Out-of-plane weak ferromagnetism at room temperature in lattice-distortion non-collinear antiferromagnet of single-crystal Mn_(3)Sn

Out-of-plane weak ferromagnetic(OWFM)spin arrangements with topological properties can realize a series of interesting physical properties.However,this spin structure tends to exist at low temperatures.The OWFM structure can also be induced at room temperature by hydrostatic pressure,whereas this isotropic approach tends to form helical AFM structures.We report the OWFM spin arrangement in single crystal Mn_(3)Sn by an anisotropic strategy of high-stressconstrained compression deformation at room temperature.Both experimental and theoretical simulation results show that the alignment of the OWFM spin structure is due to the distortion of the atomic scale caused by the strain energy during deformation.The OWFM spin arrangement can significantly change the magnetic property of Mn_(3)Sn.As a result,the remanent magnetization M_(r)for the deformed sample(0.056μ_(B)/f.u.)is about eleven times that for the pre-deformed sample(0.005μ_(B)/f.u.),and the coercivity(H_(c))increases from 0 k Oe(pre-deformed sample)to 6.02 k Oe(deformed sample).Our findings provide a way to generate the OWFM spin structure at room temperature and may give fresh ideas for creating antiferromagnetic materials with excellent physical properties.

Multidimensional In_(2)O_(3)/In_(2)S_(3) heterojunction with lattice distortion for CO_(2) photoconversion

Photocatalytic CO_(2)reduction to sustainably product of fuels is a potential route to achieve clean energy conversion.Unfortunately,the sluggish charge transport dynamics and poor CO_(2)activation performance result in a low CO_(2)conversion efficiency.Herein,we develop a multidimensional In_(2)O_(3)/In_(2)S_(3)(IO/IS)heterojunction with abundant lattice distortion structure and high concentration of oxygen defects.The close contact interfaces between the junction of the two phases ensure undisturbed transmission of electrons with high‐speed.The increased free electron concentration promotes the adsorption and activation of CO2 on the catalyst surface,leaving the key intermediate*COOH at a lower energy barrier.The perfect combination of the band matching oxide and sulfide effectively reduces the internal energy barrier of the CO2 reduction reaction.Furthermore,the lattice distortion structure not only provides additional active sites,but also optimizes the kinetics of the reaction through microstructural regulation.Remarkably,the optimal IO/IS heterojunction exhibits superior CO_(2)reduction performance with CO evolution rate of 12.22μmol g^(−1)h^(−1),achieving about 4 times compared to that of In_(2)O_(3)and In2S3,respectively.This work emphasizes the importance of tight interfaces of heterojunction in improving the performance of CO_(2)photoreduction,and provides an effective strategy for construction of heterojunction photocatalysts.

Lattice distortion in disordered antiferromagnetic XY models

The behavior of lattice distortion in spin 1/2 antiferromagnetic XY models with random magnetic modulation is investigated with the consideration of spin-phonon coupling in the adiabatic limit. It is found that lattice distortion relies on the strength of the random modulation. For strong or weak enough spin phonon couplings, the average lattice distortion may decrease or increase as the random modulation is strengthened. This may be the result of competition between the random magnetic modulation and the spin phonon coupling.

Dielectric Properties and Lattice Distortion in Rhombohedral Phase Region and Phase Coexistence Region of PZT Ceramics

In this paper, the relation between the dielectric properties and the lattice distortion in the phase coexistence region is discussed using a phase statistical distribution model, and in the rhombohedral phase region the two connection equations on the dielectric properties and the lattice distortion are established. Particularly, the relation between the dielectric properties and the lattice distortion is investigated in the phase coexistence region of PZT ceramics, and the fitting value of the volume fraction of the tetragonal phase VT to composition x in the equation is determined. Further,the fitting results are well consistent with the related experimental data. It involves more profound physical process than relation between the dielectric properties and composition x.

Effects of anharmonic lattice distortion on orbital and magnetic orderings in KCuF_3

Lattice, magnetic and orbital structures in KCuF3 are self-consistently determined by our cluster self-consistent field approach based on a spin-orbital-lattice Hamiltonian. Two stable structures are obtained and found to be degenerate, which confirms the presence of the coexistent phases observed experimentally. We clearly show that due to the inherent frustration, the ground state of the system only with the superexchange interaction is degenerate; while the Jahn-Teller distortion, especially the anharmonic effect, stabilizes the orbital ordered phase at about 23% in the x2-y2 orbit and at 77% in the 3z2-r2 orbit. Meanwhile the magnetic moment of Cu is considerably reduced to 0.56μB, and magnetic coupling strengths are highly anisotropic, Jx/Jxy ≈ 18. These results are in good agreement with the experiments, implying that the anharmonic Jahn-Teller effect plays an essential role in stabilising the orbital ordered ground state of KCuF3.

