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Equilibrium molecular dynamics (EMD) simulations have been performed to investigate the structural analysis and thermal conductivity (λ) of semiconducting (8,0) and metallic (12,0) zigzag single-walled carbon nanotubes (SWCNTs) for varying ±γ(%) strains. For the first time, the present outcomes provide valuable insights into the relationship between the structural properties of zigzag SWCNTs and corresponding thermal behavior, which is essential for the development of high-performance nanocomposites. The radial distribution function (RDF) has been employed to assess the buckling and deformation understandings of the (8,0) and (12,0) SWCNTs for a wide range of temperature T(K) and varying ±γ(%) strains. The visualization of SWCNTs shows that the earlier buckling and deformation processes are observed for semiconducting SWCNTs as compared to metallic SWCNTs for high T(K) and it also evident through an abrupt increase in RDF peaks. The RDF and visualization analyses demonstrate that the (8,0) SWCNTs can more tunable under compressive than tensile strains, however, the (12,0) zigzag SWCNTs indicate an opposite trend and may tolerate more tensile than compressive strains. Investigations show that the tunable domain of ±γ(%) strains decreases from (-10%≤ γ ≤+19%) to (-5%≤ γ ≤+10%) for (8,0) SWCNTs and the buckling process shifts to lower ±γ(%) for (12,0) SWCNTs with increasing T(K). For intermediate-high T(K), the λ(T) of (12,0) SWCNTs is high but the (8,0) SWCNTs show certainly high λ(T) for low T(K). The present λ(T, ±γ) data are in reasonable agreement with parts of previous NEMD, GK-HNEMD data and experimental investigations with simulation results generally under predicting the λ(T, ±γ) by the ∼1% to ∼20%, regardless of the ±γ(%) strains, depending on T(K). Our simulation data significantly expand the strain range to -10% ≤ γ ≤ +19% for both zigzag SWCNTs, depending on temperature T(K). This extension of the range aims to establish a tunable regime and delve into the intrinsic characteristics of zigzag SWCNTs, building upon previous work. [ABSTRACT FROM AUTHOR]

In this research work we have synthesized copper sulfide (Cu2−xS) nanostructures by the hydrothermal method. The post-sulfurization was performed by using tube furnace to reduce sulfur deficiency and to minimize impurities present in the crystal-lattice. The samples were synthesized by various pH values of precursor solution. The samples were characterized by XRD, RAMAN spectroscopy, SEM, Hall measurements and Seebeck effect. XRD analysis revealed the formation of hexagonal covellite (CuS) and chalcocite (Cu2S) phases of copper sulfide. Despite these phases XRD data also showed the dominating hexagonal digenite (Cu1.8S) phase of copper sulfide. We observed a decreasing trend in average crystalline size with the increasing pH values of the samples from the XRD data. We have found maximum average crystalline size of 39.1679 nm at pH value of 4. The formation of LO mode of hexagonal covellite phase of copper sulfide was observed from RAMAN analysis. The SEM images revealed the formation of flower-like nanostructures at the lowest pH value. It strengthened our argument that the crystallinity of nanostructures is inversely proportional to the pH value. We have achieved maximum values of Seebeck coefficient and conductivity at room temperature as 73.920 µV/K and 0.909 S/cm, respectively. The Seebeck coefficient and conductivity graphs showed an increasing trend due to the energy filtering effect in mesoporous structure. The maximum value of power factor was 4.91 × 10–7 Wm−1 K−2. [ABSTRACT FROM AUTHOR]