Article
Physics, Applied
T. D. Gustafson, E. M. Golden, E. M. Scherrer, N. C. Giles, A. A. Grabar, S. A. Basun, D. R. Evans, J. E. Slagle, L. E. Halliburton
Summary: Electron paramagnetic resonance (EPR) is used to study photoinduced changes in the charge states of sulfur vacancies and Cu ions in tin hypothiodiphosphate. The research found that at low temperatures, exposure to light causes the transfer of electrons from Cu+ ions to sulfur vacancies to form Cu2+, while at high temperatures the sulfur vacancies release electrons back to Cu2+ ions.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Energy & Fuels
Guiyang Yu, Xin Zhou, Haitao Zhao, Wenxiang Zhang, Wenfu Yan, Gang Liu
Summary: The presence of metastable sulfur vacancies enhances the intrinsic H2 evolution behavior of semiconductors, potentially offering a new approach to design semiconductor photocatalysts that are less dependent on cocatalysts.
Article
Chemistry, Physical
Changyi Wu, Lei Sun, Jinchen Han
Summary: The effects of quantum size on the thermoelectric properties of 2D beta-bismuth were investigated using first principles and the Boltzmann transport equation. The results showed that the Seebeck coefficients decrease with increasing L/lambda ratio, while the electrical and thermal conductivity exhibit the opposite trend. It was also found that 2D bismuth with three or more layers has semimetal properties, and the electron affinity, ionization energy, and work function do not vary significantly with quantum size effects.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Changyi Wu, Lei Sun, Jinchen Han
Summary: The study investigates the influence of quantum size on the thermoelectric properties of 2D beta-bismuth. The results show that quantum size has a significant impact on the thermoelectric properties, especially when the L/lambda ratio is less than 0.1. The Seebeck coefficients of electrons and holes decrease as the L/lambda ratio increases, while the electrical and thermal conductivity show the opposite trend. Additionally, it is observed that 2D bismuth with three or more layers exhibits semimetal properties and a semiconductor-semimetal transition is observed in 2D bismuth.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Meng Li, Huaisuo Yao, Shunyu Yao, Gang Chen, Jingxue Sun
Summary: Lattice strain is an effective strategy for promoting photocatalytic activity. This study focuses on vacancy-induced strain, which can lead to tensile stress and adjust the energy band structure to enhance the interface charge transfer rate.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Guohui Li, Yuanyuan Sun, Xiaomin Hong, Wenling Lu, Wenli Chen, Yue Deng, Zhenfan Sun, Wei Sun
Summary: This study designed and synthesized an indium-doped SnS2 sample with a multi-level structure composed of 10-nm-thick ultrathin sheets. The hydrogen production on the doped sample is about twice as high as that on SnS2, attributed to the hierarchical structure and effective attraction of hydrogen ions by trivalent indium ions' negative charge.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Mengjuan Diao, Hui Li, Yanhui Sun, Ying Liang, Zhiyang Yu, Danil W. Boukhvalov, Zhipeng Huang, Chi Zhang
Summary: This study successfully improved the reverse saturable absorption of SnS2 by introducing defects through plasma treatment, with nanosheets treated with Ar plasma for 40 seconds showing a nearly 9-fold increase in nonlinear absorption coefficient compared to untreated samples. S vacancies introduced in-gap states, enhancing the excited-state absorption, while Sn defects had limited contribution to nonlinear absorption.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
Jing Wu, Wenda Zhong, Chenfan Yang, Wenli Xu, Rong Zhao, Hui Xiang, Qin Zhang, Xuanke Li, Nianjun Yang
Summary: Water electrolysis is a promising approach to produce green hydrogen, but the full utilization of electrocatalysts for promoting hydrogen evolution reaction (HER) is still challenging. In this study, a nonstoichiometric titanium sulfide/nickel sulfide (TiS2-x/NiS) hetero-catalyst was designed to induce high-density sulfur vacancies, resulting in excellent HER performance. The presence of sulfur vacancies regulates the electronic structure of active sites, leading to reduced energy barrier for water dissociation and optimized adsorption free energy for H* intermediates. This strategy provides a new way to design high-performance and cost-effective HER electrocatalysts in universal media.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Nanoscience & Nanotechnology
Xiaolan Xue, Hongwei Chen, Yan Xiong, Renpeng Chen, Minghang Jiang, Gao Fu, Zhonghua Xi, Xiao Li Zhang, Jing Ma, Weihai Fang, Zhong Jin
