Here, we report an experimental study on the rotational dynamics of hard magnetic hexaferrite nanoparticles in water. A stable aqueous colloid of SrFe12O19 was synthesized by the borate glass-ceramic dissolution technique and studied by TEM, small-angle X-ray scattering (SAXS), magnetometry, and optical transmission methods in applied DC and AC magnetic fields. The particles represent nanoplates with a mean diameter of 50 nm and a mean thickness of 5 nm having a coercive force of 4700 Oe and a saturation magnetization of 51.5 emu/g. According to magnetic field dependent SAXS data, a probability orientation function was suggested considering the colloidal particle rotation in the applied field as an activation-free process. The magnetization dynamics of the colloidal rotators was described by an interplay of magnetic torque and drag force in the frame of a non-interacting particle model. At frequencies below 100 Hz, the particles are able to fully rotate after the magnetic field. At higher frequencies, the complete following becomes impossible due to the energy dissipation and the particle movement changes to oscillations around randomly oriented axes. These vibrational axes can be aligned by a strong external permanent magnetic field, causing the coherent particle oscillations and correspondingly the rise of the high-frequency response of the colloid optical transmission. As a result, the efficient magneto-optical light modulation has been achieved at frequencies exceeding 5 kHz, revealing the fastest response rates among known colloidal magneto-optical media.

The interest in alternative energy sources grows rapidly and demands improved materials. The cutting-edge investigations focus attention on the development and optimization of solid electrolytes for advanced energy storage. Their chemical and structural stability defines both battery performance and lifetime, yet it is studied poorly even for well-known superionic conductors such as NASICON-based compounds. In this work, we studied the Li1.3Al0.3Ti1.7(PO4)3 (LATP) stability toward water. Corresponding ceramics were synthesized in pellet form through the solid-state reaction and had been immersed in deionized water for different periods of time with subsequent electrochemical (electrochemical impedance spectroscopy), structural (powder X-ray diffraction analysis, Raman spectroscopy, computational modeling), chemical (ceramicsenergy-dispersive X-ray spectroscopy; mother-solutionsinductively coupled plasma mass spectrometry), and morphological (scanning and transmission electron microscopy) analyses. Water exposure triggers drastic conductivity losses (64% for σt) with accompanying lithium elution (exceeds 13 atomic%) and unit cell shrinkage. All these changes reach a plateau after 2 h of water exposure.

The paper reports operando study of ultra-thin (50 nm) graphene oxide membranes by grazing incidence x-ray scattering in air dehumidification experiments. Absorption of water vapors in GO layers follows a modified Kelvin equation revealing condensation in an elastic slit, while desorption of water is limited by a few outer GO layers providing bottleneck restrictions to water transport and resulting in classical H2-type isotherms. GO interlayer distances (d) vary in range from 7.2 Å to 11.5 Å depending on partial water pressures in a feed stream and permeate. The permeance of water vapor through GO decreases steadily with decreasing interlayer distance between GO sheets from ~80 000 l/(m 2 • atm • h) to ~30 000 l/(m 2 • atm • h) falling down to negligible values below d ≈ 9.2 Å. Water transport in GO is described by Poiseuille equation and hopping diffusion depending on the number of water layers between GO planes, and was modelled with semi-empirical methods. It is shown the performance of thin GO membranes is strongly governed by the interstitial water quantity as dictated by water partial pressure.

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Here we report on the spontaneous assembly of Ti3C2Tx MXene flakes into monolayer films at the liquid–air interface.