Reversible (i.e.smart) transition observed in sputtered vanadium oxide (major V⁺⁵, minor V⁺⁴) films, further investigated detailed structural, thermal, optical, electrical and nanomechanical behaviours.

For the first time, multicomponent alloys belonging to a B2-ordered single phase were designed and fabricated by melting route. The design concept of high entropy alloys is applied to engineering the transition metal sublattice of binary B2 aluminide. The equiatomic substitution of transition metal elements in the Ni sublattice of binary AlNi followed to produce Al(CoNi), Al(FeNi), Al(CoFe), Al(CoFeNi), Al(CoFeMnNi), and Al(CoCuFeMnNi) multicomponent alloys. CALculation of PHAse Diagrams (CALPHAD) approach was used to predict the phases in these alloys. X-ray diffraction and transmission electron microscopy were used to confirm the B2 ordering in the alloys. Thermal stability of the B2 phase in these alloys was demonstrated by prolonged heat treatments at 1373 K and 1073 K up to 200 h.

The precise mechanism governing the reversible semiconductor‐to‐metal transition (SMT) in V₂O₅ remains elusive, yet its investigation is of paramount importance due to the remarkable potential of V₂O₅ as a versatile “smart” material in advancing optoelectronics, plasmonics, and photonics. In this study, distinctive experimental insights into the SMT occurring in amorphous V₂O₅ through the application of highly sensitive, temperature‐dependent, in situ analyses on a V₂O₅ thin film deposited on soda‐lime glass are presented. The ellipsometry measurements reveal that the complete SMT occurs at ≈340 °C. Remarkably, the refractive index and extinction coefficients exhibit reversible characteristics across visible and near‐infrared wavelengths, underscoring the switch‐like behavior inherent to V₂O₅. The findings obtained from ellipsometry are substantiated by calorimetry and in situ secondary ion mass spectrometry analyses. In situ electron microscopy observations unveil a separation of oxidation states within V₂O₅ at 320 °C, despite the thin film retaining its amorphous state. The comprehensive experimental investigations effectively demonstrate that alterations in electronic state can trigger the SMT in amorphous V₂O₅. It is revealed for the first time that the SMT in V₂O₅ is solely contingent upon electronic state changes, independent of structural transitions, and importantly, it is a reversible transformation within the amorphous state itself.

A novel double mechanical masking‐based sample preparation method is introduced for in‐situ transmission electron microscopy (TEM) characterizations. In the current study amorphous vanadium pentoxide thin film deposition is carried out by using the developed double mask on a transparent window of TEM chip on precisely selected spots by a reactive sputtering technique. The prepared sample is less damaged since it is not subjected to ion beam exposure. And the probability of achieving a viable TEM sample is also enhanced compared to classical preparation methods. In‐situ temperature‐based electron diffraction pattern sequences are recorded for amorphous vanadium pentoxide in the temperature region of 25 to 500˚C. This allowed observing the crystallization temperature at ∼416˚C. The pre‐ and post‐heat‐treated microstructure and electron diffraction pattern of the vanadium pentoxide thin film showed the formation of a mixed crystalline and amorphous film. Thus, a most reliable, reusable and cost effective TEM sample preparation method was demonstrated.