Unraveling Metal-insulator Transition Mechanism of VO2Triggered by Tungsten Doping

Understanding the mechanism of W-doping induced reduction of critical temperature (T(C)) for VO(2) metal-insulator transition (MIT) is crucial for both fundamental study and technological application. Here, using synchrotron radiation X-ray absorption spectroscopy combined with first-principles calculations, we unveil the atomic structure evolutions of W dopant and its role in tailoring the T(C) of VO(2) MIT. We find that the local structure around W atom is intrinsically symmetric with a tetragonal-like structure, exhibiting a concentration-dependent evolution involving the initial distortion, further repulsion, and final stabilization due to the strong interaction between doped W atoms and VO(2) lattices across the MIT. These results directly give the experimental evidence that the symmetric W core drives the detwisting of the nearby asymmetric monoclinic VO(2) lattice to form rutile-like VO(2) nuclei, and the propagations of these W-encampassed nuclei through the matrix lower the thermal energy barrier for phase transition.