29.6 mg g-1 for As(V) and Cr(VI) at 2?C, Co = 5.5 and 5.3 mg L-1, respectively, were obtained. Thermodynamic study indicated favourable process at a higher temperature. Preliminary fixed-bed column study and results fitting with Bohart-Adams, Yoon-Nelson, Thomas, and Modified dose-response model showed good agreement with results from the batch study.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68808720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, aluminium matrix boron carbide (B4C) and carbon nanofiber (CNF) reinforced hybrid composite was produced by powder metallurgy method and their microstructure and mechanical properties were investigated. The samples were produced at 6 percentage volume ratios using hot pressing technique. Microstructure examination, hardness measurement, transverse rupture test, and wear tests were carried out in order to determine the mechanical properties of the samples. Also three-point bending test was performed to determine their transverse rupture strength (TRS). Wear tests were carried out based on the ball on disc method. The microstructure examination revealed that the reinforcing elements were relatively homogeneously distributed in the aluminium matrix. In addition, the fracture was brittle due to the notch effect and agglomeration occurred with increasing amount of CNF. As the CNF amount of the samples increased, their hardness values increased but their TRS values decreased. Results of the wear test indicate that the increased amount of CNF increased the wear resistance. The friction coefficient values of the samples varied between 0.535 and 0.646. When the hardness was examined together with TRS and wear test results, the most suitable sample was determined to be Al-7%B4C-1%CNF
{"title":"Microstructure and mechanical properties of aluminium matrix boron carbide and carbon nanofiber reinforced hybrid composites","authors":"Faik Okay, S. Islak","doi":"10.2298/sos2202125o","DOIUrl":"https://doi.org/10.2298/sos2202125o","url":null,"abstract":"In this study, aluminium matrix boron carbide (B4C) and carbon nanofiber (CNF) reinforced hybrid composite was produced by powder metallurgy method and their microstructure and mechanical properties were investigated. The samples were produced at 6 percentage volume ratios using hot pressing technique. Microstructure examination, hardness measurement, transverse rupture test, and wear tests were carried out in order to determine the mechanical properties of the samples. Also three-point bending test was performed to determine their transverse rupture strength (TRS). Wear tests were carried out based on the ball on disc method. The microstructure examination revealed that the reinforcing elements were relatively homogeneously distributed in the aluminium matrix. In addition, the fracture was brittle due to the notch effect and agglomeration occurred with increasing amount of CNF. As the CNF amount of the samples increased, their hardness values increased but their TRS values decreased. Results of the wear test indicate that the increased amount of CNF increased the wear resistance. The friction coefficient values of the samples varied between 0.535 and 0.646. When the hardness was examined together with TRS and wear test results, the most suitable sample was determined to be Al-7%B4C-1%CNF","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68808765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Series of CuO/CuCo2O4 composites were prepared by using the combustion method followed by heating at 750oC with different molar ratios of Cu/Co. Characterization of different composites is systematically investigated with various analytical techniques. X-ray diffraction patterns and Fourier-transform infrared spectroscopy indicate the growth of well crystalline CuCo2O4 nanoparticles with a cubic spinel structure. Images of transmission electron microscope and scanning electron microscope show a uniform particle distribution. From UV-visible spectra, the calculated optical band gaps of various solids were ranged between 1.2 and 1.8 eV. Electrical properties were measured at temperature ranged from 303 to 463 K in a frequency range from 102 to 106 Hz. The AC conductivity satisfied the Jonscher equation, especially at high frequency. The obtained data of conductivity and dielectric constant indicated that the prepared samples behave as semiconductor materials. Finally, it can be concluded that the CuO/CuCo2O4 composite showed attractive multi-functional features for electrical applications.
