Lattice Distortion Research Articles

Trace Yb doping-induced cationic vacancy clusters enhance thermoelectrics in P-type PbTe

Alloying has been widely used to enhance thermoelectric (TE) performance, but achieving high TE performance remains challenging due to strong coupling between electrical and thermal transport in lead telluride-based materials. In this Letter, trace doping of the rare earth element Yb in a Pb0.95Na0.04Te matrix effectively regulates charge carriers by competing with cation vacancies. This mechanism optimizes carrier concentration and phonon scattering, resulting in a high power factor of ∼27 μW cm−1 K−2 and a low lattice thermal conductivity of ∼0.42 W m−1 K−1 at 823 K in Pb0.94Na0.04Yb0.01Te. First-principles calculations reveal that Yb doping induces local lattice distortions in PbTe, potentially forming pseudo-nanostructures in localized regions. This strategy leads to a peak zT of ∼2.4 at 823 K and an average zT of ∼1.4 from 303 to 823 K in Pb0.94Na0.04Yb0.01Te. Our findings suggest that the competition between dopant cations and cation vacancies reduces thermal conductivity via local lattice distortions while simultaneously improving electrical conductivity at high temperatures. This synergistic control of electrical and thermal transport offers an approach for boosting zT in TE materials.

Exploring parameter dependence of atomic minima with implicit differentiation

Interatomic potentials are essential to go beyond ab initio size limitations, but simulation results depend sensitively on potential parameters. Forward propagation of parameter variation is key for uncertainty quantification, whilst backpropagation has found application for emerging inverse problems such as fine-tuning or targeted design. Here, the implicit derivative of functions defined as a fixed point is used to Taylor-expand the energy and structure of atomic minima in potential parameters, evaluating terms via automatic differentiation, dense linear algebra or a sparse operator approach. The latter allows efficient forward and backpropagation through relaxed structures of arbitrarily large systems. The implicit expansion accurately predicts lattice distortion and defect formation energies and volumes with classical and machine-learning potentials, enabling high-dimensional uncertainty propagation without prohibitive overhead. We then show how the implicit derivative can be used to solve challenging inverse problems, minimizing an implicit loss to fine-tune potentials and stabilize solute-induced structural rearrangements at dislocations in tungsten.

High Entropy: A General Strategy for Broadening the Operating Temperature of Magnetic Refrigeration.

Lattice distortion and disorder in the chemical environment of magnetic atoms within high-entropy compounds present intriguing issues in the modulation of magnetic functional compounds. However, the complexity inherent in high-entropy disordered systems has resulted in a relative scarcity of comprehensive investigations exploring the magnetic functional mechanisms of these alloys. Herein, we investigate the magnetocaloric effect (MCE) of the high-entropy intermetallic compound Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Co2. Notably, the operating temperature range of the MCE broadens by an order of magnitude from 9 to 83 K while maintaining the refrigeration capacity compared to ErCo2. Atomic-scale microstructure analysis and atomic pair distribution function measurements reveal that lattice distortion stabilizes the cubic structure and induces disorder in the chemical environment of magnetic atoms. First-principles calculations point out that the enhanced average correlation energy raises the Curie temperature. The random distribution of elements across these sites induces local magnetic disorder around magnetic atoms with lower correlation energy, broadening the operating temperature range of MCE. This study not only significantly advances the understanding of the magnetic behavior of high-entropy alloys but also promotes the research progress of high-entropy functional compounds.

Modulating Electronic Spin State of Perovskite Fluoride by Ni─F─Mn Bond Activating the Dynamic Site of Oxygen Reduction Reaction.

Establishing the relationship between catalytic performance and material structure is crucial for developing design principles for highly active catalysts. Herein, a type of perovskite fluoride, NH4MnF3, which owns strong-field coordination including fluorine and ammonia, is in situ grown on carbon nanotubes (CNTs) and used as a model structure to study and improve the intrinsic catalytic activity through heteroatom doping strategies. This approach optimizes spin-dependent orbital interactions to alter the charge transfer between the catalyst and reactants. As a result, the oxygen reduction reaction (ORR) activity of NH4MnF3 on CNTs is significantly enhanced by partial substitution of Mn sites with Ni, such as a half-wave potential (E1/2) of 0.86V and a limiting current density of 5.26mA cm-2, which are comparable to those of the commercial Pt/C catalysts. Experimental and theoretical calculations reveal that the introduction of Ni promotes lattice distortion, adjusts the electronic states of the active Mn centers, facilitates the transition from low-spin to intermediate-spin states, and shifts the d-band center closer to the Fermi level. This study establishes a novel approach for designing high-performance perovskite-based fluoride electrocatalysts by modulating spin states.

