eric abavare - Academia.edu (original) (raw)

Papers by eric abavare

Physical Review B, Jun 27, 2013

We report first-principles calculations that reveal atomic and electronic structures of interface... more We report first-principles calculations that reveal atomic and electronic structures of interfaces consisting of Si(110) face and 3C-SiC (111) face in which the lattices match apparently but the atomic densities in both sides are different. We find two distinct interface structures in the total-energy difference of 4-5 meV perÅ 2 for both the Si-Si interface and the Si-C interface: The interface of sparse Si(110) and dense SiC(111) exhibits bistability. We find that the stable and metastable structures are associated with vacant channels along a particular direction which are stabilized by the existence of over-coordinated atoms (floating bonds). We reveal that the coexistence of the floating bonds and the dangling bonds (under-coordinated atoms) and then the electron transfer from the dangling-to the floating bonds are the microscopic mechanism of the stabilization of the interface. We also find that atomic scale undulation mainly confined in the Si region also exists to stabilize the interface. The calculated interface energies show that the Si-Si interface is energetically favorable compared with the Si-C interface. Calculated energy bands exhibit semiconducting characteristics for all the stable and metastable interfaces.

arXiv (Cornell University), Jul 21, 2021

Plasticity in body centered cubic (bcc) refractory metals are largely due to the stress tensor in... more Plasticity in body centered cubic (bcc) refractory metals are largely due to the stress tensor induced either by solute or thermal activation. The mechanism of the solute atom(s) residence causes instability in such metals. Earlier research have considered the mechanism of oxygen (O) or carbon (C) in tungsten (W), even though the major component of the environment is nitrogen (N). In this article, the density functional theory (DFT) was employed to investigate the

The International Promotion Agency of Culture Technology, May 1, 2021

Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2011

structures of 3C-SiC(111)/Si(110) interfaces

A Thesis submitted to the School of Graduate Studiesin Partial Fulfillment of the Requirements fo... more A Thesis submitted to the School of Graduate Studiesin Partial Fulfillment of the Requirements for the Award of Masters in Business Administration(Finance Option) , 2015

Radiation protection dosimetry, 2021

The protection of man and his environment from undue exposure from radio frequency electromagneti... more The protection of man and his environment from undue exposure from radio frequency electromagnetic field requires identification of the location where exposures are likely to be higher than safe levels established by international safety standards. A wideband measurement with a spectrum analyzer and a log-periodic antenna in conjunction with the three-point spatial average method was used. The results ranged from 16.21 to 2907.00 mVm-1 and complied with a maximum of 1.08% of the ICNIRP reference level. Private frequency modulation (FM) sources were identified as the major source of exposure to the public with a mean value of 337.70 ± 133.70 mVm-1 against 122.30 ± 36.47 mVm-1 for the public FM transmitters. Even though the result was lower than a workplace assessment, it was, however, higher than similar works conducted in Africa and Palestine. Finally, four sensitive locations were identified for further research work.

Journal of Materials Science Research, 2020

Zeolites based on the numerous applications can be utilised in providing solutions to some challe... more Zeolites based on the numerous applications can be utilised in providing solutions to some challenges of our world. With the ability to store thermal energy as chemical potential, zeolites are able to store thermal energy for long periods. This can occur with very minimal loss of energy and indefinitely unless the zeolite comes into contact with an adsorbate. The use of zeolite - water as adsorbent - adsorbate pair in thermal energy storage (TES) applications have been studied and have shown good results. However, the cost of zeolites synthesized from reagents continue to hamper the effective use of this adsorbent. Zeolite A was synthesized from kaolin from Wassa in Ghana based on a modified synthesis route. The adsorption properties of the zeolite utilising a designed and fabricated TES system using amounts of 100g, 200g, 300g, 400g and 500g of zeolite with a 1:1.5 ratio to water. Adsorption isosteres were plotted with the temperature and pressure values recorded and results showed...

3C-SiC(111) on Si (110) surface with a particular alignment of the two planes offers almost perfe... more 3C-SiC(111) on Si (110) surface with a particular alignment of the two planes offers almost perfect fake matching of the lattice periodicity, albeit dense 3C-SiC and sparse Si in spite of the large lattice mismatch ∼20% between them. We here report total-energy electronic-structure calculations based on real-space density functional theory (RSDFT), which elucidate new reconstruction mechanism of dense 3C-SiC(111) on sparse Si(110) surface with the relaxed superstructures displaying undulation near the interface. We explore a variety of candidate interface structures and reach two distinctive types called type I and II which show bistability at the interface. We define interface energy as the energy difference between the total energy of the interface structure and the energy of the bulk constituent atoms. In type I, the interface energy where the silicon faces meet each other (silicon-silicon) is calculated as 9.571 eV/cell or 0.117 eV/Å2 whereas the interface energy where the silic...

