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379 results on '"Sun, Shaodong"'

35. Growth of brookite TiO2 nanorods by thermal oxidation of Ti metal in air.

Author

Zhang, Jie, Yang, Qing, Matsushita, Tomoji, Sun, Shaodong, and Tatsuoka, Hirokazu

Abstract

The multiphase TiO2 containing brookite and rutile were grown by thermal oxidation of Ti metal in the range of 650–800 °C. The surface seeds formed by HCl acid solution etching at 80 ℃ promoted the growth of brookite nanorods. The co-growth of two nanorods with a diameter of about 150 nm was observed at 800 °C. The growth mechanism was discussed in consideration of the diffusion behaviour as a function of oxidation temperature and time. The thermal oxidation is a diffusion-controlled process as described by Ds = 3.4exp[−165.5/RT]. The diffusion coefficient at 800 °C is 40 times that at 700 °C, which is the transformation temperature for the diffusion of oxygen in Ti and self-diffusion of Ti. The cathodoluminescent property was evaluated and a strong broad emission band from 400 to 700 nm was observed. The luminescence mechanism is related to the self-trapped excitons on the TiO6 octahedral, oxygen vacancies, the formation of Ti3+ ions and associated defects. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Composition-dependent phase transformation path involving 4O martensite in Ni–Mn–Sn magnetic shape memory alloys.

Author

Li, Yansong, Bai, Jing, Sun, Shaodong, Jin, Miao, Zhang, Yu, Liang, Xinzeng, Gu, Jianglong, Zhang, Yudong, Esling, Claude, Zhao, Xiang, and Zuo, Liang

Subjects
SHAPE memory alloys, PHASE transitions, MARTENSITE, ELECTRONIC density of states, MARTENSITIC transformations, MAGNETIC declination
Abstract

The experimental discovery of four-layer orthorhombic (4O) martensite has added new research motivation to the Ni–Mn–Sn magnetic shape memory alloy. Herein, the martensitic transformation, magnetic properties, and electronic structures of Ni2Mn1+xSn1−x alloys are investigated using the first-principles calculations. The results show that the increasing Mn content destabilizes the stability of austenite (A) compared to the non-modulated (NM) martensite. This composition adjustment promotes the occurrence of martensitic transformation in the range of 0.375 ≤ x ≤ 0.75, and the corresponding phase transition sequence is A → 4O → NM during cooling. An intense hybridization bond exists between excess Mn and its surrounding atoms. The increasing antiferromagnetic interaction between excess Mn and normal Mn weakens each atomic moment and, thus, the total magnetic moment. Furthermore, the physical essence of the phase stability and magnetic properties variation with composition was explained based on the electronic density of states. [ABSTRACT FROM AUTHOR]

Published
2022
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48. A multielement alloying strategy to tune magnetic and mechanical properties in NiMnTi alloys via Co and B.

Author

Liu, Xin, Bai, Jing, Sun, Shaodong, Xu, Jiaxin, Jiang, Xinjun, Guan, Ziqi, Gu, Jianglong, Cong, Daoyong, Zhang, Yudong, Esling, Claude, Zhao, Xiang, and Zuo, Liang

Subjects
MAGNETIC properties, ALLOYS, IRON-manganese alloys, MARTENSITIC transformations, ANTIFERROMAGNETISM, MARTENSITE, AUSTENITE
Abstract

The phase stability, martensitic transformation, and magnetic and mechanical properties of (Ni2-xCoxMn1.5Ti0.5)1-yBy (0 ≤ x ≤ 0.625; y = 0.03 and 0.06) alloys are systematically studied through the first-principles calculations method. The Co and B atoms are inclined to be aggregated distribution in the Ni2Mn1.5Ti0.5 alloy, and the phase stability of the austenite and non-modulated (NM) martensite decreases by co-doping. The ferromagnetic activation effect in the austenite occurs when x = 0.03 and y = 0.625. The magnetism of the austenite changes from an antiferromagnetic to a ferromagnetic state, which is ascribed to the elongation of the nearest neighboring distance of Mn–Mn, the nearest Mn–Mn distance increases from 2.50–2.79 to 2.90–2.94 Å, while the NM martensite always shows antiferromagnetism. Additionally, the doped B accelerates the change from antiferromagnetic to ferromagnetic for the austenite, but B-doping decreases the stability of the whole alloy system. The Co and B co-doping increases the stiffness of the NiMnTi alloy but decreases toughness and plasticity. However, the toughness and plasticity of the NiCoMnTiB alloy are better than those of the NiMnTiB alloy, indicating that the Co doping increases the d-orbital hybridization in the NiMnTiB alloy. The above results are expected to support the performance design of the NiMnTi-based alloy. [ABSTRACT FROM AUTHOR]

Published
2022
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