Comparison between helium plasma induced surface structures in group 5 (Nb, Ta) and group 6 elements (Mo, W)

Abstract

Group 5 elements (niobium and tantalum) and group 6 elements (molybdenum and tungsten) were exposed to helium plasma, and the resulting surface structures were observed by electron microscopy. Group 5 elements showed hole structures, where the size of the holes ranged from several tens of nm to a few hundred nm in diameter, while group 6 elements showed fiber-like structures. As a first step in understanding such differences, the difference in helium agglomeration energies and changes in the stress tensor as a function of the number of He atoms at interstitial sites were investigated for each element using density functional theory. The calculations revealed that helium atoms prefer to agglomerate in both of these groups. However, helium in group 6 elements can agglomerate more easily than group 5 elements due to higher binding energy. These results indicate a possible correlation between the shape of helium plasma induced surface nanostructures and the atomic level properties due to helium agglomeration.

Fabrication of photocatalytically active vanadium oxide nanostructures via plasma route

“…Those initial morphology changes are thought to develop into fiberform nanostructures. Similar fuzzy nanostructure growth has been identified on other metals including molybdenum, nickel, titanium, iron, rhenium, and tantalum [16][17][18][19][20][21], indicating that significant morph ology changes accompanied by the He bubble growth are common to many metals. As the plasma irradiation's bottom up approach only requires a one-step dry process [22], materials fabricated using this process are anticipated to be useful for industrial application.…”

Triple Hybrid Simulation Method for Tungsten Fuzzy Nanostructure Formation

“…The physical and chemical properties of the fuzzy nanostructures have also been investigated in order to advance plasma applications. In addition, the formation of nanostructures due to helium-plasma irradiation has been confirmed for several metals other than tungsten [7][8][9].…”

Increased Photoelectrochemical Performance of Vanadium Oxide Thin Film by Helium Plasma Treatment with Auxiliary Molybdenum Deposition

“…[7,8] Various processing methods have been used to fabricate vanadium oxide thin films and nanostructures. For example, pulsed laser deposition (PLD), [9] magnetron sputtering, [10] chemical vapor deposition (CVD), [11] plasma-enhanced CVD, [12] solgel method, [13,14] and sol-gel dip coating [15] were used to deposit thin films; hydrothermal process, [16] thermal pyrolysis, [17] electrospinning, [18] ion beam sputtering, [19] and helium (He) plasma treatment [5] were used for nanostructuring.Among these methods, He plasma treatment is a novel method, which forms fiberform nanostructures (FNs) called fuzz on various metals including tungsten, molybdenum, rhenium, rhodium, tantalum, platinum, niobium, and V. [5,[20][21][22][23][24][25] The process is a bottom-up process accompanied by the growth of He bubbles on the top surface layer (thickness of 100-200 nm) and the formation and diffusion of adatoms. [26][27][28][29][30] Application of oxidized fuzz has been studied including the application of tungsten trioxides (WO 3 ) as gas sensors [31][32][33][34][35][36] WO 3 , iron oxides, [37,38] titania, [39,40] and V oxides [5] as photoelectrodes.…”

“…Among these methods, He plasma treatment is a novel method, which forms fiberform nanostructures (FNs) called fuzz on various metals including tungsten, molybdenum, rhenium, rhodium, tantalum, platinum, niobium, and V. [5,[20][21][22][23][24][25] The process is a bottom-up process accompanied by the growth of He bubbles on the top surface layer (thickness of 100-200 nm) and the formation and diffusion of adatoms. [26][27][28][29][30] Application of oxidized fuzz has been studied including the application of tungsten trioxides (WO 3 ) as gas sensors [31][32][33][34][35][36] WO 3 , iron oxides, [37,38] titania, [39,40] and V oxides [5] as photoelectrodes.…”