For over two decades Na0.5Bi0.5TiO3 (NBT) -based lead-free piezoelectrics have attracted attention due to its ability to exhibit large electric-field driven strain. Compared to the popular Pb(Zr, Ti)O3 (PZT)-based piezoelectrics, which exhibit electrostrain of about 0.3%, the derivatives of NBT-based lead-free piezoelectrics at the ergodic—non ergodic relaxor crossover exhibit larger electric-field driven strain ∼0.45%. In recent years, there has been a concerted effort to increase the maximum electrostrain in lead-free piezoceramics. Recent reports suggest that oxygen deficient NBT- based piezoceramics can exhibit electrostrain ∼ 1%. In this paper we explore this phenomenon in detail and show that the large electric field driven strain is primarily a consequence of reducing the thickness of the disc dimension below 500 microns.
{"title":"Is electrostrain > 1% in oxygen deficient Na0.5Bi0.5TiO3 a composition effect?","authors":"Getaw Abebe Tina, Gudeta Jafo Muleta, Gobinda Das Adhikary, Rajeev Ranjan","doi":"10.1093/oxfmat/itad021","DOIUrl":"https://doi.org/10.1093/oxfmat/itad021","url":null,"abstract":"For over two decades Na0.5Bi0.5TiO3 (NBT) -based lead-free piezoelectrics have attracted attention due to its ability to exhibit large electric-field driven strain. Compared to the popular Pb(Zr, Ti)O3 (PZT)-based piezoelectrics, which exhibit electrostrain of about 0.3%, the derivatives of NBT-based lead-free piezoelectrics at the ergodic—non ergodic relaxor crossover exhibit larger electric-field driven strain ∼0.45%. In recent years, there has been a concerted effort to increase the maximum electrostrain in lead-free piezoceramics. Recent reports suggest that oxygen deficient NBT- based piezoceramics can exhibit electrostrain ∼ 1%. In this paper we explore this phenomenon in detail and show that the large electric field driven strain is primarily a consequence of reducing the thickness of the disc dimension below 500 microns.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":"288 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139248066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The global pandemic caused by COVID-19 has increased awareness of the need for best practices to prevent the transmission of virus diseases. Antimicrobial films have been employed in packaging food items to minimize the spread of foodborne illnesses. However, the ongoing COVID-19 pandemic accelerated the demand for novel antimicrobial materials to prepare packaging films to minimize the virus spread through food items during processing and transportation. Considering the environmental pollution caused by single-use plastics, the demand for biodegradable polymers for packaging films has also increased in the current pandemic. This review aims to outline emerging bio-based antimicrobial materials and their incorporation into biopolymers as carriers for antimicrobial films, highlighting their potential as effective measures in preparing for future pandemics.
{"title":"Bio-based materials for antimicrobial films in food applications: Beyond the COVID-19 pandemic era","authors":"Bharath Perumal Pillai, Bhuvaneshwari Balasubramaniam, Raju Kumar Gupta, Ankit Tyagi","doi":"10.1093/oxfmat/itad016","DOIUrl":"https://doi.org/10.1093/oxfmat/itad016","url":null,"abstract":"\u0000 The global pandemic caused by COVID-19 has increased awareness of the need for best practices to prevent the transmission of virus diseases. Antimicrobial films have been employed in packaging food items to minimize the spread of foodborne illnesses. However, the ongoing COVID-19 pandemic accelerated the demand for novel antimicrobial materials to prepare packaging films to minimize the virus spread through food items during processing and transportation. Considering the environmental pollution caused by single-use plastics, the demand for biodegradable polymers for packaging films has also increased in the current pandemic. This review aims to outline emerging bio-based antimicrobial materials and their incorporation into biopolymers as carriers for antimicrobial films, highlighting their potential as effective measures in preparing for future pandemics.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41826753","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}
L. Vásárhelyi, D. Sebők, Imre Szenti, Ádám Tóth, Sára Lévay, R. Vajtai, Z. Kónya, Á. Kukovecz
In practically every industry, mixing is a fundamental process, yet its 3D analysis is scarce in the literature. High-resolution computed tomography (micro-CT) is the perfect X-ray imaging tool to investigate the mixing of granular materials. Other than qualitative analysis, 3D micro-CT images provide an opportunity for quantitative analysis, which is of utmost importance, in terms of efficiency (time and budget), and environmental impact of the mixing process. In this work, lacunarity is proposed as a measure of mixing. By the lacunarity calculation on the repeated micro-CT measurements, a temporal description of the mixing can be given in three dimensions. As opposed to traditional mixing indices, the lacunarity curve provides additional information regarding the spatial distribution of the grains. Discrete element method simulations were also performed and showed similar results to the experiments.
