Novel Cu0.96V0.02M0.02O (M = Mn, Fe, Co, Ni) nanocompositions: Remarkable optical and room temperature superparamagnetic properties

Wahba, Mohammed Ahmed, Talaat A. Hameed, Walid Sharmoukh, and Saad Mabrouk Yakout. "Novel Cu0. 96V0. 02M0. 02O (M= Mn, Fe, Co, Ni) nanocompositions: Remarkable optical and room temperature superparamagnetic properties." Optical Materials 127 (2022): 112254.

for full paper see

https://www.sciencedirect.com/science/article/abs/pii/S0925346722002889

Abstract

Multifunctional CuO semiconductor is a promising material for the full development of electronic, spintronics, terahertz and biomedical devices. In this study, new CuO compositions with strong room temperature superparamagnetic, terahertz optical conductivity and terahertz dielectric constant properties were realized. Pure CuO, Cu0.96V0.02Mn0.02O, Cu0.96V0.02Fe0.02O, Cu0.96V0.02Co0.02O and Cu0.96V0.02Ni0.02O nanopowders were synthesized by sol-gel method. The XRD confirmed the synthesis of single phase of monoclinic CuO structure. Based on the reduction on unit cell volume, the incorporation of V3+/4+, Mn2+, Fe3+, Co2+ and Ni2+ ions into CuO lattice have been verified. The dopants lead to formation of fine spherical nanoparticles with homogenous distribution and similar size. The TEM image of Cu0.96V0.02Fe0.02O reveals the formation of uniform spherical-nanoparticles possesses define surface edges with average size of 29 nm. The FTIR vibrational absorption modes of the synthesized CuO nanocompositions ruled out the presence of impurities or the existence of Cu2O phase. Optically, both (V, Mn) and (V, Co) codoping induced a red shift in the band gap energy of CuO (1.39 eV) on contrast to (V, Fe) and (V, Ni) with obvious blue shift. CuO codoped with different transition elements has been studied by terahertz time-domain spectroscopy (THz-TDS) in the range from 0.3 to 3 THz. The higher atomic weight elements show higher values of dielectric constant and optical conductivity. Cu0.96V0.02Fe0.02O exhibited an excellent intrinsic superparamagnetic curve with semi-saturation magnetization of ∼0.39 emu/g, coercivity and retentivity values close to zero.

Terahertz Testing Technique for Fiber-Reinforced Composite Materials

Zhong, Shuncong, and Walter Nsengiyumva. "Terahertz Testing Technique for Fiber-Reinforced Composite Materials." In Nondestructive Testing and Evaluation of Fiber-Reinforced Composite Structures, pp. 273-314. Springer, Singapore, 2022.

for full paper see https://link.springer.com/chapter/10.1007/978-981-19-0848-4_6

Abstract

Terahertz (THz) systems constitute an effective tool for the NDT&E community for the testing and characterization of fiber-reinforced composite materials. However, their systems are still very complicated and expensive to commercialize. Also, establishing the inspection limits for the vast majority of fiber-reinforced composite structures is still not achieved because this technique is relatively new in the area of material testing and evaluation. Nevertheless, this technique presents several advantages including the fact that it can see “through” the defects in thin composites and examine the underlying fabric of the material, overcoming the shadowing effect that is commonly observed with other NDT techniques such as ultrasonic testing and most of the radiographic testing techniques. Although the technology had been deferred for many years because of the inadequacy of its emission and detection devices, the so-called “THz gap”, this problem has recently been addressed thanks to the development of highly performing semiconductors and ultrafast electronics. To date, extremely short pulses required for the energy frequency of the THz waves can be achieved, suggesting that spatial resolution of the inspection levels higher than those of the normal microwave-based NDT techniques can be reached using THz systems. A lot has been done but much still needs to be done, particularly because there are no reported studies on the inspection of moisture uptake in fiber-reinforced composite structures nor are there any studies that confidently inspect conductive materials using THz waves. Indeed, this would be a highly valued milestone to the literature if it was achieved. In applications involving the inspection of thick composites and sandwich structures, THz systems do not, unfortunately, provide reliable inspection results owing to the attenuation and/or the scattering effects of the THz waves in thick sections.

… Although tremendous progress has been made in the THz technology in recentyears, typically the signal-to-noise ratio (SNR) is somewhat smaller except whenusing some of the most advanced THz systems such as Teraview (TeraView TPS …

Multifunctional Elastic Nanocomposites with Extremely Low Concentrations of Single-Walled Carbon Nanotubes

Novikov, Ilya V., Dmitry V. Krasnikov, Anton M. Vorobei, Yaroslav I. Zuev, Hassaan A. Butt, Fedor S. Fedorov, Sergey A. Gusev et al. "Multifunctional Elastic Nanocomposites with Extremely Low Concentrations of Single-Walled Carbon Nanotubes." ACS Applied Materials & Interfaces (2022).

for full paper see https://pubs.acs.org/doi/abs/10.1021/acsami.2c01086

Abstract

Stretchable and flexible electronics has attracted broad attention over the last years. Nanocomposites based on elastomers and carbon nanotubes are a promising material for soft electronic applications. Despite the fact that single-walled carbon nanotube (SWCNT) based nanocomposites often demonstrate superior properties, the vast majority of the studies were devoted to those based on multiwalled carbon nanotubes (MWCNTs) mainly because of their higher availability and easier processing procedures. Moreover, high weight concentrations of MWCNTs are often required for high performance of the nanocomposites in electronic applications. Inspired by the recent drop in the SWCNT price, we have focused on fabrication of elastic nanocomposites with very low concentrations of SWCNTs to reduce the cost of nanocomposites further. In this work, we use a fast method of coagulation (antisolvent) precipitation to fabricate elastic composites based on thermoplastic polyurethane (TPU) and SWCNTs with a homogeneous distribution of SWCNTs in bulk TPU. Applicability of the approach is confirmed by extra low percolation threshold of 0.006 wt % and, as a consequence, by the state-of-the-art performance of fabricated elastic nanocomposites at very low SWCNT concentrations for strain sensing (gauge factor of 82 at 0.05 wt %) and EMI shielding (efficiency of 30 dB mm–1 at 0.01 wt %).

EMI-shielding efficiency of the nanocomposites in the THz range was tested using a time-domain spectrometer (TeraView TPS 3000). Both disk shaped samples with a thickness of 0.5 mm (the same were used for impedance tests) and thin film samples were used for testing, ranging in thickness from 0.1–0.2 mm, depending on the SWCNT loading in the nanocomposites.