Influence of pressure and hydrocarbons on carbide formation in the plasma synthesis of TiC nanoparticles

Journal of Magnetism and Magnetic Materials

Ушаков

Demin

et al. 2019

The laws governing the formation of residual stresses in copper oxide nanoparticles in the process of their direct plasma-chemical synthesis in a low-pressure arc discharge plasma are studied. Correlation dependences of the residual stress and the magnetization of nanoparticles on the pressure of the gas mixture of 10% O 2 + 90% Ar are presented. The problems associated with the bifurcation of the magnetization curves during cooling in zero (ZFC) and non-zero (FC) magnetic field, non-equilibrium behavior, relaxation of magnetization and magnetic viscosity of the obtained CuO nanoparticles are discussed.

Section: Methodsmentioning

confidence: 99%

Investigation of the residual stresses effect on the magnetic properties of CuO nanoparticles synthesized in a low-pressure arc discharge plasma

Journal of Magnetism and Magnetic Materials

Ушаков

Demin

et al. 2019

“…In a sufficiently high vacuum of ~ 10 -1 Pa powder consists of particles of two types: spherical particles with size of 0.5 -3 μm, wherein fine condensate dropped, and spherical particles with size of 0.5 -10 μm, which represent agglomerates of smaller particles with size about 0.1 μm [24,25]. The percentage of nanopowders in this case is negligible.…”

Section: Introductionmentioning

confidence: 99%

“…According to the previous research, the properties of powders produced in the plasma arc discharge of low pressure, depend mainly on the gas mixture pressure in a plasma-chemical reactor [24]. Dispersion of produced powders depends mainly on two processes: evaporation and ionization of a liquid metal on a cathode surface, and condensation form a plasma-vapor phase.…”

Section: Introductionmentioning

confidence: 99%

Plasma-chemical synthesis of copper oxide nanoparticles in a low-pressure arc discharge

Uschakov

Лепешев

et al. 2016

Vacuum

Abstract. The influence of a pressure of gas mixture (10 vol% O 2 + 90% N 2 ) on an average size of copper oxide nanoparticles, produced in the plasma of low pressure arc discharge, has been studied as a basic process variable. A correlation between the dependence of average particle size on gas mixture pressure and the dependence of discharge gap voltage on product of interelectrode distance by a gas mixture pressure, has been found. The estimation was carried out by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). A mathematical model of the cathode region, which shows the applicability of the similarity theory to the low pressure arc discharge, has been represented.

“…According to such processes a number of thermal plasma processes have been developed. The vacuum arc plasma evaporation (VAPE) method is commonly used in the processes for the deposition of thin films and the production of nanoparticles [28][29][30][31][32][33].…”

mentioning

confidence: 99%

Particularities of the Magnetic State of CuO Nanoparticles Produced by Low-Pressure Plasma Arc Discharge

Лепешев

Ушаков

et al. 2016

J Supercond Nov Magn

Self Cite

Copper oxide nanoparticles were produced by direct plasmachemical synthesis in a plasma arc discharge of low pressure. The formation of CuO nanoparticles with an average size of 12 nm and narrow size distribution intervals was determined by using the X-ray diffraction analysis and TEM microscopy methods. It was defined by using a vibration magnetometer and a SQUID magnetometer, that the magnetic properties of CuO nanoparticles with such size were extremely different from the magnetic properties of bulk antiferromagnetic CuO. Structural defects, caused the formation of a ferromagnetic state, remaining at least up to the room temperature. The temperature of corresponding antiferromagnetic ordering was significantly decreased (down to ~ 100 K). Meanwhile, some of the copper surface spins showed a spin-glass behavior at low temperatures.