{"title":"Lacunarity as a quantitative measure of mixing—a micro-CT analysis-based case study on granular materials","authors":"L. Vásárhelyi, D. Sebők, Imre Szenti, Ádám Tóth, Sára Lévay, R. Vajtai, Z. Kónya, Á. Kukovecz","doi":"10.1093/oxfmat/itad014","DOIUrl":"https://doi.org/10.1093/oxfmat/itad014","url":null,"abstract":"\u0000 In practically every industry, mixing is a fundamental process, yet its 3D analysis is scarce in the literature. High-resolution computed tomography (micro-CT) is the perfect X-ray imaging tool to investigate the mixing of granular materials. Other than qualitative analysis, 3D micro-CT images provide an opportunity for quantitative analysis, which is of utmost importance, in terms of efficiency (time and budget), and environmental impact of the mixing process. In this work, lacunarity is proposed as a measure of mixing. By the lacunarity calculation on the repeated micro-CT measurements, a temporal description of the mixing can be given in three dimensions. As opposed to traditional mixing indices, the lacunarity curve provides additional information regarding the spatial distribution of the grains. Discrete element method simulations were also performed and showed similar results to the experiments.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49498063","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}
Ashwani Kumar, A. Prasad, B. Jayabalan, S. Mukherjee, J. Jain, Krishanu Biswas, S. Singh
In the present study, the wear behavior of the Fe-14Cr-1Ti-1W-0.5L2O3 oxide dispersion strengthened (ODS) steels has been reported. The ball-on-disc wear tester with SiC ball as counter surface was used to perform the wear tests. The effect of normal load (10 to 40 N with the interval of 10 N) on the wear behavior of the alloy has been investigated. Further, to understand the operative wear mechanism of the alloy, detailed microstructural and compositional analyses have also been carried out using scanning electron microscopy (SEM). The highest width of wear track was obtained as 896 ± 78 µm at 40 N normal load. The wear rate of the alloy was found to increase from 4.54 ±0.12 × 10-6 mm3/m to 25.48 ±1.15 × 10-6 mm3/m with the normal load from 10 to 40 N at constant sliding velocity and distance. Moreover, the microstructure analyses of the worn surfaces, wear debris and counter surface have shown the prominent wear mechanism to be combination of adhesion, abrasion, oxidation and plastic deformation. Addition of lanthana was found to reduce the wear rate of ferritic steels.
