In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on prepar...In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on preparation, X-ray diffraction with Rietveld refinement, AC susceptibility, DC resistivity measurements, and heat treatment effects. Two heat treatment types were applied: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. As the rare earth Ln’s ionic radius increased, certain parameters notably changed. Specifically, c parameter, surface area S, and volume V increased, while critical temperature Tc and holes (p) in the CuO<sub>2</sub> plane decreased. The evolution of these parameters with rare earth Ln’s ionic radius in [AO] heat treatment is linear. Regardless of the treatment, the structure is orthorhombic for Ln = Eu, tetragonal for Ln = Nd, orthorhombic for Ln = Sm [AO], and pseudo-tetragonal for Sm [O]. The highest critical temperature is reached with Ln = Eu (Tc [AO] = 87.1 K). Notably, for each sample, Tc [AO] surpasses Tc [O]. Observed data stems from factors including rare earth ionic size, improved cationic and oxygen chain order, holes count p in Cu(2)O<sub>2</sub> planes, and in-phase purity of [AO] samples. Our research strives to clearly demonstrate that the density of holes (p) within the copper plane stands as a determinant impacting the structural, electrical, and superconducting properties of these samples. Meanwhile, the other aforementioned parameters contribute to shaping this density (p).展开更多
We report the structural, optical and electrical properties of Graphene-Vanadium oxide nanoparticles (rGO/VO-NPs) nanocomposites prepared via a hydrothermal method on glass substrates. The samples have been characteri...We report the structural, optical and electrical properties of Graphene-Vanadium oxide nanoparticles (rGO/VO-NPs) nanocomposites prepared via a hydrothermal method on glass substrates. The samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, ultraviolet-visible spectra (Uv-Vis) (absorbance/reflectance) and electrical conductivity. Our results are revealing a remarkable effect on the morphology and structure of vanadium oxide nanoparticles. Hence, the graphene layers improved their electrical conductivity and highly influenced their optical properties. Therefore, the obtained results may lead to better performance for a large field of applications.展开更多
It is universally known that the preparation of high quality graphene on a large scale and in a cost-effective manner is essential for many technological applications. Graphene oxide (GO) has emerged as the precursor ...It is universally known that the preparation of high quality graphene on a large scale and in a cost-effective manner is essential for many technological applications. Graphene oxide (GO) has emerged as the precursor of choice for bulk production of graphene-based materials, as it can be synthesized from inexpensive graphite powders. In this paper, a simple method is described for reduction of GO solution by a free and green irradiation based technique. The majority of oxygen-containing functional groups of GO are removed by sun light. This methodology provides an effective way to quantitatively produce high quality graphene sheets. This paper presents irradiation by sun light of synthesized graphene oxide nano-flakes prepared by Hummer’s method. These nano-flakes have been successfully reduced while the dynamic of this irradiation process is discussed. The irradiated nano-flakes of graphene oxide have been investigated using X-Ray diffraction, ATR-FTIR and UV-Vis-NIR.展开更多
Graphene is a single layer of carbon atoms arranged in a two dimension hexagonal lattice. It appeared very quickly that this exceptional material had truly outstanding electronic, mechanical, thermal and optical prope...Graphene is a single layer of carbon atoms arranged in a two dimension hexagonal lattice. It appeared very quickly that this exceptional material had truly outstanding electronic, mechanical, thermal and optical properties. The main goal of this work is the confinement of graphene nanosheets in an individual polymeric nanofiber and the study of their vibrational and thermal properties in one dimension. After their preparation, graphene sheets were mixed with Polyethylene oxide (PEO) solution to be electrospinned. The synthesized nanofibers were systematically investigated by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements and their morphology and structure were characterized by atomic force microscopy (AFM), optical microscope and Scanning Electron Microscope (SEM) and finally thermogravimetric analysis (TGA) to check G/PEO mass ratio and interactions to prove the capability of PEO to be a good envelope for the confinement and the alignment of graphene nanosheets in a one dimensional system.展开更多
Graphene is a two-dimensional crystal of carbon atoms arranged in a honeycomb lattice. It is a zero band gap semimetal with very unique physical and chemical properties which make it useful for many applications such ...Graphene is a two-dimensional crystal of carbon atoms arranged in a honeycomb lattice. It is a zero band gap semimetal with very unique physical and chemical properties which make it useful for many applications such as ultra-high-speed field-effect transistors, p-n junction diodes, terahertz oscillators, and low-noise electronic, NEMS and sensors. When the high quality mass production of this nanomaterial is still a big challenge, we developed a process which will be an important step to achieve this goal. Atomic Force Microscopy, Scanning Electron Microscopy, Scanning tunneling microscopy, High Resolution Transmission Electron Microscopy, X-Ray Diffraction, Raman spectroscopy, Energy Dispersive X-ray system were investigated to characterize and examine the quality of this product.展开更多