Molecules, 2020

Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to po... more Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl2. The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl2 molecule adsorbed spontaneously on the Fullerene or nanocages and endoth...

Surfaces and Interfaces, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Results in Materials, 2019

Ab initio calculations based on density functional theory was carried out to study the electronic... more Ab initio calculations based on density functional theory was carried out to study the electronic properties of (3,3), (4,2), (5,2) and (6,0) boron nitride nanotubes when interacting with nickel, titanium, palladium and gold metal atoms. These interactions occurred via adsorption, intercalation, nitrogen substitutional doping and boron substitutional doping. The wide band gaps intrinsic to the pristine boron nitride nanotubes were successfully tuned upon interaction with the metal atoms irrespective of the type of interactions. However, for most of the interactions that occurred via intercalation and nitrogen substitutional doping, the boron nitride nanotube was found to possess semi-metallic properties. More states were added in the density of states upon interaction in which the d orbital of the transition metal atoms was found to be the major contributor to the increase in density of states.

Results in Physics, 2019

Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2... more Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2), (6,0) and (5,1) carbon nanotubes were studied using first principles calculations. The Fermi energy levels of the carbon nanotubes studied were found to increase during interactions with the transition metal atoms. Amongst the four metals, gold atom was found to have an enhanced interaction with the nanotubes transforming from semiconducting to a conducting tube. Titanium was also found to show similar characteristics to gold only when the atom was placed in the middle of the carbon nanotubes. Nickel and palladium atoms interactions did not affect much the electronic properties of the carbon nanotubes, with some slight changes in the electronic properties at some specific sites of the nanotubes. It is proposed from this study that, the carbon nanotube-metal interactions could be used as a guide to shed light on the electronic properties of such materials which could become promising engineering materials and revolutionize the electronic industry.

Radiation Protection Dosimetry, 2018

The analysis of channel power and electric field strength at various locations from mobile base s... more The analysis of channel power and electric field strength at various locations from mobile base stations using power sensor, spectrum analyzer and log-periodic antenna revealed maximum potential exposure between the range of 61.1 and 254.7 m. Generally, the potential exposure values ranged from 0.0717 to 0.8950 mW m-2 with a maximum deviation of 22.22%. GSM900 was found to be more pronounced than GSM1800 and UMTS2100. Though the results complied with ICNIRP reference levels with a wide margin of 0.01%, it was higher than some previous work and South African mean value of 0.16 mW m-2, agreed with similar work elsewhere but lower than a global average value of 0.730 mW m-2.

Radiation Protection Dosimetry, 2018

This paper describes an effort to respond to the suggestion in World Health Organization (WHO) re... more This paper describes an effort to respond to the suggestion in World Health Organization (WHO) research agenda to better quantify potential exposure levels from a range of radiofrequency (RF) sources at 200 public access locations in Ghana. Wide-band measurements were performed-with a spectrum analyser and a log-periodic antenna using three-point spatial averaging method. The overall results represented a maximum of 0.19% of the ICNIRP reference levels for public exposure. These results were generally lower than found in some previous but were 58% (2.0 dB) greater, than found in similar work conducted in the USA. Major contributing sources of RF fields were identified to be FM broadcast and mobile base station sites. Three locations with the greatest measured RF fields could represent potential areas for epidemiological studies.

Cogent Engineering, 2016

This work is licensed under a Creative Commons Attribution 4.0 International License Newcastle Un... more This work is licensed under a Creative Commons Attribution 4.0 International License Newcastle University ePrints-eprint.ncl.ac.uk Yaya A, Ewels CP, Efavi JK, Agyei-Tuffour B, Kan-Dapaah K, Onwona-Agyeman B, Abavare EKK, Hassanali A, Briddon PR. A study of polybromide chain formation using carbon nanomaterials via density functional theory approach. Cogent Engineering 2016, 3(1), 1261509.

physica status solidi (b), 2014

We perform total-energy electronic-structure calculations based on density functional theory in t... more We perform total-energy electronic-structure calculations based on density functional theory in the framework of the local density approximation to discuss the surface energy convergence of non-polar Si(110)-and polar 3C-SiC(111)-terminated surfaces. Whilst the non-polar surface show monotonic convergence in surface energy, the polar surface is oscillatory. The relaxations of 3C-SiC(111)-and α-6H(0001)-terminated surfaces are very similar; however, the two structures are electronically different due to differences in the relative energetic positions of their dangling bonds. Comparing the energetic positions of the dangling bonds, the calculation revealed that the carbon dangling bond is about 1.32 eV lower in energy than that of silicon in the 3Cterminated surface. Again, the presence of these dangling bond states makes both polar and non-polar surfaces show metallic behaviour, as indicated in their respective dispersion curves.

