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Wang, Yongxin; Shi, Yunhui; Cheng, Jiabao; Xu, Yao; Wang, Yizhan; Qiu, Jiawei
doi: 10.1039/d5cp00778jpmid: 40522005
Chemical mechanical polishing (CMP) is a critical technique that combines chemical etching and mechanical grinding to achieve atomic-level surface planarization and eliminate subsurface damage in various materials, playing a key role in wafer thinning and smoothing. CeO2 abrasives, owing to their unique electronic structure and moderate chemical reactivity, exhibit excellent properties such as high polishing rate, reactivity, and selectivity. With advancements in manufacturing processes and the growing demand for ultra-flat surfaces, the preparation and application of CeO2-based abrasives in CMP have emerged as key research areas. This review paper provides an overview of the synthesis methods for typical CeO2-based abrasives and their applications. Additionally, the application of CeO2-based abrasives in CMP slurries is discussed, focusing on their use in polishing silicon-based materials and other non-silicon-based materials. Finally, the common challenges associated with CeO2-based abrasives in CMP are summarized, and future directions and potential advancements in this field are prospected.
Kung, Jocky C. K.; Kádek, Alan; Kölbel, Knut; Bandelow, Steffi; Bari, Sadia; Buck, Jens; Caleman, Carl; Commandeur, Jan; Damjanović, Tomislav; Dörner, Simon; Fahmy, Karim; Flacht, Lara; Heidemann, Johannes; Huynh, Khon; Kopicki, Janine-Denise; Krichel, Boris; Lockhauserbäumer, Julia; Lorenzen, Kristina; Lu, Yinfei; Pogan, Ronja;
Bigting, Kevin V.; Carden, Jordan J.; Nag, Shubhadeep; Lawrence, Jimmy; Su, Yen-Fang; An, Yaxin
doi: 10.1039/d5cp01334hpmid: 40525255
Graft polymers are promising in energy and biomedical applications. However, the diverse architectures make it challenging to establish their structure–property relationships. We systematically investigate how backbone and side-chain architectures influence four key properties: glass transition temperature (Tg), self-diffusion coefficient (D), radius of gyration (Rg), and packing density (ρ). Using molecular dynamics simulations, we analyze a dataset of 500 graft polymers with randomly positioned side chains. Tg and D exhibit decoupled relationships due to the distinct topological effects. Furthermore, we develop dense neural networks (DNNs) and convolutional neural networks (CNNs) to pave the way to polymer design with desired properties.
Sun, Dengning; Du, Xiaokun; Chen, Jing; Ye, Tao; Shen, Hao; Wang, Ruirui; Wang, Ying; Liu, Guoqiang; Wan, Yangyang; Sun, Zhongti
doi: 10.1039/d5cp01837dpmid: 40501214
Kim, SeongMin; Kim, So-Hee; Kim, Sang-Woo
doi: 10.1039/d5cp00376hpmid: 40524550
Utilizing first-principles density functional theory, we computed the surface electronic structure of a polytetrafluoroethylene (PTFE) slab with various dangling bond (DB) configurations. As the number of surface DBs increases, the lowest unoccupied level (LUL) associated with electron affinity (EA) decreases, resulting in a rise in the DBs’ formation energy, indicating an unstable state and electron deficiency. Particularly in spinless DB states, only one localized lowest unoccupied surface state (LUSS) forms below the conduction band minimum (CBM). To investigate charge transfer, a contact model between various spin-state DBs and the Al slab was performed. Furthermore, axial or radial extension in the DB-PTFE system confirms reduced LUL (CBM or LUSS), attributed to F atoms moving away, facilitating easier electron entry from the external environment. These calculations lead to the proposal of an electron transfer model between the metal and DB-PTFE.
Allia, Hadjer; Rodríguez-Expósito, Ana; Palacios, María A.; Jiménez, Juan-Ramón; Carneiro Neto, Albano N.; Moura, Renaldo T.; Piccinelli, Fabio; Navarro, Amparo; Quesada-Moreno, María Mar; Colacio, Enrique
doi: 10.1039/d4cp04862hpmid: 40326868
Seven mononuclear lanthanide complexes have been isolated and structurally characterised. Four of them are cationic, whose charges are balanced by chloride counteranions, and exhibit pentagonal bipyramidal coordination geometry, whereas the rest of them are neutral and display octahedral coordination environment. In all cases, the coordination sphere of the LnIII ions consists of two di(1-adamantyl)benzylphosphine oxide ligands in axial positions, whereas in the equatorial plane the former contains a chloride and four water molecules and the latter a solvent molecule and three chloride ligands. We report a detailed photophysical investigation, including time-dependent density functional theory (TD-DFT) calculations and intramolecular energy transfer (IET) analysis, which reveals two distinct lanthanide sensitization mechanisms. Compound-specific energy transfer pathways occur through either the S1 or T1 states, as supported by calculated IET rates and resonance with lanthanide acceptor transitions. In addition, dc and ac magnetic properties were measured on complexes 1 and 2, showing that compound 1 behaves as a bi-functional compound, exhibiting field-induced single molecule magnet behaviour together with YbIII-centred NIR luminescence. The relaxation of the magnetization in this pentagonal bipyramidal complex takes place through Raman and direct processes, as supported by ab initio calculations.
