Ultra-light-weight microwave X-band EMI shielding or RAM material made from sustainable pyrolysed cork templates.

Cork is a renewable and sustainable material, highly porous and lightweight. We valorised waste cork and recycled wine stoppers to make pyrolysed/carbonised solid cork, for use as economic and sustainable microwave (MW) absorbers at the microwave X-band (8-12 GHz), without binder or additives. Although cork is already a very lightweight material (0.16 g cm-3), the pyrolysed cork is five-times less dense at 0.031 g cm-3, was amorphous graphitic carbon, and had an excellent shielding effectiveness (SET) of -18 to -38 dB, depending on thickness, with attenuation of the electromagnetic energy through internal reflection within the cellular cork structure. Furthermore, this ultra-light-weight material has an extremely high MW specific shielding effectiveness or efficiency (SSE), between -640 to -1235 dB g-1 cm3 over the entire X-band range, depending on thickness (3.0-8.6 mm), one of the highest reported for any pure carbon material, this upper value being more than twice that of any previously reported graphite-based foams.

Silica-Based Organic-Inorganic Hybrid Fluorescent Ink for Security Applications.

A facile formulation of fast-drying fluorescent ink made from nanostructured fluorescent silica nanocrystals is presented. The rheostable viscous ink suitable for screen printing was developed by careful selection of organic vehicle components, which was later printed onto various rigid and flexible substrates. Photoluminescence studies of the printed film confirmed that the formulated ink composition did not show noticeable influence on the excitation property of the fluorescent silica. The developed cost-effective and fast-curing fluorescent silica ink with desirable luminescent property makes it a suitable candidate for information encryption, optical devices, and energy conversion applications.

Printable Hierarchical Nickel Nanowires for Soft Magnetic Applications.

Hierarchical nickel nanowires (h-NiNWs) were synthesized by a simple reduction method and their electrical, magnetic, and electromagnetic characteristics were investigated. These nanowires possess a high magnetic saturation (M s) of 51 emu/g and also a coercivity (H c) of 34.5 Oe, which makes them suitable for soft magnetic sensor applications. Hall transport is being reported for the first time for h-NiNWs, and electrical conductivity at room temperature was studied to assess their applicability as a Hall sensor wherein the Hall coefficient R H was found to be -1.39 × 10-12 Ω cm/Oe. Electromagnetic characterization of synthesized h-NiNWs shows excellent microwave shielding effectiveness of above 24 dB for the Ku band (12.4-18 GHz) and a maximum value of 32 dB at 14 GHz for a sample with a thickness of about 1 mm. A room-temperature-curable screen-printable ink was formulated using the synthesized magnetic nanostructures and printed on different flexible substrates. Printed patterns show promising ferromagnetic properties, and they could be potential candidates for soft magnetic sensor applications.

Silver-Decorated Boron Nitride Nanosheets as an Effective Hybrid Filler in PMMA for High-Thermal-Conductivity Electronic Substrates.

High-thermal-conductivity and low-dielectric-loss polymer nanocomposites have gained tremendous attention in microelectronics technology. Against this background, the present study deals with the development of a high-thermal-conductivity, low-dielectric-constant, and low-loss polymer nanocomposite based on silver nanoparticle (AgNP)-decorated boron nitride nanosheets (BNNSs) as the filler in poly(methyl methacrylate) (PMMA) matrix. The nanocomposites were prepared through a facile solution-blending process. Elemental mapping of the prepared nanocomposite indicates the uniform distribution of filler particle in PMMA matrix. An impressive high-thermal conductivity (TC) enhancement of around 363% was achieved for nanocomposite of 0.35 V f of hybrid filler (1.48 W/m K) compared to pristine PMMA (0.32 W/m K). The addition of AgNP reduces the thermal contact resistance (R c) by bridging individual BNNS, thereby improving thermal transport. Measured TC values were fitted with a theoretical model that showed good agreement. Dielectric measurements performed at radiofrequencies and microwave frequencies revealed that the nanocomposites show a low dielectric constant (<5), low loss (10-2), and very low alternating current conductivity (10-7 S/cm). The results suggest that silver-decorated BNNS is a promising hybrid filler for effective thermal management.