- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Stable Structural Phase of Potassium-Doped <i>p</i> -Terphenyl and Its Semiconducting State
摘要： The potassium-doped p-terphenyl compounds were synthesized in recent experiments and the superconductivity with high transition temperatures were reported, but the atomic structure of potassium-doped p-terphenyl is unclear. In this paper, we studied the structural and electronic properties of potassium-doped p-terphenyl with various doping levels by the first-principles simulation. We first find out the low energy position of K atom in intralayer interstitial space of the molecular layer, then examine whether two rows of K atoms can be accommodated in this one space, at last the effect of the interlayer arrangement between adjacent two molecular layers on total energy is taken into account. Our results show that the doped K atoms prefer to stay at the bridge site of single C-C bond connected two phenyls instead of locating at the site above the phenyl ring, distinct from the situation of K-doped picene and phenanthrene. Among the possible structural phases of Kx-p-terphenyl, the K2-p-terphenyl phase with P212121 group symmetry is determined to be most appropriate, which is different from the one in recent report. The stable K2-p-terphenyl phase is semiconducting with an energy gap of 0.3 eV and the bands from the lowest unoccupied molecular orbitals are just fully filled by the electrons transferred from K atoms.
关键词： Plasmonics,First-principles simulation,Semiconducting state,Magnetic,Potassium-doped p-terphenyl,Superconductivity,Optical,Hybrid Materials
更新于2025-09-10 09:29:36
-
Codoping Er-N to Suppress Self-Compensation Donors for Stable <i>p</i> -Type Zinc Oxide
摘要： Stable p-type doping of zinc oxide (ZnO) is an unsolved but critical issue for ultraviolet optoelectronic applications despite extensive investigations. Here, an Er-N codoping strategy for defect engineering of ZnO to suppress the self-compensation of the donor-type intrinsic point defects (IPDs) over the acceptor-type ones is proposed. Via first-principles calculations, the influence of nitrogen and erbium concentration on the stability of ZnO is investigated. The complex (ErZn-mNO) consisting of multiple substitutional N on O sites and one substitutional Er on Zn site is a crucial stabilizer. With an increase of the concentration of N, the absorption edges redshift to lower energy due to the impurity band broadening in the bandgap. The results suggest that codoping Er-N into the ZnO matrix is a feasible way to manufacture stable p-type ZnO.
关键词： p-type ZnO,Er-N codoping,first principles,defect formation energy
更新于2025-09-10 09:29:36
-
Effects of Ag Doping and Point Defect on the Magnetism of ZnO
摘要： The magnetism sources and magnetic mechanism of Ag doping and point defect, which coexist in the presence of ZnO, are frequently controversial. To solve these problems, the effects of Ag doping and Zn or O vacancy on the magnetism of ZnO were investigated using geometry optimization and energy calculation according to the first-principles generalized gradient approximation + U (GGA+U) method of density functional theory. Results revealed that the system which Ag doping and Zn vacancy coexists in ZnO could achieve room-temperature ferromagnetism. This system had an extremely high spin polarization, which was advantageous for the spin electron injection sources applied in dilute magnetic semiconductors. Result also revealed that the magnetism of Zn14AgO16 was caused by the electron hybrid coupling effects among the O-2p, Ag-4d, Ag-5s, and Zn-4s orbits. And these effects were produced by the hole carriers after complexes were formed by the Ag doping and Zn vacancy. With regard to the most stable structure of the ground state, all doping systems which Ag replacing Zn and O vacancy coexisted in ZnO and those which Ag replacing Zn, interstitial Ag, and O vacancy coexisted in ZnO were all non-magnetic. Thus, these doping systems were unsuitable for dilute magnetic semiconductors. By contrast, the doping systems of interstitial Ag and Zn vacancy were magnetic, although the magnetism was relatively weak, thus rendering such systems inapplicable as well.