Summary: This study presents the synthesis of V-O-S-rich anatase-phase black TiO2-xSy nanoplatelets, with narrowed bandgap and enhanced light absorption, for nitrogen fixation to produce ammonia. Theoretical calculations reveal the synergistic effect of oxygen vacancies and sulfur dopants on visible-NIR light absorption and photoexcited carrier transfer/separation.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Physics, Applied
Pankaj Priyadarshi, Neophytos Neophytou
Summary: Monte Carlo statistical ray-tracing methods are commonly used for simulating carrier transport in nanostructured materials. A novel Monte Carlo ray-tracing algorithm is presented in this study, which is computationally more efficient compared to existing algorithms. The new method, a hybrid of the analytical Boltzmann transport equation and Monte Carlo, utilizes a reduced number of ray-tracing particles and avoids current statistical challenges. The algorithm demonstrates efficiency and accuracy in simulating nanostructures with defects, making it a more robust and user-friendly method for studying transport in nanostructured materials under low-field steady-state conditions.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Sang-il Kim, Joonho Bang, Jiwoo An, Seokown Hong, Geukchan Bang, Weon Ho Shin, TaeWan Kim, Kimoon Lee
Summary: The effect of Br substitution on enhancing the thermoelectric properties of n-type layered SnSe2 was investigated, showing an increase in electrical conductivity and power factor with higher Br content. The Seebeck coefficient decreased as Br content increased, leading to an enhanced power factor at room temperature. The density functional theory calculations supported the findings by showing increased valley degeneracy in the conduction band minimum with Br substitution.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Green & Sustainable Science & Technology
Taotao Qiang, Lu Chen, Yajuan Xia, Xiangtao Qin
Summary: A novel direct Z-scheme heterostructure photocatalyst MoS2/SnS2 was synthesized using a hydrothermal method, showing excellent photocatalytic performance in the reduction of Cr (VI) and degradation of organic dyes. By leveraging the heterojunction and sulfur vacancies, the MoS2/SnS2 photocatalyst achieved significantly enhanced photocatalytic efficiency.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Chemistry, Multidisciplinary
Lutz Baumgarten, Thomas Szyjka, Terence Mittmann, Andrei Gloskovskii, Christoph Schlueter, Thomas Mikolajick, Uwe Schroeder, Martina Mueller
Summary: The reliability of ferroelectric HfO2- and HZO-based memory devices is strongly influenced by the choice of electrode materials. Interface conditions, such as band alignment, defect formation, and doping, are recognized as decisive factors for device performance. Hard X-ray photoelectron spectroscopy reveals two opposite scenarios of band alignment in TiN/HZO/TiN and IrO2/HZO/IrO2, explaining the conditions for stable device performance and degradation. A key condition for the stability of ferroelectric devices is identified as the alignment of the charge neutrality level with the metallic Fermi level. Oxygen-deficient HfO2-based interfaces, where the Fermi level of the metal electrode is close to the conduction band of the ferroelectric insulator, can achieve stable device performance.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Riddhimoy Pathak, Debattam Sarkar, Kanishka Biswas
Summary: By co-doping Ag and Mg in SnTe, the TE performance can be significantly improved, enhancing the Seebeck coefficient and reducing thermal conductivity to achieve a high figure of merit at 865 K.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Bin Su, Zhanran Han, Yilin Jiang, Hua-Lu Zhuang, Jincheng Yu, Jun Pei, Haihua Hu, Jing-Wei Li, Yu-Xiao He, Bo-Ping Zhang, Jing-Feng Li
Summary: In this work, it is discovered that rare earth elements can effectively serve as dopants for SnSe, greatly improving the electrical transport properties of p-type polycrystalline SnSe. Particularly, significant enhancement in electrical conductivity and power factor is achieved by Na/Er co-doping at 873 K. The lattice thermal conductivity is reduced due to the presence of abundant defects (dislocations, stacking faults, and twin boundaries). As a result, a peak thermoelectric figure of merit ZT (2.1) as well as a high average ZT (0.77) are achieved in polycrystalline SnSe.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
V Haborets, K. Glukhov, J. Banys, Yu Vysochanskii
Summary: The family of phosphorus-containing chalcogenide materials can be extended by searching for new van der Waals compounds, with potential new properties predicted through DFT calculations. Substitution of elements and changes in the lattice structure have been shown to impact the electronic and phonon spectra of these compounds.