Inhibiting Lattice Distortion of Ultrahigh Nickel Co-Free Cathode Material for Lithium-Ion Batteries.

Ultrahigh nickel cathode materials are widely utilized due to their outstanding energy and power densities. However, the presence of cobalt can cause significant lattice distortion during charge and discharge cycles, leading to the loss of active lithium, the formation of lattice cracks, and the emergence of a rock salt phase that hinders lithium-ion transport. Herein, we developed a novel cobalt-free, aluminum-doped cathode material, LiNi0.93Mn0.06Al0.01O2 (NMA), which effectively delays the harmful H2-H3 phase transition, reduces lattice distortion, alleviates stress release, and significantly enhances structural stability. Compared to commercially available Co-rich LiNi0.83Co0.11Mn0.06O2 (NCM) materials, NMA offers a cost reduction of approximately 16% while maintaining comparable capacity. Moreover, NMA exhibits superior rate performance and long-term cycling stability in both half-cell and full-cell configurations. These findings pave the way for the development of cost-effective, high-performance, and durable cobalt-free cathode materials, offering promising potential for future research and commercial applications.

Lattice Distortions Promoting the In-Depth Reconstruction of Ni-Based Electrocatalysts with Enriched Oxygen Vacancies for the Electrochemical Oxidation of 5-Hydroxymethylfurfural toward 2,5-Furandicarboxylic Acid.

The electrocatalytic 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) toward 2,5-furandicarboxylic acid (FDCA) has been considered a promising approach for the substitution of the energy-consuming and hazardous oxygen evolution reaction and for the valorization of renewable biomass. However, it is limited by the susceptibility of HMF to the oxidative environment and requires efficient electrocatalysts. Herein, a NiMo complex (NiMo-N) is provided as the precatalyst for the HMFOR, exhibiting favorable performances with a current density of 450 mA·cm-2 achieved at an anodic potential of 1.4 V vs RHE (similarly hereinafter) with 50 mmol/L (mM) HMF and over 95% HMF conversion and FDCA FE for at least five cycles. Combined with quasi situ and in situ analysis, it is confirmed that the extensive lattice distortions in the precatalyst facilitate the in-depth reconstruction, increasing the accessible Ni sites and defective oxygen vacancies (Ov), which would promptly convert to high-valence Ni and active O species during the reaction. The improved performance is then attributed to the incorporation of the improved chemisorption and dehydrogenation ability of HMF by the as-evolved active sites.

Lattice deformation induced by hot carriers in graphene

Lattice deformation induced by hot carriers in graphene

Tunable Organic‐Inorganic p‐π‐d Electron Conjugation Triggers d‐π Hybridization in Quinonized MnO2 Superlattice toward Ultrastable and High‐Rate Zn−MnO2 Batteries

AbstractZn‐MnO2 batteries with two‐electron transfer harvest high energy density, high working voltage, inherent safety, and cost‐effectiveness. Zn2+ as the dominant charge carriers suffer from sluggish kinetics due to the strong Zn2+−MnO2 coulombic interaction, which is also the origin of pestilent MnO2 lattice deformation and performance degradation. Current studies particularly involve H+ insertion‐dominating chemistry, where the long‐term cycle stability remains challenging due to the accumulative Zn2+ insertion and structural collapse. Herein, a simultaneously enhanced and stabilized Zn2+/H+ co‐insertion chemistry is proposed by the quinone‐hybridized MnO2 superlattice, a first‐of‐this‐kind structure with a distinctive organic–inorganic‐extended p‐π‐d conjugation, which enables a tunable interlayer d‐π hybridization. Theoretical and experimental results substantiate that the interlayer d‐π hybridization triggers the enhancement of polarons occupancy near Fermi level, the downward shift of O p‐band center, the elevated Mn t2g occupation and thus improved [MnO6] stability upon unprecedentedly high Zn2+ contribution. The notable d‐π hybridization endows MnO2 superlattice an ultrahigh specific capacity (435.9 mAh g−1 at 0.25 A g−1), state‐of‐the‐art cycle stability (~100 % capacity retention after 30,000 cycles at 10 A g−1) with substantially enhanced rate performance. Our findings enlighten a new paradigm in the adjustment of Zn2+/H+ co‐insertion chemistry towards high‐performance rechargeable aqueous batteries.

