Volume 8 Issue 11, November 2016

Hybrid calcium titanyl oxalate (HCTO) composite containing anisotropic spindly microparticles and irregular nanoparticles have been synthesized via a facile precipitation route under mild conditions for the first time. The hybrid particles act synergistically to enhance electrorheological (ER) activity and reduce field-off viscosity, thereby resulting in ER fluids with ultrahigh ER efficiency. The results presented thus provide a new strategy for improving the performance of ER fluids.

New design of the p-MTJ spin-valve using W bridging and capping layer demonstrated no significant crystallinity degradation and no considerable Fe atoms diffusion, thus achieving the TMR ratio of ~143% at an ex-situ annealing temperature of 400 ^oC. A better crystallinity of the MgO layer for W case than Ta case would be related to less diffusion amount of metal atoms and lattice strain in MgO layer. In addition, higher Fe and Co atom concentrations of Co₂Fe₆B₂ free and pinned layers for W case than Ta case would be associated with less solubilities in W layers than Ta layers.

A new stress-driven structural collapse and etching mechanism for the synthesis of Au nanorings via a direct one-pot solution-based chemical reaction is presented. The nanoparticle-mediated recrystallization process contributes to the formation of Au nanoframes that contain unusual stress, which promotes the breakup of the nanoframes and conversion into Au nanorings. The Au nanorings have tunable hole sizes and exhibit interesting localized surface plasmon features owing to the coupling of bonding and antibonding modes on the inner and outer surfaces of the nanorings.

ZrTe₅ has attracted intensive research interests because of the potential topological property. Here based on the transports and optic experiments, we observe unusual Landau quantization, non-trivial Berry phase and highly anisotropic carrier mass, which reveals quasi-two-dimensional Dirac fermions in bulk ZrTe₅. The system is understood as locating at the critical point between a three-dimensional (3D) Dirac semimetal and a topological insulator. New physics or device application can be possibly realized in this quasi-2D ultra-relativistic system beyond graphene.

Morphology and nanomechanical properties by atomic force microscopy (AFM) in 1:1 correspondence for the poly(N-isopropylacrylamide) (PNIPAM) hydrogel in a water environment. Measurements were performed in force volume mode at medium resolution (64 × 64) using a 2550 nm spherical tip: morphology (A) and Young’s modulus mechanical map (B). Force (nN) vs indentation (nm) graph (C) that highlights the raw data and Hertz fit. Histogram of Young’s modulus values in log-normal scale with Gaussian distribution fits (D) for the quantitative analysis and error calculation.

To achieve the room-temperature Datta-Das spin transistor at the nanoscale, we propose a new mechanism to produce giant Rashba splittings in the quantum-well-state (QWS) of normal metal (NM) thin films by exploiting the asymmetric properties of spin states at the topological insulator (TI) interface based on the NM/TI heterostructure. In such a hybrid system, the TI spin–momentum-locking Dirac-surface states strongly modify the NM QWSs, leading to extremely large Rashba splittings in the NM QWSs. The giant Rashba splitting as well as the nearly 100% spin polarizations in the NM QWSs manifest great potential for manipulating spin without magnetic fields in spintronic devices.

Spherical, twiddle and hollow hemispherical reduced graphene oxide (rGO) structures could be fabricated by tuning the GO assembly in the diffusion-controlled micro-droplets, and their size and thickness could be adjusted by controlling the concentration of GO and pH of the droplets. Besides, the porous rGO architecture was produced via wet etching of rGO-SiO₂ composites, and their plasamon effect was characterized.

Centimeter-sized, epitaxial hexagonal boron nitride (h-BN) few-layer films were heteroepitaxially grown on Ni(111) single-crystal substrates using atmospheric pressure chemical vapor deposition with ammonia-borane single precursor. The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and the remaining Ni(111) substrates were repeatedly re-used. Over repeated growth and transfer after the initial annealing, no significant degradation of Ni(111) substrates was observed and the crystallinity of h-BN layers was reproduced reliably. The grown h-BN films showed typical physical characteristics of h-BN, with a high uniformity over a wide area. The large-area synthesis and transfer of atomically thin uniform epitaxial h-BN layers can be applied in various fields where high quality two-dimensional insulating layers are required.

A highly conductive fibers and sensitive textile pressure sensors are developed by extremely low-temperature atomic layer deposition (ALD) of Pt. The low-temperature Pt ALD is achieved under 100 °C without any reactive reactant, enabling cotton fibers to have excellent electrical properties. The pressure sensors fabricated using the conductive fibers exhibit high performances, and can be applied to smart fabrics which can distinguish features of occupants.

This review summarizes recent developments in the direct synthesis and ion exchange-based reactions leading to hybrid organic–inorganic and all-inorganic lead halide perovskite nanocrystals. Optical properties related to quantum confinement effects, single emission spectroscopy and lasing are considered. Perovskite nanocrystals have been employed as an active material in several applications such as light-emitting devices, solar cells and photodetectors.