Jiang, Yuanqi; Wen, Dadong; Xu, Qiang; Lv, Jian; Zhao, Rui; Peng, Ping
doi: 10.1039/d5cp00247hpmid: 40421810
The cause of the anomalous shift in the first maximum peak of radial distribution functions (RDFs) with decreasing temperature in metallic melts and glasses remains highly controversial. In this study, we show that the first RDF peak exhibits anomalous expansion as the temperature decreases during the non-equilibrium solidification (γ1 = 1 × 1010 K s−1 and γ2 = 1 × 1011 K s−1) of liquid tantalum. This behavior is primarily due to alterations in both the geometric and electronic structures of the system. In terms of geometric structure, for example, at the cooling rate of γ1, the system forms a significant number of cage-like icositetrahedral Voronoi polyhedra (0,0,12,2) and standard icosahedral Voronoi polyhedra (0,0,12,0) at low temperatures. These Voronoi polyhedra have longer bond lengths and lower binding energies compared to their high-temperature counterparts. Furthermore, these Voronoi polyhedra nest together, forming a stable Ta26-C2v atomic configuration with minimal changes in bond lengths. This unique geometric arrangement contributes fundamentally to the anomalous expansion of the first peak of the RDF. Regarding the electronic structure, the temperature influences the interactions between Ta atoms. At higher temperatures, the electronic localization functions (ELFs) and the Mulliken bond overlap populations (Qi–j) are significantly increased, leading to stronger electronic interactions and a denser arrangement of nearest-neighbor atoms with shorter bond lengths. Consequently, the combined effects of geometric and electronic structural changes during non-equilibrium solidification could explain the anomalous expansion of the first peak of the RDF.
Showing 1 to 10 of 51 Articles
doi: 10.1039/d5cp00604jpmid: 40304431
Gas-phase activation and dissociation studies of biomolecules, proteins and their non-covalent complexes using X-rays hold great promise for revealing new insights into the structure and function of biological samples. This is due to the unique properties of X-ray molecular interactions, such as site-specific and rapid ionization. In this perspective, we report and discuss the promise of first proof-of-principle studies of X-ray-induced dissociation of native (structurally preserved) biological samples ranging from small 17 kDa monomeric proteins up to large 808 kDa non-covalent protein assemblies conducted at a synchrotron (PETRA III) and a free-electron laser (FLASH2). A commercially available quadrupole time-of-flight mass spectrometer (Q-Tof Ultima US, Micromass/Waters), modified for high-mass analysis by MS Vision, was further adapted for integration with the open ports at the corresponding beamlines. The protein complexes were transferred natively into the gas phase via nano-electrospray ionization and subsequently probed by extreme ultraviolet (FLASH2) or soft X-ray (PETRA III) radiation, in either their folded state or following collision-induced activation in the gas phase. Depending on the size of the biomolecule and the activation method, protein fragmentation, dissociation, or enhanced ionization were observed. Additionally, an extension of the setup by ion mobility is described, which can serve as a powerful tool for structural separation of biomolecules prior to X-ray probing. The first experimental results are discussed in the broader context of current and upcoming X-ray sources, highlighting their potential for advancing structural biology in the future.
p-Block element-based electrocatalysts featuring a tunable electronic structure to achieve exceptional N2 activation and proton suppression have garnered extensive interest for the electrochemical N2 reduction reaction (NRR). Albeit various reaction mechanisms were proposed to understand and optimize the NRR performance, methods to effectively design and rapidly screen potential candidates are still elusive. Herein, a couple of explicit and interpretable descriptors on the entire p-block element-based electrocatalysts are put forward to predict NRR activity and selectivity via high-throughput theoretical simulations and a symbolic regression algorithm, taking two-dimensional (2D) bismuthine with p-block elements doped in or adsorbed as an example. The descriptors are merely composed of inherent atomic properties (p orbital electron number, electron affinity, electronegativity, atomic radius, etc.) combined with algebraic operators, independent of the intricate DFT calculations. Multi-task regression results demonstrate that the doped and adsorbed bismuthine systems possess the same descriptors, namely, the descriptors of doped-Bi can accurately forecast the NRR performance of adsorbed-Bi, and vice versa. Five potential candidates (5/40) with outstanding NRR activity, selectivity and stability are screened. C-doped and Si-doped bismuthine possess less negative limiting potentials of the NRR [UL(NRR)] of −0.46 and −0.68 V and positive [UL(NRR) − UL(HER)] values of 1.15 and 0.13 V, respectively, superior to those of the majority of reported p-block element-based electrocatalysts, which are expected to be verified by the experimental research. This work offers a feasible solution for developing promising electrocatalysts for the NRR and potentially other electrochemical reactions on the basis of explainable descriptors using geometric information and intrinsic atomic quantities.