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Guzman, D., Aguilar, C., Rojas, P., Criado, J. M., Dianez, M. J., Espinoza, R., et al. (2019). Production of Ag-ZnO powders by hot mechanochemical processing. T. Nonferr. Metal. Soc., 29(2), 365–373.
Abstract: Ag-CdO composites are still one of the most commonly used electrical contact materials in low-voltage applications owing to their excellent electrical and mechanical properties. Nevertheless, considering the restriction on using Cd due to its toxicity, it is necessary to find alternative materials that can replace these composites. In this study, the synthesis of Ag-ZnO alloys from Ag-Zn solid solutions was investigated by hot mechanochemical processing. The hot mechanochemical processing was conducted in a modified attritor mill at 138 degrees C under flowing O-2 at 1200 cm(3)/min for 3.0 h. The microstructure and phase evolution were investigated using X-ray diffractometry, field emission gun scanning electron microscopy and transmission electron microscopy. The results suggest that it is possible to complete the oxidation of Ag-Zn solid solution by hot mechanochemical processing at a low temperature and short time. This novel synthesis route can produce Ag-ZnO composites with a homogeneous distribution of nanoscale ZnO precipitates, which is impossible to achieve using the conventional material processing methods. Considering the fact that the fundamental approach to improving electric contact material performance resides in obtaining uniform dispersion of the second-phase in the Ag matrix, this new processing route could open the possibility for Ag-ZnO composites to replace non-environmentally friendly Ag-CdO.
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Kumar, N., Gajraj, V., Rameshbabu, R., Mangalaraja, R. V., Joshi, N. C., & Priyadarshi, N. (2022). Redox additive electrolyte assisted promising pseudocapacitance from strictly 1D and 2D blended structures of MnO2/rGO. Mater. Charact., 189, 111991.
Abstract: A promising sustainable energy storage characteristic is achieved in redox additive electrolyte by developing strict blend of one dimensional (1D) and two dimensional (2D) structures. Hydrothermal reaction is followed to obtain the desired morphology. Two dimensional (2D) reduced graphene oxide (rGO) is added into the redox reaction between potassium permanganate and sodium nitrite to obtain nanocomposite comprising 1D and 2D blended structures of MnO2/rGO. Their structures and morphologies are studied by XRD, Raman and HRTEM analyses, respectively. The pseudocapacitive behaviour is studied in a redox additive electrolyte comprising KOH and K3Fe(CN)(6). The effect of electrolytic concentration was studied by varying the concentration of K3Fe(CN)6. The specific capacity is considerably enhanced up to 1741 F/g, 8.75 A/g with increase in concentration of K3Fe (CN)6. The role of redox couple [Fe(CN)(6)](3)-/[Fe(CN)(6)](4)-played a key role in adding the charge movement across the electrode which tuned well with the manganese ions to obtain one of the most promising pseudo-capacitances from the developed 1D and 2D blended structures of MnO2/rGO. For in-depth analysis of Fe ions movement, a symmetric supercapacitor cell is constructed to achieve a commendable specific capacitance of 216 F/g at 3.75 A/g. Prolong cycling hinted decreasing electrolytic interfacial layers resulting in fast reversible ki-netics of Fe(III) -> Fe(II) ions to achieve astonishing capacity retention of 127% after 3000 cycles.
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Nandhakumar, E., Selvakumar, P., Arulraj, A., Vivek, E., Venkatraman, M. R., Sasikumar, A., et al. (2023). Investigation on rod like SnO2@CdCO3 nanocomposite-based electron transport layer for CsPbBr3 heterojunction perovskite solar cell applications br. Mater. Lett., 330, 133396.
Abstract: A novel carbonate-based nanocomposite synthesized by hydrothermal technique for planar perovskite solar cells (PPSCs) applications. According to this study, SnO2@CdCO3and SnO2/SnO2@CdCO3 performs as dual electron transporting layers for CsPbBr3 based perovskite solar cell. The fabricated PSCs with architecture of FTO/SnO2/ SnO2@CdCO3/CsPbBr3/C showed a Voc of 0.84 V, Jsc of 12.30 mA cmi 2, PCE of 6.67 % and FF of 0.64 are obtained at ambient condition.
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Thandapani, P., Aepuru, R., Beron, F., Mangalaraja, R. V., Varaprasad, K., Zabotto, F. L., et al. (2023). Multiferroic Electroactive Polymer Blend/Ferrite Nanocomposite Flexible Films for Cooling Devices. ACS Appl. Polym. Mater., 5(8), 5926–5936.
Abstract: In recent days, the interest toward the development ofmulticaloricmaterials for cooling application is increasing, whereas multiferroicmaterials would be the suitable alternative to the conventional refrigerants.To explore them, the poly(methyl methacrylate)/poly(vinylidenefluoride-co-hexafluoropropylene) (PMMA/PVDF-HFP) blend and PMMA/PVDF-HFP/Zn0.5Cu0.5Fe2O4 flexible multiferroicnanocomposite films were fabricated by the solution casting method.The structural analyses prove that the strong interfacial interactionbetween the PMMA/PVDF-HFP blend and the Zn0.5Cu0.5Fe2O4 (ZCF) through hydroxyl (-OH) andcarbonyl group bonding with PVDF-HFP enhanced the thermal stabilityand suppressed the electroactive & beta; phase from 67 to 62%. Experimentalresults show that 10 wt % of superparamagnetic ZCF nanoparticles witha particle size of 6.8 nm induced both the magnetocaloric and magnetoelectriceffects in a nonmagnetic PMMA/PVDF-HFP ferroelectric matrix at roomtemperature. A set of isothermal magnetization curves were recordedin the magnetic field strength of 0-40 kOe and a temperaturerange of 2-400 K. The maximum magnetic entropy changes (& UDelta;S (M)) of -0.69 J & BULL;kg(-1) K-1 of ZCF nanoparticles and -0.094 J & BULL;kg(-1) K-1 of PMMA/PVDF-HFP/ZCF nanocompositesshowed an interesting table-like flat variation in the temperaturerange of 100-400 K as a function of the magnetic field. Thesamples display a large temperature span with a relative cooling power of 293 and 40 J & BULL;kg(-1) for ZCF and PMMA/PVDF-HFP/ZCF,respectively. The magnetoelectric effect of the PMMA/PVDF-HFP/ZCFcomposite was proved, but it generated only 1.42 mV/m & BULL;Oe in theapplied field of 5 kOe. Hence, the entropy change of the present nanocompositewas only due to the magnetocaloric effect, where the magnetoelectriccross-coupling coefficient was negligible. The multicaloric effectcould be established if the nanocomposite showed a larger magnetoelectriccross-coupling in addition to the magnetocaloric effect. This approachprovides the research findings in functional multiferroic polymernanocomposites for miniaturized cooling devices.
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