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Tran Dang Thanh,Phan, T. L.,Phung Quoc Thanh,Hoang Nam Nhat,Duong Anh Tuan,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.6
<P>This paper presents a detailed study on the Co-doping influence on the electrical and magnetotransport properties of La0.7Ca0.3Mn1-xCoxO3(x = 0.09-0.17) prepared by solid-state reaction. Magnetic measurements versus temperature revealed a gradual decrease of the magnetization (M) and Curie temperature (T-C) with increasing Co concentration (x). The T-C values vary from 194 to 159 K as changing x from 0.09 to 0.17, respectively. H/M versus M-2 performances around T-C prove the x = 0.09 sample undergoing a first-order magnetic phase transition (FOMT) while the samples with x >= 0.11 undergo a second-order magnetic phase transition (SOMT). The other with x = 0.10 is considered as a threshold concentration of the FOMT-SOMT transformation. Considering temperature dependences of resistivity, rho(T), in the presence and absence of the magnetic field, the samples (excepting for x = 0.17) exhibit a metal-insulator transition at T (P) = 60-160 K, which shifts toward lower temperatures with increasing x. In the metallic-ferromagnetic region, the rho(T) data are well fitted to a power function rho(T) = rho(0) + rho(2) T-2 + rho(4.5) T-4.5. This indicates electron-electron and electron-magnon scattering processes are dominant at temperatures T < T (P). In addition, the conduction data at temperatures T > theta(D)/2 (theta(D) is the Debye temperature) and T (P) < T < theta(D)/2 obey the small-polaron and variable-range hopping models, respectively. The values of activation energy E-p, and density of states at the Fermi level N(E-F) were accordingly determined. Here, N(E-F) increases while E-p decreases when an external magnetic field is applied. We also have found that N(E-F) increases when materials transfer from the FOMT to the SOMT, and N(E-F) value becomes smallest for the sample having the coexistence of the FOMT and SOMT (i.e., x = 0.10).</P>
Magnetic properties and magnetocaloric effect in Fe90-x Sn x Zr10 alloy ribbons
Phan, T. L.,Dan, N. H.,Thanh, T. D.,Mai, N. T.,Ho, T. A.,Yu, S. C.,Le, Anh-Tuan,Phan, M. H. Korean Physical Society 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.8
<P>This work points out the possibility of tuning the magnetocaloric (MC) effect in Fe90-x Sn (x) Zr-10 alloy ribbons in the temperature range from 235 to 315 K by changing the Sn-doping content (x). Under an applied field change from 0 to 50 kOe, the maximum magnetic-entropy changes around the ferromagnetic-paramagnetic phase transition are about 3.6, 4.1 and 3.3 J kg(-1)center dot K-1 for x = 0, 2 and 4, respectively, which correspond to relative cooling powers of 280 similar to 410 J center dot kg(-1). Studying the magnetic properties of the alloy ribbons based on Banerjee's criteria and assessing the magneticordering parameter n = dLn|Delta S (m) |/dLnH (where Delta S (m) and H are the magnetic-entropy change and the magnetic field, respectively) reveals that the alloys undergo a second-order phase transition and exhibit a short-range ferromagnetic order. The nature of these phenomena is further analyzed by means of the results obtained from the analyses of the crystal structure, the Curie-Weiss law, and the Griffith phase.</P>
Yen H. Vo,Thanh V. Le,Hieu D. Nguyen,Tuong A. To,Hiep Q. Ha,Anh T. Nguyen,Anh N.Q. Phan,Nam T.S. Phan 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
Zirconium-based metal-organic framework MOF-808 was synthesized, and sulfated with aqueous sulfuric acid. Sulfated MOF-808 was utilized as a recyclable heterogeneous catalyst for the synthesis of quinazolinones from β-ketoesters and benzamides, and for the synthesis of benzimidazoles from β-ketoesters and o-phenylenediamines in glycerol as a green solvent. The sulfated MOF-808 catalyst was more active than many heterogeneous and homogeneous catalysts. The combination of the sulfated MOF-808 and glycerol was also effective for the reaction of o-aminothiophenols with β-diketones or cyclic β-diketones to produce benzothiazoles. To our best knowledge, MOF-based catalysts were not previously utilized as heterogeneous catalyst in glycerol as green solvent.
Khoa D. Nguyen,Son H. Doan,Anh N.V. Ngo,Tung T. Nguyen,Nam T.S. Phan 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.44 No.-
A metal–organic framework Fe3O(BPDC)3 was synthesized, and used as a productive heterogeneouscatalyst for the direct C–N coupling of azoles with ethers via oxidative C–H activation to produce azolederivatives. The MOF-based catalyst displayed higher catalytic efficiency than many homogeneouscatalysts as well as several MOFs in the transformation. The MOF-based catalyst could be reused manytimes for the synthesis of azole derivatives by the direct C–N coupling of azoles with ethers without anoteworthy deterioration in catalytic efficiency. To the best of our knowledge, this direct C–N couplingreaction was not previously performed in the presence of heterogeneous catalysts.
Ngoc Thuy Nguyen,Nhat Thong Tran,Tan Phat Phan,Anh Thu Nguyen,My Xuyen T. Nguyen,Nguyen Ngan Nguyen,Young Ho Ko,Dai Hai Nguyen,Tran T.T. Van,DongQuy Hoang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.108 No.-
While the efficient usage of biomass waste can significantly help in addressing environmental issues,there are only a few reports that discuss about processing such waste effectively at a low-cost. Such challengearises from the strong association between the components biomass. In this study, an abundantagricultural byproduct, rice husk (RH), was used as the starting resource. A simple biorefining processof alkaline peroxide treatment followed by acid precipitation and ethanol extraction was performed onRH to obtain cellulose, hemicellulose, lignin, and silica. The chemical structures, morphologies, andphysic-chemical properties of the separated components were identified through a wide range of characterizationapproaches. The final products obtained from of this process were (i) bundles of fiber-likecellulose with a fiber width of 6 mm and (ii) small particles of hemicellulose and lignin with nonuniformshapes. The lignocelluloses products had over 90 wt% carbon with 52.28% crystalline ratio. Meanwhile, the other products comprising hemicelluloses, lignin, and silica were amorphous. The outcomeof this study contributes to expanding and developing the simple and efficient conversion processof biomass waste into sustainable value-added materials. It is crucial to reduce the environmental impactby using renewable materials as the new building block resources for synthetic chemicals.