Physical Review B, Jun 27, 2013

We report first-principles calculations that reveal atomic and electronic structures of interface... more We report first-principles calculations that reveal atomic and electronic structures of interfaces consisting of Si(110) face and 3C-SiC (111) face in which the lattices match apparently but the atomic densities in both sides are different. We find two distinct interface structures in the total-energy difference of 4-5 meV perÅ 2 for both the Si-Si interface and the Si-C interface: The interface of sparse Si(110) and dense SiC(111) exhibits bistability. We find that the stable and metastable structures are associated with vacant channels along a particular direction which are stabilized by the existence of over-coordinated atoms (floating bonds). We reveal that the coexistence of the floating bonds and the dangling bonds (under-coordinated atoms) and then the electron transfer from the dangling-to the floating bonds are the microscopic mechanism of the stabilization of the interface. We also find that atomic scale undulation mainly confined in the Si region also exists to stabilize the interface. The calculated interface energies show that the Si-Si interface is energetically favorable compared with the Si-C interface. Calculated energy bands exhibit semiconducting characteristics for all the stable and metastable interfaces.

arXiv (Cornell University), Jul 21, 2021

Plasticity in body centered cubic (bcc) refractory metals are largely due to the stress tensor in... more Plasticity in body centered cubic (bcc) refractory metals are largely due to the stress tensor induced either by solute or thermal activation. The mechanism of the solute atom(s) residence causes instability in such metals. Earlier research have considered the mechanism of oxygen (O) or carbon (C) in tungsten (W), even though the major component of the environment is nitrogen (N). In this article, the density functional theory (DFT) was employed to investigate the

The International Promotion Agency of Culture Technology, May 1, 2021

Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2011

structures of 3C-SiC(111)/Si(110) interfaces

A Thesis submitted to the School of Graduate Studiesin Partial Fulfillment of the Requirements fo... more A Thesis submitted to the School of Graduate Studiesin Partial Fulfillment of the Requirements for the Award of Masters in Business Administration(Finance Option) , 2015

Radiation protection dosimetry, 2021

The protection of man and his environment from undue exposure from radio frequency electromagneti... more The protection of man and his environment from undue exposure from radio frequency electromagnetic field requires identification of the location where exposures are likely to be higher than safe levels established by international safety standards. A wideband measurement with a spectrum analyzer and a log-periodic antenna in conjunction with the three-point spatial average method was used. The results ranged from 16.21 to 2907.00 mVm-1 and complied with a maximum of 1.08% of the ICNIRP reference level. Private frequency modulation (FM) sources were identified as the major source of exposure to the public with a mean value of 337.70 ± 133.70 mVm-1 against 122.30 ± 36.47 mVm-1 for the public FM transmitters. Even though the result was lower than a workplace assessment, it was, however, higher than similar works conducted in Africa and Palestine. Finally, four sensitive locations were identified for further research work.

Journal of Materials Science Research, 2020

Zeolites based on the numerous applications can be utilised in providing solutions to some challe... more Zeolites based on the numerous applications can be utilised in providing solutions to some challenges of our world. With the ability to store thermal energy as chemical potential, zeolites are able to store thermal energy for long periods. This can occur with very minimal loss of energy and indefinitely unless the zeolite comes into contact with an adsorbate. The use of zeolite - water as adsorbent - adsorbate pair in thermal energy storage (TES) applications have been studied and have shown good results. However, the cost of zeolites synthesized from reagents continue to hamper the effective use of this adsorbent. Zeolite A was synthesized from kaolin from Wassa in Ghana based on a modified synthesis route. The adsorption properties of the zeolite utilising a designed and fabricated TES system using amounts of 100g, 200g, 300g, 400g and 500g of zeolite with a 1:1.5 ratio to water. Adsorption isosteres were plotted with the temperature and pressure values recorded and results showed...

3C-SiC(111) on Si (110) surface with a particular alignment of the two planes offers almost perfe... more 3C-SiC(111) on Si (110) surface with a particular alignment of the two planes offers almost perfect fake matching of the lattice periodicity, albeit dense 3C-SiC and sparse Si in spite of the large lattice mismatch ∼20% between them. We here report total-energy electronic-structure calculations based on real-space density functional theory (RSDFT), which elucidate new reconstruction mechanism of dense 3C-SiC(111) on sparse Si(110) surface with the relaxed superstructures displaying undulation near the interface. We explore a variety of candidate interface structures and reach two distinctive types called type I and II which show bistability at the interface. We define interface energy as the energy difference between the total energy of the interface structure and the energy of the bulk constituent atoms. In type I, the interface energy where the silicon faces meet each other (silicon-silicon) is calculated as 9.571 eV/cell or 0.117 eV/Å2 whereas the interface energy where the silic...