Relation between martensitic transformation temperature range and lattice distortion ratio of NiMnGaCoCu Heusler alloys

In order to study the relation between martensitic transformation temperature range AT （where AT is the difference between martensitic transformation start and finish temperature） and lattice distortion ratio （c/a） of martensitic transforma~ tion, a series of Ni46Mnz8_xGa22Co4Cux （x = 2-5） Heusler alloys is prepared by arc melting method. The vibration sample magnetometer （VSM） experiment results show that AT increases when x 〉 4 and decreases when x 〈 4 with x increasing, and the minimal AT （about 1 K） is found at x = 4. Ambient X-ray diffraction （XRD） results show that AT is proportional to c/a for non-modulated Ni46Mn28_xGa22Co4Cux （x = 2-5） martensites. The relation between AT and c/a is in agreement with the analysis result obtained from crystal lattice mismatch model. About 1000-ppm strain is found for the sample at x = 4 when heating temperature increases from 323 K to 324 K. These properties, which allow a modulation of AT and temperature-induced strain during martensitic transformation, suggest Ni46Mn24Ga22Co4Cu4 can be a promising actuator and sensor.

CALCULATION OF BRAVAIS LATTICE AND LATTICE DISTORTION OF γ-TiA1 BASED ALLOY

Some ambiguous ackowledgements about unit cells of γ phase and α_2 phase of TiAl alloy are discussed in this paper correct unit cell parameters of γ and α_2 -phase are put forward. Meanwhile, lattice distortions of rapid-solidified TiAl2Cr2Nb alloy powders and thin films are determined by XRD method.

Theoretical Study of Electron Paramagnetic Resonance Spectra and Local Lattice Distortion for Mn^(2+) in Zn(ClO_4)_2·6(H_2O)Mg(ClO_4)_2·6(H_2O)

The electron paramagnetic resonance（EPR） spectra of trigonal Mn^（2＋） centers in Zn（ClO4）2·6（H2O） and Mg（ClO4）2·6（H2O） crystals were studied on the basis of the complete energy matrices for a d^5 configuration ion in a trigonal ligand field. It was demonstrated that the local lattice structure around a trigonal Mn^（2＋） center has an compressed distortion along the crystalline c3 axis, and when Mn^（2＋） is doped in the Zn（ClO4）2·6（H2O） and Mg（ClO4）2·6（H2O） crystals, there is a similar local distortion. From the EPR calculation, the local lattice structure parameters R=2.183 2 ？, for Zn（ClO4）2·6（H2O）, R=2.130 2 ？, for Mg（ClO4）2·6（H2O） have been determined.

Lattice distortion in disordered antiferromagnetic XY models

The behavior of lattice distortion in spin 1/2 antiferromagnetic XY models with random magnetic modulation is investigated with the consideration of spin–phonon coupling in the adiabatic limit. It is found that lattice distortion relies on the strength of the random modulation. For strong or weak enough spin–phonon couplings, the average lattice distortion may decrease or increase as the random modulation is strengthened. This may be the result of competition between the random magnetic modulation and the spin–phonon coupling.

Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

Quasi-2D Dion-Jacobson(DJ)tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental stability.However,the bulky organic spacers usually form a natural quantum well structure,which brings a large quantum barrier and poor film quality,further limiting the carrier transport and device performance.Here,we designed three organic spacers with different chain lengths(ethylenediamine(EDA),1,3-propanediamine(PDA),and 1,4-butanediamine(BDA))to investigate the quantum barrier dependence.Theoretical and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect,which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative relaxation.In addition,EDA cation shows strong interaction with the inorganic octahedron,realizing large aggregates in precursor solution and high-quality films with improved structural stability.Furthermore,femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different nphases.Finally,the quasi-2D DJ(EDA)FA_(9)Sn_(10)I_(31)solar cells achieves a 7.07%power conversion efficiency with good environment stability.Therefore,this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for qua si-2D DJ lead-free perovskites.

Ultra‑Efficient and Cost‑Effective Platinum Nanomembrane Electrocatalyst for Sustainable Hydrogen Production

Hydrogen production through hydrogen evolution reaction(HER)offers a promising solution to combat climate change by replacing fossil fuels with clean energy sources.However,the widespread adoption of efficient electrocatalysts,such as platinum(Pt),has been hindered by their high cost.In this study,we developed an easy-to-implement method to create ultrathin Pt nanomembranes,which catalyze HER at a cost significantly lower than commercial Pt/C and comparable to non-noble metal electrocatalysts.These Pt nanomembranes consist of highly distorted Pt nanocrystals and exhibit a heterogeneous elastic strain field,a characteristic rarely seen in conventional crystals.This unique feature results in significantly higher electrocatalytic efficiency than various forms of Pt electrocatalysts,including Pt/C,Pt foils,and numerous Pt singleatom or single-cluster catalysts.Our research offers a promising approach to develop highly efficient and cost-effective low-dimensional electrocatalysts for sustainable hydrogen production,potentially addressing the challenges posed by the climate crisis.

