z Materials Science inc. Nanomaterials & Polymers Extraction of the Very High Tunneling Current and Extremely Stable Emission Current from GdB 6 /W-Tip Source Synthesized Using Arc Plasma Sachin R. Suryawanshi, [a] Nilesh Kanhe, [b] Vikas L. Mathe, [a, b] Deodatta M. Phase, [c] Dattatray J. Late, [d] and Mahendra A. More* [a] Herein, we report the one step arc plasma synthesis of the GdB 6 (Gadolinium hexaboride) nanoparticles and its field emission (FE) characteristics on tungsten point substrate (GdB 6 / W). The SEM / TEM analysis revealed the GdB 6 nanoparticles on W point substrate exhibit irregular shaped, grainy, dense, course morphology, i. e. uniformly covering the entire tip substrate surface. For GdB 6 /W point source, the values of the turn-on and threshold fields, defined as field required to draw an emission current density ~ 1 mA/cm 2 and ~ 100 mA/cm 2 , respectively are found to be ~ 2.2 and ~ 2.7 V/mm, for anode- cathode separation of ~ 1 mm. Interestingly, a very high emission current density of ~ 3.5 A/cm 2 has been drawn from the GdB 6 /W point emitter at relatively lower applied field of ~ 6.4 V/mm. The field enhancement factor found to be ~ 10,250. The GdB 6 /W point electron source exhibits a good emission current stability at ~ 10 mA for a period of 6 hr. The emission current stability is enumerated in terms of standard deviation and its magnitude has been measured to be only 1.72 % with respect to the average value. The superlative field emission characteristics signify the GdB 6 /W point electron source as potential candidates for vacuum micro/nanoelectronics device applications. Introduction Rare earth metal hexaboride (RB 6 ) based cold cathodes have gain the technological importance due to its unique a set of physico-chemical properties such as low workfunction(f), high melting point (> 2500 o C), low vapour pressure, low sputtering coefficient (in contrast to LaB 6 ) for being an ideal cold cathode. [1–10] Among all of RB 6 it is well known that the GdB 6 have low workfunction (1.5 eV) as compared to the other. [2, 4, 9, 11] Cold cathodes are essential elements in a variety of applications that include miniature X-ray sources, cathode-ray tube mon- itors, and flat panel display . [12–16] The electron source can be produced from the suitable cathode materials either via thermionic emission or via field emission. Mainly, as compared to thermionic emission, field emission based devices/cathodes characteristically attracts more attention due to the relaxation in the operating field range, room temperature operation (ideally 0 K), good emission current stability, longevity, high brightness, reduced device size, and low sputtering the cathode material. In principally, the field emission current density exponentially depends on the f of the emitter and applied field (E) as via the Fowler-Nordheim (F  N) equation. [17] Providentially, the RB 6 having a lower f in the range of 1.5- 3 eV in contrast to metals, semiconductor having f is usually in the range of 4 to 8 eV. For such high f material electron emission occurs relatively at large applied field (typically the order of 10 9 V/m), which can also induce the vacuum break- down and high electrical discharge. From a practical application point of view, the key issues are relaxation in operating field, a very high emission current density and stable emission current, longevity of the cathode material are obligatory. As the turn-on or threshold field values are dependent on the ‘extrinsic’ (shape and size) forms of the emitter, and its ‘intrinsic’ properties, such as workfunction, mechanical strength etc. In this regards, various researchers have been made the attempts to synthesize polymorphs of the RB 6 and explore their FE characteristics. [1, 3, 4, 6 9] We have reported earlier the crystal- line thin film of LaB 6 on different metal foils and tips substrates by PLD and its FE characteristics. [18] In the RB 6 family, it is found that single nanowire GdB 6 based field emitter delivers the higher emission current than that of the LaB 6. [9] But the emission current of GdB 6 nanowire is comparative very less as compare to our present result comprised the thin adherent layer of GdB 6 on W-tip. Recently, we have been reported the enhance field emission behaviour of the GdB 6 -Cu 2 O and GdB 6 - ZnO heteroarchitecture assembly via facile synthesis route. [19, 20] Also the Silicon nanotubes coated on W-tip was used as a field [a] S. R. Suryawanshi, Dr. V. L. Mathe, M. A. More Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, Savitribai Phule Pune University, Pune 411007, India E-mail: mam@physics.unipune.ac.in datta099@gmail.com [b] N. Kanhe, Dr. V. L. Mathe Department of Physics, Arts, Commerce and science college, Satral, Ah- mednagar-413711, India [c] D. M. Phase UGC-DAE Consortium for Scientific Research Indore Centre, University Campus, Khandwa Road, Indore, India [d] D. J. Late National Chemical Laboratory (NCL-CSIR), Dr. Homi Bhabha Road, Pune 411008, India Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/slct.201601587 Full Papers DOI: 10.1002/slct.201601587 562 ChemistrySelect 2017, 2, 562 – 566  2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim