The phase transition and thermochromic characteristics of W/Mg-codoped monoclinic VO2 nanoparticle and its composite film

Abstract

Monoclinic VO2(M) nanoparticles codoped with 1.5 at. % W and 2.9 at. % Mg were synthesized by the hydrothermal treatment and post-thermal transformation method of V2O5-H2C2O4-H2O with Na2WO4 and Mg(NO3)2. The composite thin film of the W/Mg-codoped VO2(M) with a commercial acrylic block copolymer was also prepared on PET substrate by wet-coating method. The reversible phase transition characteristics of the codoped VO2(M) nanoparticles and the composite film were investigated from DSC, resistivity and Vis-NIR transmittance measurements compared with the undoped and W-doped VO2(M) samples. Mg-codoping into W-doped VO2(M) nanoparticles synergistically enhanced the transition characteristics by increasing the sharpness of transition while the transition temperature (Tc) lowered by W-doping was maintained. The codoped composite film showed the prominently enhanced NIR switching efficiency compared to only W-doped VO2(M) film with a lowered Tc.