Unveiling Doping Kinetics in Cu(I) Metal Halides for Customized Luminescent Performance.

Intentional doping plays a pivotal role in customizing metal halides' electronic and optical features. This work manipulates the incorporation and distribution of Mn2+ in Cu(I) halide by controlling the elemental steps involved in the growth-doping kinetics as well as investigates the localized lattice and electronic structures in different doping configurations. Complementary experimental and theoretical results demonstrate that a uniform and relatively high Mn2+ doping level can be achieved by a step-tailored strategy that encompasses reducing the growth rate of the halide matrix, enhancing the surface adsorption of Mn2+, and facilitating the incorporation of the dopants. The optimized doping configuration mitigates severe lattice distortion and decreases the non-radiative transition rate, resulting in explicit dual-band emission and an enhanced photoluminescence quantum yield. This work underscores an effective synthesis strategy to harness the full potential of Mn2+-doped metal halides beyond Cu(I)-based ones and also showcases a new working paradigm of separately controlling the doping procedures for obtaining metal halides with customized optical/optoelectronic properties.

First-Principles Study on the Electronic Structure and Optical Properties of BiOIO3 Doped with As, Se, and Te

This study calculates the electronic structure and optical properties of intrinsic BiOIO3 and X-BiOIO3 (X = As, Se, or Te) using PBE (Perdew–Burke–Ernzerhof) and MBJ (Modified Becke–Johnson) functionals based on density functional theory, with MBJ showing better correlation with experimental values. The X-BiOIO3 systems exhibit relative stability under MBJ potential and show crystal lattice distortion compared to intrinsic BiOIO3, creating localized potential differences that enhance polarization and adjust the bandgap. Doping reduces the bandwidth and increases energy level density, promoting electron transitions. Consequently, based on the computational results presented in this paper, it can be inferred that both BiOIO3 and X-BiOIO3 facilitate water hydrolysis and oxygen generation due to their favorable energy band positions. Notably, Se-BiOIO3 exhibits the highest visible light absorption capacity, which may enhance photocatalytic efficiency by strengthening the built-in electric field and promoting charge carrier generation.

Tunable Organic-Inorganic p-π-d Electron Conjugation Triggers d-π Hybridization in Quinonized MnO2 Superlattice toward Ultrastable and High-Rate Zn-MnO2 Batteries.

Zn-MnO2 batteries with two-electron transfer harvest high energy density, high working voltage, inherent safety, and cost-effectiveness. Zn2+ as the dominant charge carriers suffer from sluggish kinetics due to the strong Zn2+-MnO2 coulombic interaction, which is also the origin of pestilent MnO2 lattice deformation and performance degradation. Current studies particularly involve H+ insertion-dominating chemistry, where the long-term cycle stability remains challenging due to the accumulative Zn2+ insertion and structural collapse. Herein, a simultaneously enhanced and stabilized Zn2+/H+ co-insertion chemistry is proposed by the quinone-hybridized MnO2 superlattice, a first-of-this-kind structure with a distinctive organic-inorganic-extended p-π-d conjugation, which enables a tunable interlayer d-π hybridization. Theoretical and experimental results substantiate that the interlayer d-π hybridization triggers the enhancement of polarons occupancy near Fermi level, the downward shift of O p-band center, the elevated Mn t2g occupation and thus improved [MnO6] stability upon unprecedentedly high Zn2+ contribution. The notable d-π hybridization endows MnO2 superlattice an ultrahigh specific capacity (435.9 mAh g-1 at 0.25 A g-1), state-of-the-art cycle stability (~100 % capacity retention after 30,000 cycles at 10 A g-1) with substantially enhanced rate performance. Our findings enlighten a new paradigm in the adjustment of Zn2+/H+ co-insertion chemistry towards high-performance rechargeable aqueous batteries.