{"title":"Wear behavior of nano-La2O3 dispersed ferritic ODS steel developed by spark plasma sintering","authors":"Ashwani Kumar, A. Prasad, B. Jayabalan, S. Mukherjee, J. Jain, Krishanu Biswas, S. Singh","doi":"10.1093/oxfmat/itad013","DOIUrl":"https://doi.org/10.1093/oxfmat/itad013","url":null,"abstract":"\u0000 In the present study, the wear behavior of the Fe-14Cr-1Ti-1W-0.5L2O3 oxide dispersion strengthened (ODS) steels has been reported. The ball-on-disc wear tester with SiC ball as counter surface was used to perform the wear tests. The effect of normal load (10 to 40 N with the interval of 10 N) on the wear behavior of the alloy has been investigated. Further, to understand the operative wear mechanism of the alloy, detailed microstructural and compositional analyses have also been carried out using scanning electron microscopy (SEM). The highest width of wear track was obtained as 896 ± 78 µm at 40 N normal load. The wear rate of the alloy was found to increase from 4.54 ±0.12 × 10-6 mm3/m to 25.48 ±1.15 × 10-6 mm3/m with the normal load from 10 to 40 N at constant sliding velocity and distance. Moreover, the microstructure analyses of the worn surfaces, wear debris and counter surface have shown the prominent wear mechanism to be combination of adhesion, abrasion, oxidation and plastic deformation. Addition of lanthana was found to reduce the wear rate of ferritic steels.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42121524","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}
P. Vishwakarma, S. Pandey, Anshu Kumar Singh, Sanny Rathore, K. Ram, Rajiv Giri, A. Srivastava
Poly-aromatic hydrocarbons (PAHs) such as benz[α]anthracene (BaA) are often released from cigarette smoke, and threat to public health severely. In this quest, several filtration techniques have been proposed for the elimination of these toxins, but the challenges remain same in the terms of low efficiency, high cost and complex manufacturing processes. Herein, we report a simple, cost-effective and reusable multiwalled carbon nanotube membrane-based filter for enhanced removal (∼90%) of BaA from cigarette smoke. In terms of the excellent thermal stability of Multiwalled Carbon Nanotubes membrane, the adsorbed PAHs could be removed simply by a thermolysis process. We believe that the present study may serve as inspiration for the design and development of high-performance fibrous materials for filtering and separation applications.
{"title":"Reusable and Thermostable Multiwalled Carbon Nanotubes Membrane for Efficient Removal of Benz[α]Anthracene from Cigarette Smoke","authors":"P. Vishwakarma, S. Pandey, Anshu Kumar Singh, Sanny Rathore, K. Ram, Rajiv Giri, A. Srivastava","doi":"10.1093/oxfmat/itad012","DOIUrl":"https://doi.org/10.1093/oxfmat/itad012","url":null,"abstract":"\u0000 Poly-aromatic hydrocarbons (PAHs) such as benz[α]anthracene (BaA) are often released from cigarette smoke, and threat to public health severely. In this quest, several filtration techniques have been proposed for the elimination of these toxins, but the challenges remain same in the terms of low efficiency, high cost and complex manufacturing processes. Herein, we report a simple, cost-effective and reusable multiwalled carbon nanotube membrane-based filter for enhanced removal (∼90%) of BaA from cigarette smoke. In terms of the excellent thermal stability of Multiwalled Carbon Nanotubes membrane, the adsorbed PAHs could be removed simply by a thermolysis process. We believe that the present study may serve as inspiration for the design and development of high-performance fibrous materials for filtering and separation applications.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48077583","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}
Anshu Kumar Singh, S. Pandey, P. Vishwakarma, Raghvendra Pratap, Ranjana Verma, Anamika Pandey, Rajiv Giri, A. Srivastava
These days, textile industries pose a more significant threat to surface water and groundwater sources directly or indirectly by discharging wastewater containing various dyes and organic pollutants to these water sources. The phase-junction-engineered heterogeneous photocatalysis carried out by visible-light-driven semiconductor photocatalysts is opening a new window for the degradation of environmental organic pollutants. In this work, we have reported a one-step bottom-up hydrothermal synthesis of biphasic tungsten oxide (o/h-WO3) and performed a photodegradation experiment under visible light irradiation for the efficient degradation of organic pollutants such as Methylene blue (MB) methyl violet (MV), respectively. The XRD, RAMAN, TEM, and UV-vis characterization techniques were used to investigate the structural, morphological, and optical properties of the as-synthesized o/h-WO3. Moreover, the low calculated band gap ( ̴ 2.8 eV) and the anionic nature of o/h-WO3 suggest it as an efficient visible-light-driven photocatalyst suitable for heterogeneous photocatalysis. The photodegradation experiment performed under visible light using o/h-WO3 photocatalyst showed better degradation efficiency of 71% and 89% for MB and MV, respectively, in 100 min. The dyes followed first-order kinetics, and their kinetic rate constants were calculated using the Langmuir-Hinshelwood model. Furthermore, the recyclability study of the photocatalyst was also performed and discussed the underlying mechanism for the photodegradation of the organic dyes.
