Vanadium dioxide (VO₂) thin films of different thicknesses were prepared by regulating the deposition time (2, 2.5, 3, and 3.5 h). The impact of deposition time on the microstructure, surface morphology, and cross-section morphology was investigated. The results showed that the grain size increased with the film thickness. Meanwhile, the influence of film thickness on the residual stress was evaluated by X-ray diffraction. The phenomenon of “compressive-to-tensile stress transition” was illustrated as the thickness increased. The change of dominant mechanism for residual stress was used for explaining this situation. First, the composition of residual stress indicates that growth stress play a key role. Then, the effect of “atomic shot peening” can be used to explain the compressive stress. Lastly, the increased grain size, lower grain boundary density, and “tight effect” in the progress of film growth cause tensile stress.

The present work reported the intrinsic mechanical behavior of vanadium dioxide (VO₂) thin film deposited on a SiO₂ substrate using a combination of nanoindentation tests and a theoretical model. The effect of phase transition on mechanical parameters was studied by adjusting the test temperature. A new model that can simultaneously extract the elastic modulus and hardness was derived by introducing a dimensional analysis. The results showed that the thin film exhibits a hardness of 9.43 GPa and a Young’s modulus of about 138.5 GPa at room temperature, compared with the values of 5.71 GPa and 126.9 GPa at a high temperature, respectively. It can be seen that the intrinsic mechanical parameters decrease to a certain extent after a phase transition. Finally, the numerical simulation results were consistent with those of the experiments, which verified the effectiveness of the new method. In addition, this study also provided useful guidance for mechanical tests on other ultra-thin films.

Colored reflective paints are attractive for building cooling and aesthetics. However, coloration of the paints could paradoxically increase the solar absorption, decreasing the cooling capabilities. In this work, we introduced a novel coloration strategy by using metal ion-doped ZnO nanoparticles as fillers to achieve chromatic paints with high cooling capabilities. With inorganic binder of aqueous K₂SiO₃ solution, it observed that the Mg-doping enabled the paint to deliver a high cooling power of 103.8 W/m², while Fe-, Cu- and Co-doping strategies created pale buff (L* = 84.6, a* = 2.9, b* = 16.3), olive green (L* = 66.8, a* = −7.9, b* = 18.7), and pale gray (L* = 81.5, a* = −0.6, b* = 2.1) colors with highly remained cooling power of 83.9, 75.4 and 61.1 W/m², respectively. Physical characterizations indicated that the maintained crystal structures and similar band gaps could be the main reasons for high cooling capabilities of the colored paints. In addition, the high temperature differences and strong adhesion capabilities of paints on concrete substrates enabled them to present promising cooling energy savings for buildings.

When the site conditions are complex and the building structure is sensitive to settlement, post-grouting can be adopted for bored grouting pile to improve its bearing capacity, reduce settlement and improve the safety of pile foundation. In this paper, the ultimate bearing capacity of pile foundation is tested by self-balance method, and the ultimate bearing capacity of the two test piles is improved by 95% and 33.3% respectively. The post-grouting has a good impact on the formation with poor bearing capacity and denaturation index.