Valley transport in Kekulé structures of graphene

Valleytronics is an emergent discipline in condensed matter physics and offers a new way to encode and manipulate information based on the valley degree of freedom in materials. Among the various materials being studied, Kekulé distorted graphene has emerged as a promising material for valleytronics applications. Graphene can be artificially distorted to form the Kekulé structures rendering the valley-related interaction. In this work, we review the recent progress of research on Kekulé structures of graphene and focus on the modified electronic bands due to different Kekulé distortions as well as their effects on the transport properties of electrons. We systematically discuss how the valley-related interaction in the Kekulé structures was used to control and affect the valley transport including the valley generation, manipulation, and detection. This article summarizes the current challenges and prospects for further research on Kekulé distorted graphene and its potential applications in valleytronics.

Synergetic effect of lattice distortion and oxygen vacancies on high-rate lithium-ion storage in high-entropy perovskite oxides

High-entropy oxides(HEOs)have gained great attention as an emerging kind of highperformance anode materials for lithium-ion batteries(LIBs)due to the entropy stabilization and multi-principal synergistic effect.Herein,the porous perovskite-type RE(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))O_(3)(RE(=La,Sm,and Gd)is the abbreviation of rare earth)HEOs were successfully synthesized by a solution combustion synthesis(SCS)method.Owing to the synergistic effect of lattice distortion and oxygen vacancies(Ov),the Gd(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))O_(3) electrode exhibits superior high-rate lithium-ion storage performance and excellent cycling stability.A reversible capacity of 403 mAh·g^(-1) at a current rate of 0.2 A·g^(-1) after 500 cycles and a superior high-rate capacity of 394 mAh·g^(-1)even at 1.0 A·g^(-1)after 500 cycles are achieved.Meanwhile,the Gd(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))O_(3) electrode also exhibits a pronounced pseudo-capacitive behavior,contributing to an additional capacity.By adjusting and balancing the lattice distortion and oxygen vacancies of the electrode materials,the lithium-ion storage performance can be further regulated.

Impact of W alloying on microstructure, mechanical property and corrosion resistance of face-centered cubic high entropy alloys: A review

Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.

Tailoring Carbon Distribution inα/γPhase of Ductile Iron and Its Effects on Thermal Conductivity

The effects of carbon distribution on the microstructure and thermal conductivity of ductile iron were investigated in the present study.The microstructure of as-cast and quenched ductile iron were characterized by OM and SEM.Results showed that the microstructure of as-cast ductile iron was composed of spheroidal graphite,ferrite with the volume of 80%,and a small amount of pearlite,and quenched ductile iron was composed of spheroidal graphite,coarse/fine acicular martensite(α_(M)phase)and high-carbon retained austenite(γphase).The volume fraction of retained austensite and its carbon content for direct quenched ductile iron and tepmered ductile iron were quantitatively analysed by XRD.Results revealed that carbon atoms diffused fromα_(M)phase toγphase during tempering at low temperatures,which resulted in carbon content in retainedγphase increasing from 1.2 wt%for the direct quenched sample to about 1.9 wt%for the tempered samples.Consequently,the lattice distortion was significantly reduced and gave rise to an increase of thermal conductivity for ductile iron.

Temperature-induced lattice distortion in CuGeO_(3) nanocrystals

Lattice distortion represents the fundamental factor of crystalline materials and contributes significantly to structural-related properties.Herein,we discover an unexpected temperature-induced lattice distortion in CuGeO_(3) nanocrystals,resulting in color changes of CuGeO_(3).The structural distortions in CuGeO_(3) nanocrystals are characterized by Rietveld analysis in detail,where its cell parameter b and cell volume reveal first decrease and then increase characteristics and correspond well with the XRD patterns and Raman spectra.Besides,both the experimental characterizations and theoretical calculations confirm that the optical and band structural changes mainly arise from the twisted octahedral field of[CuO_(6)],where the lattice distortions regulate the crystal field splitting energy of[CuO_(6)]and account for its changed d-d transition.Furthermore,tetracycline photodegradation is employed as an example to evaluate the effect of lattice distortion on photocatalytic performance,which also highlights the importance of modulating lattice distortion in photocatalysis.This work provides an approach to simply regulate the lattice distortion for nanorods by manipulating calcination temperatures.

