Hydrogen Bonding in Liquid Ammonia.

The nature of hydrogen bonding in condensed ammonia phases, liquid and crystalline ammonia has been a topic of much investigation. Here, we use quantum molecular dynamics simulations to investigate hydrogen bond structure and lifetimes in two ammonia phases: liquid ammonia and crystalline ammonia-I. Unlike liquid water, which has two covalently bonded hydrogen and two hydrogen bonds per oxygen atom, each nitrogen atom in liquid ammonia is found to have only one hydrogen bond at 2.

FIB-Assisted Fabrication of Single Tellurium Nanotube Based High Performance Photodetector.

Nanoscale tellurium (Te) materials are promising for advanced optoelectronics owing to their outstanding photoelectrical properties. In this work, high-performance optoelectronic nanodevice based on a single tellurium nanotube (NT) was prepared by focused ion beam (FIB)-assisted technique. The individual Te NT photodetector demonstrates a high photoresponsivity of 1.

Electric-Field-Induced Room-Temperature Antiferroelectric-Ferroelectric Phase Transition in van der Waals Layered GeSe.

Searching van der Waals ferroic materials that can work under ambient conditions is of critical importance for developing ferroic devices at the two-dimensional limit. Here we report the experimental discovery of electric-field-induced reversible antiferroelectric (AFE) to ferroelectric (FE) transition at room temperature in van der Waals layered α-GeSe, employing Raman spectroscopy, transmission electron microscopy, second-harmonic generation, and piezoelectric force microscopy consolidated by first-principles calculations. An orientation-dependent AFE-FE transition provides strong evidence that the in-plane (IP) polarization vector aligns along the armchair rather than zigzag direction in α-GeSe.

Strain-engineering on GeSe: Raman spectroscopy study.

Among the IV-VI compounds, GeSe has wide applications in nanoelectronics due to its unique photoelectric properties and adjustable band gap. Even though modulation of its physical characteristics, including the band gap, by an external field will be useful for designing novel devices, experimental work is still rare. Here, we report a detailed anisotropic Raman response of GeSe flakes under uniaxial tension strain.

Robust finite-time and fixed-time chaos synchronization of PMSMs in noise environment.

This paper addresses the robust stochastic finite-time and fixed-time chaos synchronization of two permanent magnet synchronous motors (PMSMs) in noise environment. The novel adaptive finite-time and fixed-time control schemes are implemented, respectively, which can not only ensure that the stochastic chaos synchronization of PMSMs can be achieved in a fast rate, but also determine the control gains successfully(not necessary to set them in advance). The sufficient conditions are derived in the light of the stochastic finite-time and fixed-time stability theories, where the upper bound of synchronization time can be estimated.

Ion adsorption-induced reversible polarization switching of a van der Waals layered ferroelectric.

Solid-liquid interface is a key concept of many research fields, enabling numerous physical phenomena and practical applications. For example, electrode-electrolyte interfaces with electric double layers have been widely used in energy storage and regulating physical properties of functional materials. Creating a specific interface allows emergent functionalities and effects.

Enhanced and Balanced Charge Transport Boosting Ternary Solar Cells Over 17% Efficiency.

Ternary architecture is one of the most effective strategies to boost the power conversion efficiency (PCE) of organic solar cells (OSCs). Here, an OSC with a ternary architecture featuring a highly crystalline molecular donor DRTB-T-C4 as a third component to the host binary system consisting of a polymer donor PM6 and a nonfullerene acceptor Y6 is reported. The third component is used to achieve enhanced and balanced charge transport, contributing to an improved fill factor (FF) of 0.

Phonon-Suppressed Auger Scattering of Charge Carriers in Defective Two-Dimensional Transition Metal Dichalcogenides.

Two-dimensional transition metal dichalcogenides (TMDs) draw strong interest in materials science, with applications in optoelectronics and many other fields. Good performance requires high carrier concentrations and long lifetimes. However, high concentrations accelerate energy exchange between charged particles by Auger-type processes, especially in TMDs where many-body interactions are strong, thus facilitating carrier trapping.

Optical Control of Non-Equilibrium Phonon Dynamics.

The light-induced selective population of short-lived far-from-equilibrium vibration modes is a promising approach for controlling ultrafast and irreversible structural changes in functional nanomaterials. However, this requires a detailed understanding of the dynamics and evolution of these phonon modes and their coupling to the excited-state electronic structure. Here, we combine femtosecond mega-electronvolt electron diffraction experiments on a prototypical layered material, MoTe, with non-adiabatic quantum molecular dynamics simulations and electronic structure calculations to show how non-radiative energy relaxation pathways for excited electrons can be tuned by controlling the optical excitation energy.

The First Examples of Lithium-Containing Mixed-Alkali Strontium Borates with Different Dimensional Anionic Architectures and Short Cutoff Edges.

Three new mixed-alkali strontium borates, Li KSr (BO ) , Li Rb Sr (BO ) , and Li Rb SrB O , have been synthesized by the high-temperature solution method by adjusting the molar ratios of the reactants. They represent the first examples of lithium-containing mixed-alkali strontium borates. The structures of the three compounds show different dimensional anionic architectures, with Li KSr (BO ) and Li Rb Sr (BO ) possessing isolated BO units, whereas Li Rb SrB O has three-dimensional (3D) open frameworks with three types of channels occupied by the strontium and rubidium atoms.

LiCsLa(BO) and LiKLa(BO): new mixed alkali metal lanthanum borates with three-dimensional open frameworks and short cut-off edges.

Two new mixed alkali metal lanthanum borates, LiCsLa(BO) and LiKLa(BO), were synthesized through a high-temperature solution method and millimeter-sized colorless crystals were obtained. The structures of LiCsLa(BO) and LiKLa(BO) have an intricate three-dimensional (3D) open framework with one-dimensional (1D) infinite channels surrounded by cation polyhedra and isolated BO units. In particular, LiCsLa(BO) exhibits a short cut-off edge <190 nm and a large experimental band gap of 6.

ScMO(BO) (M = Ca and Cd): new Sc-based oxyborates featuring interesting edge-sharing sandwich-like chains and UV cut-off edges.

Two new isostructural rare-earth oxyborates ScMO(BO) (M = Ca and Cd) with a three-dimensional (3D) cationic framework and parallel arranged [BO] triangles have been synthesized by the flux method. In the 3D cationic framework, an interesting sandwich-like basic building unit (BBU) is constructed by two [Ca(1)O] chains and two [Sc(1)O] chains. ScMO(BO) melt incongruently, which shows that title compounds can be grown by the flux method.