Lattice Strain Research Articles

Lattice Strain Regulated by Hetero/Homo Atom Interface Merging on NiMo Nanocluster for High-Performance Hydrogen Production.

Lattice strain engineering represents a cutting-edge approach capable of delivering enhanced performance across various applications. The lattice strain can affect the performance of electrochemical catalysts by changing the binding energy between the surface-active sites and intermediates. In this work, lattice strain is regulated through a homo/heterogeneous atomic interface merging. The strong lattice strain and electronic interactions between Ni and Mo facilitated the reaction kinetic of HER. The prepared NiMo@SSM exhibits excellent HER catalytic performance with 70 mV overpotential at the current density of 10 mA cm-2 and long-term stability. The method of controlling lattice strain through hetero/homo atom interface merging provides a new strategy for designing high-performance alkaline HER electrocatalysts.

Domain switching and shear-mode piezoelectric response induced by cross-poling in polycrystalline ferroelectrics

The mechanisms contributing to the electromechanical response of piezoelectric ceramics in the shear mode have been investigated using high-energy synchrotron x-ray diffraction. Soft lead zirconate titanate ceramic specimens were subjected to an electric field in the range 0.2–3.0 MV m−1, perpendicular to that of the initial poling direction, while XRD patterns were recorded in transmission. At low electric field levels, the axial strains remained close to zero, but a significant shear strain occurred due to the reversible shear-mode piezoelectric coefficient. Both the axial and shear strains increased substantially at higher field levels due to irreversible ferroelectric domain switching. Eventually, the shear strain decreased again as the average remanent polarization became oriented toward the electric field direction. The lattice strain and domain orientation distributions follow the form of the total strain tensor, enabling the domain switching processes to be monitored by the rotation of the principal strain axis. Reorientation of this axis toward the electric field direction occurred progressively above 0.6 MV m−1, while the angle of rotation increased from 0° to approximately 80° at the maximum field of 3.0 MV m−1. A strong correlation was established between the effective strains associated with different crystallographic directions, which was attributed to the effects of elastic coupling between grains in the polycrystal.

High-Throughput UV-Induced Synthesis and Screening of Alloy Electrocatalysts.

The combination of different elements in alloy catalysts can lead to improved activity as it provides opportunities to tune the electronic structures of surface atoms. However, the synthesis and performance screening of alloy catalysts through a vast chemical space are cost- and labor-intensive. Herein, a UV-induced, high-throughput method is reported for the synthesis and screening of alloy electrocatalysts in a fast and low-cost manner. A platform that integrates 37 mini-reaction-cells enables simultaneous UV-induced photodeposition of alloy nanoparticles with up to 37 compositions. These mini-reaction-cells further allow a transfer-free, high-throughput electrochemical performance screening. Binary (PtPd, PtIr, PdIr), ternary (PtPdIr, PtRuIr) and quaternary (PtPdRuIr) alloys have been synthesized with the activity of the binary alloys (57 compositions) for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) being screened. The predicted high performance of identified alloy compositions are subsequently validated by standard measurements using a rotating disk electrode configuration. It is found that the as-synthesized alloy nanoparticles are rich in twin boundaries and thus possess lattice strain. Density functional theory calculation implies that the high ORR activity of the screened Pt0.75Pd0.25 alloy originates from the interplay between the differentiated adsorption sites because of alloying and the strain-induced modulation of the d-band center.

Controllability of optical, electrical, and magnetic properties of synthesized Cd-doped MgFe2O4 nanostructure

This study explores the synthesis of cadmium-magnesium co-doped magnesium ferrite (Mg1+xCdxFe2–2xO4, 0.00 ≤ x ≤ 0.30, Δx = 0.05) via a citric acid-assisted sol-gel auto-combustion method. X-ray diffraction (XRD) analysis revealed crystal structure changes due to Cd and Mg co-doping, with the 0.25 Cd sample showing the smallest crystallite size and highest lattice strain. High-resolution transmission electron microscopy (HRTEM) confirmed the nanostructure and largest surface area for this sample. Diffuse reflectance spectra, analyzed using the Kubelka-Munk relation, indicated that the 0.25 Cd sample had the lowest energy gap (2.08 eV), supported by band position calculations. Electrical conductivity and charge transport mechanisms were examined at various temperatures. Magnetization studies showed reduced saturation magnetization at x = 0.25, ascribed to cation distribution changes and spin canting, with coercivity and anisotropy decreasing with higher Cd content. Overall, the 0.25 Cd sample exhibited optimized optical, electrical, and magnetic properties due to its distinct microstructure.