{"title":"Exploring the optical and electrical characteristics of CuO/CuCo2O4 composites","authors":"N. Deraz, H. Saleh, A. Abdel-karim","doi":"10.2298/sos2203265d","DOIUrl":"https://doi.org/10.2298/sos2203265d","url":null,"abstract":"Series of CuO/CuCo2O4 composites were prepared by using the combustion method followed by heating at 750oC with different molar ratios of Cu/Co. Characterization of different composites is systematically investigated with various analytical techniques. X-ray diffraction patterns and Fourier-transform infrared spectroscopy indicate the growth of well crystalline CuCo2O4 nanoparticles with a cubic spinel structure. Images of transmission electron microscope and scanning electron microscope show a uniform particle distribution. From UV-visible spectra, the calculated optical band gaps of various solids were ranged between 1.2 and 1.8 eV. Electrical properties were measured at temperature ranged from 303 to 463 K in a frequency range from 102 to 106 Hz. The AC conductivity satisfied the Jonscher equation, especially at high frequency. The obtained data of conductivity and dielectric constant indicated that the prepared samples behave as semiconductor materials. Finally, it can be concluded that the CuO/CuCo2O4 composite showed attractive multi-functional features for electrical applications.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Sánchez-Cuevas, G. Rosas, O. Navarro, C. Mercado-Zúñiga, L. Bretado-Aragón, F. Reynoso-Marín, J. Zárate-Medina
In this work, the multi-walled carbon nanotubes (MWCNTs) were purified with an acid treatment and subsequently dispersed using ultrasound and a nonionic surfactant solution of ethoxylated lauric alcohol 7 moles of ethylene oxide (E7E). Then, carbon nanotubes (CNTs) were used as a reinforcement phase (0.4 wt.% and 0.8 wt.%) in the Al- 10Mg alloy. The high-energy ball milling was employed for the nanocomposites processing, and the resulting powders consolidate by uniaxial pressure. Measurements of Vickers microhardness, nanohardness, displacement, and Young's modulus were carried out on the compacts. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy (RS). Good dispersion of MWCNTs was achieved using 0.5 mg/ml of the E7E surfactant. The CNTs were dispersed in the Al-10Mg matrix using 0.25 h of milling. After powders compaction, the Al-10Mg/0.4MWCNTs nanocomposite presented a microhardness of 190 HV, nanohardness of 3.5 GPa, and Young's modulus 116 GPa.
{"title":"Powder metallurgy and hardness of the Ll-10Mg alloy reinforced with carbon nanotubes","authors":"J. Sánchez-Cuevas, G. Rosas, O. Navarro, C. Mercado-Zúñiga, L. Bretado-Aragón, F. Reynoso-Marín, J. Zárate-Medina","doi":"10.2298/sos2204387s","DOIUrl":"https://doi.org/10.2298/sos2204387s","url":null,"abstract":"In this work, the multi-walled carbon nanotubes (MWCNTs) were purified with an acid treatment and subsequently dispersed using ultrasound and a nonionic surfactant solution of ethoxylated lauric alcohol 7 moles of ethylene oxide (E7E). Then, carbon nanotubes (CNTs) were used as a reinforcement phase (0.4 wt.% and 0.8 wt.%) in the Al- 10Mg alloy. The high-energy ball milling was employed for the nanocomposites processing, and the resulting powders consolidate by uniaxial pressure. Measurements of Vickers microhardness, nanohardness, displacement, and Young's modulus were carried out on the compacts. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy (RS). Good dispersion of MWCNTs was achieved using 0.5 mg/ml of the E7E surfactant. The CNTs were dispersed in the Al-10Mg matrix using 0.25 h of milling. After powders compaction, the Al-10Mg/0.4MWCNTs nanocomposite presented a microhardness of 190 HV, nanohardness of 3.5 GPa, and Young's modulus 116 GPa.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"595 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Djordjevic, M. Vlahović, Slavica Mihajlović, Sanja Martinović, Nenad Vušović, Jasmina Lozanović-Šajić
During mechanical activation, qualitative changes that can produce various phenomena occur in the material. In this study, anhydrous sodium carbonate was mechanically activated for 2, 7, 14, and 28 minutes in a vibro mill at a frequency of 3000 oscillations per minute. After activation, four series of activated samples were stored in the air at room conditions for 31 days (relaxation period). To monitor the kinetics of the transformation process of activated sodium carbonate samples, i.e. the mechanism of sodium bicarbonate formation during relaxation, Fourier-transform infrared (FTIR) spectroscopy analysis was used. FTIR testing was performed as a function of relaxation time for all four series of samples, with characteristic groups observed: CO32-, HCO3- and OH-. The obtained results provided kinetics parameters for the transformation of sodium carbonate into sodium bicarbonate due to the chemisorption of moisture and carbon dioxide from the atmosphere.
