VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2024-03-28T20:24:54ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2022-10-26T21:59:41Z2022-10-26T21:59:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4757This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47572022-10-26T21:59:41ZElectrical measurement-type surface plasmon resonance sensor, Electrical measurement-type surface plasmon resonance sensor chip, and method for detecting change in surface plasmon resonanceAmrita SanaGiles AllisonHironoki SuzukiHidemi KatoMasao AndoViet Cuong Le2022-10-26T21:59:36Z2022-10-26T21:59:36Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4758This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47582022-10-26T21:59:36ZElectrical measurement-type surface plasmon resonance sensor, Electrical measurement-type surface plasmon resonance sensor chip, and method for detecting change in surface plasmon resonanceAmrita SanaGiles AllisonHironoki SuzukiHidemi KatoMasao AndoViet Cuong Le2022-09-20T15:38:40Z2022-09-20T15:38:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4759This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47592022-09-20T15:38:40ZElectricity measuring type surface plasmon resonance sensor, Electricity measuring type surface plasmon resonance sensor chip, method for detecting surface plasmon resonance changesAmrita SanaGiles AllisonHironoki SuzukiHidemi KatoMasao AndoViet Cuong Le2021-12-13T03:53:43Z2021-12-13T03:53:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4633This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46332021-12-13T03:53:43ZMagnetic and electrical properties of Ni‑doped Ba(Ti0.8Zr0.2)O3
materialsIn this work, Ni-doped lead-free ferroelectric Ba(Ti0.8Zr0.2)O3 materials were well synthesized by a simple chemical route. The complex magnetic behavior of the materials was explained by the random distribution of Ni cations into the Ba(Ti0.8Zr0.2)O3 host lattice. As increasing the Ni concentration to 9 mol%, nonlinear electric polarization behavior remained unchanged in the Ba(Ti0.8Zr0.2)O3 materials. The observations in nonlinear magnetization and electric polarization in Ni-doped Ba(Ti0.8Zr0.2)O3 materials suggested an extension of new material functions to the development of advanced materials for electronic devices.Dang Co Nguyencond@vnu.edu.vn2021-06-28T02:42:11Z2022-08-22T03:59:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4498This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44982021-06-28T02:42:11ZNANOSTRUCTURED LAYERS AND LANGMUIR-SCHAEFER FILMS OF TUNGSTEN TRIOXIDEGlobal warming is a pressing issue and many studies have been performed to solve this problem, including applications of nanomaterials in energy-saving systems. This research focuses on the fabrication of tungsten trioxide (WO3) films, a nanomaterial, used in electrochromic devices such as smart window due to its chromic properties.
We synthesized stable floating layers of octadecylamine (ODA) and Na2WO4 in the interface of water-air employing Langmuir-Blodgett method. The compression and chemical volumes were precalculated using Hyperchem to find optimal values. Sodium tungstate salt dissolved in double-distilled water and was poured into the trough. Solution ODA in chloroform was spread on the surface of a liquid by Hamilton syringe and then compressed with the rate of 1.42 cm2/min. The obtained complex ODA and anion was transferred to a glass substrate, annealed at above 350°C, and analyzed. Available wetting methods showed that the substrate turned from a hydrophobic state to a hydrophilic state upon annealing. The absorbance spectrum showed increased absorption in the UV region and relatively low absorption in the visible region (bleached state). Under SEM analysis, the particles were distributed evenly, with some inconsistent particle groupings. Further improvements will be implemented with film quality and annealing temperatures, as well as deposition methods.Thi Thao Vuvtthao@vnu.edu.vnTri Duc LuongThanh Hung ChuDuc Cuong Nguyencuongnd@vnu.edu.vn2021-06-28T02:34:32Z2021-06-28T02:34:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4548This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45482021-06-28T02:34:32ZElectrodeposited nickel–graphene nanocomposite coating: influence of graphene nanoplatelet size on wear and corrosion resistanceIn this paper, we broaden our previous work, which investigated the influence of graphene nanoplatelets (GNPs) size on
microstructure and hardness of composite coatings, to determine the effect of GNP size on wear-resistance and anti-corrosion
property of GNP-reinforced nickel coating (Ni/GNPs). The experimental results indicated that the small GNP material size
could enhance the wear resistance for nickel composite coating with the wear rate of 13.2 × 10–
4 mm3/
Nm, the wear depth
of 17.69 μm. Meanwhile, the anti-corrosion property is enhanced significantly, this is shown via the low corrosion current
density (Icorr value of 1.16 × 10–
7 A/cm2) and the high corrosion potential (Ecorr value of − 0.1661 V). In addition, the mass
lost in salt fog testing is low with the weight of 12.3 mg, which decreased down to ~ 55.27% compared to pristine Ni coating.