Effects of Thermal Energy on the Formation of Lattice Strain in VO2 Thin Films Grown on TiO2(001).

Film thickness is a well-known experimental parameter for controlling lattice strain in oxide films. However, due to environmental and resource conservation considerations, films need to be as thin as possible, increasing the need to find alternative factors for strain management. Herein, we present the importance of thermal energy as a factor for the formation of lattice strain in the oxide films, specifically focusing on the effects of laser fluence during pulsed laser deposition (PLD) on the in-plane lattice strain of vanadium dioxide (VO2) thin films grown on titanium dioxide (TiO2) (001). VO2 thin films were deposited using a KrF excimer laser (λ = 248 nm) at laser fluences ranging from 0.88 to 1.70 J/cm2. The film thickness ranged from 10-15 nm, below the critical thickness. Films grown at higher laser fluences exhibited smooth surfaces and completely strained in-plane lattices. In contrast, films grown at lower laser fluences displayed numerous small islands and relaxed in-plane lattice strain. The metal-insulator transition (MIT) temperature was lower for films grown at higher laser fluencies compared to those grown at lower laser fluences. It was also revealed that Ti-V interdiffusion occurs, forming a solid solution (V1-xTixO2) near the interface. These observations suggest that the thermal energy of the particles, influenced by laser fluence, is a critical factor in the formation of lattice strain in metal oxide films and also that laser fluence in PLD is an effective experimental parameter for strain management in oxide films. Our findings enhance the understanding of lattice strain formation in metal oxides and offer insights for establishing effective methods for controlling lattice strain in metal oxide films.

X-ray crystallographic diffraction study by whole powder pattern fitting (WPPF) method: Refinement of crystalline nanostructure polymorphs TiO2

High crystalline preferred oriented low strain anatase utilizing a novel and unique approach employing the powder X-ray diffraction (XRD) technique is the prime focus of the investigation. This process effectively enhanced controlled crystalline phase growth with 86.70 % anatase and 13.30 % rutile confirmed through Rietveld refinement in the WPPF method. The prominent crystalline phase providing insights into lattice parameters a = b = 3.7882 Å, c = 9.5143 Å, α=β=γ= 90.0° where lattice strain 0.280 %, lattice volume 136.533 Å3, specific surface area 84.69 m2/g, dislocation density 2.94 × 10–3 nm−2, morphology index 0.722, preference growth -0.087 and packing efficiency 70.13 %. The most intense diffraction was attributed to the (101) plane at 2θ= 25.288° The average crystallite size through various models was 18.45 nm (Scherrer equation), 34.08 nm (Williamson-Hall plot), 22.12 nm (Monshi-Scherrer model), 18.49 nm (Sahadat-Scherrer model), 22.44 nm (Size-strain plot model) and 17.87 nm (Halder-Wagner model) confirming the formation of nano-sized anatase phase of titanium dioxide nanoparticles. The standard powder nanocrystals exhibit a crystallinity of 67.87 %, underscoring the efficacy of the highly oriented anatase with desirable structural and diffraction properties. `This reduction in crystal structure defects and strain, alongside a smaller lattice volume improved stability and high crystalline anatase predominant (101) was observed at low temperatures.

Significant dependence of the efficiency of energy-saving thermochromic VO2 on slight changes of its properties in the visible due to strain and/or vacancies

There are worldwide efforts to maximize the energy saving achieved by VO2-based thermochromic coatings. In particular, there are very different values of the modulation of integral solar energy transmittance, reported by various laboratories on various templates even for seemingly very similar coatings. A detailed analysis reveals that this is largely due to the combination of the intentional and well understood transmittance modulation in the infrared (always beneficial) with not yet understood slight transmittance modulation in the visible (sometimes beneficial, sometimes harmful, and always multiplied by strong solar irradiance). Ab-initio calculations are used to examine the hypothesis that the transmittance modulation in the visible can be controlled by lattice strain and/or slightly off-stoichiometric [O]/[V] ratio. The presented phenomenon opens a pathway which may lead, in a case of reproducible preparation of correctly altered VO2, to significantly enhanced energy saving.

