Cathodic Arc Discharge for Synthesis of Carbon Nanoparticles

In this chapter, the authors report further experimental details and several physical analyses of the floating powder and propose a model for the formation mechanism. They discussed the ability to analyze carbon nanoparticle formation in terms of a charged dusty plasma process. The detected carbon nanoparticles using a Langmuir probe technique are in agreement with the presence of fullerene-sized molecules in the plasma. The plasma can also be visually observed to surround the anode, indicating the direction of plasma expansion. There is a plasma zone between electrodes surrounded by a gas bubble due to vaporization of the surrounding liquid, as the arc temperature is estimated to be around 4000 K. The extremely sharp temperature gradient in the gas bubbles emanating from the hot plasma region to the gas–water interface is essential to cause rapid solidification of the vaporized carbon. Subsequent to the formation of onions, carbon particles coagulate into larger van der Waals crystals.


Phenomenological approaches on the phase transition mechanisms of some ferroelectric materials
Kara, Nazan; Yurtseven, Hasan Hamit; Kiracı, Ali; Department of Physics (2023-1-25)
Several phenomenological studies were carried out to investigate the phase transition mechanisms of some ferroelectric crystals. In particular, we focused on the compressible Ising model to explain the anomalous behavior of specific heat for such ferroelectrics exhibiting second-order phase transitions in the vicinity of the transition temperatures. The temperature dependence of some thermodynamic functions such as internal energy, enthalpy, entropy, and free energy of some ferroelectric materials was also ...
Transition metal-doped janus monolayer SMoSe with excellent thermal spin filter and spin Seebeck effect
Ding, Guangqian; Wei, Mian; Surucu, Gokhan; Liang, Zhengyong; Wang, Xiaotian (Elsevier BV, 2019-10-15)
Motivated by the recent experimental synthesis of the novel janus monolayer SMoSe, we propose the design of spin caloritronic material based on transition metal-doped SMoSe monolayer. Using density functional theory combined with the non-equilibrium Green's function method, we show that a perfect thermal spin filter and a negative differential thermoelectric resistance are obtained in Fe-doped SMoSe janus monolayer. For Cr-doped SMoSe janus monolayer on the other hand, the thermal induced spin-up and spin-d...
Photocatalytic activity in nano sized titanium dioxide structures
Oymak, Mert Mehmet; Üner, Deniz; Özen, İstem; Department of Chemical Engineering (2012)
The objective of this thesis is to investigate the photocatalytic activity in nanosized TiO2 structures. Two different structures were used for two different reaction systems. In the first part of the study, TiO2 coated on glass beads by a sol-gel procedure were used to test the photocatalytic CO2 reduction reaction with H2O and H2 in the gas phase. The results of photocatalytic CO2 reduction reaction revealed that CO2 reduction step of the overall reaction proceeds in dark; while illumination is required f...
Metamagnetic Phase Transitions in La1-xNdxMn2Si2
Emre, B.; Yurtseven, Hasan Hamit (2013-04-01)
Experimental measurements for the magnetization at various temperatures are analyzed using a mean field model for the purely ferromagnetic spin configuration near the metamagnetic phase transitions in La1-x Nd (x) Mn2Si2 (x=0.3) at a constant magnetic field (50 mT). By fitting the temperature dependence of the magnetization from the free energy in the mean field model to the experimental data for this compound, the coefficients in the free energy expansion are determined. Our analysis of the magnetization d...
The Thermal Characterization of Crude Oils in a Limestone Matrix of Different Particle Size
Kök, Mustafa Verşan (2014-05-03)
In the first part of this research, the effect of particle size (35-100 mesh) on the calcination kinetics of a limestone sample was investigated by thermogravimetric analysis technique. Thermal studies showed that two main weight loss regions are observed in limestone samples of different particle size. In the second part of the research, thermal analysis of a medium crude oil sample in a limestone matrix of different particle size is analyzed. Two different reaction regions were observed known as low tempe...
Citation Formats
H. E. Ünalan, Cathodic Arc Discharge for Synthesis of Carbon Nanoparticles. 2011, p. 163.