Di Wu

Gd₂Zr₂O₇ ceramics with different grain sizes ranging from nanoscale to submicron scale (91, 204, and 634 nm) were irradiated at room temperature using 190 keV He ions with doses ranging from 5 × 10¹⁶ to 5 × 10¹⁷ ions/cm². We fully characterized the pre‐ and post‐irradiation samples using grazing‐incidence X‐ray diffraction (GIXRD), scanning electron microscope (SEM), and atomic force microscope (AFM) as the grain size and degree of irradiation vary. The results suggested that all three Gd₂Zr₂O₇ samples demonstrate outstanding radiation tolerance to displacement damage by retaining their crystallinity after irradiation at 5 × 10¹⁷ ions/cm². which is equal to 16 displacement per atom (dpa) at peak positions. Although lattice expansion was observed at a He irradiation at 5 × 10¹⁶ ions/cm² and beyond, the lattice remained stable for the nanograin ceramic, while the degree of distortion for the sample with the largest grain size (634 nm) continuously increased. Moreover, a delayed He bubble evolution process was seen for the nanograin ceramic, which did not appear for the submicron‐grained sample. Interestingly, the grain size‐dependent surface blistering was also found to be a function of ion fluence. After He irradiation at 5 × 10¹⁷ ions/cm² the AFM root‐mean‐square(RMS) roughness variation for Gd₂Zr₂O₇ ceramics of 91, 204, and 634 nm were 4.8, 7.0, and 11.1 nm, respectively.

Nanoscale oxide-based negative electrodes are of great interest for lithium ion batteries due to their high energy/power density, and enhanced safety. The crystallinity effect of mesoporous TiO₂nanoparticle electrode was investigated in this work.

Silica-encapsulated gold core@shell nanoparticles (Au@SiO₂CSNPs) were synthesizedviaa tunable bottom-up procedure to catalyze the aerobic oxidation of benzyl alcohol.

Real-time DRIFTS reveals the formation of acetone enolate and its subsequent aldolization via an Eley–Rideal type mechanism on Zn₁Zr₁₀O_z.

This mini review summarizes recent advances in experimental thermodynamics of metal–organic frameworks (MOFs). Taking advantage of the development in mechanochemistry, near-room temperature solution calorimetry, and low-temperature heat capacity measurements, the energetic landscape, entropy trends, and Gibbs free energy evolutions of MOFs with true polymorphism [Zn(MeIm)₂, Zn(EtIm)₂, and Zn(CF₃Im)₂] as framework topology varies were thoroughly explored by integrated calorimetric and computational methodologies. In addition, the formation enthalpies of MOFs with ultrahigh porosity (MOF-177 and UMCM-1) and the simplest structure (metal formates) have been determined. The studies summarized below highlight the complex interplays among interrelated compositional, chemical, and topological (structural) factors in the determination of the thermodynamic parameters of MOFs.

Here, we report a study on the radiation resistance enhancement of Gd₂Zr₂O₇ nanograin ceramics, in which amorphization, cell volume expansion, and multi‐stage helium (He) bubble formation are investigated and discussed. Gd₂Zr₂O₇ ceramics with a series of grain sizes (55‐221 nm) were synthesized and irradiated by 190 keV He ion beam up to a fluence of 5 × 10¹⁷ ions/cm². Both the degree of post irradiation cell volume expansion and the amorphization fraction appear to be size‐dependent. As the average grain size evolves from 55 to 221 nm, the degree of post irradiation cell volume expansion increases from 0.56% to 1.02%, and the amorphization fraction increases from 6.8% to 11.1%. Additionally, the threshold He concentrations (at.%) of bubbles at different formation stages and locations, including (a) bubbles at grain boundary, (b) bubble‐chains, and (c) ribbon‐like bubbles within the grain, are all found to be much higher in the nanograin ceramic (55 nm) compared with that of the submicron sample (221 nm). We conclude that grain boundary plays a critical role in minimizing the structural defects, and inhibiting the multi‐stage He bubble formation process.

A detailed investigation of planetary ball‐milling for coarsened AlON powder was carried out. Our results showed that the weight ratios of milling ball‐to‐powder, the revolution rate and the planetary ball‐milling time have significant impacts on the microscopic morphology, particle size distribution and average particle size of powder. The process and mechanism were analyzed, and the outcome of our study can be used to optimize the complicated planetary ball‐milling method by controlling the planetary ball‐milling time or adjusting the revolution rate at the final stage of planetary ball‐milling. Sequentially, using fine and uniform AlON powder by optimized planetary ball‐milling with an average particle size below 300 nm and excellent sintering properties, highly transparent AlON ceramic with an in‐line transmittance of 84% at 2000 nm was successfully prepared through pressureless sintering at 1880°C for 6 hours using the elaborative treated powder synthesized from carbothermal nitridation method.