Effect of dopants and surface oxides on the electronic properties of dislocations in p-type SiC

Abstract Understanding the electronic properties of dislocations is key to tailoring the properties of silicon carbide (SiC)-based electronic devices. By combining the Kelvin probe force microscopy (KPFM) analysis and first-principles calculations, we investigate the effect of aluminum (Al) dopants and surface oxides on the electronic properties of dislocations in p-type SiC. It is found that dislocations, including threading screw dislocations (TSDs), threading edge dislocations (TEDs), and basal plane dislocations (BPDs) create deep acceptor-like states in p-type SiC. The defect levels move upwards in the order of BPD, TED and TSD, which closely relates with the lattice distortion of dislocations. Interestingly, we find that the defect levels of dislocations are higher than that of Al in p-type SiC. First-principles calculations indicate that the defect formation energies of Al dopants at the cores of dislocations are higher than those in the perfect region of p-type SiC, as a result of the steric effect. This indicates that the concentration of Al acceptors at the dislocation cores is lower than that in the perfect region, resulting in the higher defect level positions of dislocations in p-type SiC. Additionally, we find that surface oxidation reduces the difference of defect-level positions between dislocations and the perfect region of p-type SiC, which paves the way for tailoring the electronic properties of dislocations in p-type SiC.

Phase stability, electronic, mechanical, lattice distortion, and thermal properties of complex refractory-based high entropy alloys TiVCrZrNbMoHfTaW with varying elemental ratios.

This study examines the intricate area of refractory-based high entropy alloys (RHEAs), focusing on a series of complex compositions involving nine diverse refractory elements: Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. We investigate the phase stability, bonding interactions, electronic structures, lattice distortions, mechanical, and thermal properties of six RHEAs with varying elemental ratios using VASP and OLCAO DFT calculations. Through comprehensive analysis, we investigate the impact of elemental variations on the electronic structure, interacting bond dynamics, lattice distortion, thermodynamic, mechanical, and thermal properties within these RHEAs, providing an insight into how these specific elemental variations in composition give rise to changes in the calculated properties in ways that would guide future experimental and computational efforts. The correlation between the lattice distortion, mechanical, and thermal properties is explored in detail in this work. Our findings reveal significant insights into how these factors contribute to the unique properties of RHEAs, such as enhanced strength, ductility, and resistance to corrosion and wear. This research not only advances our understanding of the fundamental aspects of RHEAs but also opens new avenues for the design and application of these materials in various industrial sectors.

NiCo2O4/P,N‐doped Carbon with Engineered Interface to Improve the Rechargeability of Zn‐Air Batteries at High Energy Demands

The search for cost‐effective, high‐performance bifunctional catalysts for Zn‐air batteries (ZABs) requires extensive research into precious‐metal‐free materials. This study provides insight into the synergy between nickel cobaltite and P,N‐doped carbon modified through interface engineering by inducing oxygen vacancies in the spinel and non‐metallic heteroatoms in the carbon material. NiCo2O4 with various oxygen vacancy levels was synthesized via an ethylene glycol‐assisted solvothermal route. This resulted in significant changes in the structural and morphological properties, such as reduced crystallite size, lattice distortion, and increased oxygen vacancies, as observed from the physicochemical results. This was further verified by X‐ray photoelectron spectroscopy (XPS) and high‐resolution transmission electron microscopy (HR‐TEM), which showed a homogeneous dispersion of nickel cobaltite nanorods on the carbonaceous matrix, along with an increased concentration of pyridinic nitrogen and the formation of P–N and P–C bonds, both of which enhance electrocatalytic activity. NiCo2O4DI/P,N‐C exhibited superior discharge polarization behavior, achieving power and current densities of 124.4 mW cm−2 and 215.8 mA cm−2. The catalyst presented excellent stability (up to 100 h), while Pt‐IrO2/C lasted near 21 h. These results demonstrate the great potential of tailoring surface defects and heteroatom doping via interface engineering, resulting in high‐performance precious‐metal‐free electrocatalysts for long‐lasting and high‐efficiency ZABs.

