Glassy Interface Research Articles

Improving the electrochemical performance of SnO2 anode materials via glassy interface construction

Despite the ideal specific theoretical capacity, SnO2-based electrode materials, considered potential anode materials, face challenges due to serious volume expansion and poor safety performance. In this study, we propose a novel approach called SnO2/Li2O–B2O3 (SLB), where SnO2 is cladded with a Li2O–B2O3 interface construction. This glassy flexible matrix effectively fixes the active particles within the framework, curbing volume expansion, and facilitating high-efficiency ion transport. Additionally, the presence of the glassy interface construction converts the well-known irreversible conversion/inversion reaction into a reversible process, resulting in a significant enhancement of the coulombic efficiency. At a current density of 0.5 A g−1, SLB demonstrates improved cycling stability with a capacity of 566.3 mAh g−1 after 300 cycles. Even at a higher current density of 1.0 A g−1, the capacity remains at 363.4 mAh g−1 after 800 cycles. Moreover, the artificial protection layer, composed of the Li2O–B2O3/Sn interface construction matrix, greatly enhances the flame resistance of the electrode material at abnormally high temperatures, thanks to the excellent thermal stability of the flexible glassy matrix. This interface modification represents a promising approach to address the challenges and significantly advance the commercialization of SnO2-based anode materials.

Tough, Bioinspired Transparent Glass‐Ceramics

Transparent materials with high strength and toughness are highly demanded as engineering materials for consumer electronic, structural, and optical applications. In this article number 2200350 by Qiang Fu and co-workers, a simple bioinspired approach is reported to achieve a combination of high fracture toughness (KIC = 2.0 MPa·m1/2) and optical transparency in a lithium disilicate/apatite glass-ceramic through the creation of an acicular crystalline phase and a weak glassy interface. A tortuous crack path with a high degree of crack deflection, similar to those found in nacre, is observed in the material.

Tough, Bioinspired Transparent Glass‐Ceramics

Transparent materials with high strength and toughness are highly demanded as engineering materials for consumer electronic, structural, and optical applications. Inspired by the “brick‐and‐mortar” structure in nacre, transparent glass/polymer composites have demonstrated an exceptionally high toughness and impact resistance. However, these composites suffer from low strength and low working temperatures due to polymeric components. Herein, a simple bioinspired approach to achieve a combination of high fracture toughness (KIC = 2.0 MPa m1/2) and optical transparency in a lithium disilicate/apatite glass‐ceramic through the creation of an acicular crystalline phase and a weak glassy interface is reported. This bioinspired approach represents a new pathway to manufacturing transparent materials for a variety of applications where mechanical performance is a necessity.

Interfacial Fourier transform shear rheometry of complex fluid interfaces

Nonlinear rheometry of interfaces is very challenging because of the limits of current day instrumentation and the intricate coupling of flows at interfaces and in the bulk. The use of time periodic flows may constitute a first step in addressing this issue. Fourier transform rheology (FTR) measurements with quasi-monolayers at the air-water interface are used in order to assess the suitability of the different devices to investigate nonlinear interfacial shear viscoelasticity. The probe material was a poly (methyl methacrylate) forming a soft glassy interface, whereas complementary measurements were performed with a polystyrene latex suspension forming a predominantly viscous interface at intermediate surface coverages. The obtained data with the magnetic rod rheometer (ISR) were compared against those obtained with the bicone and the double wall ring geometries attached to standard rotational rheometers. In particular, an unexpected appearance of even in addition to odd harmonics is discussed in terms of flow field asymmetry.

Asphaltene-laden interfaces form soft glassy layers in contraction experiments: a mechanism for coalescence blocking.