The incorporation of SiOC polymer‐derived ceramics into porous carbon materials could provide tailored shapeable, mechanical, electrical, and oxidation‐resistant properties for high‐temperature applications. Understanding the thermodynamic and kinetic stability of such materials is crucial for their practical application. We report here the dependence of structures and energetics of SiOC and SiOC‐modified carbon‐bonded carbon fiber composites (CBCFs) on the pyrolysis temperature using spectroscopic methods and high‐temperature oxide melt solution calorimetry. The results indicate that a SiOC ceramic pyrolyzed at 1200°C and 1600°C is energetically stable with respect to an isocompositional mixture of cristobalite, silicon carbide, and graphite by 4.9 and 10.3 kJ/mol, respectively, and more energetically stable than that pyrolyzed at 1450°C. Their thermodynamic stability is related to their structural evolution. SiOC‐modified CBCFs become energetically less stable with increasing preparation temperature and concomitant increase in excess carbon content.

We report the crystallography, structure, and thermodynamics of a new U(V)-containing compound, UTa₃O₁₀.

Si–O–C‐based amorphous or nanostructured materials are now relatively common and of interest for numerous electronic, optical, thermal, mechanical, nuclear, and biomedical applications. Using plasma‐enhanced chemical vapor deposition (PECVD), hydrogen atoms are incorporated into the system to form SiOCH dielectric films with very low dielectric constants (k). While these low‐k dielectrics exhibit chemical stability as deposited, they tend to lose hydrogen and carbon (as labile organic groups) and convert to SiO₂ during thermal annealing and other fabrication processes. Therefore, knowledge of their thermodynamic properties is essential for understanding the conditions under which they can be stable. High‐temperature oxidative drop solution calorimetry measurement in molten sodium molybdate solvent at 800°C showed that these materials possess negative formation enthalpies from their crystalline constituents (SiC, SiO₂, C, Si) and H₂. The formation enthalpies at room temperature become less exothermic with increasing carbon content and more exothermic with increasing hydrogen content. Fourier transform infrared spectroscopy (FTIR) spectroscopy examined the structure from a microscopic perspective. Different from polymer‐derived ceramics with similar composition, these low‐k dielectrics are mainly comprised of Si–O(C)–Si networks, and the primary configuration of carbon is methyl groups. The thermodynamic data, together with the structural analysis suggest that the conversion of sp² carbon in the matrix to surface organic functional groups by incorporating hydrogen increases thermodynamic stability. However, the energetic stabilization by hydrogen incorporation is not enough to offset the large entropy gain upon hydrogen release, so hydrogen loss during processing at higher temperatures must be managed by kinetic rather than thermodynamic strategies.

The inclusion of solvent in metal–organic framework (MOF) materials is a highly specific form of guest–host interaction.

Organic ligand–inorganic nanoparticle (NP) interactions are crucial in both natural and engineering conditions. This paper reports a rich energetics of organic–NP binding as a function of molecular coverage for ethanol–nanocalcite system. A stepwise, yet gradually and continuously evolved energetics from weak associating to strong bonding to classical capping is revealed. Such information may reinforce our understanding of complex phenomena at organic–NP interfaces, and may also aid exploratory material scientists by providing solid, fundamental thermodynamic insights.

The CO₂ adsorption enthalpy on an alkylamine-appended MOF, mmen-Mg₂(dobpdc), was directly identified by adsorption calorimetry at 298, 323 and 348 K. The data suggest three adsorption events as function of coverage: two types of strong chemisorption and one weak physisorption. A multistage reaction mechanism was proposed.

Energetics and structural evolution of Na–Ca exchanged zeolite A vary significantly as function of calcium contents and temperature.

Enthalpies of formation for sodium–calcium exchanged zeolite A.

Using micro-sized aluminum powder (11 wt.%) and nano-sized Al₂O₃ powder (89 wt.%) with five different phase compositions, AlON powders were synthesized at different temperatures in flowing-nitrogen atmosphere. Our results suggest that for starting materials with low γ-Al₂O₃/total Al₂O₃ ratio R (0 and 0.15), a calcination temperature of 1 750 °C is required to obtain single-phase AlON. This temperature is about 50 °C higher than for other batches starting with larger R values (0.5, 0.85, and 1.0). The AlON powders fabricated from reactants with a high R value in this work show narrower particle size distribution and better particle homogeneity than those prepared from batches with lower R values.

Different polymorphs with very similar energetics can be made by slight changes in growth conditions. This is, to our knowledge, the first direct experimental validation of a complex energy landscape for superlattice self-assembly. Our results suggest that fundamental thermodynamic driving forces can be harnessed to tailor specific superlattice assemblies of potential technological significance.

Confinement of molecules in nanoscale pores is important in both science and technology. This paper reports a systematic analysis of the structural, thermodynamic, and dynamic behavior on confinement of a rigid organic molecule in a series of silica frameworks with different pore sizes (0.8 to 20.0 nm). The comprehensive data set enables the strength of guest–host interactions to be calculated; structure, phase, and dynamics of confined guests in pores of various diameters to be analyzed; and different types of inclusion to be described. The evolution from single-molecule confinement to multimolecule adsorption/confinement to nanocrystal confinement is documented. This provides a conceptual model linking confinement on various length scales.