Preparation and microstructural characterization of (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions

(Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ (0 ≤ x ≤ 1.0) powders with an average particle size of 100 nm were synthesized with chemical-coprecipitation and calcination method, and were characterized by X-ray diffractometry and scanning electron microscopy. The sintering behaviour of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ powders was studied by pressureless sintering at 1600–1700 °C for 10 h in air. The relative densities of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions increase with increasing the sintering temperature, and gradually decrease with increasing the content of neodymium and cerium at identical temperature levels. (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions have a single phase of defect fluorite-type structure among all the composition combinations studied. The lattice parameters of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions agree well with the Vegard's rule.     

Electron-Capture Cross Sections of Ground-State O2+ Recoil Ions in Slow Collisions with H2 and O2

We report the measured total charge-transfer (electron-capture) cross sections for the ground state O2+ (X2Πg) ions with H₂ and O₂ molecular gases in the collision energy range between 0.50 and 2 keV. The time-of-flight technique has been used to measure the fast neutral products from O2+ charge transfer reactions. The analyzed process has cross sections that continue to increase slowly, as a function of incident energy. Measured cross sections for O2++H2, O₂ systems are compared with previously available experimental and theoretical results in the literature.     

Theoretical analysis and synthesis of Al4O4C and Al2CO phase in the resin bonded Al-Al2O3 refractory in N2-flowing

In flowing nitrogen, Al₄O₄C and Al₂CO bonded Al₂O₃-based composite was successfully prepared by a gaseous phase mass transfer pathway at 1600 °C for 3 h after an Al-AlN core-shell structure was formed in the resin bonded Al-Al₂O₃ refractory at 580 °C for 8 h. The formation mechanism of Al₄O₄C and Al₂CO phase is as follows. An Al-AlN core–shell structure is built at 580 °C for 8 h and broken at higher temperatures, and then, Al(g) reacts with C from the resin and N₂ to form Al₄C₃ and AlN, respectively. Owing to the exothermic reaction of the Al₄C₃ and AlN formation, the reaction temperature in the resin bonded Al-Al₂O₃ refractory is above the practical environmental temperature; for instance, the reaction temperature is above 1715 °C at 1600 °C in this work. Therefore, Al₄C₃ reacts with Al₂O₃ to generate Al₄O₄C and then Al₄O₄C is transformed into Al₂OC by the reaction ${\mathrm{Al}}_4{\mathrm{O}}_{\mathrm{4}}{C(s)+\text{Al}}_4{\mathrm{C}}_{\mathrm{3}}(s)\to {\mathrm{4Al}}_{\mathrm{2}}\text{OC}(s)$ at elevated temperatures. Al₂OC solid solution is finally formed through the dissolution of AlN into Al₂OC.     

The role of Co ion substitution in SnFe2O4 spinel ferrite nanoparticles: Study of structural,vibrational, magnetic and optical properties

In order to accurately investigate the effect of cobalt substitutions in tin ferrite (SnFe₂O₄) properties, we prepared Co_xSn_1-xFe₂O₄ nanoparticles for different Co concentrations, x?=?0.0, 0.25, 0.50, 0.75, and 1.00 using a simple co-precipitation method. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and diffuse reflectance spectra (DRS) are used to study of structural, magnetic, morphology, and optical properties. The XRD and FTIR results confirmed the formation of cubic spinel structure. The lattice parameter and unit cell volume of tin ferrite nanoparticles were found to increase by entering and increasing Co⁺² content in 0.25, and then significantly decrease for higher contents. In accordance with the XRD results, a slight shift in main band υ₁ (${\mathit{Fe}}_{\mathrm{tetra}}^{+3}?O)$ to lower wavenumber and then to higher wavenumber were observed in the IR spectra of Co content x?<?0.25 and x?>?0.25, respectively. In turn to, saturation magnetization, remanent magnetization and anisotropy constant of SnFe₂O₄ nanoparticles were gradually increased for x?=?0.50 and then decreased for x?>?0.50.