These results are attributed to the uniform distribution of the small GNP size inside Ni matrix as well as the grain refinement
effect of composite coating when using the small GNP size.Van Hau TranVan Trinh PhamVan Tu NguyenNguyen Duc Duoc PhanThi Phuong MaiXuan Toan NguyenDinh Phuong DoanPhuong Hoai Nam Nguyennamnph@vnu.edu.vnDinh Lam VuNgoc Minh PhanHung Thang Buithangbh@ims.vast.vn2021-06-21T07:07:39Z2021-06-21T07:07:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4497This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44972021-06-21T07:07:39ZNANOSTRUCTURED LAYERS AND LANGMUIR-SCHAEFER FILMS OF TETRAPHENYLPORPHINEThis work aimed to obtain stable nanostructured floating monolayers and thin films of tetraphenylporphin (H2TPP) by the Langmuir-Schaefer (LS) method. The layer structure was analyzed within the framework of the model of a nanostructured M-monolayer using a quantitative method for analyzing compression isotherms [1-4]. The obtained LS films were examined by electron absorption spectroscopy (Fig. 1a) and electron microscopy (SEM) (Fig. 1b).
(a) (b)
Fig. 1. (a) UV-vis spectra of a solution of H2TPP in CH2Cl2 (red) and its LS-films (49 layers, black). On the UV-vis insert, the spectra of films of various thicknesses (2-49 layers); (b) SEM image of LS-film H2TPP.
It was found that H2TPP at the water-air interface at different initial degrees of surface coverage (cface) forms nanostructured edge-on monolayers. The main characteristics of the layers are determined. It was shown that H2TPP forms two-dimensional nanostructures of a very large size - about 60 nm in diameter. In LS-films, these nanostructures are combined into even larger ones - the average diameter is about 250 nm (Fig. 1b). The spectra of Н2ТРР LS films are characterized by a strong bathochromic shift of the Soret band (by 21 nm) and Q-bands (by 4-6 nm) relative to the spectrum of the solution (Fig. 1a), which indicates the formation of J-type nanoaggregates.Thi Thao Vuvtthao@vnu.edu.vn2021-06-21T07:06:26Z2021-06-21T07:06:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4500This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45002021-06-21T07:06:26ZStructural evolution and magnetic properties of Bi0.86Nd0.14Fe1-xTixO3 ceramicsCeramic Bi0.86Nd0.14Fe1-xTixO3 (0.02 ≤ x ≤ 0.1) compounds were prepared to study the structural evolution, microstructure, and magnetic properties. The structural analysis by X-ray diffraction and Rietveld refinement revealed a coexistence of the polar rhombohedral (R3c symmetry) and antipolar orthorhombic (Pbam symmetry)
structures over the entire composition range, while Raman scattering spectroscopy detected not only the phonon
vibrations of the R3c and Pbam but also the Pbnm symmetries. The microstructure investigation showed the small
and large grain size regions corresponding to the R3c and Pbam/Pbnm phases, respectively. The dependence of
magnetization on the Ti concentration suggested that the weak ferromagnetism observed in the compounds arised from the intrinsic collapse of cycloidal order rather than defect-induced magnetism. The magnetic aging observed at room temperature was explained on the basic of phase switching and spin frustration at the phase boundary. The influence of phase switching induced by an external electric field on the magnetic properties was also studied to reveal the contribution of phase boundary spins to the net magnetization.Thi Minh Hong Nguyenhongntm@vnu.edu.vnDang Co Nguyencond@vnu.edu.vnThi Anh Hoanhht@vnu.edu.vnDinh Tu Buibuidinhtu@vnu.edu.vn2021-06-21T07:06:12Z2021-06-21T07:06:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4499This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44992021-06-21T07:06:12ZElectronic structure and multiferroic properties of (Y, Mn)-doped barium hexaferrite compoundsWe have systematically studied the crystal and electronic structures and the magnetic and electrical polarization properties of polycrystalline Ba0.95Y0.05Fe12−xMnxO19 (denoted as BaYFe12−xMnxO19) compounds with x = 0–2. The analyzes of X-ray diffraction patterns and Raman scattering spectra indicated their single phase in the M-type hexaferrite structure. With increasing x, the lattice constant a slightly increased while c decreased, which related to the Jahn-Teller effect. Though an increase of x reduced gradually magnetization in a range of 23–32 emu/g, the coercive force increased from 3.3 kOe for x = 0 to about 4 kOe for x = 0.5–2. The study of the electrical polarization properties proved the dependence of the shape of electric hysteresis loops on x and applied electric field. The samples with x = 0 and 0.5 exhibit a weak ferroelectricity with the maximum polarization of ~0.11 μC/cm2 for x = 0, and of ~0.06 μC/cm2 for x = 0.5. Meanwhile, the other samples showed nearly circular hysteresis loops, which are characteristic of conductive materials. Detailed investigations indicated an increase in leakage current when x increased. All of such phenomena are tightly related to the chemical shift of Mn2+ → Mn3+ and the replacement of Mn2+,3+ for Fe3+ in BaYFe12−xMnxO19. These oxidation states and the chemical shift of Mn have been confirmed upon analyzing X-ray absorption spectraDuc Thang Phampdthang@vnu.edu.vnDang Co Nguyencond@vnu.edu.vnThi Minh Hong Nguyenhongntm@vnu.edu.vnThi Anh Hoanhht@vnu.edu.vn