Effect of grain size on precipitation and microstrain of nanocrystalline NiTi alloys

The effect of aging treatment on the microstructure, phase transformation behavior and mechanical properties of nanocrystalline NiTi alloy was studied. The nanocrystalline NiTi alloys with different grain sizes were acquired by cold drawing followed by annealing at 350–500 °C for 10 min. The annealed samples were aged at 250–400 °C for 48 h. The Ti3Ni4 precipitates were found in aged nanocrystalline NiTi alloys. In the sample with smaller average nanograin size, the precipitates were found at the edge of grain boundaries and little lattice strain was shown in R phase matrix. In the sample with larger average grain size, the precipitates were found in the nanograins and exhibited a coherent interface with the matrix. The nanocrystalline R phase NiTi matrix exhibited a significant compressive stress at the end of the coherent precipitate. The coherent precipitates in sample aged at 250 °C after annealing at 500 °C suppress the stress-induced R → B19′ phase transformation and increased the upper plateau stress. The precipitation in sample aged at 250 °C after annealing at 350 °C unable to suppress the martensitic transformation effectively.

ZnO/SnO2 based composite heterostructure for NO2 gas sensing properties

In recent years, interest in heterostructures and research on them has been increasing day by day. While semiconductors mainly exhibit different characteristics, they can exhibit different characteristics when they come together to form a heterostructure, and investigating the reasons for these is of great interest. For this purpose, in this study, such a hetero structure (ZnO/SnO2) was obtained by the Sol-Gel Dip Coating (SGDC) combined method and its effects on its characteristics against NO2 gas were tried to be examined.In this study, SnO2/ZnO composite heterostructures were grown by SGDC method. In this sense, this study is a first in the literature in terms of enlarging this structure with the SGDC technique. The number of SnO2 cycles was kept constant at 1 cycles and the ZnO layers were at different cycles as 1, 2, 3 and 5. The effect of ZnO cycles number on structural, morphological and most importantly NO2 gas detection properties was investigated in the formed heterostructures. In the XRD results, both ZnO and SnO2 peaks were observed and it was determined that these peaks belonged to the hexagonal wurtzite phase for ZnO and to the tetragonal rutile phase for SnO2. The lattice strain and crystallite size were calculated using Williamson-Hall and Scherrer method. The SEM images of ZnO-SnO2 manifest the change in the microstructure with increasing ZnO layer. The microstructure consisted of thin crystalline plates and small round-shape particles. The nano plates and walls shape and size changed with increasing ZnO layers. The operating temperature was defined as 165 °C for all sensors from NO2 gas sensing measurements. The responses of 1 ppm NO2 gas concentrations were calculated as 20 %, 201 %, 1078 % and 676 % for Z1S1, Z2S1, Z3S1 and Z5S1 heterosturucture respectively.

Roles of Al/Ni ratio and solidification cooling rate in grain boundary engineering of AlxCrFeMnNi(2-x) high entropy alloy

In this work, the roles of Al/Ni ratio and solidification cooling rate in grain size, dendrite morphology and grain boundary characteristic of the AlxCrFeMnNi(2-x) (x = 0.3, 0.7 and1.0) high-entropy alloys (HEAs) were investigated. The results show that the increasing of Al/Ni ratio results in a transition from single-phase FCC to dual-phase BCC + B2 along with the reverse precipitation behavior of BCC phase. While the phase composition is not affected by solidification cooling rate. With the increasing of Al/Ni ratio and solidification cooling rate, a significant columnar-to-equiaxed transition (CET) behavior can be observed. That is, grain refinement and transition from columnar dendrites to equiaxial and cellular dendrites. This is mainly attributed to the constitutional supercooling (CS) caused by the solute interaction effect of Al and Ni, and which can be evaluated by P and Q parameters. In addition, in-situ formation of serrated grain boundaries (SGBs) can be also observed in solidification microstructures, and with the increasing of Al/Ni ratio, the proportion of SGBs increases gradually. Whether the B2 precipitated phase is present or not, the formation mechanism of SGBs is mainly attributed to the lattice strain energy caused by the segregation of Al and Ni. The strategy simultaneously achieving grain refinement, CET and in-situ forming SGBs during solidification by tailoring Al/Ni ratio opens new perspectives for grain boundary engineering.

