Structure and magnetic properties of carbon microspheres prepared by solid-phase pyrolysis of organic compounds

Manukyan, Aram; Mirzakhanyan, A. A.; Khachaturyan, Ruben; Gyulasaryan, A. T.; Kocharian, Armen; Yuzyuk, Yu. I.; Sharoyan, É. G.

doi:10.3103/s1068337215020140

Cited by 6 publications

(12 citation statements)

References 14 publications

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“…The paramagnetism of the carbon matrix is apparently due either to impurity nitrogen atoms or to the electronic states in nanographites at the zig-zag edges. The magnetic properties of the carbon matrix obtained after the solid-phase pyrolysis of a metal free phthalocyanine were also studied in our previous works [21,22]. In series samples with copper -Cu m /C, at temperatures < 50 K, paramagnetism prevails (see the inset in Fig.…”

Section: Magnetic Measurementsmentioning

confidence: 96%

Ferromagnetism and giant paramagnetism of copper nanoparticles in Cum/C nanocomposites

Manukyan

Gyulasaryan

Kocharian

et al. 2019

Journal of Magnetism and Magnetic Materials

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A B S T R A C TCarbon coated copper nanoparticles, Cu m /C nanocomposites, were synthesized using solid-phase pyrolysis in solid solutions of copper phthalocyanine and metal free copper phthalocyanine, (CuPc) x (H 2 Pc) 1−x where x 0 1. The weight concentration of copper in percentages consistently varies from 0 to 12 wt% and the sizes of copper nanoparticles in samples changes from 2 nm to 500 nm. Samples containing 8 and 12 wt% Cu have a bimodal size distribution. The X-ray diffraction data and HRTEM images show a face-centered cubic structure of Cu nanocrystallites that uniformly distributed in the carbon matrix. The temperature and field dependences of the magnetization in all copper-containing samples exhibit both ferromagnetic and giant-paramagnetic properties in the measured temperature range of 10-300 K. The saturation magnetization of ferromagnetic nanoparticles falls in the range 0.2-1.5 emu/g and weakly depends on the temperature from helium up to the room temperatures. The paramagnetic magnetizations in Cu/C nanocomposites at H = 50 kOe and T = 10 K are practically an order of magnitude higher in all the samples than the ferromagnetic saturation magnetizations. The paramagnetic susceptibilities of the Cu m /C nanocomposites at 10 K are of the order of (0.3-1)10 −4 emu/ g Cu Oe, which are one and a half to two orders of magnitude higher than the specific paramagnetic susceptibility of the carbon matrix.

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Section: Magnetic Measurementsmentioning

confidence: 96%

Ferromagnetism and giant paramagnetism of copper nanoparticles in Cum/C nanocomposites

Manukyan

Gyulasaryan

Kocharian

et al. 2019

Journal of Magnetism and Magnetic Materials

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“…4). There are two narrow peaks at ≈1350 cm -1 and ≈1590 cm -1 , which correspond, respectively, to D-and G-bands of partially graphitized carbon microspheres [12]. A very broad band in the range of 1000-3500 cm -1 in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…As seen, the nearly spherical nanoparticles are sufficiently homogeneously dispersed in carbon matrix. Note that there is also a certain amount of carbon microspheres of 2-3 μm diameter in the matrix (more about them see in [11,12]). …”

Section: Resultsmentioning

confidence: 98%

“…As seen, there is a considerable difference between samples synthesized at different temperatures. Comparison with tabulated data [13] shows that a broad peak at ≈25° corresponds to partially graphitized carbon microspheres (d 002 ≈ 0.345 nm) [11,12], while four more narrow peaks in the spectrum (Fig. 3a) relate to Zn nanocrystallites with hexagonal symmetry.…”

Section: Resultsmentioning

confidence: 98%

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Characterization of zinc and zinc cyanide nanoparticles in carbon matrices prepared by solid-phase pyrolysis of zinc-phthalocyanine

et al. 2016

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Abstract⎯Using solid-phase pyrolysis of Zn-phthalocyanine (ZnC 32 H 16 N 8 ), we have prepared zinc and zinc cyanide nanoparticles in carbon matrices with a zinc concentration of 3 at %. The structure and composition of samples were investigated by the methods of scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. It is shown that at low pyrolysis temperature (700°C) only the Zn nanoparticles are formed, whereas at higher temperature (900°C) a certain amount of Zn(CN) 2 nanoparticles are also synthesized. The mean diameter of nanoparticles is about 150 nm, and their size distribution has a logarithmically normal shape.

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“…We have also developed the method of solid phase pyrolysis of non-metallic phthalocyanine alloy H 2 Pc [H 2 (C 32 N 8 H 16 )]. By solid-phase pyrolysis of polycrystalline samples, the carbon microspheres consisting of nanographite crystallites and amorphous carbon have been produced [13][14][15]. Varying the parameters of solid-state pyrolysis and dilution of metal-phthalocyanine powders with the non-metal phthalocyanine give a unique opportunity to obtain the metal nanoparticles with sizes from one to 200 nm; at that, the atomic concentration of the ISSN 1068-3372, Journal of Contemporary Physics (Armenian Academy of Sciences), 2017, Vol.…”

Section: Introductionmentioning

confidence: 99%

FMR and EPR in Ni@C nanocomposites: Size and concentration effects

et al. 2017

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Ni@C nanoparticles encapsulated in carbon coating have been investigated depending on the size and concentration of Ni in carbon. The nanoparticles of nickel were prepared with the average diameters changing in a broad range of 4-45 nm, and the concentration of Ni in C varies in 2-12 wt%. To prepare the Ni@C nanocomposites the solid solutions of nickel phthalocyanine-metal-free phthalocyanine (NiPc) x (H 2 Pc) 1-x , 0 ≤ x ≤ 1 were synthesized and the solidphase pyrolysis of these compounds was performed. In the case of ultradispersive Ni nanoparticles (the interval of quantum dots is 1-10 nm), a considerable shift of the resonance field and broadening of resonance absorption field were revealed in the spectra of FMR at room temperature. The data were interpreted taking into account the essential contribution of the surface magnetic anisotropy, the magnetic field of which far exceeds the magnetic field of volume anisotropy.

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Structure and magnetic properties of carbon microspheres prepared by solid-phase pyrolysis of organic compounds

Cited by 6 publications

References 14 publications

Ferromagnetism and giant paramagnetism of copper nanoparticles in Cum/C nanocomposites

Ferromagnetism and giant paramagnetism of copper nanoparticles in Cum/C nanocomposites

Characterization of zinc and zinc cyanide nanoparticles in carbon matrices prepared by solid-phase pyrolysis of zinc-phthalocyanine

FMR and EPR in Ni@C nanocomposites: Size and concentration effects

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