Article
Materials Science, Ceramics
Qiang Zheng, Tiantian Gong, Fengyi Wu, Nasir Ilyas, Zhenghu Huang, Yanzhuo Li, Yong Luo, Hao Fu
Summary: A series of 6BaO center dot 1CaO center dot 2Al(2)O(3) + x wt% Sc2O3 impregnants were synthesized and impregnated into porous tungsten matrices, resulting in multi-phase structures. The addition of 3 wt% Sc2O3 significantly improved the electron emission performance of the cathodes. The relationship between emission properties and phase concentration was analyzed, showing a deterioration with increasing Sc2O3 content due to higher concentration of non-active BaAl2O4 phase.
CERAMICS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Shu-han Li, Jian-quan Li
Summary: The characteristics of the virtual cathode are linearly related to the filament temperature of the emissive probe, with the depth and spatial scale of the virtual cathode increasing as the filament temperature increases. Numerical simulation results are in good agreement with theoretical calculations.
Article
Materials Science, Multidisciplinary
Wei Liang, Songhe Meng, Qingxuan Zeng, Xinxing Han
Summary: This study investigated the effect of emission characteristics on thermionic emission cooling (TEC) using a W-La2O3 cathode at high temperatures. The results showed that the TEC effect and cathode current density increased nonlinearly with temperature. The flow patterns of emission current under operating conditions determined the magnitude and trend of the TEC effect.
Article
Engineering, Electrical & Electronic
Keval Gadani, K. N. Rathod, Davit Dhruv, V. G. Shrimali, Bhargav Rajyaguru, Joyce Joseph, A. D. Joshi, D. D. Pandya, K. Asokan, P. S. Solanki, N. A. Shah
Summary: This study investigates the structural, microstructural, resistive switching characteristics, and charge conduction mechanisms of Y0.95Ca0.05MnO3 (YCMO) manganite films grown on Nb:SrTiO3 substrates irradiated with 100 MeV O(+7) swift heavy ions. The observed resistive switching behavior is attributed to changes in the depletion region, movement of oxygen vacancies, and tunneling processes at the interface barriers between YCMO and SNTO. The films exhibit endurance and retention behaviors, indicating their reproducibility, dynamic stability, and reliability as non-volatile memory devices.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Engineering, Electrical & Electronic
Wang Xingqi, Wang Xiaoxia, Luo Jirun, Qi Shikai, Li Yun
Summary: By doping scandia into Y-Gd-Hf-O cathodes, the anti-electron bombardment ability has been significantly improved. The cathode can maintain a high emitting current after long-term electron bombardment at high temperatures, indicating its excellent performance. The formation of a cermet structure and a n-type semiconductor layer on the cathode surface further enhance its thermionic emission capabilities.
JOURNAL OF ELECTRONICS & INFORMATION TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Mujan N. Seif, Qunfei Zhou, Xiaotao Liu, T. John Balk, Matthew J. Beck
Summary: This article discusses the increasing demand for cathodes with enhanced emission properties and the research on Sc-containing cathodes. Despite the superior emission properties of scandate cathodes, commercial integration still faces challenges.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Materials Science, Multidisciplinary
Jian-quan Li, Xin-yao Xie, Shu-han Li, Qing-he Zhang
Summary: This study compares different theories for estimating the filament temperature of an emissive probe with a two-color infrared pyrometer to evaluate their temperature acquisition capability. The results show that the Stefan-Boltzmann law provides reliable temperature and virtual cathode calculations, while the Richardson-Dushman formula struggles to obtain accurate spatial size of the virtual cathode.
Article
Materials Science, Multidisciplinary
Antonio M. Mantica, Michael J. Detisch, T. John Balk
Summary: Characterizing the work function of emitting surfaces is an important aspect of thermionic emission research. Materials with lower work functions can thermionically emit higher current densities at lower temperatures, leading to longer lifetimes for vacuum electron devices utilizing thermionic emitters. The Kelvin probe system is commonly used to measure a material's work function by measuring contact potential difference. However, the traditional application of this technique fails to produce meaningful results when the sample under inspection and the Kelvin probe are in thermal disequilibrium. This paper outlines a modified application of the Kelvin probe system that allows for meaningful measurements of asymmetric contact potential difference, enabling the determination of work function values for high temperature samples, including those relevant to thermionic emitters (>1000 degrees C).
