Large-scale synthesis of tungsten single-crystal microtubes via vapor-deposition process

Low-temperature growth of tetragonal tungsten nanowire arrays on tungsten substrate using Ni solid catalysts

“…We previously found that hexagonal W nanowire arrays could grow directly on Si, SiO 2 or Al 2 O 3 substrates, but could not synthesize tetragonal W nanowire arrays on W substrate, by catalyst-free CVD method [2,3]. Here, we further reported the successful growth of tetragonal W nanowire arrays on W substrates by Ni-catalyzed CVD method.…”

“…Obviously, these characteristics are quite different from the direct CVD-grown W nanowires with hexagonal cross-section, faceted growth tip and [111] growth direction [2,3], and the Ni-catalyzed W nanowires with circle cross-section, round growth tips and [100] growth direction [16]. Combining our previous studies about the direct CVD-grown W nanowires based vapor-solid mechanism and the catalystinduced W nanowires based on vapor-solid-solid mechanism with the above-mentioned results, we proposed the following mechanism to explain the formation process of the synthesized tetragonal W nanowires (Fig.…”

“…The catalytic growth of W nanowires was carried out in a refitted horizontal tube [2,3], which was similar to the fabrication of W nanowires by direct CVD-grown. Typically, the W substrate covered with annealed Ni film was placed on the exit of a quartz tube (20 mm in diameter), which was loaded with 10 g high-purity WO 3 standard cubic centimeters per minute) and high-purity N 2 gas carried with water vapor (Pressure, 1 atm; Flow: 100 standard cubic centimeters per minute) were introduced into the furnace tube and the quartz tube, respectively. After maintained at 950 1C for 6 h, the N 2 gas was shut off and the system was cooled gradually to room temperature.…”

“…Very recently, W nanowires and the oxide nanowires, with well-defined singlecrystalline structure and unique geometry, have attracted intensive attention due to their great potential applications as field emitters and strength agents [2][3][4][5][6][7][8][9][10][11][12][13]. So far, various methods have been developed to fabricate W nanowires, such as direct CVD [2][3][4][5], metal-catalyzed CVD [14][15][16][17][18], electron beam induced deposition [19][20][21] and self-organization methods [22,23]. In terms of feasibility, metal-catalyzed CVD method has been developed to be one of the most successful methods for controlling synthesis of semiconductor nanowires [24][25][26].…”

Downsizing of single crystalline high aspect ratio tungsten nanowires

“…For example, a vacuum pyrolysis/carbothermal treatment (VPC) as reported by Li et al . Various physical vapor deposition methods, like an electron‐beam‐induced deposition , direct chemical vapor deposition methods (CVD) , a nickel‐catalyzed CVD leading to single crystalline wires , and also an electron and ion beam induced chemical vapor deposition method producing amorphous tungsten wires have been reported . During the last years a new and sophisticated method for the production of nanowires was established.…”