Study of electrical conductivity of the coatings of bimetallic Au-Ag nanoparticles

Abstract

The "metallic" temperature variation of the electrical resistivity of chemical nano goldsilver coatings with a silver content of 6.6% at. up to 13.1% at. determined in the temperature range 4.2-300 K. Features of low-temperature measurements of the resistance of nano-coatings were found and explained. The possibility of the appearance of superconductivity in them is discussed. IntroductionIn July 2018, a message appeared from Indian scientists about the development and properties of a new superconducting compound in the form of a chemical coating of nanoparticles (NPs) of gold with silver [1]. The temperature dependences of the resistance of manufactured coatings, on which the linear change of resistance typical for metals is replaced by a sharp drop to zero in the temperature range of 236 K (-37 °C) characteristic of the superconducting transition, are presented in this message. Measurement of the magnetic permeability of the coating samples showed the presence of a diamagnetic response below the transition temperature, which indicates the presence of the Meissner effect. In addition, an external magnetic field of 0.1 to 3 T biased the beginning of the transition to lower temperatures.The combination of these experimental results is usually sufficient evidence of the existence of superconductivity. It was also reported that one of the samples had a transition temperature of 320 K (+47 °C), which meant that room temperature superconductivity (PCB) was achieved for the first time in the history of superconductivity with normal external atmospheric pressure. Attempts to test the possibility of the existence of such a compound [2,3] after the specified message were made. In [2], nanoscale films consisting of alternating layers of gold and silver were made and studied. It should be noted that the vacuum thermal method of sputtering gold and silver, applied in [2], is very far from the chemical synthesis of these components in [1]. As a result, superconductivity has not been found out. The technique for

Evaluation of strategies to incorporate silver nanoparticles into electrospun microfibers for the preparation of wound dressings and their antimicrobial activity

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“…These results confirm that the presence of AgNPs and the post-treatments applied to the fibers cause a reduction in their diameter. In the case of Ag, the increase in the conductivity of the polymeric solution [40], and the application of post-treatments, such as temperature [41] and UV light [42][43][44] promote the complete elimination of solvent and cause a formation of covalent bonds promoting the crosslinking of polymeric chains, ordering the molecules and reducing the diameter of the fibers. Respecting to the wt.…”

Crystallographic structure, antibacterial effect, and catalytic activities of fig extract mediated silver nanoparticles

“…Metal-based nanoparticles, notably Ag NPs, have captured significant scientific interest owing to their exceptional biological and physicochemical characteristics [ 1 , 2 ]. Compared to their bulk counterparts, Ag NPs display distinct properties like catalytic activity, high thermal and electrical conductivity, chemical stability, surface-enhanced Raman scattering, good redox activity, nonlinear optical behavior, and antimicrobial effects [ [3] , [4] , [5] ]. These attributes make them highly versatile and applicable in diverse fields such as cosmetics, shampoos, soaps, detergents, electronics, medicine, and more [ 6 , 7 ].…”

Biosynthesis of Silver Nanoparticles Functionalized with Histidine and Phenylalanine Amino Acids for Potential Antioxidant and Antibacterial Activities

“… 4 These particular interests are associated with their unique chemical, physical, and biological characteristics in comparison to bulk size. 5 They possess high thermal and electrical conductivity, 6 surface-enhanced Raman scattering properties, chemical stability, catalytic activity, 7 nonlinear optical behavior, 8 drug delivery, and antimicrobial effects. 9 Owing to their unique properties, AgNPs have been widely applied in many fields, such as shampoos, soaps, detergents, 10 cosmetics, 11 toothpastes, electronics, optics, and medical and pharmaceutical products.…”