Article
Chemistry, Physical
Philippe F. F. Weck, Carlos F. F. Jove-Colon, Eunja Kim
Summary: Polymorphism and phase transitions in sodium diuranate (Na2U2O7) are investigated using density functional perturbation theory (DFPT). The thermal properties of different polymorphs of Na2U2O7 are predicted for the first time, and the energetically degenerate behavior of the alpha and beta phases is observed. Gibbs free energy calculations reveal that there is no direct solid-solid phase transition between the beta and gamma phases at high temperatures, suggesting a multi-step process involving beta-phase decomposition and recrystallization into the gamma phase. These findings are consistent with experimental observations.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Inorganic & Nuclear
Stamatios Strikos, Boby Joseph, Frederico G. Alabarse, George Valadares, Deyse G. Costa, Rodrigo B. Capaz, Mohammed ElMassalami
Summary: This study investigates phase transitions in SrAl2Si2 crystal under different pressure and temperature conditions, establishing a preliminary P-T diagram through theoretical and empirical analyses. The results show a relatively low critical pressure for the α-to-β transition, but a high activation barrier between the α phase and metastable β phase.
INORGANIC CHEMISTRY
(2021)
Article
Physics, Fluids & Plasmas
Milan Zukovic, Georgii Kalagov
Summary: We investigate the impact of competing pairwise higher-order interactions (HOI) on the critical behavior of the XY model. Our findings reveal that the critical properties of this generalized model can deviate significantly from the standard XY model, depending on whether the number of HOI terms is odd or even. Odd numbers of HOI terms lead to two consecutive phase transitions, while even numbers of HOI terms only result in two phase transitions under certain conditions.
Article
Multidisciplinary Sciences
Caorong Zhang, Junwei Huang, Kun Zhai, Keivan Akhtari, Zhiwei Shen, Lingyi Ao, Zeya Li, Feng Qin, Yukai Chang, Ling Zhou, Ming Tang, Xueting Dai, Caiyu Qiu, Yi Zhang, Lin Wang, Zhongyuan Liu, Yongjun Tian, Mohammad Saeed Bahramy, Hongtao Yuan
Summary: Researchers have observed an insulator-to-superconductor transition driven by valence fluctuation in the van der Waals insulator GeP. The transition is caused by valence skipping of the Ge cation, transforming GeP from a layered compound to a three-dimensional covalent system and resulting in a maximum superconducting critical temperature of 10 K.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Jiuye Zhao, Jiazhi Huang, Chunyang Yu, Chunyi Cui, Jun Chang
Summary: Density functional theory (DFT) simulation was used to investigate the effect of P doping on ye'elimite and its substitution preference. The results showed that increasing P doping affected the crystal structure of ye'elimite and revealed a preference for substituting S atoms.
Article
Materials Science, Multidisciplinary
Adrien Stoliaroff, Camille Latouche, Stephane Jobic
Summary: In this study, two crystalline allotropic forms of selenium in ambient conditions were investigated using density functional theory, revealing information such as energy-volume relationships, pressure-energy relationships, phonon properties, and pressure-temperature phase diagrams. It was found that the low p-type conductivity of the trigonal phase is mainly attributed to selenium self-interstitials, while the very low conductivity of the metastable phase is related to deep native defects. Additionally, it was discovered that antimony may have a positive impact on the conductivity of selenium.
Article
Chemistry, Physical
Tomasz Kostyrko
Summary: The electronic and spatial structure of an armchair carbon nanotube (CNT) deposited on a (110) surface of titanium dioxide (rutile) was studied using density functional theory (DFT) and a tight binding model. It was found that an electrostatic potential from the ionic surface of the rutile crystal can induce an energy gap in the electronic structure of the metallic CNT, depending on the symmetry of the CNT arrangement. The external potential applied in the model leads to lattice distortion and enhancement of the energy gap, with good quantitative agreement with DFT results.
