Waves in periodic media undergo multiple scattering and interference. As a result, their frequency spectrum is divided into bands in which waves pass freely, and gaps in which waves cannot propagate. This band diagram depends on the physical and geometrical properties of the periodic cell, through a dispersion relation. Using a new representation of the dispersion relation of laminates, we show...

Ca(x)Zn(1-x)O alloys are potential candidates to achieve wide band-gap, which might significantly promote the band gap engineering and heterojunction design. We performed a crystal structure search for CaO-ZnO system under pressure, using an ab initio evolutionary algorithm implemented in the USPEX code. Four stable ordered Ca(x)Zn(1-x)O structures are found in the pressure range of 8.7-60 GPa....

in this paper, undopedzno and co-znonano structureswith different molar ratio of cobalt have been synthesized by the sonochemical method. structure have been characterized by fourier transform (ftir) and uv–vis spectroscopy,scanning electron microscopy (sem), energy dispersive analytical x-ray (edax), and x-ray diffraction (xrd) methods. moreover, the direct band gap has been calculated by tauc...

in the present study, co-zno and co-ni-zno nanoparticles were synthesized by sonochemical methods and the structural and optical properties were investigated through fourier transform infrared spectroscopy (ftir), uv-vis spectroscopy, field emission scanning electron microscopy (fe-sem), x-ray diffraction (xrd), and photoluminescence spectroscopy (pl) methods. morphology of nanoparticles obtain...

The dispersion diagram of infinite periodic structures is useful for the practical design of waveguide filters. Starting from the dispersion diagram of a unit cell, it is possible to generate a finite structure with very similar passand stop-bands (gaps). However, truncation of the infinite periodic structure degrades the pass-band performance. In this paper, these impairments are overcome by m...

We calculate the global phase diagram using classical statistical mechanics for an isotropic pair potential that has been previously [Rechtsman et al., Phys. Rev. Lett. 95, 228301 (2005)] shown to produce the low-coordinated two-dimensional honeycomb crystal as the ground-state structure. Low-coordinated crystals are of practical interest because they have desirable photonic band-gap properties...

s-doped and bare mesoporous tio2 were prepared using titanium tetraisopropoxide and thiocarbamide as raw materials. prepared materials were characterized by means of fourier transform infrared spectroscopy ft-ir, thermogravimetry-differential scanning calorimetry (tg-dsc), x-ray diffraction (xrd), uv–vis absorption spectroscopy, brunauer–emmett–teller (bet) specific surface area and barrett–joy...