Influence of morphology and crystallinity on field emission properties of NiFe2O4 nanoparticles grown by high-temperature vapor phase condensation route

Abstract

The nanocrystallites of NiFe2O4 have been successfully synthesized by gas phase condensation using the dc thermal plasma arc method (NF-1) and by the chemical co-precipitation method (NF-2). The field emission studies were carried out on as-synthesized NF-1 and compared with NF-2 nanoparticles. The emission characteristic shows that NF-1 particles have a low turn-on field of 2.3 V μm−1 as compared to NF-2 particles, which have a turn-on field of 3.5 V μm−1. The Fowler–Nordheim plots obtained from the current–voltage characteristics show overall linear behavior as expected from the quantum mechanical tunneling phenomenon. Our results show that both nanoparticles exhibit good emission stability as an emitter without severe deviations from the initial set value. The highly faceted surfaces, along with high crystallinity of NF-1 nanoparticles, is responsible for improved field emission properties than that of NF-2 prepared by the chemical co-precipitation method.