Article
Nanoscience & Nanotechnology
Jungang Heo, Youngboo Cho, Hyeonseung Ji, Min-Hwi Kim, Jong-Ho Lee, Jung-Kyu Lee, Sungjun Kim
Summary: In this study, we compare the resistive switching characteristics of Ti/ZrOX/TiN and Ti/ZrOX/HfAlOX/TiN devices. The bilayer structure of the ZrOX-based device leads to reduced power consumption and higher on/off ratio. The transport mechanism of the Ti/ZrOX/HfAlOX/TiN device is clarified using 1/f noise measurement technique. Additionally, the suitability of the Ti/ZrOX/HfOX/TiN device as a neuromorphic device is assessed through simulation testing.
Article
Chemistry, Analytical
Golezar Gilanizadehdizaj, Debes Bhattacharyya, Jonathan Stringer, Kean Aw
Summary: This article investigates the conduction mechanisms in sensors made from a composite film consisting of reduced graphene oxide (rGO) structures filled with a silicone elastomer. These soft and flexible sensors are suitable for wearable applications. The study reveals that the sensors exhibit three conducting regions with different mechanisms, including Schottky/thermionic emission and Ohmic conduction.
Article
Energy & Fuels
A. Urbaniak, A. Czudek, A. Eslam, R. Wuerz, M. Igalson
Summary: This work focuses on interpreting defect spectroscopy results in CIGS solar cells and provides a comprehensive analysis of experimental data. It discusses the challenges in interpreting the observed signals and the co-existing physical models in the CIGS community. The main contribution is the introduction of a new model that describes the results of admittance spectroscopy, explaining the characteristic features of the measured signals and their dependence on hole concentration and grain boundary barriers.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Materials Science, Multidisciplinary
Rousan Debbarma, Ngoc Hoang Lan Nguyen, Vikas Berry
Summary: Defects in two-dimensional nanomaterials play a crucial role in their electrical behavior and need to be carefully considered. Some of the conduction mechanisms discussed include thermally activated conduction, nearest neighbor hopping, Efros-Shklovskii variable range hopping, and Mott variable range hopping.
APPLIED MATERIALS TODAY
(2021)
Article
Chemistry, Physical
Eduily Benvindo Vaz Freire, Anderson Lira de Sales Santos, Giordano Frederico da Cunha Bispo, Maria de Andrade Gomes, Zelia Soares Macedo, Robert A. Jackson, Mario Ernesto Giroldo Valerio
Summary: Cadmium silicates, especially the CdSiO3 phase, exhibit persistent luminescence properties, with the CdO pseudo-Schottky defects causing CdO deficiency and formation of Si-Si bonds responsible for the intrinsic luminescence. The presence of additional cadmium silicate phases, such as Cd2SiO4 or Cd3SiO5, is also linked to the CdO deficiency induced by the defects.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Jianke Liu, Xingyu Luo, Wenbin Cao
Summary: In this study, ZnO linear resistors were mixed with MgO, TiO2, Al2O3, and different concentrations of Sc2O3 to enhance electrical characteristics. The effects of Sc2O3 doping on micro-morphology and electrical properties were investigated. Through XRD, EDS, and SEM, it was found that Sc2O3 doping inhibited the growth of ZnO grains. The doping resulted in improved linear performance, increased resistivity, and affected dielectric properties. The ZnO linear resistors showed excellent performance with appropriate Sc2O3 doping.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Physics, Fluids & Plasmas
G. R. Johnson, M. D. Campanell
Summary: Recent simulations of planar sheaths with strong electron emission show transitions from SCL to inverse sheaths. With increased emitted flux, trapped ion cloud expands and causes thermionic current beyond saturation limit. For fixed emission flux and swept bias, trapped ions lead to large thermionic current escape below plasma potential.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Review
Chemistry, Multidisciplinary
Livia Giordano, Karthik Akkiraju, Ryan Jacobs, Daniele Vivona, Dane Morgan, Yang Shao-Horn
