Nickel doping effect on structure and ac conductivity of resorcinol formaldehyde/SiO2-Ni nanocomposites synthesized by sol–gel process

Effect of The Nickel And Temperature Dependent Electrical Properties C-SiO2 -Ni Composites

“…In quantum mechanical tunnel effect model (QMT), s does not vary with temperature and almost equal to 0.8 [49][50][51]. Previous studies done by Gouadria et al [39] on nanocomposite based on a carbon matrix doped with 50% silica shows the existence of a quantum mechanical tunnel model (QMT) for the sample treated at 675°C whose the frequency exponent is independent of the temperature and almost equal to 0,87. Previous studies by Ben Mansour et al [16] on nanocomposite based on pyrogallol and formaldehyde (PF) based carbon matrix doped by Nickel oxide (NiO) processed at 625 indicates the presence of a small polaron hopping model.…”

“…In quantum mechanical tunnel effect model (QMT), s does not vary with temperature and almost equal to 0.8 [49][50][51]. Previous studies done by Gouadria et al [39] on nanocomposite based on a carbon matrix doped with 50% silica shows the existence of a quantum mechanical tunnel model (QMT) for the sample treated at 675°C whose the frequency exponent is A linear adjustment of Eq. (1), gives the values of s are illustrated in Fig.…”

“…We notice that the existence of the NDR is correlated with the conductivity of the material, in fact, for samples with high resistivity the NDR persists at ambient temperature, is the case for C-SiO 2 -Ni 5% -625 which has a conductivity equal to σ = 1.63410 − 5 (Ω.cm) −1 [37,38]. While when conductivity increases the NDR does not appear at ambient temperature and only appears for low measuring temperatures, is the case for C-SiO 2 -Ni 5% -650 ( σ = 1.54*10 − 3 (Ω.cm) −1 [39]) and for C-SiO 2 -Ni 5% -675( σ = 4.1*10 − 3 (Ω.cm) −1 [38,40]). As a conclusion of our work, we can explain that insulating materials have the advantage of the appearance of the NDR at ambient temperature.…”

Carbon Yarn‐Ball‐Entangled SiO2 Anode with Excellent Electrochemical Performance for Lithium‐Ion Batteries

“…Various nanostructured SiO 2 have shown greatly enhanced conductivity and electrochemical reactivity compared to micrometer-sized SiO 2 . [12,[15][16][17][18][19][20][21][22][23] To alleviate the detrimental effect of pulverization, conductive shells, cages, and continuous matrices have been developed to accommodate the lattice volume variation of SiO 2 during lithiation/delithiation. [9,24] Carbonaceous materials have been extensively studied for the encapsulation of nanoscale SiO 2 , with examples such as amorphous coating layers, [13,19,25,26] continuous shells and tubes, [17,23,27,28] and hollow SiO 2 /carbon spheres.…”

“…[16,23,29] Some metal oxides such as TiO 2 and NiO shells have also been employed to encapsulate SiO 2 particles. [20,30] Carbon nanosheets/plates, [31] interwoven carbon nanofibers/nanotubes, [21,32,33] mesoporous carbon composites, [18,26,28,34,35] graphene sheets/aerogels, [36] reduced graphene oxide matrices, [22,37] and MXene architectures [38] have been engineered to load dispersed nanoscale SiO 2 particles. The electrochemical performance of the encapsulated SiO 2 strongly depends on the shell or cage, which are usually delicately synthesized by either expensive chemical reagents such as polydopamine and guanine, or by sophisticated procedures such as etching and templates.…”