Original Article in 2017

A novel way of exploiting incipient piezoelectric strain of lead-free piezoceramics is introduced by demonstrating that a crystallographically constrained polarization allows a maximum use of potentially available electrostriction in materials. This approach enables the incipient piezoceramics to overcome their inherent weaknesses hindering their commercialization.

Ab initio calculations reveal that defects As_Ga, Bi_Ga, As_Ga+Bi_As and Bi_Ga+Bi_As are the dominant minority-electron traps and defects V_Ga and V_Ga+Bi_As are the dominant minority-hole traps in the metastable alloy GaAsBi grown under As-rich condition. Changing the growth away from the As-rich condition and/or using hydrogen passivation are suggested to reduce the deleterious effects of these defects.

A semiconducting molecular ferroelectric (2-(ammoniomethyl)pyridinium)SbI₅ was designed. It shows an above-room-temperature Curie temperature (T_c=360 K), a large spontaneous polarization (P_s=4 μC cm⁻²) and small bandgap (2.03 eV) that are comparable to those of the well-known semiconducting ferroelectrics BiFeO₃ (E_g=2.7 eV) and SbSI (E_g=2.0 eV). The implementation of ferroelectricity into hybrid semiconducting materials will move the applications of hybrid semiconducting molecular ferroelectrics in optoelectronic and photovoltaics devices forward.

In both the rhombohedral and the cubic phase GeTe, resonant levels induced by indium dopants have been demonstrated. The experimental Seebeck coefficients of In_xGe_1−xTe show large enhancement as compared with other prior dopants. The enhanced Seebeck coefficient, combined with the reduced thermal conductivity, leads to a reasonably high ZT of 1.3 near 355 °C in In_0.02Ge_0.98Te. The average ZT is enhanced by ~70% across the whole temperature range. The present results suggest that indium-doped GeTe can be a promising base-material for even higher thermoelectric performance.

Core-shell & co-doping nanoscale metal-organic particles (NMOPs), with high strong NIR absorbance, high radio-sensitizing capability and intrinsic biodegradability are developed via a post-synthesis cation exchange strategy for multimodal imaging guided synergistic thermo-radiotherapy. After coating with polydopamine and further conjugation with polyethylene glycol (PEG), such NMOP-PEG nanoparticles show effective tumor retention, and could be utilized for effective synergistic thermo-radiotherapy of cancer. Importantly, those NMOPs show no appreciable toxicity to the treated mice, and could be rapidly excreted from the body owing to their biodegradability.

In this work, the authors reported a three-dimensional room temperature quasistatic magnetic cloak using a ferromagnetic metallic bilayer structure by showing prominent cloaking effect in a wide frequency range from 5 to 250 kHz. The practical potential was also verified through a commercial handheld metal probe working at 25 kHz.

Redox-flow batteries (RFBs) seem to be tailor-made for the storage of sustainably generated electrical energy and are, in particular combined with photovoltaics and wind farms, well suited for the establishment of smart grids, which are essential to render the ‘Energiewende’. Therefore, an all-organic symmetric RFB with a bipolar molecule containing two redox-active nitronyl nitroxide units, connected via a tetraethylene glycol chain, as a charge-storage material, was developed. The synthesized molecule was electrochemically characterized in detail and its potential as organic redox-active material for an application in a symmetric RFB was investigated in a static and in a pumped laboratory test cell as well.