{"title":"Catalyst-Free Biphasic Orthorhombic/Hexagonal Tungsten Oxide System with Enhanced Photocatalytic Response Under Visible Light","authors":"Anshu Kumar Singh, S. Pandey, P. Vishwakarma, Raghvendra Pratap, Ranjana Verma, Anamika Pandey, Rajiv Giri, A. Srivastava","doi":"10.1093/oxfmat/itad009","DOIUrl":"https://doi.org/10.1093/oxfmat/itad009","url":null,"abstract":"\u0000 These days, textile industries pose a more significant threat to surface water and groundwater sources directly or indirectly by discharging wastewater containing various dyes and organic pollutants to these water sources. The phase-junction-engineered heterogeneous photocatalysis carried out by visible-light-driven semiconductor photocatalysts is opening a new window for the degradation of environmental organic pollutants. In this work, we have reported a one-step bottom-up hydrothermal synthesis of biphasic tungsten oxide (o/h-WO3) and performed a photodegradation experiment under visible light irradiation for the efficient degradation of organic pollutants such as Methylene blue (MB) methyl violet (MV), respectively. The XRD, RAMAN, TEM, and UV-vis characterization techniques were used to investigate the structural, morphological, and optical properties of the as-synthesized o/h-WO3. Moreover, the low calculated band gap ( ̴ 2.8 eV) and the anionic nature of o/h-WO3 suggest it as an efficient visible-light-driven photocatalyst suitable for heterogeneous photocatalysis. The photodegradation experiment performed under visible light using o/h-WO3 photocatalyst showed better degradation efficiency of 71% and 89% for MB and MV, respectively, in 100 min. The dyes followed first-order kinetics, and their kinetic rate constants were calculated using the Langmuir-Hinshelwood model. Furthermore, the recyclability study of the photocatalyst was also performed and discussed the underlying mechanism for the photodegradation of the organic dyes.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41518009","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}
Inherently poor lattice thermal conductivity (κL) is highly desired for applications like thermoelectricity, thermal management in electronics, thermal barrier coatings and refractories. Recently, complex crystalline materials have drawn serious scientific attention because of various interesting underlying physical phenomena which explain the unique thermal properties. In this review, we have discussed various interesting concepts and their consequences leading to ultralow κL in complex bulk chalcogenide minerals having multiple scattering channels for heat carrying phonons. The primary focus of this review is on the Ag and Cu based large unit cell structures with low heat capacity and a liquid-like superionic conduction of cations. The Ag/Cu sublattice of these materials that followed the phonon-liquid electron crystal concept strongly reduces the transportation of phonons and enhances the scattering process. The presence of large number of atoms in the unit cell result in low acoustic phonons cut-off frequency, robust acoustic-optical phonons scattering, poor sound velocity and strong crystal anharmonicity inside the crystalline lattice.
