Article
Chemistry, Physical
Ramiz Zulkharnay, Neil L. Allan, Paul W. May
Summary: Surface modification of diamond with the addition of metals or other electropositive adsorbates can result in negative electron affinity (NEA). Scandium adsorption on diamond is energetically favorable, especially on the oxygenated surface. Most stable scandium adsorption configurations possess NEA, with the highest NEA value found on the oxygenated diamond surface.
Article
Chemistry, Physical
Sami Ullah, Gary Wan, Christos Kouzios, Cameron Woodgate, Mattia Cattelan, Neil Fox
Summary: Wideband gap diamond-based materials are being studied for energy harvesting and quantum applications, with Sn identified as a potential candidate for negative electron affinity on diamond surfaces. Experimental results show that SnO termination on diamond surfaces can lead to NEA and reduce the work function, making it a stable option for device applications. The intercalation of Li with SnO planes enhances the stability of LiO termination on diamond surfaces and reduces the work function even further, showing potential for more efficient diamond surface terminations.
APPLIED SURFACE SCIENCE
(2021)
Article
Physics, Applied
Yu Yang, Franz A. Koeck, Xingye Wang, Robert J. Nemanich
Summary: A thin layer of Al2O3 was used as an interface layer to increase the hole mobility of diamond, reduce Coulomb scattering, and improve material performance.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Zhaolong Sun, Gao Nan
Summary: The structural and electronic properties of boron and nitrogen coterminated diamond surface with various B/N ratios were investigated. The results showed that the diamond surface characteristics changed with increasing B/N ratio and B and N related surface states were introduced into the bandgap region of bulk diamond.
DIAMOND AND RELATED MATERIALS
(2022)
Article
Engineering, Mechanical
Hyeontaek Oh, Euihyun Jo, Hye Woon Jang, Hyeongjun Jung, Sang Hyeok Park, A. Young Kim, Jong Hoon Jung, Ji Ho Youk, Minbaek Lee
Summary: A hard coating material was synthesized to enhance the electrical and mechanical properties of TENGs. This hard coating material exhibited superior performance in a large-scale demonstration.
EXTREME MECHANICS LETTERS
(2022)
Article
Chemistry, Physical
Egor Ukraintsev, Alexander Kromka, Wiebke Janssen, Ken Haenen, Daisuke Takeuchi, Petr Babor, Bohuslav Rezek
Summary: By surface treatment using electrochemically grown polypyrrole, the secondary-electron emission and photoelectron emission from boron-doped diamond are enhanced, surpassing the electron emission intensity from the hydrogen-terminated surface with negative electron affinity. This enhancement is stable for at least one month in air and persists in vacuum even after thermal annealing.
Article
Materials Science, Multidisciplinary
Zhaolong Sun, Bo Cui, Pingping Liang, Qimeng Liu, Nan Gao, Hongdong Li
Summary: This study explores the potential of hafnium (Hf) terminated diamond surfaces in achieving negative electron affinity (NEA). By using swarm-intelligence structural search and first-principles calculations, the researchers found that Hf-terminated diamond surfaces exhibit stable NEA properties and high thermal stability, making them promising candidate materials for electron emission applications.
DIAMOND AND RELATED MATERIALS
(2024)
Article
Chemistry, Physical
Pengfei Qiao, Kang Liu, Sen Zhang, Zhenhua Su, Bing Dai, Jiecai Han, Jiaqi Zhu
Summary: The energy band diagram of the Si-treated diamond surface was investigated experimentally, which showed similarities to a hydrogen-terminated surface. This may be the origin of the reported C-Si diamond two-dimensional hole gas channel.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Shivam Kansara, Sanjeev K. Gupta, Yogesh Sonvane, P. N. Gajjar
Summary: This study investigated the properties of palladium (Pd) and platinum (Pt) nanowires as hydrogen storage materials using density functional theory (DFT), revealing strong hydrogen adsorption capabilities on both Pd and Pt nanowires. The hydrogen gravimetric storage capacity of Pd MNWs was found to be higher than that of Pt NWs.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Chaiyawat Kaewmeechai, Yongyut Laosiritaworn, Atchara Punya Jaroenjittichai
Summary: Cs2BX6 double halide perovskites exhibit remarkable preferences such as low-cost and simple processability, tunable bandgaps, large-absorption coefficient, high mobility and fast respond under excitation. The band alignment of Cs2BX6 is found to be type-I, regardless of whether they were grouped by the same transition-metal or same halide. The valence band shift is more influential cause of bandgap variation in Ti-compounds than the change in conduction band.