A critical discussion of elasto-visco-plastic self-consistent (EVPSC) models

Two recently proposed elasto-visco-plastic self-consistent (EVPSC) models, based on solving for stress or stress increment, are discussed, and their results are compared with the ones of the visco-plastic self-consistent (VPSC) approach. The advantages and shortcomings of the models are demonstrated, with emphasis on how the grain responses are affected by the time increment and inclusion-medium interaction strength used. Experimental data obtained for an FCC stainless steel is used as the benchmark system for performing the simulations and assessing the reliability of the results. Predictions of stress-strain response of the aggregate, standard deviations in intergranular stress and strain rate, along with the evolution of internal lattice strain are presented and compared, with special focus on their dependence on the incremental approach chosen. We find that the chosen time increment may significantly affect predicted grain responses. To avoid such effect a method based on using two separate time increments is proposed, one for approximating the stress rate and another for actual integration of stress, strain, and state variables. The proposed method successfully eliminates the dependence of results on the time increment used, thus allowing more reliable computations while preserving the computational efficiency of the elasto-visco-plastic model.

Radiation damage in He irradiated nanolayered Zr/Nb at different temperatures

Nanolayered Zr/Nb metals are considered promising for advanced nuclear reactors due to their superior resistance to irradiation. In this study, Zr/Nb multilayers were irradiated with 50 keV He+ ions to a fluence of 1 × 1017 ions/cm2 at temperatures of room temperature, 350 °C, and 500 °C to investigate irradiation-induced structural changes. X-ray diffraction (XRD) analysis indicated low-angle shifts of 0.08-0.54° and high-angle shifts of 0.08-0.42° in the irradiated Zr and Nb layers, suggesting tensile and compressive strains, respectively. At 500 °C, the selected-area electron diffraction (SAED) observed a 9.2% lattice expansion in Zr and a 0.13% contraction in Nb. Geometric phase analysis (GPA) revealed varying strain distributions, transitioning from incoherent to coherent interfaces with increasing irradiation damage. Transmission electron microscopy (TEM) identified the presence of He bubbles in the Zr layer as one of the reasons for strain differences. Nanoindentation tests showed an increase at a depth of 150 nm hardness of 0.831 GPa at 500 °C compared to 350 °C. These results are attributed to differences in crystal structure, vacancy dynamics, interfacial effects, and lattice strain influences. Stability of Zr/Nb interfaces after He irradiation was studied. This study provides insights into the radiation behavior of Zr/Nb nanoscale metallic materials, enhancing our understanding of their potential as structural materials in nuclear energy systems.

Strain induced magnetic switching in ferrimagnetic Mn2Ge: A first principles study

This study employs first-principles calculations to investigate the electronic and magnetic properties of Ni2In type Mn2Ge. Our total energy calculations suggests that ferrimagnetic state is more probable compared to the ferromagnetic state as the ground state for hexagonal Mn2Ge. The applied lattice strain is found to have influence in flipping the spins of Mn atoms from a ferromagnetic state to an antiferromagnetic state. An analysis of the electronic band structure reveals the metallic nature in Mn2Ge. However, the existence of Weyl points and Dirac nodal lines introduces an additional layer of complexity, positioning hexagonal Mn2Ge as an attractive topological ferrimagnetic material with unique magnetostrictive properties. These insights might pave the way for further investigation and potential applications in the realm of spin-based technologies.

