Excellent Field‐Emission Performances of Neodymium Hexaboride (NdB₆) Nanoneedles with Ultra‐Low Work Functions

Abstract

High‐quality NdB6 nanostructures with a low work function are successfully synthesized via an one‐step catalyst‐free chemical vapor deposition process. Field emission properties of these nanostructures (curve nanowires, short‐straight nanorods, long‐straight nanowires, and nanoneedles) are systematically investigated and found to be strongly affected by the tip morphologies and temperatures. The nanoneedles with sharp tips demonstrate the lowest turn‐on (2.71 V/μm) and threshold (3.60 V/μm) electric fields, as well as a high current density (5.37 mA/cm2) at a field of 4.32 V/μm in comparision with other nanostructures. Furthermore, with an increase in temperature from room temperature to 623 K, the turn‐on field of the nanoneedles decreases from 2.71 to 1.76 V/μm, and the threshold field decreases from 3.60 to 2.57 V/μm. Such excellent performances make NdB6 nanomaterials promising candidates for application in flat panel displays and nanoelectronics building blocks.

Electron Emission Devices for Energy‐Efficient Systems

“…Due to this, it is important to understand surface the roughness and morphology of the electrode to accurately estimate field emission current. Commonly observed morphologies are nanorods, nanowires, nanotubes, nanosheets, nanoneedles, nanocones, nanoflowers, nanofiber, nanoterapods, and nanocryastallites . The analysis of these studies reveals that although β is different for different morphologies, it is in the same order of magnitude.…”

“…In the last couple of decades, large number of new materials and composites have been studied to reveal their field emission performance including different metals, semiconductors, metal oxides, sulfides, carbides, nitrides, ferrites, perovskite solids, hexaborides, and so on. Apart from these materials, low‐dimensional materials are getting significant attention recently.…”

Interplay of electronic, magnetic, and structural properties of GdB6 from first principles

“…They present intriguing physical properties, such as low work function (~2.4-2.6 eV), high thermal conductivity, superconductivity, heavy fermion behavior and high melting points [2][3][4][5][6]. For example, the metallic LaB 6 , a well-known thermionic and field electron emission cathode material, becomes superconducting below 0.45 K [6,7]; PrB 6 is believed to be antiferromagnetic (AFM) at low temperatures [8]; NdB 6 has shown favourable field-emission performances [9,10]; EuB 6 is a ferromagnetic (FM) semiconductor with two ferromagnetic transitions [11,12]; CeB 6 shows heavy fermion behavior and is famous as a dense Kondo material [5]; and mixed valence SmB 6 is the first known topological Kondo insulator [13,14] where strong fermions can exhibit topological surface states.…”

Bulk and surface properties of SmB6

“…Rare-earth hexaboride nanowires have been synthesized by a variety of methods including vapor-liquid-solid mechanism [97,98], chemical vapor deposition with [99] and without [100] a catalyst, and palladium-nanoparticle-assisted chemical vapor deposition [101]. Electrical resistance measurements are argued to be consistent with the presence of topological surface states [102][103][104][105].…”