关键词： Point defect,Ag doping,ZnO,Magnetism,First-principles,Vacancy
更新于2025-09-10 09:29:36
-
Comparison of geometry models in the study of perovskite heterostructures
摘要： Based on the first-principles calculations, the influence of different geometry models on the theoretical results about the electronic properties of LaAlO3/SrTiO3 perovskite heterostructures has been studied. The results show that the superlattice model can indicate n-type conductivity of interfaces, but it is limited to describe the insulator-metal transition of heterostructures. The sandwich and thin film models with the vacuum layer can take into account the surface termination effect on the electronic properties of the interface. The AlO2 or LaO atomic layer as the outmost surface termination is selected during constructing the model, leading to the distinct electronic properties of the heterostructures. The build-in electric filed appears in the AlO2-terminated structure, whereas it does not exist in LaO-terminated structure. Therefore, the AlO2-terminated structure can give a clear description about the insulator-metal transition of heterostructure and the charge transfer mechanism. The build-in electric filed, the atomic rumpling and surface termination effect of perovskite materials codetermine the conductivity of interfaces. The results would be helpful to construct theoretical model and understand the novel electronic properties during investigating other perovskite heterostructures.
关键词： perovskite heterostructure,surface termination,theoretical models,first-principles method
更新于2025-09-10 09:29:36
-
Two-dimensional Dy doped MoS2 ferromagnetic sheets
摘要： Magnetic two-dimensional materials have attracted immense consideration as spintronic devices. However, design and synthesis of the magnetic two-dimensional MoS2 crystals with more controllable electronic structure and better conductivity are still great challenges. Here, we make a breakthrough to synthesize the MoS2:Dy sheets with robust adjustable room-temperature ferromagnetic properties by a gas-liquid chemical deposition method. The as-synthesized samples are characterized by XRD, Raman, TEM, HRTEM and XPS. Furthermore, the magnetic properties of the samples are also investigated by VSM and Squid. The maximum observed saturation magnetization is 0.023 emu/g. The origin of ferromagnetism in the samples is investigated by using the ?rst-principles calculations based on the density functional theory. The ferromagnetism is mainly related to the exchange interactions among the S 3p, Mo 4d and Dy 5d orbits. The results indicate that the transformation of the localized charges can e?ectively engineer and manipulate the magnetic properties of 2D materials, making MoS2 a potential candidate for spintronics and electronic applications and providing a new perspective on other 2D layered materials in spintronics application.
关键词： High pressure,2D materials,MoS2,First principles calculations,Ferromagnetism,Dy doping
更新于2025-09-10 09:29:36
-
First Principle Study on Optical Properties of Tri-Group Doped (6,6) SiC Nanotubes
摘要： The optical properties of tri-group (B, Al, Ga, In) doped (6,6) SiC nanotubes (SiCNTs) are studied from first principles. The results show that the main absorption and dispersion of SiCNTs caused by the intrinsic transition appear in the ultraviolet-visible region (below 500 nm), and the tri-group doping increases the minimum dielectric constant value resulting in enhanced transmittance. In addition, the tri-group doping can introduce a weak absorption and dispersion region in the near-mid-infrared region, and the response peak blue shifts as the diameter of the doping atom increases. Comparative studies of reflectance, absorptivity, and transmittance show that the key factors affecting the transmittance of SiCNTs are reflectance (or refractive index) rather than absorption coefficient.
关键词： ultraviolet-visible region,SiC nanotubes,near-mid-infrared region,tri-group doped,optical properties,first principles,transmittance
更新于2025-09-10 09:29:36
-
Predicted semiconducting beryllium sulfides in 3D and 2D configurations: Insights from first-principles calculations
摘要： Light-metal sulfides have attracted great attention due to the technological application as energy storage devices. Combining first-principles calculations with structure searching, sulfur-rich compounds were explored theoretically in Be-S system. Interestingly, our results identify a hitherto unknown stoichiometry BeS2 in bulk and two-dimensional (2D) configuration. With the pressure increasing, BeS2 in bulk adopts P1(cid:2) structure at ambient pressure, C2 phase over 1.6GPa and then a cubic c-BeS2 with unique S2 2- dimmers up to 5.8GPa. The monolayer penta-BeS2 with Be2S3 pentagons and bilayer BeS structure are presented. Predicted c-BeS2, 2D BeS2 and BeS phases show a semiconducting character, interestingly, c-BeS2 is found to have a direct band gap of 1.52eV. The discovery of unknown beryllium sulfides and the understanding of electronic and chemical bonding properties will provide prerequisite for the potential application in electrochemistry.
