Fertile field emission response in scrambled SmNiO3 nanopins

Abstract

Abstract This present work focuses on the synthesis of scrambled SmNiO 3 nanopins by the hydrothermal route, structural and morphological characterizations, and observing their potential electric field emission response with density functional theory (DFT) study. The Rietveld refinement of X-ray diffraction (XRD) and Raman characterization study reveals an orthorhombic phase (space group Pnma , No. 62) of SmNiO 3 , along with Raman-active NiO 6 octahedral vibrational modes and Sm-O lattice motion. The high-resolution scanning and tunneling electron microscopy images exhibit monodispersed hierarchically self-assembled pin-like surface morphology with a crystal lattice spacing of 3.16 Å for 110 planes, which offers exceptional field emission response. The chemical states of Sm, Ni, and O were interpreted by X-ray photoelectron (XPS) spectroscopy in +3 oxidation states (4f 5 configuration), mixed Ni 3 ⁺/Ni 2 ⁺ valence states, and -2 lattice and defect states, respectively. The current density (J) vs. electric field (E) plots demonstrate a maximum field emission current density ~ 30 µA/cm 2 @ 8.4 V/µm, and very enduring field emission current stability was observed over a long period of time, 3 h 20 min, with bright field emission fringes. Very low turn-on (E turn-on ) and threshold (E threshold ) were discerned ~ 5.1 V/µm @1 µA/cm 2 and ~ 7.64 V/µm @10 µA/cm 2 from J-E curves. The local work function (φ) was calculated to be ~5.13 eV by density functional theory (DFT) calculations, and the field enhancement factor (β) was measured to be ~3343. The noteworthy electric field emission response, low turn-on field, and long-term stable field emission enable SmNiO 3 nanopins to be a high-efficiency electron source for field-emitting display (FED), X-ray source, vacuum transistor device, etc.