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Electrical and Mechanical Properties of CeO2-Based Thin-Film Coatings Obtained by Electrophoretic Deposition
摘要： Nanometer Ce0.8(Sm0.75Sr0.20Ba0.05)0.2O2 – δ powder with mean nanoparticle size of 15 nm has been obtained by laser evaporation of a solid-phase target followed by condensation. The nanopowder has been used to prepare suspensions for electrophoretic deposition in a mixed isopropanol : acetyl acetone = 50 : 50 vol % disperse medium offering the unique property of self-stabilization. Optimal conditions for electrophoretic deposition have been found, and uniform thin-film electrolytic coatings have been formed on a La2NiO4 cathodic carrier substrate (12–15% porosity). It has been shown that the resulting electrolyte offers a high adhesivity and has, after sintering at 1400°C, a compact granular structure with grains from 1 to 8 μ m in size. The conductivity of the 2-μ m-thick electrolyte equals 0.1 S/cm at 650°C.
关键词： solid oxide fuel cells,nanopowder,electrophoretic deposition,conductivity,CeO2-based thin-film coatings
更新于2025-09-09 09:28:46
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi, Georgia (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Magnetometry and NMR Study of Carbon Nanopowders Doped with Cobalt Nanoclusters and Self-assembly of their Polymer Nanocomposites under Magnetic Field
摘要： The RF resonant magnetometry and NMR studies were carried out on carbon nanoparticles doped with magnetic cobalt clusters, which were synthesized by a technology combining of the hydrocarbon vapor pyrolysis and the chemical vapor deposition (CVD) process in a horizontal continuous reactor. The RF resonant magnetometry data show that the obtained carbon cobalt nanopowders are superparamagnetic at room temperatures and ferromagnetic at liquid nitrogen temperatures. The NMR study with the excitation by additional magnetic video-pulses of nanopowders obtained by using different hydrocarbons pyrolysis made it possible a fast assessment of their magnetic phase and hardness properties. The simple non-contact RF resonant magnetometry study of self-assembling processes in carbon cobalt polymer composite films synthesized using these nanopowders was made also.
关键词： magnetic nanoclusters,carbon nanopowder,core-shell structure,self-assembly,NMR,cobalt
更新于2025-09-04 15:30:14
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Improve spectroscopic structural and AC electrical conductivity of PC/PEO blend using graphene
摘要： Nanocomposites of polycarbonate (PC) and polyethylene oxide (PEO) embedded with graphene oxide (GO) nanopowder have been prepared using casting method. Prepared nanocomposites are studied and investigated using di?erent characterization techniques. The X-ray di?raction (XRD) pattern reveals the semi-crystalline nature of PC/PEO blend. There are no signi?cant peaks characterizing pure graphene. The intensity of the main X-ray peak characterizing the blend is decreased with the increase of graphene content con?rming a mod- i?cation in the blend due to an addition of graphene oxide. The FT-IR spectra display the main characteristic IR bands due to vibrational function groups for the components. The Optical absorption spectra are measured as a function of wavelength in the range of 190–1100 nm. The UV/V spectra show two absorption bands at 290 and 620 nm due to electronic transitions. The value of Eg is obtained using indirect transition and its decrease with increasing the amount of graphene. The behavior of ε′ and ε″ decreased with the increase of frequencies is observed. After adding graphene, the frequency is increased due to the dipole moment. The decrease of ε″ with increases of both the frequency and the temperature attributed to the origin of ε″ is the conduction losses. The decrease of dissipation factor (tan δ) is ascribed to the internal polarization mechanism related to applied fre- quencies. The maximum value of the peak at M″ relation explained as being the result of the distribution of relaxation time.
关键词： Graphene nanopowder,AC conductivity,FT-IR,XRD,PC/PEO blend
更新于2025-09-04 15:30:14
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A low temperature approach for photo/cathodoluminescent Gd <sub/>2</sub> O <sub/>2</sub> S:Tb (GOS:Tb) nanophosphors
摘要： Titrating the aqueous solution of equimolar RE(NO3)3 and (NH4)2SO4 with NH4OH to pH~9 at ~4 °C produced an amorphous precursor that yielded phase-pure and well dispersed RE2O2S nanopowder (RE=Gd0.99Tb0.01; GOS:Tb) via a RE2O2SO4 intermediate upon annealing in H2. The powders calcined at the typical temperatures of 700/1200 °C exhibited unimodal size distributions and have the average crystallize sizes of ~17/55 nm, average particle sizes of ~284/420 nm, and specific surface areas of ~14.62/4.53 m2/g (equivalent particle sizes: ~56/180 nm). The 1200 °C product exhibited sharp green luminescence at ~544 nm (FWHM = 2.3 nm; λex = 275 nm), with an absolute quantum yield of ~24.8% and a fluorescence lifetime of ~1.34 ms at room temperature. It was also shown that the powder possesses favorable thermal stability (the activation energy for thermal quenching of luminescence ~0.305 eV) and is stable under electron beam irradiation up to 7 kV and 50 μA. The synthetic technique has the advantages of scalability and favorable dispersion and high chemical/phase purity for GOS powder, which may allow the sintering of scintillation ceramics at lower temperatures.
关键词： low-temperature processing,oxysulfide,GOS,luminescence,nanopowder
更新于2025-09-04 15:30:14