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

Abstract

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.

Bimetallic Copper–Iron Oxide Nanoparticle-Coated Leathers for Lighting Applications

“…Such high coercivity on the order of 1300–3700 Oe (1 Oe = 1 G) is reported for the spherical hematite hierarchical nanostructures with a diameter of 20–80 nm obtained by glycine-assisted hydrothermal synthesis. , The calcined Cu NPs exhibit weak ferromagnetic behavior with a saturation magnetization value of 1 emu/g, a minimal coercivity of 45 G, and a remanence of 0.007 emu/g (Figure b and Figure S6b). Such weak ferromagnetic behavior with saturation magnetization in the range of 0.2–1.5 emu/g was reported for carbon-coated Cu nanoparticles with average sizes of 2–500 nm . The calcined bimetallic Cu-IO NPs present a strong ferromagnetic behavior with a hysteresis loop and perfect saturation magnetization even at fields less than 0.5 T and a fairly high magnetic moment of 19 emu/g (Figure c).…”

“…Such weak ferromagnetic behavior with saturation magnetization in the range of 0.2−1.5 emu/g was reported for carbon-coated Cu nanoparticles with average sizes of 2−500 nm. 47 The calcined bimetallic Cu-IO NPs present a strong ferromagnetic behavior with a hysteresis loop and perfect saturation magnetization even at fields less than 0.5 T and a fairly high magnetic moment of 19 emu/g (Figure 4c). It is also interesting to notice that the calcined Cu-IO NPs show coercivity and remanence of 151.7 G and 3.7 emu/g, respectively (Figure S6c).…”

Graphene@Metal Nanocomposites by Solution Combustion Synthesis

“…However, totally excluding some influence of small amounts of impurities is not possible without an additional study. On the other hand, ferromagnetism in diamagnetic materials, like copper, in a nanoscale was reported earlier in refs – , wherein it suggested that ferromagnetism in carbon–copper nanocomposites may be connected with charge transfer between the metal and carbon phases by two possible mechanisms. In the case of electron transfer from the copper to scsG phase, surface and near-surface layers of copper have electron configurations similar to that of ferromagnetic nickel.…”

Structure and Magnetism of Few-Layer Nanographene Clusters in Carbon Microspheres

“…At present, we are solving these problems using different capabilities of the solid-phase pyrolysis method. Earlier we studied and found interesting size effects relevant to magnetism in nanocomposites Ni@C and Cu@C, which were also obtained by solid-phase pyrolysis. , …”