Theoretical and Experimental Advances in High-Pressure Behaviors of Nanoparticles

Abstract

Using compressive mechanical forces, such as pressure, to induce crystallographic phase transitions and mesostructural changes while modulating material properties in nanoparticles (NPs) is a unique way to discover new phase behaviors, create novel nanostructures, and study emerging properties that are difficult to achieve under conventional conditions. In recent decades, NPs of a plethora of chemical compositions, sizes, shapes, surface ligands, and self-assembled mesostructures have been studied under pressure by in-situ scattering and/or spectroscopy techniques. As a result, the fundamental knowledge of pressure–structure–property relationships has been significantly improved, leading to a better understanding of the design guidelines for nanomaterial synthesis. In the present review, we discuss experimental progress in NP high-pressure research conducted primarily over roughly the past four years on semiconductor NPs, metal and metal oxide NPs, and perovskite NPs. We focus on the pressure-induced behaviors of NPs at both the atomic- and mesoscales, inorganic NP property changes upon compression, and the structural and property transitions of perovskite NPs under pressure. We further discuss in depth progress on molecular modeling, including simulations of ligand behavior, phase-change chalcogenides, layered transition metal dichalcogenides, boron nitride, and inorganic and hybrid organic–inorganic perovskites NPs. These models now provide both mechanistic explanations of experimental observations and predictive guidelines for future experimental design. We conclude with a summary and our insights on future directions for exploration of nanomaterial phase transition, coupling, growth, and nanoelectronic and photonic properties.

Randomly Layered Superstructure of In2O3 Truncated Nano-Octahedra and Its High-Pressure Behavior

“…As a result, octahedron translation was paired with the breaking of binding ligands, which likely led to the layer fragmentation into smaller parts and subsequent peak broadening. Additionally, higher pressure might induce a sintering process, leading to an increase in total entropy by disrupting the p 31 m symmetry and causing irreversible phase transition ( vide infra ). In stage IV, the fwhm continued to increase, albeit at a significantly slower rate, as pressure was released from 17.13 to 0.08 GPa.…”

“…Unveiling this random-layer superlattice not only expands the catalog of known self-assembled superlattice structures but also paves the way for innovative approaches in interpreting structural insights from small-angle X-ray scattering (SAXS) . This has potential implications for applications such as optical and electronic functionalities …”

Compressibility Studies of Copper Selenides Obtained by Cation Exchange Reaction Revealing the New CsCl Phase

“…Understanding the stability of the structure constitutes a crucial aspect in ascertaining the ideal design and applications of nanocrystals (NCs). − The study of phase transitions under extreme conditions , has been instrumental in unraveling the fundamental properties and behaviors of various chalcogenide-based nanomaterials. High pressure can induce reversible or irreversible phase transformations in nanostructures − as well as to lead to their morphological changes resulting in the synthesis of nanostructures with different morphologies such as nanowires from quasi-spherical NCs .…”

Linear Regulation of Red Emission in an Organic–Inorganic Manganese Bromide via Pressure

“…The manipulation strategies of the local coordination environment consist mainly of chemical doping, temperature, and pressure regulation. − Among these, the versatility of high-pressure technology in luminescence regulation has received extensive attention with its application in pressure sensing in recent years. − Previous studies have demonstrated that Mn-based OIMHs are very promising materials, especially in the topics of pressure-induced enhancement and piezochroism. , Upon hydrostatic compression, the lattice distortion of Mn-based OIMHs could lead to a decrease in interatomic distances and variation of the band gaps. , This results in alterations of crystal field splitting energy, causing changes in high-pressure structures and optical properties like emission intensity and wavelength. , However, the instability of halide compounds upon compression would result in complicated phase transitions, which manifest as changes in optical properties. , This distorts the linear correlation between pressure and emission wavelength/intensity; for example, the self-trapped exciton emission is abruptly enhanced when reaching the pressure of a phase transition in CsCu 2 I 3 . In addition, the insensitivity and irreversibility of optical properties to pressure limit their applications.…”