Summary: The transition from fossil fuels to renewable energy requires the development of efficient and cost-effective energy storage technologies. Utilizing the energy of intermittent renewable sources, such as solar and wind, to perform (electro)catalytic reactions and generate fuels can be a promising approach. However, current catalysts heavily rely on expensive or rare elements, which calls for the discovery and development of materials containing earth-abundant elements. Descriptors that correlate fundamental physical properties, such as electronic structure, with catalytic activity have proven to be a powerful tool in advancing the discovery and design of new catalyst materials. The energy of the oxygen 2p states has been proposed as a descriptor for oxide properties and catalytic activity.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Lane E. Schultz, Benjamin Afflerbach, Izabela Szlufarska, Dane Morgan
Summary: The study explores the use of characteristic temperatures from molecular dynamics to predict metallic Glass Forming Ability (GFA) through machine learning models. Regression models trained on 21 compositions showed weak correlation between model predictions and target values. Decision tree-based methods were used for binary GFA classification, achieving maximum F1 score for the precision-recall with Good GFA as positive class.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Jun Young Kim, Lukasz Gelczuk, Maciej P. Polak, Daria Hlushchenko, Dane Morgan, Robert Kudrawiec, Izabela Szlufarska
Summary: This study investigates the formation energies and charge transition levels of defects in two-dimensional transition metal dichalcogenides (TMDs) through a combination of experimental and computational approaches. The reduction of TMDs to two dimensions is found to significantly impact defect properties, potentially explaining differences in optical properties observed in differently synthesized 2D TMDs.
NPJ 2D MATERIALS AND APPLICATIONS
(2022)
Article
Physics, Applied
Ajay Annamareddy, Bu Wang, Paul M. M. Voyles, Dane Morgan
Summary: Short-timescale atomic rearrangements play a crucial role in the kinetics of glasses, with significant movement of one atom dominating the rearrangements while others experience only minor relaxation. The rates and directions of these rearrangements are influenced by the distribution of activation barriers for individual atoms and how these distributions vary in the system.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Jingrui Wei, Ben Blaiszik, Aristana Scourtas, Dane Morgan, Paul M. Voyles
Summary: The information content of atomic-resolution STEM images can be summarized by a few parameters, with column position being the most significant. Neural networks have been used to automatically locate atomic columns in STEM images, resulting in numerous NN models and training datasets. In this study, a benchmark dataset of simulated and experimental STEM images was developed to evaluate the performance of recent NN models for atom location. The models showed high performance for images of varying quality and crystal lattices. However, they performed poorly for images outside the training data, such as interfaces with large difference in background intensity. The benchmark dataset and models are available through the Foundry service.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Jun Meng, Mehrdad Abbasi, Yutao Dong, Corey Carlos, Xudong Wang, Jinwoo Hwang, Dane Morgan
Summary: This study characterized the structural and electronic properties of a-TiO2 thin films grown on Si by ALD, revealing the medium-range ordering in the film and establishing a realistic atomic model. Additionally, an improved multi-objective optimization package, StructOpt, was provided for structure determination of complex materials.
Article
Nanoscience & Nanotechnology
Mehrdad Abbasi, Yutao Dong, Jun Meng, Dane Morgan, Xudong Wang, Jinwoo Hwang
Summary: The evolution of medium range ordering (MRO) and crystallization behavior of amorphous TiO2 films grown by atomic layer deposition were investigated using in situ four-dimensional scanning transmission electron microscopy. The degree of MRO increases with temperature and reaches the maximum when crystallization starts to occur. In addition, post-annealing only develops a small portion of MRO into crystal nuclei, while the remaining MRO regions undergo structural relaxation. Crystallographic defects within crystal phases were observed, which may affect the corrosion resistance of the film. Understanding and controlling MRO is important for optimizing ALD-grown amorphous films for future functional devices and renewable energy applications.
