3 MeV proton irradiation effects on surface, structural, field emission and electrical properties of brass
Year: 2018
Authors: Ali M.A., Bashir S., Akram M., Mahmood K., Faizan-ul-Haq., Hayat A., Mutaza G., Chishti N.A., Khan M.A., Ahmad S.
Autors Affiliation: Govt Coll Univ, CASP, Lahore, Pakistan.
Abstract: Ion-induced modifications of brass in terms of surface morphology, elemental composition, phase changes, field emission properties and electrical conductivity have been investigated. Brass targets were irradiated by proton beam at constant energy of 3 MeV for various doses ranges from 1 x 10(12) ions/cm(2) to 1.5 x 10(14) ions/cm(2) using Pelletron Linear Accelerator. Field Emission Scanning Electron Microscope (FESEM) analysis reveals the formation of randomly distributed clusters, particulates, droplets and agglomers for lower ion doses which are explainable on the basis of cascade collisional process and thermal spike model. Whereas, at moderate ion doses, fiber like structures are formed due to incomplete melting. The formation of cellular like structure is observed at the maximum ion dose and is attributed to intense heating, melting and re-solidification. SRIM software analysis reveals that the penetration depth of 3 MeV protons in brass comes out to be 38 mu m, whereas electronic and nuclear energy losses come out to be 5 x 10(-1) and 3.1 x 10(-4) eV/angstrom respectively. The evaluated values of energy deposited per atom vary from 0.01 to 1.5 eV with the variation of ion doses from 1 x 10(12) ions/cm(2) to 1.5 x 10(14) ions/cm(2). Both elemental analysis i.e. Energy Dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) supports each other and no new element or phase is identified. However, slight change in peak intensity and angle shifting is observed. Field emission properties of ion-structured brass are explored by measuring I-V characteristics of targets under UHV condition in diode-configuration using self designed and fabricated setup. Improvement in field enhancement factor (beta) is estimated from the slope of Fowler-Nordheim (F-N) plots and it shows significant increase from 5 to 1911, whereas a reduction in turn on field (E-o) from 65 V/mu m to 30 V/mu m and increment in maximum current density (J(max)) from 12 mu A/cm(2) to 3821 mu A/cm(2) is observed. These enhancements in field emission characteristics are correlated with the growth of surface structures, specifically agglomers which are responsible for electric field convergence. Electrical by four probe method has been correlated with maximum current density and decreasing trend is observed with increasing ion doses.
Journal/Review: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
Volume: 423 Pages from: 7 to: 15
More Information: We are thankful to Higher Education Commission (HEC) of Pakistan for funding the project Upgradation of laser facilities at GCU Lahor. We are also grateful to Prof. Dr. Riaz Ahmed (Director, IOP, GCU) and Prof. Dr. Shahid Rafique (Dean of Natural Sciences, UET, Lhr) for providing facilities of XRD and Four Probe Method.KeyWords: Ion irradiation; 3 MeV proton; FESEM analysis; Field emission properties; XRD analysisDOI: 10.1016/j.nimb.2018.03.004Citations: 14data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2025-05-18References taken from IsiWeb of Knowledge: (subscribers only)