In previous studies, the adsorption kinetics of asphaltenes at the water-oil interface were interpreted utilizing a Langmuir equation of state (EOS) based on droplet expansion experiments.1-3 Long-term adsorption kinetics followed random sequential adsorption (RSA) theory predictions, asymptotically reaching ∼85% limiting surface coverage, which is similar to limiting random 2D close packing of disks. To extend this work beyond this slow adsorption process, we performed rapid contractions and contraction-expansions of asphaltene-laden interfaces using the pendant drop experiment to emulate a Langmuir trough. This simulates the rapid increase in interfacial asphaltene concentration that occurs during coalescence events. For the contraction of droplets aged in asphaltene solutions, deviation from the EOS consistently occurs at a surface pressure value ∼21 mN/m corresponding to a surface coverage ∼80%. At this point droplets lose the shape required for validity of the Laplace-Young equation, indicating solidlike surface behavior. On further contraction wrinkles appear, which disappear when the droplet is held at constant volume. Surface pressure also decreases down to an equilibrium value near that measured for slow adsorption experiments. This behavior appears to be due to a transition to a glassy interface on contraction past the packing limit, followed by relaxation toward equilibrium by desorption at constant volume. This hypothesis is supported by cycling experiments around the close-packed limit where the transition to and from a solidlike state appears to be both fast and reversible, with little hysteresis. Also, the soft glass rheology model of Sollich is shown to capture previously reported shear behavior during adsorption. The results suggest that the mechanism by which asphaltenes stabilize water-in-oil emulsions is by blocking coalescence due to rapid formation of a glassy interface, in turn caused by interfacial asphaltenes rapidly increasing in concentration beyond the glass transition point.

Cooling field dependence of exchange bias in phase-separated La0.88Sr0.12CoO3

We report the observation of exchange bias phenomena in the hole-doped perovskite cobaltite La0.88Sr0.12CoO3 in which a spontaneous phase separation occurs. When the sample is cooled in a static magnetic field through a freezing temperature, the magnetization hysteresis loops shift to the negative field. Moreover, the exchange bias strongly depends on the cooling field. These results highlight the important role of a glassy interface between the intrinsic inhomogeneous phases in a phase-separated system.

Boundary lubrication with a glassy interface.

Recently introduced constitutive equations for the rheology of dense, disordered materials are investigated in the context of stick-slip experiments in boundary lubrication. The model is based on a generalization of the shear transformation zone (STZ) theory, in which plastic deformation is represented by a population of mesoscopic regions which may undergo nonaffine deformations in response to stress. The generalization we study phenomenologically incorporates the effects of aging and glassy relaxation. Under experimental conditions associated with typical transitions from stick-slip to steady sliding and stop-start tests, these effects can be dominant, although the full STZ description is necessary to account for more complex, chaotic transitions.

Toughening Si<SUB>3</SUB>N<SUB>4</SUB>/SiC-Whisker Composite by <I>in-situ</I> Reaction to Control Whisker-Matrix Interface

Controlling the interfacial conditions between the matrix and whiskers is critical to toughen whisker reinforced ceramic (WRC) composites. The interface was controlled by coating carbon on the SiC whisker surface in the present work. The carbon was coated by thermal decomposition of methane (CH 4 ) gas. The SiC whisker content was 15 vol% in the Si 3 N 4 matrix, which contained sintering additives of 3 mol% α-Al 2 O 3 and Y 2 O 3 each. The sintered bodies were obtained by hot-pressing at 1800°C for 1 or 1.5 h in N 2 atmosphere under the applied load of 30 MPa. The bending strength and the fracture toughness are increased by the carbon coating. The coated carbon and the silicon oxide impurity phase on SiC whiskers and the Si 3 N 4 surface reacts during hot pressing to form β-SiC on the whisker surface. The newly formed SiC phase is confirmed by TEM observation and electron diffraction analysis. The amount of the glassy interface phase is reduced by the in-situ SiC forming reaction, and eliminated at the interface of SiC whiskers and the Si 3 N 4 matrix in portions depending upon reacted quantity to have direct bonding between the Si 3 N 4 matrix and SiC whiskers. The interfacial condition for toughening is improved by this present carbon coating method.

An Assessment of Minoan Slips from Pseira, Crete, Using Scanning Electron Microscopy

Tenacity of slip adherence on MM II and LM IB pottery is investigated using the SEM. Results indicate that the degree of adherence is due to an advanced vitrification which causes a glassy interface to form between the slip and the fabric of vessels. Superior adherence, moreover, is related to the darkness of the final slip color, which generally is closer to black on MM II vessels.

Contrast effects at grooved interfaces

This paper presents an investigation, based on computer simulations, of the Fresnel-fringe effects associated with surface grooving at grain boundaries. Three models are considered, corresponding to (a) a grooved surface without an interfacial film, (b) a non-grooved glassy interface, and (c) a combination of the two. It is shown that under certain circumstances the intersection of a grain boundary with a surface can cause contrast effects similar to those produced by the presence of a glassy layer within the grain boundary.