Molecules, 2020

Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to po... more Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl2. The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl2 molecule adsorbed spontaneously on the Fullerene or nanocages and endoth...

Surfaces and Interfaces, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Results in Materials, 2019

Ab initio calculations based on density functional theory was carried out to study the electronic... more Ab initio calculations based on density functional theory was carried out to study the electronic properties of (3,3), (4,2), (5,2) and (6,0) boron nitride nanotubes when interacting with nickel, titanium, palladium and gold metal atoms. These interactions occurred via adsorption, intercalation, nitrogen substitutional doping and boron substitutional doping. The wide band gaps intrinsic to the pristine boron nitride nanotubes were successfully tuned upon interaction with the metal atoms irrespective of the type of interactions. However, for most of the interactions that occurred via intercalation and nitrogen substitutional doping, the boron nitride nanotube was found to possess semi-metallic properties. More states were added in the density of states upon interaction in which the d orbital of the transition metal atoms was found to be the major contributor to the increase in density of states.

Results in Physics, 2019

Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2... more Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2), (6,0) and (5,1) carbon nanotubes were studied using first principles calculations. The Fermi energy levels of the carbon nanotubes studied were found to increase during interactions with the transition metal atoms. Amongst the four metals, gold atom was found to have an enhanced interaction with the nanotubes transforming from semiconducting to a conducting tube. Titanium was also found to show similar characteristics to gold only when the atom was placed in the middle of the carbon nanotubes. Nickel and palladium atoms interactions did not affect much the electronic properties of the carbon nanotubes, with some slight changes in the electronic properties at some specific sites of the nanotubes. It is proposed from this study that, the carbon nanotube-metal interactions could be used as a guide to shed light on the electronic properties of such materials which could become promising engineering materials and revolutionize the electronic industry.

Radiation Protection Dosimetry, 2018

The analysis of channel power and electric field strength at various locations from mobile base s... more The analysis of channel power and electric field strength at various locations from mobile base stations using power sensor, spectrum analyzer and log-periodic antenna revealed maximum potential exposure between the range of 61.1 and 254.7 m. Generally, the potential exposure values ranged from 0.0717 to 0.8950 mW m-2 with a maximum deviation of 22.22%. GSM900 was found to be more pronounced than GSM1800 and UMTS2100. Though the results complied with ICNIRP reference levels with a wide margin of 0.01%, it was higher than some previous work and South African mean value of 0.16 mW m-2, agreed with similar work elsewhere but lower than a global average value of 0.730 mW m-2.

Radiation Protection Dosimetry, 2018

This paper describes an effort to respond to the suggestion in World Health Organization (WHO) re... more This paper describes an effort to respond to the suggestion in World Health Organization (WHO) research agenda to better quantify potential exposure levels from a range of radiofrequency (RF) sources at 200 public access locations in Ghana. Wide-band measurements were performed-with a spectrum analyser and a log-periodic antenna using three-point spatial averaging method. The overall results represented a maximum of 0.19% of the ICNIRP reference levels for public exposure. These results were generally lower than found in some previous but were 58% (2.0 dB) greater, than found in similar work conducted in the USA. Major contributing sources of RF fields were identified to be FM broadcast and mobile base station sites. Three locations with the greatest measured RF fields could represent potential areas for epidemiological studies.

Cogent Engineering, 2016

This work is licensed under a Creative Commons Attribution 4.0 International License Newcastle Un... more This work is licensed under a Creative Commons Attribution 4.0 International License Newcastle University ePrints-eprint.ncl.ac.uk Yaya A, Ewels CP, Efavi JK, Agyei-Tuffour B, Kan-Dapaah K, Onwona-Agyeman B, Abavare EKK, Hassanali A, Briddon PR. A study of polybromide chain formation using carbon nanomaterials via density functional theory approach. Cogent Engineering 2016, 3(1), 1261509.

physica status solidi (b), 2014

We perform total-energy electronic-structure calculations based on density functional theory in t... more We perform total-energy electronic-structure calculations based on density functional theory in the framework of the local density approximation to discuss the surface energy convergence of non-polar Si(110)-and polar 3C-SiC(111)-terminated surfaces. Whilst the non-polar surface show monotonic convergence in surface energy, the polar surface is oscillatory. The relaxations of 3C-SiC(111)-and α-6H(0001)-terminated surfaces are very similar; however, the two structures are electronically different due to differences in the relative energetic positions of their dangling bonds. Comparing the energetic positions of the dangling bonds, the calculation revealed that the carbon dangling bond is about 1.32 eV lower in energy than that of silicon in the 3Cterminated surface. Again, the presence of these dangling bond states makes both polar and non-polar surfaces show metallic behaviour, as indicated in their respective dispersion curves.