Based on the variational theory, a wavelet-based numerical method is developed to calculate the defect states of acoustic waves in two-dimensional phononic crystals with point and line defects. The supercell technique...Based on the variational theory, a wavelet-based numerical method is developed to calculate the defect states of acoustic waves in two-dimensional phononic crystals with point and line defects. The supercell technique is applied. By expanding the displacement field and the material constants （mass density and elastic stiffness） in periodic wavelets, the explicit formulations of an eigenvalue problem for the plane harmonic bulk waves in such a phononic structure are derived. The point and line defect states in solid-liquid and solid-solid systems are calculated. Comparisons of the present results with those measured experimentally or those from the plane wave expansion method show that the present method can yield accurate results with faster convergence and less computing time.展开更多
In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out bot...In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm^(3+)ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD)analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM).X-ray photoelectron spectroscopy(XPS)was carried out to confirm the prese nce of Sm~(3+)on the doped NPs.Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing abso rption in the visible range,and a minimum of 3.18 eV of optical bandgap for Zn_(0.97)Sm_(0.03)O is found.Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%,followed by an increase of Zn_(0.95)Sm_(0.05)O.Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra.Theoretical analysis was also carried out with density functional theory(DFT).This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully.Later,photocatalytic activity for the optimum composition,i.e.,3 mol%,was assessed experimentally.展开更多
Halide perovskites have become a hot topic in materials research due to their potential applications in a variety of fields,from optoelectronic and thermoelectric devices to solar cells.Doping of halide perovskites ca...Halide perovskites have become a hot topic in materials research due to their potential applications in a variety of fields,from optoelectronic and thermoelectric devices to solar cells.Doping of halide perovskites can be achieved by introducing different types of dopants,such as metal cations,anions,and organic molecules,leading to increased stability and improved optoelectronic properties.Moreover,doping can introduce new functionalities,such as increased spin lifetime and thermal stability.These features make doped halide perovskites a highly promising candidate for optoelectronic applications.In this mini-review,we highlight the latest advances in ion-doped halide perovskites and their immense potential for various applications.展开更多
基金the National Natural Science Foundation of China(No.10632020)the German Research Foundation(No.ZH 15/11-1)jointly by the China Scholarship Council and the German Academic Exchange Service(No.D/08/01795).
文摘Based on the variational theory, a wavelet-based numerical method is developed to calculate the defect states of acoustic waves in two-dimensional phononic crystals with point and line defects. The supercell technique is applied. By expanding the displacement field and the material constants （mass density and elastic stiffness） in periodic wavelets, the explicit formulations of an eigenvalue problem for the plane harmonic bulk waves in such a phononic structure are derived. The point and line defect states in solid-liquid and solid-solid systems are calculated. Comparisons of the present results with those measured experimentally or those from the plane wave expansion method show that the present method can yield accurate results with faster convergence and less computing time.
文摘In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm^(3+)ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD)analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM).X-ray photoelectron spectroscopy(XPS)was carried out to confirm the prese nce of Sm~(3+)on the doped NPs.Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing abso rption in the visible range,and a minimum of 3.18 eV of optical bandgap for Zn_(0.97)Sm_(0.03)O is found.Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%,followed by an increase of Zn_(0.95)Sm_(0.05)O.Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra.Theoretical analysis was also carried out with density functional theory(DFT).This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully.Later,photocatalytic activity for the optimum composition,i.e.,3 mol%,was assessed experimentally.
基金supported by the Singapore Quantum engineering program(grant no.RF2021-QEP2-03-P10)the National Research Foundation,the Prime Minister’s Office,and the government of Singapore under its Competitive Research Programme(award no.NRF-CRP23-2019-0002)its NRF Investigatorship Programme(award no.NRF-NRFI05-2019-0003).
文摘Halide perovskites have become a hot topic in materials research due to their potential applications in a variety of fields,from optoelectronic and thermoelectric devices to solar cells.Doping of halide perovskites can be achieved by introducing different types of dopants,such as metal cations,anions,and organic molecules,leading to increased stability and improved optoelectronic properties.Moreover,doping can introduce new functionalities,such as increased spin lifetime and thermal stability.These features make doped halide perovskites a highly promising candidate for optoelectronic applications.In this mini-review,we highlight the latest advances in ion-doped halide perovskites and their immense potential for various applications.
