In this work, we demonstrate the results of studies on the synthesis, the structure and properties of carbon inverted opal (C-IOP) nanostructures, the surface of which is modified by oxide and sulfide of nickel. It is shown that the modification of the matrix C-IOP by nickel compounds led to a decreasing the specific surface area more than three times and was 250 m2/g. The specific capacitance of the capacitor with the C-IOP/NiO/Ni7S6 composite as electrode has increased more than 4 times, from 130 F/g to 600 F/g, as compared with the sample C-IOP without the modification by nickel compounds. The significant contribution of the faradaic reactions in specific capacitance of the capacitor electrodes of the composites is marked.
The study of the emission properties of opal-erbium oxide nanocomposites in the wide range of erbium
concentrations was carried out. Erbium oxide concentration was varied from 0.25 to 16%wt. Maximal output of the
photoluminescence (PL) took place at 1%wt of erbium oxide concentration. It was shown that the annealing
temperatures from 600 to 900°C were too low to exhibit sufficient emission properties of the erbium-opal composites.
The presence of the erbium silicates Er2SiO5 and Er2Si2O7 in the
opal-erbium nanocomposites was revealed by X-ray
phase analysis. Amorphous silica in opal matrix was not crystallized at the annealing during a few hours at
1000 - 1200°C. The case of the tens hours of annealing the crystoballite phase occurred. No angle dependence of the PL
intensity was observed as a result of degradation of the photonic band gap (PBG) at the annealing of the opal-erbium
oxide nanocomposites. Further modification of the material processing to achieve a strong photonic band gap reflection
peak near 1550 nm with high PL intensity in the
opal-Er2O3 composite is running.
Investigations of the spontaneous and stimulated emission spectra by optical pumping of ZnO layers deposited on SiO2-Si and opal were carried out. The stimulated emission pumped under ultra violet 337 nm N2 laser excitation was observed at 397 nm at room temperature from ZnO-SiO2-Si type and ZnO-opal type thin film structures. The threshold pumped power for the electron-hole plasma recombination laser process is of the order of 35 MW/cm2 for ZnO-SiO2-Si and 300 KW/cm2 for ZnO-opal structures.
We investigate the optical properties of thin films of two photonic systems: synthetic opal and crystalline liquid BPII. Diffraction related with three-dimensional periodic structure and interference related with light reflection from film surfaces were measured. We found a substantial change of refractive indices at the edges of the photonic bands in both materials. The relation between the frequency and the wave vector of light shows a nonlinear behavior near zone boundary.
The structure of the opal-ZnO composites has been studied by TEM and X-ray methods. It was found that the solid state reaction of the opal-ZnO interface interaction is occurring during the heat treatment of the infiltrated samples resulting in the formation of the zinc silicate β-Zn2SiO4 and its high temperature modification of willemite Zn2SiO4. Nanocomposite structure and emission properties have been studied in dependence on the filling degree. The blue luminescence at 430 nm stipulated for the β-Zn2SiO4 phase has been observed for the sample with 25 filling cycles. Angular dependences of the PL and Reflection spectra of the opal-ZnO composite with 4 filling cycles demonstrate the suppression effect of the ZnO spontaneous emission in the stop band.
ZnO infiltration technology was developed by chemical deposition from solution in to a three-dimensional opal lattice, samples of the ZnO - opal composites were prepared with the predominating UV - emission at room temperature. The embedding degree was checked up by the sample weight and by the shift of the spectral position of the reflection maximum (stop band). The both ways were in accordance with one another. The optimal synthesis conditions of the ZnO-filled opals were defined for the maximal intensity of the UV-luminescence. It is shown the use of the "raw" opals and incomplete filling of the pores by semiconducting material increase the edge excitonic emission by several times at room temperature. Angular dependences of the photoluminescence and reflectance spectra of the ZnO-infiltrated opal have been studied. These results can be used to create effective laser light sources in UV spectral range using "photonic crystal" effect.