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Hung NT, Lam NH, Nguyen AD, Bac LH, Trung NN, Dung DD, Kim YS, N Tsogbadrakh, Ochirkhuyag T, Odkhuu D. Intrinsic and tunable ferromagnetism in Bi 0.5Na 0.5TiO 3 through CaFeO 3-δ modification. Sci Rep 2020; 10:6189. [PMID: 32277074 PMCID: PMC7148307 DOI: 10.1038/s41598-020-62889-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/13/2020] [Indexed: 11/13/2022] Open
Abstract
New (1-x)Bi0.5Na0.5TiO3 + xCaFeO3-δ solid solution compounds were fabricated using a sol–gel method. The CaFeO3-δ materials were mixed into host Bi0.5Na0.5TiO3 materials to form a solid solution that exhibited similar crystal symmetry to those of Bi0.5Na0.5TiO3 phases. The random distribution of Ca and Fe cations in the Bi0.5Na0.5TiO3 crystals resulted in a distorted structure. The optical band gaps decreased from 3.11 eV for the pure Bi0.5Na0.5TiO3 samples to 2.34 eV for the 9 mol% CaFeO3-δ-modified Bi0.5Na0.5TiO3 samples. Moreover, the Bi0.5Na0.5TiO3 samples exhibited weak photoluminescence because of the intrinsic defects and suppressed photoluminescence with increasing CaFeO3-δ concentration. Experimental and theoretical studies via density functional theory calculations showed that pure Bi0.5Na0.5TiO3 exhibited intrinsic ferromagnetism, which is associated with the possible presence of Bi, Na, and Ti vacancies and Ti3+-defect states. Further studies showed that such an induced magnetism by intrinsic defects can also be enhanced effectively with CaFeO3-δ addition. This study provides a basis for understanding the role of secondary phase as a solid solution in Bi0.5Na0.5TiO3 to facilitate the development of lead-free ferroelectric materials.
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Affiliation(s)
- N T Hung
- School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi, Viet Nam
| | - N H Lam
- School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi, Viet Nam
| | - A D Nguyen
- Department of Physics, Faculty of Basic-Fundamental Sciences, Viet Nam Maritime University, 484 Lach Tray Road, Le Chan, Hai Phong, Viet Nam.,Department of Physics, University of Ulsan, Ulsan, 680-749, Republic of Korea
| | - L H Bac
- School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi, Viet Nam
| | - N N Trung
- School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi, Viet Nam
| | - D D Dung
- School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi, Viet Nam.
| | - Y S Kim
- Department of Physics, University of Ulsan, Ulsan, 680-749, Republic of Korea.
| | - N Tsogbadrakh
- Department of Physics, National University of Mongolia, Ulaanbaatar, 14201, Mongolia
| | - T Ochirkhuyag
- Department of Physics, Incheon National University, Incheon, 22012, Republic of Korea
| | - D Odkhuu
- Department of Physics, Incheon National University, Incheon, 22012, Republic of Korea.
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Bien TN, Gul WH, Bac LH, Kim JC. Preparation and characterization of copper-graphite composites by electrical explosion of wire in liquid. J Nanosci Nanotechnol 2014; 14:8750-8755. [PMID: 25958597 DOI: 10.1166/jnn.2014.9995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Copper-graphite nanocomposites containing 5 vol.% graphite were prepared by a powder metallurgy route using an electrical wire explosion (EEW) in liquid method and spark plasma sintering (SPS) process. Graphite rods with a 0.3 mm diameter and copper wire with a 0.2 mm diameter were used as raw materials for EEWin liquid. To compare, a pure copper and copper-graphite mixture was also prepared. The fabricated graphite was in the form of a nanosheet, onto which copper particles were coated. Sintering was performed at 900 degrees C at a heating rate of 30 degrees C/min for 10 min and under a pressure of 70 MPa. The density of the sintered composite samples was measured by the Archimedes method. A wear test was performed by a ball-on-disc tribometer under dry conditions at room temperature in air. The presence of graphite effectively reduced the wear of composites. The copper-graphite nanocomposites prepared by EEW had lower wear rates than pure copper material and simple mixed copper-graphite.