{"title":"Fourier-transform infrared spectroscopy analysis of mechanochemical transformation kinetics of sodium carbonate to bicarbonate","authors":"N. Djordjevic, M. Vlahović, Slavica Mihajlović, Sanja Martinović, Nenad Vušović, Jasmina Lozanović-Šajić","doi":"10.2298/sos2204481d","DOIUrl":"https://doi.org/10.2298/sos2204481d","url":null,"abstract":"During mechanical activation, qualitative changes that can produce various phenomena occur in the material. In this study, anhydrous sodium carbonate was mechanically activated for 2, 7, 14, and 28 minutes in a vibro mill at a frequency of 3000 oscillations per minute. After activation, four series of activated samples were stored in the air at room conditions for 31 days (relaxation period). To monitor the kinetics of the transformation process of activated sodium carbonate samples, i.e. the mechanism of sodium bicarbonate formation during relaxation, Fourier-transform infrared (FTIR) spectroscopy analysis was used. FTIR testing was performed as a function of relaxation time for all four series of samples, with characteristic groups observed: CO32-, HCO3- and OH-. The obtained results provided kinetics parameters for the transformation of sodium carbonate into sodium bicarbonate due to the chemisorption of moisture and carbon dioxide from the atmosphere.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68810346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As a result of advances in science and technology, the importance of metal matrix composite materials is increasing gradually today. However, in many studies, composite production is carried out with monotype ceramic particle reinforcement. In this study, the production, microstructure-hardness, and wear performance of composite-hybrid materials that had AA 7075 aluminum powder metal matrix and were reinforced by SiC and Al2O3 ceramic particles at different ratios were examined. The prepared Matrix and reinforcement powder mixtures were mixed for half an hour in the three-axis Turbula T2F type mixer and then, pressed unidirectionally and cylindrically under the pressure of 700 MPa. The pressed samples were sintered for 1 h at a temperature of 600oC in the argon atmosphere. Microstructure examinations were carried out using SEM (Scanning Electron Microscope) and optical microscope devices, while hardness measurements were obtained as a result of Brinell measurement. Wear performance of the test samples were tested in the Pin-on-disk type device at 10 N load and 500 rpm rotation speed by depending on the wear distances at 1000, 1500 and 2000 m. It was observed that hardness increased as the amount of ceramic particle in composite-hybrid samples increased. As a result of wear tests, in hybrid composites, compared to single-phase ceramic particle reinforced composites, weight losses increased depending on the increase in the reinforcement amount.
