Yongjun Zhan
Chinese Academy of Sciences
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Featured researches published by Yongjun Zhan.
Scientific Reports | 2013
Yaoming Sun; Xiudi Xiao; Gang Xu; Guoping Dong; Guanqi Chai; Hua Zhang; Pengyi Liu; Hanmin Zhu; Yongjun Zhan
VO2 (M) STF through reduction of V2O5 STF was prepared. The results illustrate that V2O5 STF can be successfully obtained by oblique angle thermal evaporation technique. After annealing at 550°C/3 min, the V2O5 STF deposited at 85° can be easily transformed into VO2 STF with slanted columnar structure and superior thermochromic properties. After deposition SiO2 antireflective layer, Tlum of VO2 STF is enhanced 26% and ΔTsol increases 60% compared with that of normal VO2 thin films. Due to the anisotropic microstructure of VO2 STF, angular selectivity transmission of VO2 STF is observed and the solar modulation ability is further improved from 7.2% to 8.7% when light is along columnar direction. Moreover, the phase transition temperature of VO2 STF can be depressed into 54.5°C without doping. Considering the oblique incidence of sunlight on windows, VO2 STF is more beneficial for practical application as smart windows compared with normal homogenous VO2 thin films.
Scientific Reports | 2016
Ziyi Cao; Xiudi Xiao; Xuanming Lu; Yongjun Zhan; Haoliang Cheng; Gang Xu
In this approach, the VO2 nanoparticles have been successfully fabricated via combusting the low-cost precursor solution consisted of NH4VO3, C2H6O2 and C2H5OH. By the XRD, TEM and XPS analysis, it can be found that the synthetic monoclinic VO2 is single crystal and no impurity is defined. After dispersing the VO2 nanoparticles into the polymer, the solar modulation of VO2-based composite film is up to 12.5% with luminous transmission and haze around 62.2% and 0.5%, respectively. In other words, the composite films show high performance of thermochromic properties. This could open an efficient way to fabricate low-cost and large-scale VO2 (M) nanoparticles and thermochromic films.
RSC Advances | 2016
Xuanming Lu; Xiudi Xiao; Ziyi Cao; Yongjun Zhan; Haoliang Cheng; Gang Xu
In this study, the VO2@SiO2@Au core–shell nanoparticles were synthesized by a solution process to tailor the color of VO2 films on the basis of surface plasmon resonance (SPR). The SiO2 interlayer not only provided more hydroxyl bonding for the silane coupling agent, which was conducive to metal deposition, but also significantly improved the anti-oxidation ability of VO2. We optimized the thickness of silica to maintain the silica layer uniform and thin (14 nm), which would impact on the optical properties. The VO2@SiO2@Au films with various Au particle sizes displayed a series of colors from brick red to purple and blue while maintaining the solar modulation ability (the maximum ΔTsol is up to 7.52%). Moreover, the phase transition temperature decreased by about 6 °C without doping due to electron injection from Au to VO2. This study proposed a novel and facile method to tune the color of VO2-based thermochromic smart films while improving the anti-oxidation ability and decreasing the phase transition temperature. It may constitute a great advance in the development of thermochromic smart films.
ACS Applied Materials & Interfaces | 2018
Yuan Lu; Xiudi Xiao; Yongjun Zhan; Changmeng Huan; Shuai Qi; Haoliang Cheng; Gang Xu
Paraffin wax (PW) is widely used for smart thermoregulation materials due to its good thermal performance. However, the leakage and low thermal conductivity of PW hinder its application in the heat storage field. Accordingly, developing effective methods to address these issues is of great importance. In this study, we explored a facile approach to obtain PW-loaded core-sheath structured flexible nanofibers films via coaxial electrospinning technique. The PW as the core layer was successfully encapsulated by the sheath-layer poly(methyl methacrylate). The diameter of the fiber core increased from 395 to 848 nm as the core solution speed rate increased from 0.1 to 0.5 mL/h. In addition, it can be seen that higher core solution speed rate could lead to higher PW encapsulation efficiency according to the transmission electron microscopy results. The core-sheath nanofiber films, moreover, possessed the highest latent heat of 58.25 J/g and solidifying enthalpy of -56.49 J/g. In addition, we found that after 200 thermal cycles, there was little change in latent heat, which demonstrated that it is beneficial for the PW-loaded core-sheath structure to overcome the leakage issue and enhance thermal stability properties for the thermoregulation film.
AOPC 2017: Optoelectronics and Micro/Nano-Optics | 2017
Yongjun Zhan; Xiudi Xiao; Yuan Lu; Ziyi Cao; Haoliang Cheng; Jifu Shi; Gang Xu
The VOx thin films are successfully prepared on glass substrate by reactive magnetron sputtering at room-temperature, and subsequently annealed by rapid thermal annealing system in N2 from 0.5Pa to 10000Pa. The effects of annealing pressure on the optical performance and phase transition temperature (Tc) of VOx thin films are systematically investigated. The results show that the VOx thin films exhibit good performance with Tlum of 28.17%, ΔTsol of 12.69%, and Tc of 42. The annealing pressure had an obvious influence on the grain size, which can be attributed to light scattering effects by gas molecule. Compared with oxygen vacancy defects, the grain size plays a decisive role in the regulation of Tc. The restricting the growth of grain can be reduced the Tc, and a little deterioration effect on optical performance can be observed. In addition, the method in this paper not only depressed the Tc, but also simplified the process and improved efficiency, which will provide guidance for the preparation and application of VOx thin films.
Journal of Alloys and Compounds | 2015
Hua Zhang; Xiudi Xiao; Xuanming Lu; Guanqi Chai; Yaoming Sun; Yongjun Zhan; Gang Xu
Solar Energy Materials and Solar Cells | 2018
Yongjun Zhan; Xiudi Xiao; Yuan Lu; Ziyi Cao; Shuai Qi; Changmeng Huan; Haoliang Cheng; Jifu Shi; Gang Xu
Applied Surface Science | 2017
Yuan Lu; Xiudi Xiao; Ziyi Cao; Yongjun Zhan; Haoliang Cheng; Gang Xu
Ceramics International | 2018
Yuan Lu; Xiudi Xiao; Yongjun Zhan; Ziyi Cao; Haoliang Cheng; Changmeng Huan; Shuai Qi; Gang Xu
Materials Letters | 2017
Ziyi Cao; Yuan Lu; Xiudi Xiao; Yongjun Zhan; Haoliang Cheng; Gang Xu