Article
Engineering, Electrical & Electronic
Lin Lin, Ryan Jacobs, Dane Morgan, John Booske
Summary: Recent experiments on the perovskite oxide SrVO3 demonstrate the potential for achieving low work functions using surface dipoles on polar perovskites. Additional density functional theory calculations suggest that many other perovskites, including BaMoO3, may also exhibit low work function. In this study, the thermionic emission behavior of BaMoO3 was investigated, showing a temperature limited emission current density that increases and saturates with increasing voltage. The material exhibits an overall effective work function comparable to LaB6, but higher than the lowest work function predicted by DFT. The discrepancy is attributed to patch field effects caused by nanoscale features on individual surface facets. BaMoO3 also exhibits some instability at high temperatures, but shows comparable emission behavior to LaB6 at temperatures below 1200 degrees C, making it a potential vacuum electron source for applications such as electron microscopes and electron beam writers.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Dongzheng Chen, Ryan Jacobs, Dane Morgan, John Booske
Summary: In the study of thermionic electron emission, the shape of the Miram curve knee, which represents the transition between the exponential region and the saturated emission regions, plays a crucial role in evaluating the quality of thermionic vacuum cathodes. This research provides a comprehensive understanding of the physical factors, including the space charge effect and the patch field effect, that determine the shape of the knee. By using a model system with a periodic, equal-width striped work function distribution, the study illustrates how these physical effects restrict the emission current density near the Miram curve knee. The results identify three key physical parameters that significantly impact the shape of the Miram curve, providing new insights for the design of thermionic cathodes in vacuum electronic devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Materials Science, Multidisciplinary
Jianqi Xi, Yeqi Shi, Vitaly Pronskikh, Frederique Pellemoine, Dane Morgan, Izabela Szlufarska
Summary: Using atomistic simulations, we investigated the behavior of helium bubbles in beryllium, focusing on their shape, stability, and diffusivity. We found that helium bubbles become unstable and change shape through plastic deformation when the helium-vacancy ratio exceeds 1.25. The dominant diffusion mechanism of helium bubbles changes from surface diffusion to volume diffusion at around 900 K. The results provide valuable insights into the microstructural evolution and properties of irradiated materials.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Multidisciplinary Sciences
Yutao Dong, Mehrdad Abbasi, Jun Meng, Lazarus German, Corey Carlos, Jun Li, Ziyi Zhang, Dane Morgan, Jinwoo Hwang, Xudong Wang
Summary: Amorphous titanium dioxide (TiO2) film coating by atomic layer deposition (ALD) is a promising strategy to extend the photoelectrode lifetime for solar fuel generation. In this work, it is revealed that residual chlorine (Cl) ligands are detrimental to the silicon (Si) photoanode lifetime. Post-ALD in-situ water treatment effectively improves the film stoichiometry and preserves the amorphous phase, leading to a substantially improved lifetime for the protected Si photoanode.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Ryan Jacobs, Priyam Patki, Matthew J. Lynch, Steven Chen, Dane Morgan, Kevin G. Field
Summary: Accurate quantification of nanoscale cavities in irradiated alloys is achieved using the Mask R-CNN model, which provides insights into alloy performance and swelling metrics. The model demonstrates good performance in terms of statistical and materials property-centric evaluations, enabling accurate assessments of swelling in alloys.
SCIENTIFIC REPORTS
(2023)
Review
Physics, Applied
Lin Lin, Ryan Jacobs, Tianyu Ma, Dongzheng Chen, John Booske, Dane Morgan
Summary: In this review, the authors define different aspects of the work function and discuss the role of electric fields in work-function measurement and interpretation. They review standard experimental approaches and computational tools for measuring and predicting work function, and explore the influence of materials chemistry and structure on work-function trends. The authors also discuss the role of work function in various applications and provide guidance for engineering work-function values.
PHYSICAL REVIEW APPLIED
(2023)
Article
Energy & Fuels
Xiu-Liang Lv, Patrick T. Sullivan, Wenjie Li, Hui-Chun Fu, Ryan Jacobs, Chih-Jung Chen, Dane Morgan, Song Jin, Dawei Feng
Summary: This study successfully synthesized an ionic liquid-mimicking catholyte for aqueous organic redox flow batteries (AORFBs) that demonstrated high performance in terms of stability, power, and energy density. The optimized catholyte showed robust cycling stability, high power density, and high energy density, paving the way for low-cost and scalable AORFBs.
Article
Chemistry, Multidisciplinary
Ziyi Zhang, Maciej P. Polak, Corey Carlos, Yutao Dong, Dane Morgan, Xudong Wang
Summary: Two-dimensional ferromagnetic materials with strong room-temperature ferromagnetism have been synthesized using an ionic layer epitaxy strategy. The ferromagnetic strength of the NiOOH nanosheets can be controlled by adjusting the surfactant monolayer density and annealing process, offering a promising pathway for achieving strong ferromagnetism in two-dimensional materials for spintronic applications.