Comparative analysis of diffuse reflection spectra and induced absorption spectra of ZrO2 micro- and nanopowders after irradiation with 100 keV electrons and protons

A comparative analysis of the structure, phase composition, morphology, and diffuse reflection spectra of zirconium dioxide micro- and nanopowders in the 0.2–2.5 μm range and the changes after irradiation with 100 keV electrons and protons is carried out. The reflective capability of nanopowders is found to be lower, though the radiation stability higher, as compared to micropowders.     

Optical Properties and Radiation Stability of Al2O3 Microparticles,Nanoparticles and Microspheres

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A comparative analysis of the diffuse reflectance spectra in the range from 200 to 2500 nm is carried out on...     

Density jump and thermal relaxation at a shock front in water containing gas bubbles

In the present article we give the results of measurements of the density jump in a shock wave propagating in water containing air or helium bubbles. We show that the thermal relaxation at the shock front depends on the properties of the gaseous component and the wave intensity. Breakup of the bubbles promotes more rapid temperature equalization between the components of the mixture.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 146–149, July–August, 1976.The authors are grateful to L. P. Gorbachev for valuable comments.     

Proton and electron irradiation induced changes in the optical properties of ZnO pigments modified with ZrO2 and Al2O3 nanopowders

The effect of the modification of ZnO powders by ZrO₂ and Al₂O₃ nanoparticles with a concentration of 1–30 wt % is investigated by diffuse reflectance spectra within the wavelength range 0.2 to 2.5 μm before and after 100 keV proton and electron irradiation. It has been established that the introduction of nanoparticles enhances the optical stability of the pigments under proton irradiation, but reduces it under electron irradiation. Samples modified by 5 wt % of ZrO₂ nanoparticles have the highest stability of optical properties after proton exposure. The degradation of optical properties under electron irradiation is not high for this concentration of nanoparticles. A decrease in the absorption of pigments modified with nanoparticles after proton exposure is determined by a decrease in the intensity of bands located in the UV and visible regions. After electron exposure the absorption bands have a high intensity in the whole spectrum range.     

Photoluminescence of zinc oxide modified by nanopowders

The modifying effect of Al₂O₃, Al₂O₃ · CeO₂, ZrO₂, ZrO₂ · Y₂O₃ nanopowders on the photoluminescence spectra of ZnO powder in the 360–660 nm range is investigated. It is found that the introduction of nanoparticles causes a decrease in the ultraviolet band intensity and an increase in the visual spectral band intensity. The change in the intensity of elementary components of the visible range band during modification seems to be explained by the emergence of oxygen and zinc vacancies (V _O⁺ and V _Zn⁻) and interstitial oxygen ions (O _i ⁻).     

Absorption band of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> micro- and nanopowders induced by proton and electron bombardment

A comparative analysis of the structure, phase composition, morphology, and diffuse reflection spectra in the region of 0.2–2.5 μm is carried out. Their changes arising from the bombardment of microand nanopowders of yttrium oxide with 100-keV protons and 100-keV electrons is examined. It is found that the reflectance of the nanopowders in the near-IR (infrared) region is less than that of the micropowders and, upon electron bombardment, their radiation resistance is slightly larger as compared to the micropowders.     

Photoluminescence quenching in zinc oxide modified by Al2O3 and Al2O3 · CeO2 Nanopowders under proton irradiations

The photoluminescence spectra of initial ZnO powder and that modified by Al₂O₃, Al₂O₃ · CeO₂ nanopowders are investigated in the range 360–660 nm before and after 100-keV proton irradiation. It is found that the introduction of nanoparticles causes a decrease in the UV-band intensity and a change in the luminescence bands in the visual spectrum due to V _O ⁺ oxygen vacancies, O _int ^- interstitial oxygen, and V _Zn ^- zinc vacancies. Luminescence quenching in the UV and visible spectra occurs under the effect of protons. The decomposition of the spectra into elementary defects and analysis of changes in their integrated intensity during modification and irradiation of the powders are carried out.