Physica Status Solidi B: Basic Solid State Physics

Xu, Yang; Li, Tao; Hu, Changyi; Zhou, Shenggang; Wei, Yan; Wang, Xian; Cao, Yong

doi: 10.1002/pssb.202300214pmid: N/A

In this work, the thermodynamic properties of TiB with B‐vacancy, Ti‐vacancy, V‐substitutional doping, and V‐interstitial doping under high temperature and high pressure are systematically analyzed using first‐principles calculations. The presence of both types of vacancies leads to a decreasing trend for the volume, whereas the different forms of V doping could cause lattice distortion and affect supercell volume. In addition, regardless of the vacancy or doping‐based modification of TiB, its constant volume heat capacity increases with the temperature and approaches the Dulong–Petit limit, while the constant pressure heat capacity slowly decreases by increasing the pressure. The presence of vacancies also affects the thermal expansion coefficient of TiB, thereby regulating its high‐temperature ductility, and the V interstitial doping approach is beneficial for improving the high‐temperature ductility of TiB. The Debye temperature of TiB with vacancies is proven more sensitive to pressure changes than the temperature, where the V doping has a significant impact on the Debye temperature of TiB. And the Debye temperature of TiB with interstitial V atoms is lower than that of TiB with substitutional V atoms, indicating that the interaction force is higher than that of the interstitial sites.

Bai, Xuefei; Hou, Qingyu; Li, Wencai; Qi, Mude; Gu, Yulan; Si, Riguleng

doi: 10.1002/pssb.202300304pmid: N/A

Under vacuum environment, an H interstitial must exist when Ga2O3 is prepared by organometallic chemical vapor deposition. However, few first‐principles systematic studies have been conducted on the influences of point vacancies (VGa, Hi) on the photocatalytic performance and magnetism of Ga2O3:(Li or Na or K) systems, and VGa is a challenge in experiments. Therefore, the first‐principles generalized gradient approximation GGA + U theory is adopted in this study. A first‐principles study is conducted on the formation energy (E f), photocatalytic performance, and magnetism of Ga30MO48 (M = Li or Na or K) and Ga30MHiO48 systems. In the results, it is shown that under Ga‐poor conditions, the Ga30MO48 and Ga30MHiO48 systems are structurally stable and prone to doping. The Ga30MHiO48 system has lower E f, more structural stability, and easier doping than the Ga30MO48 system. The Ga30KO48 system exhibits magnetism, mainly generated by the O1−‐2p spin‐polarized wandering electrons near VGa. The spin‐polarized O2−‐2p and Ga‐4s states near VGa contribute to the hybrid coupling double‐exchange interaction. Moreover, the visible spectrum of the Ga30LiHiO48 system exhibits a significant redshift, a relatively high carrier activity, carrier separation, and relative maximum lifetime. It is relatively best as a photocatalyst.

Alés, Alejandro

doi: 10.1002/pssb.202300252pmid: N/A

Ab initio calculations have been conducted on all‐d light transition metals featuring full and inverse Heusler structures with the composition Ni2XMn, where X = Fe, Co, Cr. The analysis encompasses lattice parameters, bulk modulus, and formation energy, which are thoroughly examined across various magnetic orders. Additionally, the equilibrium structures are comprehensively characterized. Elastic constants are calculated and mechanical stability is thoroughly discussed. Furthermore, tetragonal distortions, following the Bain path, are computed, and a novel stable structure is introduced. Spin‐resolved density of electronic states and band structures are scrutinized in detail. The findings reveal a behavior consistent with half‐metallicity, even though the gaps between the conduction and valence bands are exceedingly small.

Luo, Kailiang; Xu, Yang; Li, Zhengyi; Hu, Changyi; Wei, Yan

doi: 10.1002/pssb.202370031pmid: N/A

Grundmann, Marius

doi: 10.1002/pssb.202300257pmid: N/A

The problem of the potential, electrical field and charge density in a space charge region is revisited. Within the Boltzmann approximation, the asymptotic solution is found analytically. The exact solution everywhere can be found from numerically integrating an analytical function. The solution is compared to the popular abrupt (or depletion) approximation and an analytical approximation is given.