RESULTS IN PHYSICS
(2022)
Article
Physics, Condensed Matter
Jieru Li, Daniel Niesner, Thomas Fauster
Summary: Thick adamantane films on Cu(111) demonstrate a negative electron affinity and a band gap, while thinner films exhibit close-to-zero electron affinity and a shift in valence bands towards the Fermi energy due to charge transfer from Cu 3d bands.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Physics, Applied
N. L. Asfandiarov, M. V. Muftakhov, A. M. Safronov, R. V. Galeev, S. A. Pshenichnyuk
Summary: Electron attachment to 1-chloronaphthalene molecules was investigated using dissociative electron attachment spectroscopy. The dominant channel for molecular ion decay was found to be the formation of Cl- ions at three resonances. [M-H](-) and [M-Cl](-) ions were also observed, but with significantly lower formation cross sections compared to Cl- ions. Calculations predicted the presence of six stable anionic structures, where the chlorine anion is coordinated with the neutral residue via noncovalent H-Cl--H bonds. The most stable structure showed an electron affinity in agreement with experimental data. These findings are consistent with previous studies on electron attachment to bromine-substituted biphenyls, naphthalenes, and anthracenes, indicating the existence of anionic structures with non-covalent H-Hal-H bonds.
Article
Electrochemistry
Andrea Stefani, Walter Giurlani, Marco Bonechi, Andrea Marchetti, Giovanni Preda, Dario Pasini, Massimo Innocenti, Claudio Fontanesi
Summary: The electroreduction mechanism of 1-Br-2-naphtol, 1-I-2-naphtol, and two inherently chiral BINOL derivatives was characterized using integrated electrochemical and theoretical approaches. Experimental characterization based on cyclic voltammetry measurements indicated carbon-halogen bond dissociation with the formation of insoluble final products. The reduction mechanism was further analyzed at a molecular level through DFT calculations, revealing a stepwise dissociation of the carbon-halogen bond following electron uptake.
Article
Polymer Science
Adam Mizera, Alina T. Dubis, Andrzej Lapinski
Summary: The electronic and vibrational structures of pyrrole oligomer and its derivatives were investigated using Density Functional Theory (DFT) and Time-dependent DFT (TD-DFT) computations. The influence of substituent groups on the optical and electronic properties of polypyrrole and polypyrrole derivatives, as well as the molecular structure and frontier molecular orbitals of neutral and ionized oligomers, were analyzed.
Article
Physics, Condensed Matter
Sun Zhaolong, Gao Nan
Summary: In this study, the structural stabilities and electronic properties of boron (B)–nitrogen (N) co-terminated diamond (110) surface were investigated using first-principles calculations. It was found that the H/F mixed (H/F = 1.0) adsorption surface was dynamically and thermally stable, and exhibited no surface spin noise or surface-related state. Additionally, it had a positive electron affinity of 1.11 eV, making it a promising candidate for NV-based quantum sensors.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Review
Chemistry, Physical
Michael C. James, Fabian Fogarty, Ramiz Zulkharnay, Neil A. Fox, Paul W. May
Summary: Surface functionalisation of diamond can produce negative electron affinity (NEA), where the hydrogen termination, a well-known producer of NEA, can be removed by high temperatures above 700 degrees C. The review article provides an overview of thermionic emission, potential applications of diamond-based thermionic energy converters, and different surface termination schemes for NEA on diamond. Discussion on the relative merits of various NEA surfaces developed computationally and experimentally for thermionic devices is also included.
Article
Chemistry, Physical
Sergio Conejeros, M. Zamir Othman, Alex Croot, Judy N. Hart, Kane M. O'Donnell, Paul W. May, Neil L. Allan
Summary: This study reports the energetics and electronic properties of Li and N co-doped diamond, with emphasis on the behavior of LiCN4 clusters as potential shallow donors. The results suggest that substitutional Li, when combined with N, may stabilize the LiCN4 cluster to exhibit shallow donor behavior.
Article
Chemistry, Physical
Harry W. T. Morgan, Harry J. Stroud, Neil L. Allan
Summary: The study reveals that hydride ion conductivity is closely related to hydride-oxide disorder, and the diffusion rate of hydride ions is affected by a reduction in A-site cation size. Pressure can change the dominant migration pathway, while the local structural flexibility along migration pathways is determined by dimensionality and ionic size.
CHEMISTRY OF MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Ramiz Zulkharnay, Oral Ualibek, Olzat Toktarbaiuly, Paul W. May
Summary: Graphene-based materials, such as graphene oxide (GO) and chemically reduced graphene oxide (rGO) thin films, were fabricated using electrostatic spray deposition and then compared in terms of water contact angle measurements. The results show that the rGO films exhibited higher hydrophobicity compared to the GO films, indicating the removal of oxygen-containing functional groups during the reduction process enhanced their water-repellent properties.
BULLETIN OF MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Mat Tolladay, Fabrizio Scarpa, Neil L. Allan
Summary: Different computational methods were compared to determine the force between carbon atoms and their ability to accurately simulate carbon-carbon bonds breaking due to mechanical strain. DFTB3 was found to give results similar to first-principles methods, highlighting the importance of electronic behavior for determining the mechanical strength of materials at atomic-length scales.