APPLIED SURFACE SCIENCE
(2021)
Article
Physics, Condensed Matter
Jie Peng, Sijie Zhang, Keith Refson, Martin T. Dove
Summary: The crystal structures and lattice dynamics of tetragonal and orthorhombic phases of HCN were calculated using density functional theory. Negative pressure was used as a proxy for raising temperature to study the ferroelastic phase transition, which was found to involve softening of a transverse acoustic mode and be discontinuous. Analysis of the complete phonon spectrum revealed that the acoustic modes are responsible for both the large thermal expansion and the driving force for the phase transition in HCN.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Condensed Matter
Sumita Sura, Ashok K. Verma, Nandini Garg
Summary: In this study, the effects of pseudopotentials and exchange-correlation functionals on the trigonal to face-centered cubic phase transition of LaH10 were investigated using density functional theory calculations. The results showed significant variations in lattice parameters and phase transition pressure with different functionals, while exhibiting weaker dependence on pseudopotentials. Calculations also revealed that the phase transition pressure was lower in LDA compared to GGA. Additionally, the electronic properties of LaH10 at 150 GPa were found to have a weak dependence on the exchange-correlation functionals.
SOLID STATE COMMUNICATIONS
(2022)
Article
Chemistry, Inorganic & Nuclear
Ruifeng Zhou, Shuyi Yang, E. Tao, Xinyu Xiao, Lin Liu, Yun Li
Summary: The prepared GO-TiO2 composite material showed excellent adsorption performance for removing Cr3+ from wastewater. Characterization analyses demonstrated the uniform dispersion of TiO2 on the surface of GO and the retained oxygen-containing functional groups. The adsorption process followed quasi-second-order kinetic equation and Langmuir equation, with a stable removal efficiency over 85% after five cycles, indicating great potential for practical applications.
JOURNAL OF SOLID STATE CHEMISTRY
(2021)
Article
Polymer Science
Sergei A. A. Egorov
Summary: The study utilized Density Functional Theory to investigate depletion interactions between nanoparticles mediated by semiflexible polymers, revealing that the depletion attraction becomes stronger with increasing polymer chain stiffness and colloidal particle size.
Article
Engineering, Electrical & Electronic
R. Selmi, W. Cherif, A. R. Sarabando, N. M. Ferreira, L. Ktari
Summary: Polycrystalline compounds were synthesized using the ceramic method and shown to have magnetic field tunability. The samples undergo a paramagnetic-ferromagnetic phase transition within a certain temperature range, and the transition temperature increases with the increase of La doping concentration.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Multidisciplinary Sciences
Peter L. Rodriguez-Kessler, Adan R. Rodriguez-Dominguez, Alvaro Munoz-Castro
Summary: The structural evolution of Ti-n clusters in the n=33-60 size range was investigated using density functional theory computations and systematic cluster growth method. New clusters with enhanced stability were found for n=33, 38, 41, 43, 46, 48, 50, 53, 55, and 58 sizes. The theoretical electronic properties of the most stable isomers of Ti-n clusters were in good agreement with experimental data.
ADVANCED THEORY AND SIMULATIONS
(2021)
Article
Materials Science, Multidisciplinary
I. A. Shchukin, Yu D. Fomin
Summary: The crystal structure of the Stillinger-Weber system in a narrow slit pore has been investigated, revealing that the system can form multiple crystal phases depending on density. Furthermore, the system splits into several layers with varying symmetry, which is not observed in systems with only pairwise interactions.
RESULTS IN PHYSICS
(2022)
Article
Chemistry, Physical
Long Truong Nguyen, Guy Makov
Summary: In this study, the high-pressure structures of SnO and PbO were investigated using density functional theory calculations combined with an evolutionary algorithm. Two new high-pressure polymorphs were predicted, and the transition pressures to these phases were found to be consistent with experimental studies. The weakening of lone pair localization and elastic instability were identified as key factors driving pressure-induced phase transitions, with modulations of the electronic structure of SnO/PbO due to structural transitions upon compression also discussed.
