The electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts have been calculated with and without Bi 5d states using the experimental lattice parameters, via the plane-wave pseudopotential method based on density functional theory (DFT). BiOF exhibits a direct band gap of 3.22 or 3.12 eV corresponding to the adoption of Bi 5d states or not. The indirect band gaps of BiOCl, BiOBr, and Bi...

The purpose of this paper is the generalization of structure factor for rods by polygon section in two dimensional phononic crystals. If we use the plane wave expansion method (PWE) for the propagation of acoustic waves in 2D phononic crystals, structure factor will be an important quantity. In order to confirm the obtained relations, we have calculated the band structure for XY and Z vibration...

In this paper, properties of reflection phase in one-dimensional quaternary photonic crystals combining dispersive meta-materials and positive index materials are investigated by transfer matrix method. Two omnidirectional band gaps are located in the band structure of considered structure. However, we limit our studies to the frequency range of the second wide band gap. We observe that the val...

We theoretically analyze the nonlinear phase shifts induced by cascaded χ:χ processes in1-D photonic band gap (PBG) structures. We find that the enhancement of the density of modes near the band edge, coupled with a suitable choice of relative phase mismatch, leads to a new remarkable effect: the relative phase shift of the fundamental field upon transmission can be of order π over a distance o...

in this work facile sol-gel (pechni) method has been successfully established to synthesize zn4b6o13 nanocrystals which have cubic crystals with lattice parameter: a =7.48 a. the structure and morphology of the obtained material were studied by x-ray diffraction (xrd), infrared spectra (ir), scanning electron microscopy (sem) and photoluminescence analysis. the experimental results show a band ...

We predict the existence of gap solitons in a nonlinear, quadratic Fabry-Pérot negative index cavity. A peculiarity of a single negative index layer is that if magnetic and electric plasma frequencies are different it forms a photonic band structure similar to that of a multilayer stack composed of ordinary, positive index materials. This similarity also results in comparable field localization...

Abstract - This paper presents a new design of microwave microelectromechanical systems (MEMS) phase shifter for dual band wireless local area network (WLAN) applications. A bit is designed which product a constant phase shift of 11.25° by switching between two line that consist of 12 and 6 unitcells in each frequency band. A unitcell is constructed by gold membrane suspended over the coplanar ...

We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, ...

ZnS nanocrystalline thin films were grown into the polyvinyl alcohol matrix and were synthesized by chemical route. Films were prepared on glass substrate by varying the deposition parameters and pH of the solution. Nanocrystalline thin film prepared under optimum growth conditions shows band gap value 3.88 eV as observed from optical absorption data. The band gap is found to be higher (3.88 eV...

The spin or nonspin state of electrons in W-doped anatase TiO2 is very difficult to judge experimentally because of characterization method limitations. Hence, the effect on the microscopic mechanism underlying the visible-light effect of W-doped anatase TiO2 through the consideration of electronic spin or no-spin states is still unknown. To solve this problem, we establish supercell models of ...