Induced Lattice Distortion Research Articles

3D Electron Diffraction Study of Delithiation Induced Lattice Distortion in Li-rich Layered Oxide Cathode

3D Electron Diffraction Study of Delithiation Induced Lattice Distortion in Li-rich Layered Oxide Cathode

Strain and electric field control of magnetic and electrical transport properties in a magnetoelastically coupled Fe3O4/BaTiO3 (001) heterostructure

We present a study of the control of electric field induced strain on the magnetic and electrical transport properties in a magneto-elastically coupled artificial multiferroic Fe3O4/BaTiO3 heterostructure. In this Fe3O4/BaTiO3 heterostructure, the Fe3O4 thin film is epitaxially grown in the form of bilateral domains, analogous to a-c stripe domains of the underlying BaTiO3(001) substrate. By in-situ electric field dependent magnetization measurements, we demonstrate the extrinsic control of the magnetic anisotropy and the characteristic Verwey metal-insulator transition of the epitaxial Fe3O4 thin film in a wide temperature range between 20-300 K, via strain mediated converse magnetoelectric coupling. In addition, we observe strain induced modulations in the magnetic and electrical transport properties of the Fe3O4 thin film across the thermally driven intrinsic ferroelectric and structural phase transitions of the BaTiO3 substrate. In-situ electric field dependent Raman measurements reveal that the electric field does not significantly modify the anti-phase boundary defects in the Fe3O4 thin film once it is thermodynamically stable after deposition and that the modification of the magnetic properties is mainly caused by strain induced lattice distortions and magnetic anisotropy. These results provide a framework to realize electrical control of the magnetization in a classical highly correlated transition metal oxide.

Direct observation of chemical short-range order in 25 wt% Mn steel via transmission electron microscopy

In this study, we demonstrate the existence of chemical short-range order (CSRO) in high-Mn (25Mn-0.6C-Fe in wt%) austenitic steel. A definitive proof of CSRO was obtained by electron diffraction measurements and dark-field imaging via transmission electron microscopy. CSRO in the steel sample generated additional diffuse scattering in selected area electron diffraction patterns along high-index zone axes, namely, [1 1 1]γ, [1 1 2]γ, and [1 3 0]γ, which was absent along low-index zone axes, namely, [1 1 0]γ and [0 0 1]γ. We found that CSRO induced lattice distortions, and the corresponding interplanar spacing was twice that in γ-austenite. This study offers a useful approach to detect CSRO in other high-Mn steels.

Synergetic Engineering of High‐Oxidation‐State Cations on Phase Boundaries toward High‐Efficiency Water Splitting

AbstractInterfacial structure engineering with multiple high‐oxidation‐state cations, especially those that show unstable higher‐valence during catalysis towards superior electron synergy, for high‐performance electrocatalysis is of great interest and full of challenges. Lattice distortion from lattice strain at phase boundaries as a result of interfacial structure engineering is also appealing. Fe oxyhydroxide containing Fe3+ lead to unstable Fe4+ with a short lifetime on edge/defect sites during steady‐state water‐oxidation catalysis. Such material was deliberately installed to achieve atom‐scale combination with Ni3+ relevant layered double hydroxide to construct high‐energy interfaces for high‐oxidation‐state cations synergy and induce lattice distortion. The Fe‐o‐NiAlOH exhibited prominent property toward oxygen evolution reaction with 202 mV to drive 10 mA cm−2. Fe‐o‐NiAlOH also showed hydrogen evolution reaction activity, requiring an overpotential of 180 mV for 10 mA cm−2. Alkaline water electrolyzer with Fe‐o‐NiAlOH as both anodic and cathodic electrodes required only 1.64 V to reach 10 mA cm−2. This work offers an effective well‐defined electrocatalyst and shows the synergetic protocol of unstable high‐oxidation‐state cations and lattice defects for high‐performance water decomposition catalysis.