INTEGRATED FERROELECTRICS
(2021)
Article
Engineering, Electrical & Electronic
T. Babuka, O. O. Gomonnai, K. E. Glukhov, L. Yu Kharkhalis, A. Gomonnai, M. Makowska-Janusik
Summary: In this study, electronic and optical properties of the TlIn(S0.75Se0.25)(2) ferroelectric crystal were investigated using density functional theory. Four cases of sulfur atoms substitution by selenium were considered. Theoretical calculations on dielectric function, refractive index, and absorption coefficients were compared to experimental results for the first time based on band structure calculations.
INTEGRATED FERROELECTRICS
(2021)
Article
Physics, Applied
T. Babuka, O. O. Gomonnai, K. E. Glukhov, L. Yu. Kharkhalis, A. V. Gomonnai, M. Makowska-Janusik
Summary: The elastic and vibrational properties of TIInS2 and TlIn(S0.75Se0.25)(2) crystals were calculated using the DFT/PBE method with dispersion correction. The results are in good agreement with experimental data. Phonon energy anomalies in the TlIn(S0.75Se0.25)(2) crystal were also explained.
LOW TEMPERATURE PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
A. Kohutych, V Liubachko, V Hryts, Yu Shiposh, M. Kundria, M. Medulych, K. Glukhov, R. Yevych, Yu Vysochanskii
Summary: The temperature dependence of longitudinal hypersound velocity in CuInP2S6 ferrielectrics was investigated using Brillouin spectroscopy. It was found that the acoustic phonon branch exhibits pronounced softening in the paraelectric phase below T* (approximately 330K) and cooling to the first order phase transition temperature T-c (approximately 312K) into the ferrielectric phase. The softening is induced by the flexoelectric coupling of relaxational soft polar optical and acoustic branches, which is related to an inhomogeneously polarized state appearing between the paraelectric and ferrielectric phases. The anomalous thermal conductivity of the CuInP2S6 crystal near the ferrielectric transition also demonstrates a decrease in the group velocity of heat transferring phonons with cooling from T* to T-c.
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
(2022)
Article
Materials Science, Multidisciplinary
Anna N. Morozovska, Eugene A. Eliseev, Yulian M. Vysochanskii, Viktoria V. Khist, Dean R. Evans
Summary: Using the Landau-Ginzburg-Devonshire approach, the study investigates screening-induced phase transitions in core-shell ferroic nanoparticles of three different shapes: an oblate disk, a sphere, and a prolate needle. The results demonstrate that the screening length of the shell has a critical influence on the phase transitions and spontaneous polarization of the nanoparticle core. The tunable screening shell allows the control of the polar state and phase diagrams, which can be of great significance for nonvolatile memory cells.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
V. Liubachko, A. Oleaga, A. Salazar, A. Kohutych, A. Pogodin, Yu. Vysochanskii
Summary: The temperature anomalies of heat capacity and entropy in CuInP2S6 layered crystal at ferrielectric ordering can be explained by theoretical studies, which predict the appearance of a critical endpoint and a bicritical endpoint on the phase diagram. Therefore, the splitting of the heat capacity anomaly in Ag0.1Cu0.9InP2S6 mixed crystal can be interpreted as a transformation of the ferrielectric first-order phase transition observed in CuInP2S6 into a sequent paraelectric-ferrielectric second-order phase transition and an isostructural first-order transition with a sharp change of polarization in the ferrielectric phase.
