Dynamic stabilization of the electrothermal instability

Materials Chemistry and Physics

Hosokai

Akiyama

2011

We synthesized ZnO nanoflowers using a solution plasma. We examined the effects of the applied voltage and the concentration of the electrolyte on the morphology of the products. In the experiments, the zinc wire (cathode) was immersed in an electrolysis solution of K 2 CO 3 (concentration: 0.01 to 5.00 M) and was electrically melted by a glow discharge at different voltages ranging from 42 to 200 V. The results revealed that the products were nanoflowers having many nanorods (size: <100 nm). The ZnO nanoflowers had a wurtzite structure with the [0001] orientation in the growth direction. The product morphology changed with a change in the concentration of the electrolyte, C, and the applied voltage, V; that is, nanoflowers were generated under the limited conditions of (C, V) = (1.0 M, 66 V), (0.5 M, 80 V), and (0.1 M, 105 V).

Section: Formation Of Nanoparticles During Solution Plasmamentioning

confidence: 99%

Synthesis of ZnO nanoflowers by solution plasma

Materials Chemistry and Physics

Hosokai

Akiyama

2011

“…17,18 The surface of the electrode partially melts to produce nanoparticles owing to the concentration of current caused by the electrothermal instability. 19,20 A solution plasma offers many advantages: (1) simple equipment, (2) no requirement of gas supply, (3) easy mass production, (4) applicability to any metals/alloys, and (5) controllable product size. According to the major databases, the production of copper/copper oxide nanoparticles via solution plasma has never been reported, in spite of its highefficacy and low-cost production.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of copper/copper oxide nanoparticles by solution plasma

Journal of Applied Physics

Hosokai

Tsubota

et al. 2011

This paper describes the synthesis of copper/copper oxide nanoparticles via a solution plasma, in which the effect of the electrolyte and electrolysis time on the morphology of the products was mainly examined. In the experiments, a copper wire as a cathode was immersed in an electrolysis solution of a K 2 CO 3 with the concentration from 0.001 to 0.50 M or a citrate buffer (pH ¼ 4.8), and was melted by the local-concentration of current. The results demonstrated that by using the K 2 CO 3 solution, we obtained CuO nanoflowers with many sharp nanorods, the size of which decreased with decreasing the concentration of the solution. Spherical particles of copper with/ without pores formed when the citrate buffer was used. The pores in the copper nanoparticles appeared when the applied voltage changed from 105 V to 130 V, due to the dissolution of Cu 2 O.

“…The surface of the electrode partially melts to produce nanoparticles owing to the concentration of current causes by the electrothermal instability. 16,17 Fig. 2(c) shows the concentration mechanism of current.…”

Section: A)mentioning

confidence: 99%

High-speed camera observation of solution plasma during nanoparticles formation

Applied Physics Letters

Nakasugi

Akiyama

2014

The direct-current discharge plasma during nanoparticles formation was observed using a high-speed camera. Metallic plates of Au, Ni, Ti, and Zn were used as a cathode, and a Pt wire was used as an anode. Both electrodes were immersed in a 0.1M NaOH solution. The solution plasma with light emission was generated via the vapor layer surrounding the cathode by applying 190 V. The current concentration occurred at a certain point of the electrode surface, in which the electrode surface was partially melted to produce nanoparticles. According to the high-speed observation, many light-emitting points appeared on the metallic plate and immediately disappeared when a certain point was strongly heated to produce nanoparticles. Additionally, light emission points moved in a chain reaction; after the first emission point was generated, the next emission point tended to be generated in the space surrounding the first emission point. During electrolysis, holes were generated on the cathode. The current concentration strongly heated certain spots on the electrode, and the electrode momentarily melted or vaporized, resulting in the formation of nanoparticles