Influence of Ionic Liquids on the Functionality of Optoelectronic Devices Employing CsPbBr3 Single Crystals

Regulating the nucleation temperature and growth rates during inverse temperature crystallization (ITC) is vital for obtaining high-quality perovskite single crystals via this technique. Precise control over these parameters enables growing crystals optimized for various optoelectronic devices. In this study, it is demonstrated that incorporating a 1-butyl-3-methylimidazolium bromide (BMIB) ionic liquid into the precursor solution of cesium lead bromide (CsPbBr3) brings about a dual enhancement effect. This includes a reduction in nucleation temperature from 85 °C to 65 °C and a significant improvement in both optoelectronic characteristics and crystal properties. The CsPbBr3 single crystals grown using ITC with BMIB added (method (2)) demonstrate improved chemical and physical properties (crystallinity, lattice strain, nonradioactive recombination, and trap density) compared to CsPbBr3 single crystals produced through conventional 85 °C ITC alone (method (1)). The exceptional quality of CsPbBr3 single crystals produced with the inclusion of BMIB allowed for the development of a highly responsive optoelectronic device, demonstrating heightened sensitivity to green light. The findings of this investigation reveal that the growth of perovskite single crystals assisted by ionic liquid exerts a substantial impact on the characteristics of the crystals. This influence proves advantageous for the development of optoelectronic devices based on single crystals.

Promoting Charge-Carriers Dynamics by Relaxed Lattice Strain in A-site-doped Halide Perovskite for Photocatalytic H2 Evolution.

Because of the unique and superior optoelectronic properties, metal halide perovskites (MHPs) have attracted great interests in photocatalysis. Element doping strategy is adopted to modify perovskite materials to improve their photocatalytic performance. However, the contribution of bare doping-site onto photocatalytic efficiency, and the correlation between doping locations and activity have not yet to be demonstrated. Thispromoted us to explore the potential of A-site-doped MHPs for photocatalysis. Herein, we dope potassium (K+) into CsPbBr3 and first reveal that the occupied locations of K+ in CsPbBr3 is lattice incorporation rather than surface segregation, which would change from A-site substitution to interstitial site in lattice with the increase of K+ concentrations. Taking H2 evolution as a model reaction, photocatalytic activity of CsPbBr3 after K+ doping could be significantly improved ~11-fold with A-site substitution, which is superior to that of interstitial site doping. Moreover, other alkali metals including Li, Na, and Rb doping give the same results. The structure of photocatalysts during reaction confirmed the contribution of A-site doping onto enhanced photocatalytic activity. Mechanistic insights show it is a result of the relaxed residual lattice strain induced promoted charge-carriers dynamics and formed upward shifting of band after K+ A-site doping.

Promoting Charge‐Carriers Dynamics by Relaxed Lattice Strain in A‐site‐doped Halide Perovskite for Photocatalytic H2 Evolution

Because of the unique and superior optoelectronic properties, metal halide perovskites (MHPs) have attracted great interests in photocatalysis. Element doping strategy is adopted to modify perovskite materials to improve their photocatalytic performance. However, the contribution of bare doping‐site onto photocatalytic efficiency, and the correlation between doping locations and activity have not yet to be demonstrated. This promoted us to explore the potential of A‐site‐doped MHPs for photocatalysis. Herein, we dope potassium (K+) into CsPbBr3 and first reveal that the occupied locations of K+ in CsPbBr3 is lattice incorporation rather than surface segregation, which would change from A‐site substitution to interstitial site in lattice with the increase of K+ concentrations. Taking H2 evolution as a model reaction, photocatalytic activity of CsPbBr3 after K+ doping could be significantly improved ~11‐fold with A‐site substitution, which is superior to that of interstitial site doping. Moreover, other alkali metals including Li, Na, and Rb doping give the same results. The structure of photocatalysts during reaction confirmed the contribution of A‐site doping onto enhanced photocatalytic activity. Mechanistic insights show it is a result of the relaxed residual lattice strain induced promoted charge‐carriers dynamics and formed upward shifting of band after K+ A‐site doping.

Reversible Configurations of 3-Coordinate and 4-Coordinate Boron Stabilize Ultrahigh-Ni Cathodes with Superior Cycling Stability for Practical Li-Ion Batteries.

