Improved field emission properties ofα-Fe₂O₃nanoflakes with current aging treatment and morphology optimization

Abstract

a-Fe2O3 nanomaterials were synthesized by thermal oxidation of pure iron foil, and the effects of current aging treatment and morphology on their field emission properties were systematically investigated. Current aging treatment was found to be an efficient method to improve the field emission properties of a-Fe2O3 nanoflakes. Emission current density was largely enhanced from 0.05 to 5.70 mA/cm2 under an applied electrical field of 7.8 MV/m, and their threshold field decreased from larger than 11.0 to 6.6 MV/m after current aging treatment. The mechanism of the improvement in field emission performance of a-Fe2O3 nanoflakes induced by current aging treatment is discussed. a-Fe2O3 nanostructures with various morphology were synthesized by adjusting growth temperatures between 300-450℃ to optimize its morphology. a-Fe2O3 nanoflakes synthesized under 350℃ were superior field emitters: low threshold of 5.1 MV/m, high current density of 63.4 mA/cm2 and stable emission, which demonstrated that a-Fe2O3 nanoflakes could be a promising material for application as field emitters.

Structural and morphological tuning of iron oxide polymorphs by ECR plasma-assisted thermal oxidation

“…Usually, the iron oxide surface requires prolonged treatment at elevated temperatures to obtain the hematite phase and the typical morphology suitable for eldeffect electron emission. 10,25,30,43,44 From Table 4, PATO-processed lms revealed that the method of processing strongly affects the eld emission performance; the PATO-processed lms with unique morphologies were better than the conventionally processed lms. The difference in eld emission performance in the PATO-processed M-Fe and N-Fe lms was due to the surfacestabilized phase and morphology obtained in a given oxygen environment.…”

“…To improve the performance of eld emitters, nanoscale materials have been used. 10,[25][26][27][28][29][30][31] Nanostructured materials possess high aspect ratios, as well as high surface activity, and are, therefore, suitable for applications like eldeffect electron emission, gas sensors, 32 catalysts, 33,34 magnetic storage devices, 35 anode material for lithium-ion batteries, 36 thermoelectric power generators, 37 nuclear radiation sensors, 38 etc. Looking at the eld emission properties of nanostructures grown on surfaces, researchers have reported that carbon nanotubes are excellent eld emitters.…”

“…24,39 However, onedimensional (1D) materials like carbon nanotubes require prolonged treatment at high temperatures and the eld emission current (performance) is degraded with time due to surface oxidation. To overcome this problem, various stable metal oxide nanomaterials like ZnO, 40 WO 3 , 41 CuO, 42 and Fe 2 O 3 10,25,30,43,44 have been synthesized and used as eld-effect emitters. Out of the various nano-materials, iron oxide has attracted the most attention due to its environmental friendliness, non-toxicity, excellent thermal stability, and low cost.…”

“…Table 1 summarizes the reported methods used to grow the hematite phase; more specically, the types of methods, processing time and eld emission properties. To improve the eld emission performance, Junqing et al 25 reported that the sample needs additional current aging treatment, giving rise to a reduced threshold eld of 6.6 MV m À1 . Similarly, Wu et al 43 mentioned a further decrease in the threshold eld to 7.2 MV m À1 once the samples were subjected to X-ray irradiation (a dose of 9.0 Â 10 14 phs cm À2 ).…”