Butt, Mehwish Khalid; Aldaghfag, Shatha A.; Kazim, Muhammad Zafarullah; Yaseen, Muhammad; Zahid, Muhammad; Ishfaq, Mudassir

doi: 10.1002/pssb.202300206pmid: N/A

The optoelectronic and magnetic features of La1−xVxAlO3 (x = 12.5, 25, 50, 75%) perovskites are investigated within density functional theory (DFT) using generalized gradient approximation by Perdew–Burke–Ernzerhof (PBE–GGA). The effect of different percentages of vanadium (V) substitution on the properties of LaAlO3 is studied and stability is confirmed through formation energies. The spin‐polarized band structure of La1−xVxAlO3 (x = 12.5, 25, 50, 75%) elucidates their half‐metallic ferromagnetic character. Furthermore, the optical performance of the given compounds is explored by optical parameters like dielectric function, optical conductivity, refractive index, reflectivity, absorption, and extinction coefficients. The obtained results make these compounds suitable for optoelectronic applications. It is observed that the determined magnetic moment in La1−xVxAlO3 is mainly due to the V‐3d states. The regulated reduction in bandgap (Eg) with the upsurge of V doping and half‐metallic ferromagnetic nature makes them appropriate for spintronic and magnetic devices.

Li, Jianyu; Qiu, Xuchang; Kong, Shining; Zhang, Zhao

doi: 10.1002/pssb.202300246pmid: N/A

Stable precipitate takes the essential role for material strengthening in Al–Mg–Si alloys. To reveal how the stable precipitate works in material strengthening, a molecular dynamics model is carried out to show the interaction between the edge dislocations and the plate‐shaped β phase of Mg2Si. The critical resolved shear stress (CRSS) is related to the precipitate characteristics including sizes and thickness directions. The CRSS increases with the increase of the precipitate size. When the thickness direction of precipitate changes from [001] to [100], the CRSS increases from 326.76 to 368.7 MPa. This phenomenon is mainly affected by the interaction length between dislocation and β phase. With the increase of interaction length, the interaction time for dislocation to overcome pinning increases. The critical bending angle of dislocation can be affected by the interaction time and shear strain rate. The relationship between the critical bending angle and the CRSS in Al–Mg–Si alloy is then established.

doi: 10.1002/pssb.202370032pmid: N/A

Durairaj, Murugan; Sabari Girisun, T. Chidambaram

doi: 10.1002/pssb.202300216pmid: N/A

Upconverter/MoS2 heterostructure thin films fabricated by hydrothermal technique are confirmed by X‐ray diffraction and Raman studies. Field‐emission scanning electron microscopy (FESEM) and high‐resolution transmission electron microscopy (HRTEM) reveal the nanobelt structured MoS2 mingled with trapezoid structure fluoride upconverters and sphere‐shaped oxide upconverters. The films exhibit green ( H 11 / 2 2   to   I 15 / 2 4 ) and red ( F 9 / 2 4   to   I 15 / 2 4 ) emission. The influence of upconverters on the nonlinear absorption of MoS2 is exploited by Z‐scan technique using nanopulsed laser. Estimated ground‐state absorption cross section is higher than the excited‐state absorption cross section of the samples and it confirms the occurrence of saturable absorption. CeO2:Yb,Er@MoS2 exhibits stronger saturable absorption due to synergetic effects like higher linear absorption coefficient at 532 nm, stronger green emission, and reduced size. Results pave way for the design of optical switches, Q‐switches, and mode lockers using upconverter integrated MoS2 thin films.

Hao, Luyao; Chen, Wenjin; Lei, Xiaowei; Yao, Wenjing; Wang, Nan

doi: 10.1002/pssb.202300239pmid: N/A

First‐principles calculations are carried out to study the surface structure, energies, and electronic properties of Ni3Nb(100), Ni3Nb(001), and Ni3Nb(110) based on the density functional theory (DFT). The surface relaxation results reveal that the relaxations are mainly localized in the first and second atomic layer, and Ni3Nb(110)‐Ni experiences the largest surface relaxation (–16.95%), whereas Ni3Nb(001)‐NiNb undergoes smallest relaxations. The surface energies of nonstoichiometric surfaces present a linear relationship with the chemical potential of Ni (ΔμNi), while those of stoichiometric surface are independent of ΔμNi. Furthermore, Ni3Nb(001)–Ni and Ni3Nb(001)–NiNb are the most stable surfaces owing to their having the lowest surface energy in a wide range of ΔμNi, while the nonstoichiometric Ni3Nb(110)–Ni and Ni3Nb(110)–NiNb surfaces with the largest surface energies are the most unstable surfaces. The electronic structures of nonstoichiometric surfaces are different from that of the bulk Ni3Nb, whereas the effect of surface relaxation on the electronic properties of the stoichiometric surface is weak.