FePt nanoparticle formation with lower phase transition temperature by single shot plasma focus ion irradiation

Abstract

Uniform FePt nanoparticles were synthesized through nanostructuring of pulsed laser deposited FePt thin films by single shot H+ ion irradiation using a plasma focus device. The annealing temperature required for phase transition from low Ku face-centred cubic to high Ku face-centred tetragonal, for ion irradiated samples, is simultaneously lowered down to 400 °C. The energetic H+ ion irradiation significantly reduces the activation energy for atomic ordering by increasing the number of vacancies. The advantage of using a plasma focus device is that it can achieve nanostructuring in much shorter time, in single shot ion exposure with pulse duration of typically about a few hundreds of nanoseconds, as compared with much longer duration required by continuous ion sources.

Growth and Study of Plasma Assisted Nanostructured Hard Tantalum Nitride Thin Films

“…An initial decrease in the crystallite size is observed when number of focus shots is increased from four to seven, which can be attributed to the irradiation induced nanostructuring of the top deposited layer. A similar kind of result has also been reported by Jiaji et al [46]. While an increase in crystallite size has been observed with the further increase of plasma focus shots to fifteen owing to thermal annealing effect of the greater number of focus shots.…”

Dense Plasma Focus Device Based High Growth Rate Room Temperature Synthesis of Nanostructured Zinc Oxide Thin Films

“…Energetic ions from DPF devices have been used for processing thin films by irradiating them at different distances from the focus pinch; and hence, their characteristics have been experimentally and numerically estimated by many researchers [33]- [39]. The typical ion energy is found to vary from about few tens of kiloelectronvolts to about megaelectronvolts, with average ions energy of the order of hundreds of kiloelectronvolts.…”

“…Once again assuming that the ions are mostly forward directed in 20°cone; the Lee Code estimated oxygen-ion flux at 10 cm will be about 5.7 × 10 12 ion cm −2 for INTI PF. Lin et al [39] reported the hydrogen-ion flux of about 2.6 × 10 14 ion cm −2 at a 5-cm distance from the anode top for UNU-ICTP device. The hydrogen-ion flux at a 15-cm distance would be about 2.9 × 10 13 ion cm −2 .…”

“…The higher ion flux for [39] can be attributed to the fact that they measured hydrogen-ion flux at a 0.5-mm-diameter entrance hole of Faraday cup placed at a 10-cm distance along the anode axis, i.e., practically along the anode axis at almost 0°w hile the numbers from numerical simulation results of [38] were estimated with ions spreading uniformly over circular surface of 20°cone at axial distance of 10 cm. The simulation results of [38] and experimental results of [39], therefore, are in reasonably good agreement and provide approximate ion flux in the range of 10 12−13 ions cm −2 at substrate distance of 15 cm. These results can be further extrapolated to approximately estimate the ion flux at any other distances of substrate from the anode top.…”

Role of charge particles irradiation on the deposition of AlN films using plasma focus device

“…The electrode assembly is housed in a stainless steel vacuum chamber which is evacuated by a turbo pump attached with rotary vane pump down to the pressure of 10 À 4 mbar and is then filled with nitrogen gas at an optimum pressure of 1.25 mbar. The details of PF device can be found elsewhere [16,26,[30][31][32]. A BPX65 photodiode detector placed at 10 cm from the anode tip is used to characterize the nitrogen ions emitted during the radial collapse phase of PF operation.…”