Ultrahigh-Ni layered oxide cathodes are the leading candidate for next-generation high-energy Li-ion batteries owing to their cost-effectiveness and ultrahigh capacity. However, the increased Ni content causes larger volume variations and worse lattice oxygen stability during cycling, resulting in capacity attenuation and kinetics hysteresis. Herein, a Li2SiO3-coated Li(Ni0.95Co0.04Mn0.01)0.99B0.01O2 ultrahigh-Ni cathode that well-addresses all the above issues, which is also the first time to realize the real doping of B ions is demonstrated. The as-obtained cathode delivers a reversible capacity of up to 237.4 mAh g-1 (924 Wh kg-1 cathode) and a superior capacity retention of 84.2% after 500 cycles at 1C in pouch-type full-cells. Advanced characterizations and calculations verify that the boron-doping is existed in terms of 3-coordinate and 4-coordinate configurations and their high electrochemical reversibility during de-/lithiation, which greatly stabilizes oxygen anions and impedes Ni-ion migration to Li layer. Furthermore, the B-doping engineers the primary particle microstructure for better relaxing the lattice strain and accelerating Li-ion diffusion. This work advances the energy density of cathode materials into the domain of above 900 Wh kg-1, and the concept will inspire more intensive study on ultrahigh-Ni cathodes.

Multi-scale and time-resolved structure analysis of relaxor ferroelectric crystals under an electric field

Lead-based relaxor ferroelectrics exhibit giant piezoelectric properties owing to their heterogeneous structures. The average and local structures measured by single-crystal X-ray diffraction under DC and AC electric fields are reviewed in this article. The position-dependent local lattice strain and the distribution of polar nanodomains and nanoregions show strong electric field dependence, which contributes to the giant piezoelectric properties.

Microwave‐assisted control of PtNi nanoalloy clusters on the nitrogen‐doped graphene oxide for energy conversion with oxygen reduction reaction and hydrogen evolution reaction

AbstractResearch on the production and utilization of hydrogen energy is essential to overcome the environmental issues caused by fossil fuels. Herein, we anchor PtNi nanoalloy clusters (Pt‐Ni NACs) on nitrogen‐doped graphene oxide (NrGO) by a facile microwave‐assisted synthesis and analyze the variations of catalyst properties based on the PtNi composition and the presence of nitrogen. Ni inclusion in the Pt matrix can induce lattice strain and change the electronic structure, while the doped nitrogen into the graphene can enhance electron transfer and improve the durability of the catalyst through strong chemical bonding with the alloy clusters. TEM analysis discovers that the NACs are uniformly decorated in a few‐nanometer‐size on the graphene surface, and the formation of the PtNi NACs and structural changes according to composition are confirmed through XRD and XPS. In addition, the structural changes due to N‐doping and its bonding with the NACs are observed through Raman spectroscopy and XPS. Electrochemical measurements reveal that Pt2.6Ni NACs/NrGO exhibits the highest ORR onset potential (0.893 V) and the lowest HER overpotential at 10 mA cm−2 (22 mV) among other catalysts, and those activities are almost unchanged under long‐term durability tests. From these results, Pt2.6Ni NACs/NrGO is utilized in a zinc‐air battery (ZAB) system, demonstrating better battery performance than commercial Pt and Ir‐based catalysts. Moreover, it is applied to hydrogen collection, showing linear trend in hydrogen production over time, confirming the catalyst's availability in hydrogen production and utilization.image

Mitigating the Kinetic Hysteresis of Co-Free Ni-Rich Cathodes via Gradient Penetration of Nonmagnetic Silicon.

Co-free Ni-rich layered oxides are considered a promising cathode material for next-generation Li-ion batteries due to their cost-effectiveness and high capacity. However, they still suffer from the practical challenges of low discharge capacity and poor rate capability due to the hysteresis of Li-ion diffusion kinetics. Herein, based on the regulation of the lattice magnetic frustration, the Li/Ni intermixing defects as the primary origin of kinetic hysteresis are radically addressed via the doping of the nonmagnetic Si element. Meanwhile, by adopting gradient penetration doping, a robust Si-O surface structure with reversible lattice oxygen evolution and low lattice strain is constructed on Co-free Ni-rich cathodes to suppress the formation of surface dense barrier layer. With the remarkably enhanced Li-ion diffusion kinetics in atomic and electrode particle scales, the as-obtained cathodes (LiNixMn1-xSi0.01O2, 0.6≤x≤0.9) achieve superior performance in discharge capacity, rate capability, and durability. This work highlights the coupling effect of magnetic structure and interfacial chemicals on Li-ion transport properties, and the concept will inspire more researchers to conduct an intensive study.