| Synthesis of W-doped VO2 nanoparticles via an aqueous ammonia solution route using WO3 and V2O5 powders and fabrication of thermochromic smart-window composites |
| Hidetoshi Miyazaki1, Junya Sato1, Takeshi Kubota1, Shinya Tsukada2 |
1Graduate School of Natural Science Technology, Shimane University, 1060, Nishikawatsu, Matsue, Shimane, 690-8504, Japan
2Faculty of Education, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan |
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Received: October 10, 2024; Revised: January 31, 2025 Accepted: February 17, 2025. Published online: March 4, 2025. |
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| ABSTRACT |
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Ammonium vanadate (NH4VO3, NH4WxV1-xO3) precursor nanoparticles were synthesized by dissolving V2O5 and WO3 powders in aqueous ammonia, followed by precipitation through pH adjustment to 2.5. VO2 and W-doped VO2 nanoparticles were obtained by heat treating the precursor powder at 450 °C in H2, followed by 600 °C in N2 (99.9999%). The resulting VO2 particles ranged in size from sub-tens to 300 nm. These particles were embedded in a transparent urethane resin to fabricate composite films. The composite films prepared using undoped and W-doped VO2 exhibited thermochromic properties, with approximately 10% difference in transmittance in the infrared region at high and low temperatures. The transition temperature of the undoped VO2 composite film was 68.1 °C, whereas that of the W-doped VO2 (W0.026V0.974O2) composite film was 43.0 °C. The VO2 nanoparticle in this research is an inexpensive aqueous solution method and can be handled in large quantities. The thermochromic composite films can be easily synthesized by dispersing and embedding the resulting VO2 nanoparticles in a transparent resin. Furthermore, the vanadium can be recovered by firing the matrix resin of the composites. In summary, this investigation enables to design a VO2 composite films with high environmental effects and low environmental load. |
| Key words:
VO2 · Thermochromism · Composite film |
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