{"title":"Investigation of the microstructure-hardness and wear performances of hybrid/composite materials Al2O3/SiC particle reinforced in AA 7075 matrix","authors":"Zübeyde Özkan, Hakan Gökmeşe, U. Gökmen","doi":"10.2298/sos2202177o","DOIUrl":"https://doi.org/10.2298/sos2202177o","url":null,"abstract":"As a result of advances in science and technology, the importance of metal matrix composite materials is increasing gradually today. However, in many studies, composite production is carried out with monotype ceramic particle reinforcement. In this study, the production, microstructure-hardness, and wear performance of composite-hybrid materials that had AA 7075 aluminum powder metal matrix and were reinforced by SiC and Al2O3 ceramic particles at different ratios were examined. The prepared Matrix and reinforcement powder mixtures were mixed for half an hour in the three-axis Turbula T2F type mixer and then, pressed unidirectionally and cylindrically under the pressure of 700 MPa. The pressed samples were sintered for 1 h at a temperature of 600oC in the argon atmosphere. Microstructure examinations were carried out using SEM (Scanning Electron Microscope) and optical microscope devices, while hardness measurements were obtained as a result of Brinell measurement. Wear performance of the test samples were tested in the Pin-on-disk type device at 10 N load and 500 rpm rotation speed by depending on the wear distances at 1000, 1500 and 2000 m. It was observed that hardness increased as the amount of ceramic particle in composite-hybrid samples increased. As a result of wear tests, in hybrid composites, compared to single-phase ceramic particle reinforced composites, weight losses increased depending on the increase in the reinforcement amount.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Živojinović, D. Kosanović, V. Blagojević, V. Pavlović, N. Tadic, B. Vlahovic, V. Pavlović
In this study, microstructure evolution and dielectric properties of SrTiO3 ceramic have been investigated, whereby mechanical activation of SrTiO3 powders was used to modify the functional properties of ceramic materials. Microstructural SEM analysis of SrTiO3 ceramics showed that the increase in mechanical activation time results in less porous samples. Raman spectroscopy indicated changes in the broadening and asymmetry of the TO2 mode with a change in the time of mechanical activation. TO2 mode showed a Fano asymmetry due to its interaction with polarization fluctuations in polar micro-regions, which are a consequence of the presence of oxygen vacancies caused by activation. The maximum value of dielectric permittivity was observed in the sample activated for 10 min. Also, the sample activated for 10 min exhibits relatively low values of loss tangent, compared to the other mechanically activated samples, providing the best overall dielectric performance compared to other samples.
{"title":"Dielectric properties of mechanically activated strontium titanate ceramics","authors":"J. Živojinović, D. Kosanović, V. Blagojević, V. Pavlović, N. Tadic, B. Vlahovic, V. Pavlović","doi":"10.2298/sos2204401z","DOIUrl":"https://doi.org/10.2298/sos2204401z","url":null,"abstract":"In this study, microstructure evolution and dielectric properties of SrTiO3 ceramic have been investigated, whereby mechanical activation of SrTiO3 powders was used to modify the functional properties of ceramic materials. Microstructural SEM analysis of SrTiO3 ceramics showed that the increase in mechanical activation time results in less porous samples. Raman spectroscopy indicated changes in the broadening and asymmetry of the TO2 mode with a change in the time of mechanical activation. TO2 mode showed a Fano asymmetry due to its interaction with polarization fluctuations in polar micro-regions, which are a consequence of the presence of oxygen vacancies caused by activation. The maximum value of dielectric permittivity was observed in the sample activated for 10 min. Also, the sample activated for 10 min exhibits relatively low values of loss tangent, compared to the other mechanically activated samples, providing the best overall dielectric performance compared to other samples.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Randjelovic, S. Ribar, V. Mitić, Bojana Markovic, H. Fecht, B. Vlahovic
It is very important to determine microstructure parameters of consolidated ceramic samples, because it opens new frontiers for further microelectronics miniaturization and integrations. Therefore, controlling, predicting and designing the ceramic materials? properties are the objectives in ceramic materials consolidating process, within the science of sintering. In order to calculate the precise values of desired microstructure parameter at the level of the grains? coating layers based on the measurements on the bulk samples, we applied the artificial neural networks, as a powerful mathematical tool for mapping input-output data. Input signals are propagated forward, as well as the adjustable coefficients that contribute the calculated output signal, denoted as error, which is propagated backwards and replaced by examined parameter. In our previous research, we used neural networks to calculate different electrophysical parameters at the nano level of the grain boundary, like relative capacitance, breakdown voltage or tangent loss, and now we extend the research on sintered material?s density calculation. Errors on the network output were substituted by different consolidated samples density values measured on the bulk, thus enabling the calculation of precise material?s density values between the layers. We performed the neural network theoretical experiments for different number of neurons in hidden layers, according to experimental ceramics material?s density of ?=5.4x103[kg/m3], but it opens the possibility for neural networks application within other density values, as well.