Effect of Nd3+doping on structure,microstructure,lattice distortion and electronic properties of TiO_2 nanoparticles

Doped and undoped TiCh nanoparticles were prepared by Stober method and thermally treated at 600 ℃.The effect of Nd^（3＋） ion on the structure and micro structure of anatase-phase TiCh nanocrystals was studied by Rietveld refinement method using X-ray powder diffraction data.Bond lengths,bond angles,and edges distances were analyzed.The phase formation was confirmed by high-resolution transmission electron microscopy.The adjustment of Ti-0 bond length induced by the addition of Nd^（3＋） ions,reduced the octahedral distortion and altered the octahedral array in the anatase-phase TiCh nanocrystal.The changes of structure and microstructure were mainly observed for TiCh nanoparticles doped with 0.1 at.%of Nd^（3＋） ions and attributed to the cationic substitution of Ti^（4＋） ions which promoted changes in the density of states and gap band of TiCh.The dopant insertion resulted in a better structural stability of the nanocrystals that enhanced their charge transference and photocatalytic efficiency.

Lattice distortion of holmium doped bismuth ferrite nanofilms

Single-phase multiferroic BiFeO3 and rare-earth metal of holmium （Ho） doped BiFeO3 nanofilms were prepared on Pt （100）/Ti/SiO2/Si wafer via solution-gelation technique. It was suggested that the lattice distortion happened with the lattice parameter of d decreasing after doping rare-earth metal of Ho. Meanwhile, the structure of nanofilms transformed from hexahedron phase to tetragonal phase after doping Ho. The analysis on X-ray photoelectron spectroscopy （XPS） indicated that the ratio of Fe3~ cations to Fe2＋ cations increased with the increase of binding energy between Fe and O and decrease of that between Bi and O after doping Ho. The present work provided an available way on enhancing multiferroic of BiFeO3 nanofilms.

Lattice distortion and magnetic property of high entropy alloys at low temperatures

Deformation mechanisms and magnetic properties of medium and high entropy alloys(MEA/HEAs)closely relate to lattice distortion and are strongly temperature-dependent,in particular,at low temperature ranges.However,little attention has been paid to the evolution of lattice distortion with temperature decreasing and its effects on deformation behavior and magnetic state transition.In this work,we carry out in situ synchrotron radiation based X-ray powder diffraction(SR-XRD)experiments from 293 to 123 K aiming for determining lattice distortion evolutions of Cr Co Ni MEA,Cr Fe Co Ni and Cr Mn Fe Co Ni HEAs.Magnetic measurements at corresponding low temperatures and cryogenic ranges are further conducted.The in situ SR-XRD results demonstrate a general reduction of lattice distortion magnitude with temperature decreasing,which shows a similar tendency with that of reported stacking fault energy(SFE)values.It is thus suggested that lattice distortion reduction possibly makes a critical contribution to deformation mechanism transition.The magnetic measurement results show a clear ferromagnetic transition of Cr Fe Co Ni HEA when temperature is below 173 K.While,no obvious magnetic state transition is observed for Cr Co Ni MEA and Cr Mn Fe Co Ni HEA.The present findings on lattice distortion evolutions will pave the way for designing targeted HEAs with particular properties.

Active site synergy of the mixed-phase cobalt diselenides with slight lattice distortion for highly reversible and stable lithium oxygen batteries

Many non-precious metal-based catalysts with high intrinsic activity for catalytic reactions are prone to structural degradation in practical application,which leads to poor stability.In this work,we propose c-CoSe_(2)/o-CoSe_(2)as the oxygen electrode of lithium-oxygen batteries(LOBs)to improve its cycle stability.The heterogeneous interface inside c-CoSe_(2)/o-CoSe_(2)leads to an increase in the covalence bonds between Co and Se ions,which greatly enhances the robustness of the crystal lattice,thereby improving the stability of the catalyst.In addition,the strong interaction between the mixed phases is favorable for adjusting the electron density around the active sites and boosting oxygen electrode kinetics.Moreover,the epitaxial growth of o-CoSe_(2)on c-CoSe_(2)will cause abundant heterogeneous interfaces and slight lattice distortion along the interfaces,thereby providing sufficient catalytic reaction sites.The DFT calculation results show that the optimized adsorption of intermediates at the heterogeneous interface plays an important role in boosting oxygen electrode reactions and improving the electrochemical performance of LOBs.The experimental results show that LOBs with the c-CoSe_(2)/o-CoSe_(2)electrodes exhibit outstanding performance,including large specific capacity of about 23,878 m A h g^(-1),high coulombic efficiency of up to 93.66%,and excellent stability of over 176 cycles(1410 h).