Article
Physics, Condensed Matter
Michael C. James, Mattia Cattelan, Neil A. Fox, Rui F. Silva, Ricardo M. Silva, Paul W. May
Summary: Three different methods were used to deposit aluminum onto boron-doped diamond surfaces in order to create a thermally stable surface with low work function and negative electron affinity. The surface structures and properties were investigated after annealing at different temperatures, showing that the Al + O surfaces remained stable up to 800 degrees C with electron affinity values generally between 0.0 and -1.0 eV and work function generally around 4.5 +/- 0.5 eV. These values are in agreement with computer simulations.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2021)
Article
Geochemistry & Geophysics
Karen Valencia, Aldemar De Moya, Guillaume Morard, Neil L. Allan, Carlos Pinilla
Summary: In this study, density functional theory calculations were used to determine the electronic structure, acoustic, and thermal properties of Fe3S at high pressures. The results showed a magnetic transition from ferromagnetic to non-magnetic state at high pressures, leading to changes in the physical properties of Fe3S. The thermal expansion, heat capacity, and other parameters were also estimated at high pressures. The possible implications of these findings for the Earth's inner core and the core-mantle boundary of Mars were discussed.
AMERICAN MINERALOGIST
(2022)
Article
Chemistry, Multidisciplinary
Markos Poulos, Stefanos Giaremis, Joseph Kioseoglou, John Arvanitidis, Dimitris Christofilos, Sotirios Ves, Markus P. Hehlen, Neil L. Allan, Chris E. Mohn, Konstantinos Papagelis
Summary: Inelastic neutron scattering measurements of Y3Al5O12 were presented, with comparison of neutron-weighted phonon density-of-states and optical phonon frequencies to atomistic calculations within the Quasi-Harmonic Approximation. The phonon-related thermodynamic and elastic properties calculated within the QHA showed excellent agreement with experimental data.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
Article
Chemistry, Physical
Ramiz Zulkharnay, Neil L. Allan, Paul W. May
Summary: Surface modification of diamond with the addition of metals or other electropositive adsorbates can result in negative electron affinity (NEA). Scandium adsorption on diamond is energetically favorable, especially on the oxygenated surface. Most stable scandium adsorption configurations possess NEA, with the highest NEA value found on the oxygenated diamond surface.
Article
Chemistry, Multidisciplinary
Gufei Zhang, Ramiz Zulkharnay, Xiaoxing Ke, Meiyong Liao, Liwang Liu, Yujie Guo, Yejun Li, Horst-Guenter Rubahn, Victor V. Moshchalkov, Paul W. May
Summary: By investigating electrical transport phenomena, it is found that diamond nanorings (DNRs) transform into bosonic semiconductors upon the formation of Cooper pairs, exhibiting a sharp resistance increase and a giant negative magnetoresistance. In contrast, diamond half-loops (DHLs) undergo a metal-superconductor transition. This finding reveals the potential use of DNRs in manipulating Cooper pairs in superconducting quantum devices.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Ramiz Zulkharnay, Paul W. May
Summary: In situ observation reveals the large negative electron affinity (NEA) of scandium-terminated diamond, which shows high thermal stability up to 900 degrees C. The NEA values of -1.45 eV and -1.13 eV for diamond (100) and (111) surfaces, respectively, make them the highest measured NEA for a metal adsorbed onto bare diamond so far. This study provides insights into tuning the adsorbate-diamond interface and expands the material options for effective electron-emission applications.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Biochemical Research Methods
Joe Crossley-Lewis, Josh Dunn, Corneliu Buda, Glenn J. Sunley, Alin M. Elena, Ilian T. Todorov, Chin W. Yong, David R. Glowacki, Adrian J. Mulholland, Neil L. Allan
Summary: Interactive molecular dynamics simulation in virtual reality (iMD-VR) is a promising technique in molecular science, with applications in materials science and heterogeneous catalysis. This study demonstrates the use of iMD-VR in investigating lithium fast ion conduction mechanisms and exploring diffusion within zeolites.
JOURNAL OF MOLECULAR GRAPHICS & MODELLING
(2023)
Article
Chemistry, Physical
A. Archer, H. R. Foxhall, N. L. Allan, J. R. W. Shearer, D. S. D. Gunn, J. H. Harding, I. T. Todorov, K. P. Travis, J. A. Purton
Summary: This study reports molecular dynamics simulations of radiation damage cascades in different compounds, revealing the characteristics of increased volume and transition to amorphous structure in the titanium zirconate, while in the solid solution, increasing zirconium concentration can delay the onset of amorphization.
MOLECULAR SIMULATION
(2021)