{"title":"Thermoelectricity in Ag/Cu based complex crystal structure minerals with inherent low thermal conductivity","authors":"Kewal Singh Rana, A. Soni","doi":"10.1093/oxfmat/itad005","DOIUrl":"https://doi.org/10.1093/oxfmat/itad005","url":null,"abstract":"\u0000 Inherently poor lattice thermal conductivity (κL) is highly desired for applications like thermoelectricity, thermal management in electronics, thermal barrier coatings and refractories. Recently, complex crystalline materials have drawn serious scientific attention because of various interesting underlying physical phenomena which explain the unique thermal properties. In this review, we have discussed various interesting concepts and their consequences leading to ultralow κL in complex bulk chalcogenide minerals having multiple scattering channels for heat carrying phonons. The primary focus of this review is on the Ag and Cu based large unit cell structures with low heat capacity and a liquid-like superionic conduction of cations. The Ag/Cu sublattice of these materials that followed the phonon-liquid electron crystal concept strongly reduces the transportation of phonons and enhances the scattering process. The presence of large number of atoms in the unit cell result in low acoustic phonons cut-off frequency, robust acoustic-optical phonons scattering, poor sound velocity and strong crystal anharmonicity inside the crystalline lattice.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46545007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The DFT and TD-DFT method with Becke three-parameter Lee-Yang–Parr functional (B3LYP) approach at a basis set of 6-311G was used to analyze the ground state and excited state properties of newly designed D-A-D’ donor molecules based on triphenylamine and carbazole as donor units and benzothiadiazole and its derivatives as acceptor units to make a total of nine (9) potential monomers. The energies associated with highest occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO), bandgap (Eg), electron excitation (Eopt), exciton binding (Eb) and open-circuit voltage (Voc) were calculated and the simulated absorption spectra in both gas and chlorobenzene solvent were plotted. The outcomes of replacing the acceptor building unit and substituting the donor units to tailor the optoelectronic properties of the designed monomers were discussed. The monomer molecules A7, A8 and A9 are suitable for BHJ-SCs because of their small Eg, Eopt, Eb and, more importantly, large Voc values. Suggesting changing the acceptor unit and substituting the donor units of the D-A-D’ seem to be an excellent approach to tailoring the optoelectronic properties of the molecules.
{"title":"DFT and TD-DFT study of Optical and Electronic Properties of new donor-acceptor-donor (D-A-Dˈ) monomers for polymer solar cells","authors":"Melchizedek Lyakurwa, Surendra Babu Numbury","doi":"10.1093/oxfmat/itad003","DOIUrl":"https://doi.org/10.1093/oxfmat/itad003","url":null,"abstract":"\u0000 The DFT and TD-DFT method with Becke three-parameter Lee-Yang–Parr functional (B3LYP) approach at a basis set of 6-311G was used to analyze the ground state and excited state properties of newly designed D-A-D’ donor molecules based on triphenylamine and carbazole as donor units and benzothiadiazole and its derivatives as acceptor units to make a total of nine (9) potential monomers. The energies associated with highest occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO), bandgap (Eg), electron excitation (Eopt), exciton binding (Eb) and open-circuit voltage (Voc) were calculated and the simulated absorption spectra in both gas and chlorobenzene solvent were plotted. The outcomes of replacing the acceptor building unit and substituting the donor units to tailor the optoelectronic properties of the designed monomers were discussed. The monomer molecules A7, A8 and A9 are suitable for BHJ-SCs because of their small Eg, Eopt, Eb and, more importantly, large Voc values. Suggesting changing the acceptor unit and substituting the donor units of the D-A-D’ seem to be an excellent approach to tailoring the optoelectronic properties of the molecules.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44015949","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 study theoretically fundamental Coulomb-correlated complexes: neutral and charged excitons, also known as trions, in transition metal dichalogenides monolayers. We focus on the situation where one of the electrons occupies excited, high-lying, conduction band characterized by a negative effective mass. We develop the theory of such high-lying excitons and trions with negative effective mass and demonstrate the key role of the non-parabolicity of the high-lying conduction band dispersion in formation of the bound exciton and trion states. We present simple, accurate and physically justified trial wavefunctions for calculating the binding energies of Coulomb-bound complexes and compare the results of variational calculations with those of a fully numerical approach. Within the developed model we discuss recent experimental results on observation of high-lying negative effective mass trions [K.-Q. Lin et al., Nat. Commun. 13, 6980 (2022)].
