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Abstract Advanced nanomaterials are at the core of innovation for the microelectronics industry. Designing, characterizing, and testing two-terminal devices, such as metal-insulator-metal structures, is key to improving material stack design and integration. Electrical biasing within in situ transmission electron microscopy using MEMS-based platforms is a promising technique for nano-characterization under operando conditions. However, conventional focused ion beam sample preparation can introduce parasitic current paths, limiting device performance and leading to overestimated electrical responses. Here we demonstrate connectivity of TEM lamella devices obtained from a novel electrical contacting method based solely on van der Waals forces. This method reduces parasitic leakage currents by at least five orders of magnitude relative to reported preparation approaches. Our methodology enables operation of stack devices inside a microscope with device currents as low as 10 pA. We apply this approach to observe in situ biasing-induced defect formation, providing valuable insights into the behavior of an SrTiO3-based memristor.

Cubic silicon nitride (γ-Si3N4) is superhard and one of the hardest materials after diamond and cubic boron nitride (cBN), but has higher thermal stability in an oxidizing environment than diamond, making it a competitive candidate for technological applications in harsh conditions (e.g., drill head and abrasives). Here, we report the high-pressure synthesis and characterization of the structural and mechanical properties of a γ-Si3N4/Hf3N4 ceramic nanocomposite derived from single-phase amorphous silicon (Si)–hafnium (Hf)–nitrogen (N) precursor. The synthesis of the γ-Si3N4/Hf3N4 nanocomposite is performed at ~20 GPa and ca. 1500 ℃ in a large volume multi anvil press. The structural evolution of the amorphous precursor and its crystallization to γ-Si3N4/Hf3N4 nanocomposites under high pressures is assessed by the in situ synchrotron energy-dispersive X-ray diffraction (ED-XRD) measurements at ~19.5 GPa in the temperature range of ca. 1000–1900 ℃. The fracture toughness (KIC) of the two-phase nanocomposite amounts ~6/6.9 MPa·m1/2 and is about 2 times that of single-phase γ-Si3N4, while its hardness of ca. 30 GPa remains high. This work provides a reliable and feasible route for the synthesis of advanced hard and tough γ-Si3N4-based nanocomposites with excellent thermal stabililty.

CeO2-TiO2 is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO2 nanostructures decorated with CeO2 nanoparticles at the surface. As the precursor, we used H2Ti3O7 nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF–STEM mapping of the Ce4+-modified nanoribbons revealed a thin continuous layer at the surface of the H2Ti3O7 nanoribbons, while Ce3+ cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeO2 nanoparticles on the surface of the TiO2 nanoribbons, whose size increased with the calcination temperature. The use of Ce4+ raised the temperature required for converting H2Ti3O7 to TiO2-B by approximately 200 °C, and the temperature for the formation of anatase. For the Ce3+ batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state.

Abstract Resistive random‐access memories are promising candidates for novel computer architectures such as in‐memory computing, multilevel data storage, and neuromorphics. Their working principle is based on electrically stimulated materials changes that allow access to two (digital), multiple (multilevel), or quasi‐continuous (analog) resistive states. However, the stochastic nature of forming and switching the conductive pathway involves complex atomistic defect configurations resulting in considerable variability. This paper reveals that the intricate interplay of 0D and 2D defects can be engineered to achieve reproducible and controlled low‐voltage formation of conducting filaments. The author find that the orientation of grain boundaries in polycrystalline HfOx is directly related to the required forming voltage of the conducting filaments, unravelling a neglected origin of variability. Based on the realistic atomic structure of grain boundaries obtained from ultra‐high resolution imaging combined with first‐principles calculations including local strain, this paper shows how oxygen vacancy segregation energies and the associated electronic states in the vicinity of the Fermi level govern the formation of conductive pathways in memristive devices. These findings are applicable to non‐amorphous valence change filamentary type memristive device. The results demonstrate that a fundamental atomistic understanding of defect chemistry is pivotal to design memristors as key element of future electronics.

The limited number of materials with a switchable electrical polarization available for applications can be increased by exploiting the flexoelectric effect. Here, switchable polarization in nanoparticles induced by an elemental distribution dependent strain gradient up to 800 °C is demonstrated.

In this work, multi-walled carbon nanotube composites (MWCNCs) were produced by catalytic pyrolysis of post-consumer plastics with aluminium oxide-supported nickel, cobalt, and their bimetallic (Ni/α–Al2O3, Co/α–Al2O3, and NiCo/α–Al2O3) oxide-based catalysts. The influence of catalyst composition and catalytic reaction temperature on the carbon yield and structure of CNCs were investigated. Different temperatures (800, 900, 950, and 1000 °C) and catalyst compositions (Ni, Co, and Ni/Co) were explored to maximize the yield of carbon deposited on the catalyst. The obtained results showed that at the same catalytic temperature (900 °C), a Ni/Co bimetallic catalyst exhibited higher carbon yield than the individual monometallic catalysts due to a better cracking capability on carbon-hydrogen bonds. With the increase of temperature, the carbon yield of the Ni/Co bimetallic catalyst increased first and then decreased. At a temperature of 950 °C, the Ni/Co bimetallic catalyst achieved its largest carbon yield, which can reach 255 mg g−1plastic. The growth of CNCs followed a “particle-wire-tube” mechanism for all studied catalysts. This work finds the potential application of complex oxide composite material catalysts for the generation of CNCs in catalytic pyrolysis of wasted plastic.