文摘In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on preparation, X-ray diffraction with Rietveld refinement, AC susceptibility, DC resistivity measurements, and heat treatment effects. Two heat treatment types were applied: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. As the rare earth Ln’s ionic radius increased, certain parameters notably changed. Specifically, c parameter, surface area S, and volume V increased, while critical temperature Tc and holes (p) in the CuO<sub>2</sub> plane decreased. The evolution of these parameters with rare earth Ln’s ionic radius in [AO] heat treatment is linear. Regardless of the treatment, the structure is orthorhombic for Ln = Eu, tetragonal for Ln = Nd, orthorhombic for Ln = Sm [AO], and pseudo-tetragonal for Sm [O]. The highest critical temperature is reached with Ln = Eu (Tc [AO] = 87.1 K). Notably, for each sample, Tc [AO] surpasses Tc [O]. Observed data stems from factors including rare earth ionic size, improved cationic and oxygen chain order, holes count p in Cu(2)O<sub>2</sub> planes, and in-phase purity of [AO] samples. Our research strives to clearly demonstrate that the density of holes (p) within the copper plane stands as a determinant impacting the structural, electrical, and superconducting properties of these samples. Meanwhile, the other aforementioned parameters contribute to shaping this density (p).
文摘We report the structural, optical and electrical properties of Graphene-Vanadium oxide nanoparticles (rGO/VO-NPs) nanocomposites prepared via a hydrothermal method on glass substrates. The samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, ultraviolet-visible spectra (Uv-Vis) (absorbance/reflectance) and electrical conductivity. Our results are revealing a remarkable effect on the morphology and structure of vanadium oxide nanoparticles. Hence, the graphene layers improved their electrical conductivity and highly influenced their optical properties. Therefore, the obtained results may lead to better performance for a large field of applications.
文摘It is universally known that the preparation of high quality graphene on a large scale and in a cost-effective manner is essential for many technological applications. Graphene oxide (GO) has emerged as the precursor of choice for bulk production of graphene-based materials, as it can be synthesized from inexpensive graphite powders. In this paper, a simple method is described for reduction of GO solution by a free and green irradiation based technique. The majority of oxygen-containing functional groups of GO are removed by sun light. This methodology provides an effective way to quantitatively produce high quality graphene sheets. This paper presents irradiation by sun light of synthesized graphene oxide nano-flakes prepared by Hummer’s method. These nano-flakes have been successfully reduced while the dynamic of this irradiation process is discussed. The irradiated nano-flakes of graphene oxide have been investigated using X-Ray diffraction, ATR-FTIR and UV-Vis-NIR.
基金supported by USMBA,NanoAfNet and Technologia University
文摘Graphene is a single layer of carbon atoms arranged in a two dimension hexagonal lattice. It appeared very quickly that this exceptional material had truly outstanding electronic, mechanical, thermal and optical properties. The main goal of this work is the confinement of graphene nanosheets in an individual polymeric nanofiber and the study of their vibrational and thermal properties in one dimension. After their preparation, graphene sheets were mixed with Polyethylene oxide (PEO) solution to be electrospinned. The synthesized nanofibers were systematically investigated by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements and their morphology and structure were characterized by atomic force microscopy (AFM), optical microscope and Scanning Electron Microscope (SEM) and finally thermogravimetric analysis (TGA) to check G/PEO mass ratio and interactions to prove the capability of PEO to be a good envelope for the confinement and the alignment of graphene nanosheets in a one dimensional system.
文摘Graphene is a two-dimensional crystal of carbon atoms arranged in a honeycomb lattice. It is a zero band gap semimetal with very unique physical and chemical properties which make it useful for many applications such as ultra-high-speed field-effect transistors, p-n junction diodes, terahertz oscillators, and low-noise electronic, NEMS and sensors. When the high quality mass production of this nanomaterial is still a big challenge, we developed a process which will be an important step to achieve this goal. Atomic Force Microscopy, Scanning Electron Microscopy, Scanning tunneling microscopy, High Resolution Transmission Electron Microscopy, X-Ray Diffraction, Raman spectroscopy, Energy Dispersive X-ray system were investigated to characterize and examine the quality of this product.