关键词： Electronic property,First-principles calculations,Beryllium sulfides,Structural stability
更新于2025-09-10 09:29:36
-
Accelerating Pmn21-BAlNP properties prediction by machine learning based on first-principles calculation
摘要： In this paper, the CASTEP program and machine learning algorithm are used to study Pmn21-BxAl1-xNyP1-y. The mechanical stability, thermodynamic stability and molecular dynamics stability of several typical structures of Pmn21-BxAl1-xNyP1-y are estimated by CASTEP program. The results show that all the structures are stable. The data such as lattice constants and elastic properties of Pmn21-BxAl1-xNyP1-y are used as training sets of machine learning, then, the average absolute percent error (MAPE) of each model is calculated by using 7-fold cross-validation, and the lattice constant prediction model and shear modulus prediction model of Pmn21-BxAl1-xNyP1-y are selected respectively. Linear regression algorithm is used for modeling lattice constants, and Xgboost algorithm is used for modeling shear modulus. On the test sets, it is found that the error is within the acceptable range by comparing the data predicted by the models with the real data. Therefore, the machine learning prediction models of lattice constants, and shear modulus G have strong generalization ability. The electrical properties of Pmn21-BxAl1-xNyP1-y are calculated by using hybrid PBE0 functional. The direct band gaps are found in AlN, BP, AlP, B0.25Al0.75N, B0.75Al0.25P, B0.5Al0.5P, B0.25Al0.75P, AlN0.75P0.25, AlN0.5P0.5 and AlN0.25P0.75.
关键词： Pmn21-BxAl1-xNyP1-y,First-principles,Optoelectronic properties,Machine learning,Mechanical properties
更新于2025-09-10 09:29:36
-
A new two-dimensional semiconducting carbon allotrope: A first-principles study
摘要： A new two-dimensional carbon allotrope, which consists of 18 atoms in a hexagonal cell, is theoretically investigated by performing first-principle method. The allotrope displays a P6/mmm symmetry (termed as hP-C18 carbon). The new 2D carbon phase has an sp2-sp3 network, consisting of hexagons and octagons formed by near-by atoms. The calculations demonstrate that hP-C18 carbon is a metastable 2D carbon phase compared to graphene, but it is more energetically stable than penta-graphene. The dynamical, thermal and mechanical stabilities are demonstrated by phonon dispersion, ab inito MD simulations and elastic constants, respectively. The analysis of electronic band structure shows that hP-C18 is an indirect semiconductor with a band gap of 2.93 eV (HSE06). Besides, its buckled 3D structure, hP-C18-3D carbon, is also predicted. The stability of the new 3D phase is discussed by phonon dispersion and elastic constants. It is found that hP-C18-3D carbon is a super-hard indirect semiconductor with an indirect band gap of 2.24 eV (HSE06). Thus, hP-C18 carbon and its buckled 3D structure may possess not only potential electronic applications but also mechanical applications.
关键词： metastable,hP-C18 carbon,two-dimensional carbon allotrope,semiconducting,mechanical applications,first-principles study,electronic applications
更新于2025-09-10 09:29:36
-
Understanding Photoresponsive Catechol-based Polyoxotitanate Molecules: a Combined Experimental and First Principles Investigation
摘要： In this study, we employ a type of polyoxotitanate (POT) compound with a unique structure that is composed of a metal-oxo core and functionalized by catechol ligands, and characterize its electrochemical and photoresponsive properties. We find that the POT functionalized by the catechol ligand acts as a photoresponsive single source to provide the photocurrent in aqueous electrolyte. The first principles calculation confirms the intramolecular ligand-to-metal charge transfer characters. Considering the stable photocurrent output generated by the POT in the aqueous condition, we anticipate potential applications of the catechol-functionalized POT in the optoelectronic devices that require water stability and aesthetic features.
关键词： First Principles,Solar Cell,Photocurrent,Polyoxotitanate
更新于2025-09-10 09:29:36