LOW TEMPERATURE PHYSICS
(2023)
Article
Physics, Applied
Anna N. Morozovska, Eugene A. Eliseev, Mykola E. Yelisieiev, Yulian M. Vysochanskii, Dean R. Evans
Summary: Using the Landau-Ginzburg-Devonshire approach, the stress-induced transformations of polarization switching in CuInP2S6 nanoparticles of different shapes were studied. The semiconducting properties of the nanoparticles were modeled using a surface-charge layer with a small effective screening length due to the field effect. The results showed a strong and unusual influence of hydrostatic pressure on polarization switching, hysteresis loop shape, magnitude of remanent polarization, and coercive fields.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Anna N. Morozovska, Eugene A. Eliseev, Ayana Ghosh, Mykola E. Yelisieiev, Yulian M. Vysochanskii, Sergei V. Kalinin
Summary: In this study, the strain-induced polarization reversal in a ferroelectric CuInP2S6 (CIPS) thin film with conductive electrodes is explored. The study reveals an unusually strong effect of mismatch strain on the out-of-plane polarization reversal, hysteresis loop shape, dielectric susceptibility, and piezoelectric response of CIPS films.
Article
Physics, Condensed Matter
V. Pashchenko, O. Bludov, D. Baltrunas, K. Mazeika, S. Motria, K. Glukhov, Yu. Vysochanskii
Summary: The experimental studies of the paramagnetic-antiferromagnetic phase transition in the layered Cu0.15Fe0.85PS3 crystal are presented, utilizing Mossbauer spectroscopy and measurements of temperature and field dependencies of magnetic susceptibility. The observed peculiar behavior at low temperatures indicates weak ferromagnetism in the studied alloy. Ab initio simulations of the electronic and spin subsystems reveal the peculiarities of spin ordering at low temperatures and changes in interatomic interactions near the Cu substitutional atoms.
CONDENSED MATTER PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
T. T. Dang, J. Schell, A. G. Boa, D. Lewin, G. Marschick, A. Dubey, M. Escobar-Castillo, C. Noll, R. Beck, Dmitry Zyabkin, K. Glukhov, I. C. J. Yap, A. Mokhles Gerami, D. C. Lupascu
Summary: This study investigates the temperature-dependent characteristics of electromagnetic fields at the atomic scale in multiferroic bismuth ferrite (BFO) using time differential perturbed angular correlation (TDPAC) spectroscopy. The results show that the substitutional In-111 probe experiences local electric polarization and exhibits combined electric and magnetic interactions below the Neel temperature (T-N).
Article
Materials Science, Multidisciplinary
Anna N. Morozovska, Eugene A. Eliseev, Sergei Kalinin, Yulian M. Vysochanskii, Petro Maksymovych
Summary: By using the Landau-Devonshire approach and experimental results, a multiwell thermodynamic potential for the layered ferroelectric material CuInP2S6 (CIPS) was constructed, revealing the important role of nonlinear electrostriction in the material. The study calculated temperature and pressure phase diagrams and spontaneous polarization of bulk CIPS, as well as strain-induced phase transitions in thin films and stress-induced phase transitions in nanoparticles. The results also showed the significant influence of mismatch strain, elastic stress, and shape anisotropy on the phase diagrams and polar properties of nanoscale CIPS, with analytical expressions allowing for elastic control of polar properties.
Article
Materials Science, Multidisciplinary
V Liubachko, A. Oleaga, A. Salazar, R. Yevych, A. Kohutych, Yu Vysochanskii