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Bac LH, Ryu HJ, Kim BK, Kim JS, Kim JC. Production and determination of the magnetic properties of the Fe-36Ni nanopowder via electrical explosion of wire in water and compacted alloy. J Nanosci Nanotechnol 2011; 11:6433-6436. [PMID: 22121730 DOI: 10.1166/jnn.2011.4397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fe-36Ni alloy nanopowder was prepared via electrical explosion of wire in DI water. The nanopowder was reduced in hydrogen at 500 degrees C for 30 min. Spark plasma sintering at 800 and 1000 degrees C for 10 min was used to obtain bulk samples from the hydrogen-reduced nanopowder. The sintered samples were annealed at 500 degrees C for 2 h. X-ray diffraction was used to analyze the phases of the nanopowder and sintered samples. The results showed that the sintered samples were formed in gamma-(Fe-Ni) solid solution. The particles sizes and morphologies of the as-synthesized and hydrogen-reduced nanoparticles were observed via transmission electron microscopy. The morphologies of the as-synthesized nanoparticles had spherical core-shell structures. Core was gamma-(Fe-Ni) and the shell was FeO. The nanoparticles of the as-synthesized and hydrogen reduced samples were found to be nearly spherical in shape, with average diameters of 32 and 70 nm, respectively. The hysteresis loops of the as-synthesized nanopowder, hydrogen reduced nanopowder, and sintered samples revealed ferromagnetic characteristics.
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Affiliation(s)
- L H Bac
- School of Materials Science Engineering, University of Ulsan, San-29, Mugeo-2 Dong, Nam-Ku, Ulsan, 680-749, South Korea
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Yun GS, Bac LH, Kim JS, Kwon YS, Choi HS, Kim JC. Effect of synthetic temperature on the dispersion stability of gold nanocolloid produced via electrical explosion of wire. J Nanosci Nanotechnol 2011; 11:6429-6432. [PMID: 22121729 DOI: 10.1166/jnn.2011.4394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this study, gold nanocolloid was produced via the electrical explosion of wire in water, for the purpose of medical treatment. Thus, the use of other additives was avoided to stabilize the gold nanocolloid. The temperature of the water that was to be used for explosion was changed, and its effect on the stability of the gold nanocolloid was investigated. The synthetic temperature was varied from ice temperature to 80 degrees C. The morphology and particle size were studied using a transmission electron microscope. The UV-Vis spectra confirmed the formation of gold nanoparticles in the water. The stability of the gold nanocolloid was estimated using the zeta-potential and Turbiscan methods. The results showed that the synthetic temperature affected the stability of the gold nanocolloid. The TEM images of the gold nanoparticles prepared at low temperatures (0 and 20 degrees C) have several big particles. But, when the synthetic temperature was increased to 80 degrees C, most of the nanoparticles formed a spherical shape, without neck connection. Better stability was obtained in the gold nanocolloid sample prepared at a higher temperature. The gold nanocolloid that was synthesized at 80 degrees C was stable for more than three months, with small sedimentation.
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Affiliation(s)
- G S Yun
- School of Materials Science and Engineering, University of Ulsan, Daehak-ro 102, Nam-gu, Ulsan 680-749, South Korea
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Bac LH, Yun GS, Kim JS, Choi HS, Kim JC. Preparation and stability of gold colloid by electrical explosion of wire in various media. J Nanosci Nanotechnol 2011; 11:1730-1733. [PMID: 21456278 DOI: 10.1166/jnn.2011.3345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Gold colloids were prepared by electrical explosion of wire in various media: cold water (0 degrees C), room temperature water (25 degrees C), hot water (80 degrees C), 0.01 M polysorbate surfactant 20 (TW 20) solution, mixture of 0.01 M TW 20 and 0.01 M ascorbic acid. The size distribution of nanoparticles measured by transmission electron microscope was found to shift to a smaller size with a decrease of temperature and a presence of TW 20 surfactant. The multiple light scattering results showed that medium temperature and ambient medium of explosion process is much influence on the stability of colloid. The gold colloid prepared in cold water is unstable in comparison with one prepared in warm and hot water. The best stability of gold colloid obtained with explosion medium of TW 20 and ascorbic acid solution.
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Affiliation(s)
- L H Bac
- School of Materials Science and Engineering, University of Ulsan, San-29, Mugeo-2Dong, Nam-Ku, Ulsan 680-749, Korea
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Bac LH, Kim JS, Kim JC. Synthesis of Fe–Ni invar alloy nanopowder by the electrical explosion of wire in the liquid. Res Chem Intermed 2010. [DOI: 10.1007/s11164-010-0183-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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