{"title":"Excitons and trions with negative effective masses in two-dimensional semiconductors","authors":"M. A. Semina, J. V. Mamedov, M. Glazov","doi":"10.1093/oxfmat/itad004","DOIUrl":"https://doi.org/10.1093/oxfmat/itad004","url":null,"abstract":"\u0000 We study theoretically fundamental Coulomb-correlated complexes: neutral and charged excitons, also known as trions, in transition metal dichalogenides monolayers. We focus on the situation where one of the electrons occupies excited, high-lying, conduction band characterized by a negative effective mass. We develop the theory of such high-lying excitons and trions with negative effective mass and demonstrate the key role of the non-parabolicity of the high-lying conduction band dispersion in formation of the bound exciton and trion states. We present simple, accurate and physically justified trial wavefunctions for calculating the binding energies of Coulomb-bound complexes and compare the results of variational calculations with those of a fully numerical approach. Within the developed model we discuss recent experimental results on observation of high-lying negative effective mass trions [K.-Q. Lin et al., Nat. Commun. 13, 6980 (2022)].","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43125300","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. Mitra, M. Sahoo, Aiswarya Samal, S. Pradhan, Balaram Polai, Krishna R. Sahoo, S. Kar, B. K. Satpathy, T. N. Narayanan, P. Ajayan, P. V. Satyam, S. Nayak
Metal Matrix Composites (MMCs) have attracted extensive attention from both the research and industrial perspective. In this study, we prepared aluminum–reduced graphene oxide (Al–rGO) composites with enhanced thermal conductivity in an easy single-step process. Pristine Al shows a thermal conductivity of 175 Wm−1K−1 (standard deviation < 5%), which increases to 293 Wm−1K−1 for an Al–rGO composite with 1% rGO. Analysis of theoretical models shows that a higher percentage of rGO inside the Al matrix creates a continuous network resulting in more available phase space through which heat carrier phonons travel with less scattering, and hence thermal conductivity of the composite increases. Furthermore, Al–rGO composites show an approximately 5% increase in microhardness compared with pristine Al. The electrical resistivity of the composite is comparable to that of pristine Al for a narrow weight percentage of rGO, whereas a 70% enhancement in the thermal conductivity of the composite is observed for the same weight percentage range, suggesting possibilities for exploiting both high electrical and thermal conductivities for various applications.
{"title":"Large Enhancement of Thermal Conductivity of Aluminum–Reduced Graphene Oxide Composites Prepared by a Single-Step Method","authors":"A. Mitra, M. Sahoo, Aiswarya Samal, S. Pradhan, Balaram Polai, Krishna R. Sahoo, S. Kar, B. K. Satpathy, T. N. Narayanan, P. Ajayan, P. V. Satyam, S. Nayak","doi":"10.1093/oxfmat/itac015","DOIUrl":"https://doi.org/10.1093/oxfmat/itac015","url":null,"abstract":"\u0000 Metal Matrix Composites (MMCs) have attracted extensive attention from both the research and industrial perspective. In this study, we prepared aluminum–reduced graphene oxide (Al–rGO) composites with enhanced thermal conductivity in an easy single-step process. Pristine Al shows a thermal conductivity of 175 Wm−1K−1 (standard deviation < 5%), which increases to 293 Wm−1K−1 for an Al–rGO composite with 1% rGO. Analysis of theoretical models shows that a higher percentage of rGO inside the Al matrix creates a continuous network resulting in more available phase space through which heat carrier phonons travel with less scattering, and hence thermal conductivity of the composite increases. Furthermore, Al–rGO composites show an approximately 5% increase in microhardness compared with pristine Al. The electrical resistivity of the composite is comparable to that of pristine Al for a narrow weight percentage of rGO, whereas a 70% enhancement in the thermal conductivity of the composite is observed for the same weight percentage range, suggesting possibilities for exploiting both high electrical and thermal conductivities for various applications.","PeriodicalId":74385,"journal":{"name":"Oxford open materials science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46954324","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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