Study of the Effect of Y2O3 Doping on the Resistance to Radiation Damage of CeO2 Microparticles under Irradiation with Heavy Xe22+ Ions

This paper presents the results of a study on the influence of Y2O3 doping on the resistance to radiation damage and an assessment of structural changes associated with the accumulation of radiation defects in CeO2 microparticles under irradiation with heavy Xe22+ ions. The relevance of this study consists of the prospects for the use of CeO2 microparticles as materials and candidates of inert matrices of nuclear fuel. A method of solid-phase synthesis was applied to obtain microparticles with different concentrations of dopant. It included grinding of CeO2 and Y2O3 microparticles followed by thermal sintering at 1100 °C in an oxygen-containing medium to produce highly ordered microparticles. During the study of the structural characteristics of the synthesized microparticles, it was found that increasing the dopant concentration from 0.05 mol.% to 0.15 mol.% leads to an increase in the crystallinity degree as well as a decrease in dislocation density. According to the results of the assessment of the resistance of microparticles to radiation damage, it was found that an increase in the dopant concentration leads to a decrease in swelling and structural distortion by more than 2.5–3 times, which indicates an increase in the radiation resistance.

Microstructural Evolution and High-Performance Giant Dielectric Properties of Lu3+/Nb5+ Co-Doped TiO2 Ceramics

Giant dielectric (GD) oxides exhibiting extremely large dielectric permittivities (ε’ > 104) have been extensively studied because of their potential for use in passive electronic devices. However, the unacceptable loss tangents (tanδ) and temperature instability with respect to ε’ continue to be a significant hindrance to their development. In this study, a novel GD oxide, exhibiting an extremely large ε’ value of approximately 7.55 × 104 and an extremely low tanδ value of approximately 0.007 at 103 Hz, has been reported. These remarkable properties were attributed to the synthesis of a Lu3+/Nb5+ co-doped TiO2 (LuNTO) ceramic containing an appropriate co-dopant concentration. Furthermore, the variation in the ε’ values between the temperatures of −60 °C and 210 °C did not exceed ±15% of the reference value obtained at 25 °C. The effects of the grains, grain boundaries, and second phase particles on the dielectric properties were evaluated to determine the dielectric properties exhibited by LuNTO ceramics. A highly dense microstructure was obtained in the as-sintered ceramics. The existence of a LuNbTiO6 microwave-dielectric phase was confirmed when the co-dopant concentration was increased to 1%, thereby affecting the dielectric behavior of the LuNTO ceramics. The excellent dielectric properties exhibited by the LuNTO ceramics were attributed to their inhomogeneous microstructure. The microstructure was composed of semiconducting grains, consisting of Ti3+ ions formed by Nb5+ dopant ions, alongside ultra-high-resistance grain boundaries. The effects of the semiconducting grains, insulating grain boundaries (GBs), and secondary microwave phase particles on the dielectric relaxations are explained based on their interfacial polarizations. The results suggest that a significant enhancement of the GB properties is the key toward improvement of the GD properties, while the presence of second phase particles may not always be effective.

PVA/Gd2O3@Zno Nanocomposite Films as New Uv-Blockers: Structure and Optical Revealations

Herein we have synthesised Gadolinium oxide doped Zinc oxide (Gd 2 O 3 @ZnO) by solution combustion method and incorporated it as a nanofiller into Polyvinyl alcohol (PVA) polymer matrix using solution intercalation technique to get PVA/Gd 2 O 3 @ZnO nanocomposite film. The X-ray diffraction (XRD), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC) and UV-Vis spectroscopy were used to investigate the structural, morphological, glass transition temperature and optical properties of synthesized nanocomposites respectively. The optical propertiesof PVA/Gd 2 O 3 @ZnO film shows the interaction of –OH groups in PVA and dopant. From DSC, it is clear that Tg of prepared nano composites increases with increasing in dopant concentration. XRD analysis showed that the crystalline characteristics of the nanocomposites increases with increase in dopant concentration. The UV-Visible spectra reveals that there is decrease in indirect band gap of PVA from 4.94 eV to 3.12 eV and direct band gap from 4.90eV to 3.03 eV compared to pristine PVA Gd 2 O 3 @ZnO doped nanocomposite films showed multifold enhancement in optical characteristics such as refractive index of PVA doped nanocomposites compared pristine PVA, optical conductivity, finess coefficient, extinction coefficient on increasing in dopant concentration (0%, 2%, 4%, 6% and 8wt%). The optical characteristics of PVA/Gd 2 O 3 @ZnO nanocomposite films show excellent UV-blocking behaviour suggesting that, they are promising materials for optical devices.

Investigating on Structural, Optical, Magnetic and Photocatalytic Activities of ZnS and Co2+: ZnS NPs Synthesized by Hydrothermal Process Under MeB Dye

In present work, the structural, morphological, optical and photocatalytic activities of ZnS and Co2+: ZnS NPs were prepared through chemical route as hydrothermal process at room temperature. ZnS and Co2+: ZnS were characterized by using various techniques such as, XRD, SEM-EDX, TEM-SAED, UV-visible, PL and BET. The spherical-like morphology with the average crystallite size was found to be 8 to 15 nm. Among them results, it showed that the Co2+ atoms were incorporated into the ZnS lattice, forming cubic phase as the Co2+ dopant concentration increases from 0 to 2 %. The band gap energy of the ZnS and Co2+: ZnS increases from 3.5 to 4.10 eV, which enables stronger absorption of UV region. During catalytic process, Co2+ act as electron trapping center, which inhibits the recombination of the photo induced holes and electrons as showed higher degradation efficiency for MeB.