Organic Spacers Modulated Low Dose X-Ray Detection in Hybrid Halide 2D Perovskites: Unveiling Exciton Dynamics.

In this study, we investigate how modulating organic spacers in perovskites influences their X-ray detection performance and reveal the mechanism of low-dose detection with high sensitivity using femtosecond-transient absorption spectroscopy (fs-TAS). Particularly, we employ N,N,N',N'-tetramethyl-1,4-phenylenediammonium (TMPDA) and N,N-dimethylphenylene-p-diammonium (DPDA) as organic spacers to synthesize 2D perovskite single crystals (SCs). We find that DPDA-based SCs exhibit reduced interplanar spacing between inorganic layers, leading to increased lattice packing. Density functional theory (DFT) results indicate the reduced effective mass and lower lattice distortion in (DPDA)PbBr4 suppressing the formation of self-trapped exciton (STEs) and electron-phonon coupling and enhancing carrier delocalization in these SCs. Further, X-ray detection measurements reveal that (DPDA)PbBr4 demonstrates higher sensitivity than (TMPDA)PbBr4, attributed to its enhanced carrier delocalization, and higher mobility-lifetime product. The limit of detection (LoD) for (DPDA)PbBr4 is determined to be 13 nGy/s, significantly lower than both commercial detectors and state-of-the-art perovskite-based X-ray detectors. Furthermore, fs-TAS study reveals that (DPDA)PbBr4 crystals exhibit prolonged hot STE cooling and decay lifetimes, which directly correlate with their higher sensitivity. This study highlights the impact of organic spacers on X-ray detection performance, providing a framework for designing ultra-low LoD detectors essential for health and security applications.

Functionally Graded Oxide Scale on (Hf,Zr,Ti)B2 Coating with Exceptional Ablation Resistance Induced by Unique Ti Dissolving.

Multicomponent Ti-containing ultra-high temperature ceramics (UHTCs) have emerged as more promising ablation-resistant materials than typical UHTCs for applications above 2000 °C. However, the underlying mechanism of Ti improving the ablation performance is still obscure. Here, (Hf,Zr,Ti)B2 coatings are fabricated by supersonic atmospheric plasma spraying, and the effects of Ti content on the ablation performance under an oxyacetylene flame are investigated. The (Hf0.45Zr0.45Ti0.10)B2 coating shows superior ablation resistance and cycling reliability at ≈2200°C. A functionally graded oxide scale comprising an outer dense layer and an underlying fine granular layer formed. The former is a better oxygen barrier owing to fewer cracks and the latter has high strain tolerance due to finer grain size. The uniform dissolving of ≈4 mol% Ti in the inner layer results in grain refinement via sluggish diffusion and thus stress release. For the outer layer, Ti segregation at the nanoscale leads to a metastable cubic (Hf,Zr,Ti)O2 and local severe lattice distortion, inhibiting the propagation of cracks. Ti ions' unique dissolving in the oxide scale enables a strong oxygen diffusion barrier with high strain tolerance, which is responsible for superior performance. This study provides new insights into the ablation behavior of Ti-containing multicomponent UHTCs.

Recent Advances in the Performance and Mechanisms of High-Entropy Alloys Under Low- and High-Temperature Conditions

High-entropy alloys, since their development, have demonstrated great potential for applications in extreme temperatures. This article reviews recent progress in their mechanical performance, microstructural evolution, and deformation mechanisms at low and high temperatures. Under low-temperature conditions, the focus is on alloys with face-centered cubic, body-centered cubic, and multi-phase structures. Special attention is given to their strength, toughness, strain-hardening capacity, and plastic-toughening mechanisms in cold environments. The key roles of lattice distortion, nanoscale twin formation, and deformation-induced martensitic transformation in enhancing low-temperature performance are highlighted. Dynamic mechanical behavior, microstructural evolution, and deformation characteristics at various strain rates under cold conditions are also summarized. Research progress on transition metal-based and refractory high-entropy alloys is reviewed for high-temperature environments, emphasizing their thermal stability, oxidation resistance, and frictional properties. The discussion reveals the importance of precipitation strengthening and multi-phase microstructure design in improving high-temperature strength and elasticity. Advanced fabrication methods, including additive manufacturing and high-pressure torsion, are examined to optimize microstructures and improve service performance. Finally, this review suggests that future research should focus on understanding low-temperature toughening mechanisms and enhancing high-temperature creep resistance. Further work on cost-effective alloy design, dynamic mechanical behavior exploration, and innovative fabrication methods will be essential. These efforts will help meet engineering demands in extreme environments.

