Phase and shape controlled VO2 nanostructures by antimony doping

Abstract

Quasi-spherical VO 2 nanoparticles with uniform size and high crystallinity are ideal functional materials for applications in field-effect transistors, smart window coatings and switches. However, the synthesis of these VO 2 nanoparticles has long been a challenge. This article presents a novel doping strategy for the simultaneous control of the size, morphology and polymorphology of VO 2 nanoparticles. Doping can induce the change in crystal structure and exhibits a significant promoting effect on the formation of doped monoclinic VO 2 (VO 2 (M)). Specifically, by antimony (Sb 3+ ) doping, hexagonal-shaped, well crystalline monoclinic VO 2 nanoparticles with tunable sizes (8-30 nm) and controllable polymorphs were synthesized via a one-pot, hydrothermal method. Sb 3+ dopants, which are larger in radius and lower in valence than V 4+ ions, can introduce extra oxygen vacancies during the nucleation and growth of VO 2 nanoparticles. These positively charged nuclei may suppress the adsorption of VO 2+ aqua ions, and therefore inhibit the growth of the VO 2 (M) nanoparticles. Comparably, Sb 5+ dopants that possess higher valence counts than V 4+ ions can induce the growth of VO 2 (M) particles to 200-300 nm width and above 500 nm length. The Sb 3+ -doped VO 2 (M) nanoparticles exhibit excellent properties in metal-semiconductor transformation at transition temperatures ranging from 55-68 C. Films obtained by casting these nanoparticles show excellent optical properties (both visible transmittance and infrared regulation), compared with those prepared from gas phases, such as sputtering. This synthetic strategy that involves the doping of an element with a different valence count than the matrix cation may be useful for controlling the solution growth of some technologically significant nanomaterials. In addition, the formation mechanism of solid and crystalline transformation was also studied by designing a specific reaction autoclave.

Thermal kinetic analysis of metal–insulator transition mechanism in W-doped VO2

“…3a, b), suggesting that no significant changes in morphology after doping, which is in consistence with our previous report [23].…”

Recent Advances in Nanostructured Vanadium Oxides and Composites for Energy Conversion

“…Antimony (Sb 3+ ) ions have been doped to achieve sub-50 nm VO 2 (M) nanocrystals with superior uniformity in shape and size, as shown in Figures 2d,e. [29] Moreover, the reaction temperature has been reduced to 220 °C. Titanium (Ti 3+ ), bismuth (Bi 3+ ) and TiO 2 have been found to show similar effects.…”

“…Limited to the preferential growth orientation of VO 2 (B), 0D nanostructures or single crystal nanoparticles have been rarely reported. [29] Many nanostructures with higher dimensions have been successfully synthesized including nanowires, [131] nanorods, [132] nanosheets [133] and hierarchical nanostructures. [134] As shown in Figure 10a, nanowires with the diameter of 50 nm have been fabricated through a solvothermal reaction of V 2 O 5 , water and ethylene glycol.…”

Performance Demonstration and Evaluation of the Synergetic Application of Thermochromic Window and Phase Change Material in Passive Buildings

“…Vanadium dioxide (VO2) [1][2][3] and phase change materials (PCM) [4][5][6] are two of most widely studied energy efficient materials, and can be integrated into the non-transparent and the transparent building envelops, respectively. In this work, these two kinds of materials were associated together for the first time to improve the thermal comfort degree of a passive building.…”