Tuning electronic and magnetic properties through disorder in V₂O₅ nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Vanadium pentoxide (V2O5) is a material with significant applications in catalysis, energy storage, and electronics.
• Understanding the relationship between synthesis conditions, structural properties, and electronic behavior is crucial for optimizing V2O5 performance.
• The sol-gel method offers a versatile route for synthesizing V2O5 nanoparticles with controlled characteristics.

Purpose of the Study:

• To investigate the effect of calcination temperature on the structural, optical, and magnetic properties of V2O5 nanoparticles synthesized via sol-gel.
• To elucidate the underlying mechanisms responsible for the observed changes in the optical band gap and magnetic behavior.
• To explore the role of oxygen vacancies in tuning the electronic and magnetic properties of V2O5.

Main Methods:

• Sol-gel synthesis of V2O5 nanoparticles at varying calcination temperatures (400-500 °C).
• Characterization using Raman spectroscopy, X-ray diffraction (XRD), and magnetometry.
• Optical band gap determination through UV-Vis spectroscopy.
• Density Functional Theory (DFT) calculations to model structural and electronic properties.

Main Results:

• Calcination temperature significantly influenced the optical band gap, reducing it from 2.20 eV to 1.18 eV.
• XRD and Raman spectroscopy showed minor structural changes, insufficient to explain the band gap reduction.
• DFT calculations revealed that incorporating oxygen vacancies, particularly at vanadyl sites, accurately reproduced the band gap reduction.
• Oxygen vacancies induced spin-polarized interband states, leading to a predicted and experimentally confirmed ferromagnetic-like response.

Conclusions:

• Oxygen vacancies are the primary cause of the reduced optical band gap in V2O5 nanoparticles synthesized under studied conditions.
• The presence of oxygen vacancies introduces a ferromagnetic-like behavior in V2O5, transitioning it from paramagnetic.
• This research highlights a promising strategy for engineering the electronic and magnetic properties of V2O5 for novel device applications.