Synthesis and Irreversible Pressure‐Induced Emission Enhancement of Ultrathin Lead‐Free 2D Organic–Inorganic Hybrid Perovskite (i‐OA)3BiBr6 Nanosheets at Room Temperature

Abstract2D bismuth‐based perovskites have attention as a potentially transformative technology in optoelectronics due to their exceptional non‐toxic and environmentally friendly properties. However, their practical applications are hindered by the low luminous efficiency caused by self‐trapped excitons (STEs) under normal environmental conditions. Here, a new composition of lead‐free ultrathin 2D perovskite nanosheet iso‐octylamine bismuth bromide [(i‐OA)3BiBr6] is synthesized, with thicknesses down to 1.1 nm, using a solution‐based method and explored their stability. Notably, the behavior of STEs in these ultrathin nanosheets can be modulated through a pressure treatment strategy. After completely releasing the pressure, an optimal lattice distortion is stabilized, resulting in an 80‐fold increase in irreversible pressure‐induced emission. This finding highlights the critical roles of steric hindrance and hydrogen bonding cooperativity effects in the organic cationic layers, along with OA ligand passivation, in enhancing STE radiation recombination under ambient conditions. This advancement opens new possibilities for creating stable, bright STEs under ambient conditions, thus facilitating its potential applications in the fields of pressure sensing, display, and energy savings.

Effect of substrate-induced compressive strain on protonation of SrCoO2.5 epitaxial films

Abstract In this study, we grew (010)-oriented epitaxial films of brownmillerite-structured SrCoO2.5 on various substrates whose lattice mismatch against SCO ranged from 0 to -2.9% by pulsed laser deposition and investigated the effect of substrate-induced strain on their protonation in field effect transistor structures with gate layers consisting of Nafion membranes. We found that the H concentration of the SCO films that were fully compressive-strained by up to 1.3 % was ~1.7 and that it was almost independent of the magnitude of the substrate-induced strain. We also found that the H content of the strain-partially-relaxed film with a residual compressive strain of 1.3% was lower, ~1.3. These results indicate that lattice deformations arising from substrate-induced strain have insignificant effects on protonation, while lattice defects and dislocations introduced upon strain relaxation, which hinders proton diffusion in the films’ lattices, dominantly affect protonation in SrCoO2.5 films

An Atomistic Analysis of the Carpet Growth of KCl Across Step Edges on the Ag(111) Surface.

The carpet growth of alkali halide (AH) layers across step edges of substrates enables the growth of seamless and continuous large domains. Yet, information about how the AH layer adapts continuously to the height difference between the terraces on the two sides of a step is only described by continuum models, which do not give details of the ionic displacements. Here, we present a first study of thin epitaxial KCl(100) layers grown on the Ag(111) surface by scanning tunneling microscopy that provides atomistic details for the first time. Measurements were performed at room temperature. Using a Cl--decorated tip, we resolved the ionic arrangement and hence the KCl lattice distortion in the carpet growth region, in some cases even by imaging both types of ions. Our findings demonstrate the ability of the KCl lattice to distort locally over a short distance of four KCl unit cells as a result of the attractive interaction between the ions and the Ag atoms at and close to the steps. For Ag step edges covered by the KCl carpet, we observe a tendency to straighten along the ⟨110⟩ direction of the KCl layer. In addition, the carpet growth induces the formation of Ag microterraces, i.e., the splitting of higher Ag steps into multiple Ag steps of monatomic height during the KCl deposition at elevated temperatures. These microterraces have a minimum width determined by an energetically preferred fitting to the KCl lattice and allow for the carpet growth, while growth across higher Ag steps is not observed.