Structural characterization and nanoscale strain field analysis of α/β interface layer of a near α titanium alloy

Abstract In this article, the structural and nanoscale strain field of the α/β phase interface layer in Ti80 alloy were studied by using high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA). The α/β interface layer was observed in forged and different annealed Ti80 alloys, which is mainly composed of lamellar face-centered cubic (FCC) phase region and α′ + β region. The FCC phases between α and β phases show a twin relationship, and the twinning plane is ( 1 1 ¯ 1 ) (1\bar{1}1) . The orientation relationship of the β phase, the α phase, and the FCC phase is (110)β//(0001)α// ( 1 1 ¯ 1 ) (1\bar{1}1) FCC and [ 1 ¯ 11 \bar{1}11 ]β//[ 2 1 ¯ 1 ¯ 0 2\bar{1}\bar{1}0 ]α//[011]FCC. The nanoscale strain field of FCC + α and β + α′ regions was analyzed by using the GPA technology. The FCC + α region shows more significant strain gradient than the α′ + β region, and ε FCC > ε α, ε α′ > ε β. The influence of element addition on the formation mechanism of the FCC phase was discussed. The addition of Zr promotes the formation of the FCC phase by inducing lattice distortion and reducing the stacking fault energy of the α phase. In addition, the Al element forms an obvious concentration gradient around the interface layer during the cooling process of the alloy, which provides a driving force for the formation of the FCC phase.

Unlocking the optimum supercapacitance of Co3O4 by reducing the Co valence state via Mn doping

Trivalent Co in Co3O4 electrodes cannot efficiently contribute to a high capacitance based on the redox reaction between Co3O4 and CoOOH in alkaline electrolytes; In contrast, increasing the content of divalent Co can enhance the capacitance. Herein, we demonstrate that doping Mn into Co3O4 increased the content of divalent Co increases, which was accompanied by induced lattice distortion and the formation of oxygen defects. As a result, our designed Mn-doped Co3O4 electrodes were unlocked with optimum electrochemical storage performance. For instance, the (Mn0.75Co2.25O4) electrode achieved a high specific capacity of 164.44 mAh/g and outstanding cyclic stability with 96% capacity retention at a current density of 4 A/g after 3000 cycles.

Carbon encapsulation of ferromagnetic L1oFePt nanocrystals with an enhanced coercivity from distorted lattices

Pyrolysis of ferrocene over Pt coated SiO 2 substrate produces L 1 o FePt encapsulated carbon nanotubes with enhanced magnetic coercivity at room temperarure. The underlying mechanism involves spin pinning by domain boundaries and encapsulation induced lattice distortion along [001] crystallographic plane; the latter is rarely seen and is supported by ab initio calculation. Carbon encapsulation of L 1 o FePt is achieved through S–C mechanism and only takes place at specific location in pyrolytic furnace.

Enhanced visible light photoactivity of TiO2/SnO2 films by tridoping with Y/F/Ag ions

The Y, F, and Ag tridoped TiO2/SnO2 composite nanocrystalline film (YFAg–TS) with prominent photocatalytic performance was prepared by the modified sol–gel method and was characterized by utilizing X-ray diffraction (XRD), differential thermal and thermogravimetric (DTA–TG) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL). The XRD and DTA–TG results expose that the YFAg–TS catalyst is a mixed phase consisting of anatase, rutile, and chlorargyrite, which is beneficial to improving the photocatalytic performance of TiO2. The SEM, TEM, and BET results disclose that the YFAg–TS film has smaller nanoparticles, higher specific surface area, and narrower pore size compared with pure TiO2 film. The XRD and TEM results exhibit that a part of yttrium can enter the TiO2 lattice to induce lattice distortion. The XPS results confirm the presence of Y3+ state in the YFAg–TS sample, and Y3+ ions can act as the trapping site of electrons to expedite the separation of electrons and holes. The UV–vis DRS results reveal that the YFAg–TS film has an obvious absorption edge shift and a narrower bandgap (2.70 eV) compared with pure TiO2 film. The PL results show that the YFAg–TS film has the highest photogenerated electrons and holes separation efficiency and charges transfer efficiency among all samples. The photocatalytic activity of the YFAg–TS was assessed by monitoring the degradation of methyl green and formaldehyde solution. The results manifest that the YFAg–TS film has high stability and excellent photocatalytic performance. The possible synergistic photocatalytic mechanism of YFAg–TS films has been discussed in this paper.

