Enhanced electromagnon excitations in Nd-doped BiFeO3 nanoparticles near morphotropic phase boundaries.

In multiferroics, electromagnons have been recognized as a noticeable topic due to their indispensable role in magnetoelectric, magnetodielectric, and magnetocapacitance effects. Here, the electromagnons of Bi1-xNdxFeO3 (x = 0-0.2) nanoparticles are studied via terahertz time-domain spectroscopy, and the impacts of doping concentrations on electromagnons have been discussed. We found that the electromagnons in Bi1-xNdxFeO3 nanoparticles are associated with their phase transition. The total coupling weight of electromagnons is gradually increased in polar R3c structures and then reduces in the antipolar Pbam phase, and the weight in the antipolar phase is less than that of the pure R3c phase. Interestingly, a colossal electromagnon is observed at polar-antipolar and antiferromagnetic-ferromagnetic phase boundaries. Our work offers an avenue for designing and choosing materials with better magnetodielectric and magnetocapacitance properties.

Titania modification with a ruthenium(II) complex and gold nanoparticles for photocatalytic degradation of organic compounds.

Titania of fine anatase nanoparticles (ST01) was modified successively with two components, i.e., a ruthenium(II) complex with phosphonic anchoring groups [Ru(bpy)2(4,4'-(CH2PO3H2)2bpy)](2+) bpy = 2,2'-bipyridine (Ru(II)CP) and gold nanoparticles (Au). Various compositions of two titania modifiers were investigated, i.e., Au, Au + Ru(II)CP, Au + 0.5Ru(II)CP, Ru(II)CP, 0.5Ru(II)CP and 0.25Ru(II)CP, where Au and Ru(II)CP correspond to 0.81 mol% and 0.34 mol% (with respect to titania), respectively. In the case of hybrid photocatalysts, the sequence of modification (ruthenium(II) complex adsorption or gold deposition) was investigated to check its influence on the resultant properties and thus photocatalytic performance. Diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) were applied to characterize the structural properties of the prepared photocatalysts, which confirmed the successful introduction of modifiers of the ruthenium(II) complex and/or gold NPs. Different distributions of gold particle sizes and chemical compositions were obtained for the hybrid photocatalysts prepared with an opposite sequence. It was found that photocatalytic activities depended on the range of used irradiation (UV/vis or vis) and the kind of modifier in different ways. Gold NPs improved the photocatalytic activities, while Ru(II)CP inhibited the reactions under UV/vis irradiation, i.e., methanol dehydrogenation and acetic acid degradation. Oppositely, Ru(II)CP greatly enhanced the photocatalytic activities for 2-propanol oxidation under visible light irradiation.

Robustly Stable Ferroelectric Polarization States Enable Long-Term Nonvolatile Storage against Radiation in HfO2-Based Ferroelectric Field-Effect Transistors.

The ferroelectric field-effect transistors (FeFETs) with HfO2-based ferroelectric layers in the gate stacks are emerging as one of the most promising candidates for the next-generation nonvolatile memory devices due to their scalability and compatibility with conventional Si technology. Moreover, owing to the high radiation hardness of the HfO2-based ferroelectric thin films, HfO2-based FeFETs have attracted great interest in the fields of radiation-hard (rad-hard) memory. However, the reliability of their memory states under irradiation, which represents the validity of the stored information, has not been investigated. Here, we focus on the impact of the total ionizing dose (TID) on erased and programmed states of HfO2-based FeFETs. The TID radiation (X-ray) characteristics of erased and programmed HfO2-based FeFETs are characterized using an on-site read operation. Both the erased and programmed states show robust stability under irradiation at a dose rate of 90 rad(Si)/s, and even at 230 rad(Si)/s, only the erased state shows a slight variation. The possible factors contributing to memory state degradation are discussed. Through the analysis of the threshold voltage shift and subthreshold swing evolution, as well as studies of ferroelectric polarization stability under radiation, it is revealed that the erased state degradation is caused by oxide-trapped charges rather than interface degradation or polarization switching. The physical mechanism of the difference in radiation-induced oxide-trapped charges buildup in programmed and erased FeFETs is analyzed to explain different TID radiation characteristics between them. Our work suggests that the HfO2-based FeFETs have great potential in radiation environment applications.

High Temperature Resistant Separator of PVDF-HFP/DBP/C-TiO2 for Lithium-Ion Batteries.

To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 × 10 -3 S cm-1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g-1 at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments.

Memory Window and Endurance Improvement of Hf0.5Zr0.5O2-Based FeFETs with ZrO2 Seed Layers Characterized by Fast Voltage Pulse Measurements.

The HfO2-based ferroelectric field effect transistor (FeFET) with a metal/ferroelectric/insulator/semiconductor (MFIS) gate stack is currently being considered as a possible candidate for high-density and fast write speed non-volatile memory. Although the retention performance of the HfO2-based FeFET with a MFIS gate stack could satisfy the requirements for practical applications, its memory window (MW) and reliability with respect to endurance should be further improved. This work investigates the advantage of employing ZrO2 seed layers on the MW, retention, and endurance of the Hf0.5Zr0.5O2 (HZO)-based FeFETs with MFIS gate stacks, by using fast voltage pulse measurements. It is found that the HZO-based FeFET with a ZrO2 seed layer shows a larger initial and 10-year extrapolated MW, as well as improved endurance performance compared with the HZO-based FeFET without the ZrO2 seed layer. The results indicate that employing of a direct crystalline high-k/Si gate stack would further improve the MW and reliability of the HfO2-based FeFETs.

Therapeutic potential of photochemically active metal complexes based on interaction with enzymes.

Transition metal complexes with oligopyridine ligands and ruthenium or rhenium centers have attracted a widespread interest with respect to biomedical applications as they are luminescent and form triplet excited states which may form (1)O(2). These complexes have been shown to enter living cells and even cellular nuclei. In addition detailed investigations of their interaction with proteins/enzymes have shown that they are capable of binding to these biomolecules, alter the redox state of the enzyme metal centre and induce different reactivity. The application of these complexes as photoactive metallodrugs will depend on their photophysical and photochemical properties. The potential of these complexes together with relevant aspects of their chemistry will be discussed in this review.