{"title":"Artificial neural network applied on sintered BaTiO3-ceramic density","authors":"B. Randjelovic, S. Ribar, V. Mitić, Bojana Markovic, H. Fecht, B. Vlahovic","doi":"10.2298/sos2204425r","DOIUrl":"https://doi.org/10.2298/sos2204425r","url":null,"abstract":"It is very important to determine microstructure parameters of consolidated ceramic samples, because it opens new frontiers for further microelectronics miniaturization and integrations. Therefore, controlling, predicting and designing the ceramic materials? properties are the objectives in ceramic materials consolidating process, within the science of sintering. In order to calculate the precise values of desired microstructure parameter at the level of the grains? coating layers based on the measurements on the bulk samples, we applied the artificial neural networks, as a powerful mathematical tool for mapping input-output data. Input signals are propagated forward, as well as the adjustable coefficients that contribute the calculated output signal, denoted as error, which is propagated backwards and replaced by examined parameter. In our previous research, we used neural networks to calculate different electrophysical parameters at the nano level of the grain boundary, like relative capacitance, breakdown voltage or tangent loss, and now we extend the research on sintered material?s density calculation. Errors on the network output were substituted by different consolidated samples density values measured on the bulk, thus enabling the calculation of precise material?s density values between the layers. We performed the neural network theoretical experiments for different number of neurons in hidden layers, according to experimental ceramics material?s density of ?=5.4x103[kg/m3], but it opens the possibility for neural networks application within other density values, as well.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vuksanović, I. Mladenović, N. Tomić, M. Petrović, V. Radojević, A. Marinković, R. Jančić-Heinemann
Rice husk was used to produce silica particles, which were then used to reinforce the polymer matrix. The synthesized SiO2 particles were characterized using X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy with EDS. In a PMMA matrix, prepared SiO2 particles in amounts of 1, 3, and 5 wt.% were used as reinforcing agents. The goal of this research was to see if SiO2 particles had any effect on the mechanical properties of polymer composite materials. The morphology of the composites was examined using a field emission scanning electron microscope (FE-SEM). Vickers microindentation hardness and impact testing were used to determine the mechanical properties of the obtained composites. The indentation creep?s behavior of a polymethylmetacrylate (PMMA) composite material with varying amounts of nanoparticles (SiO2) was investigated and analyzed.
{"title":"Mechanical properties of biomass-derived silica nanoparticles reinforced PMMA composite material","authors":"M. Vuksanović, I. Mladenović, N. Tomić, M. Petrović, V. Radojević, A. Marinković, R. Jančić-Heinemann","doi":"10.2298/sos2202211v","DOIUrl":"https://doi.org/10.2298/sos2202211v","url":null,"abstract":"Rice husk was used to produce silica particles, which were then used to reinforce the polymer matrix. The synthesized SiO2 particles were characterized using X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy with EDS. In a PMMA matrix, prepared SiO2 particles in amounts of 1, 3, and 5 wt.% were used as reinforcing agents. The goal of this research was to see if SiO2 particles had any effect on the mechanical properties of polymer composite materials. The morphology of the composites was examined using a field emission scanning electron microscope (FE-SEM). Vickers microindentation hardness and impact testing were used to determine the mechanical properties of the obtained composites. The indentation creep?s behavior of a polymethylmetacrylate (PMMA) composite material with varying amounts of nanoparticles (SiO2) was investigated and analyzed.","PeriodicalId":21592,"journal":{"name":"Science of Sintering","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68809266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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