K0.5Na0.5NbO3Bi4−xPrxTi3O12 relaxation ferroelectric capacitor with piezoelectric unit inserted into Bi4Ti3O12 matrix

A layered perovskite structure K0.5Na0.5NbO3Bi4−xPrxTi3O12 lead-free relaxation ferroelectric capacitor was fabricated by inserting piezoelectric K0.5Na0.5NbO3 unit into Bi4Ti3O12 matrix. Pr element doping induced lattice distortion assists the matching between inserting unit and matrix. K0.5Na0.5NbO3Bi2.6Pr1.4TiO12 capacitor has aroused the large energy storage density (Ure) 69.7 J/cm3 and high efficiency (η) 78.13% at room temperature. The well performances can be captured by the randomly dispersed polar nano-regions. The inserted piezoelectric unit hosts regulate the long-range ferroelectric order, which leads to the disturbed ferroelectric order by Pr3+ doping and further forms the polar nano-regions. Raman spectra evolution is well documented to the polar nano-regions. What’s more, the energy capacitors exhibit excellent thermal stability in a temperature range of −20 ℃–140 ℃ and fatigue stability with charge/discharge cycling reaching 1 × 108. Inserting piezoelectric unit provides a strategy to design dielectric energy capacitors.

Effect of ball milling on the sintering performance of indium-gallium-zinc oxide ceramics: The diffusion mechanism and lattice distortion of milled powders

The mechanisms inducing lattice distortion and grain boundary diffusion in mixed In2O3–Ga2O3-ZnO (IGZO) powders were investigated during ball-milling treatment at different rotation speeds. After sintering, the highest relative densities for the sintered IGZO compacts were 92.87%, 98.72%, and 99.12% at rotation speeds of 100 rpm, 200 rpm, and 300 rpm, respectively, and the corresponding grain growth activation energies were 78.78, 67.17, and 49.52 kJ/mol. The sintering process of InGaZnO4 ceramics was shown to be dominated by grain boundary diffusion. X-ray diffraction line profile analysis indicated that the highest average lattice distortion of IGZO powders milled at 200 rpm and 300 rpm was 2.85 and 10.27 times higher, respectively, than that of IGZO powder milled at 100 rpm. The enhancements of the sintering properties of the IGZO powders induced by the faster milling speeds were attributed to the higher lattice distortion energies and shorter diffusion distances of the elements. This elucidated the mechanism behind the high-energy ball-milling process for achieving enhanced sintering performances in ceramic powders.

Multiple doped ZnO with enhanced thermoelectric properties

ZnO has a large thermal conductivity that hinders its satisfactory thermoelectric performance. In this work, we add multiple dopants including S, C, Fe and Ni to ZnO simultaneously. A low thermal conductivity ∼3 W m−1 K−1 is obtained, with an initial composition ZnO-1%S-0.15 %C-4%Fe2O3-3%NiO (sample #7), and comparable to the lowest reported values of ZnO-based bulk samples. We attribute the reduction to the Ni induced lattice distortion and the Fe induced microstructural changes. This composition also shows the highest power factor that is ∼60% higher than ZnO due to its highest charge carrier concentration and mobility. The overall dominant carrier scattering is through acoustic phonons rather than impurities. The resultant zT is 2.4 times higher than that of undoped ZnO at 973 K. We find multiple doped ZnO exhibits better thermoelectric performance than any single doped counterpart, providing an effective way to improve the thermoelectric properties of ZnO and other oxides.

Ti-doping induced antiferroelectric to ferroelectric phase transition and electrical properties in Sm-PbZrO3 thin films

The antiferroelectric (Pb0.985Sm0.01) (Zr1-xTix)O3 (Ti-PSZO) thin films were synthesized on Pt(111)/Ti/SiO2/Si substrates using a chemical solution deposition method. The films were crystallized in the perovskite phase with a preferential orientation along (111) direction. With Ti doping in PSZO, a gradual transformation from antiferroelectric to ferroelectric phase transition was noticed at room temperature owing to the Ti doping induced lattice distortion. The phase transition has been confirmed through the P - E hysteresis loops, X-ray diffraction (peak shifting), capacitance-voltage measurements, and Raman scattering analysis. The thin film with Ti = 0.15 doping displayed a ferroelectric behavior with high dielectric constant and large dielectric tunability of about 62%. Also, Ti doping altered the Curie temperature (Tc) and enhanced the order of dielectric diffuseness. It is believed that Ti-doping in PSZO is an effective way to induce an antiferroelectric - ferroelectric phase transition and to tailor the electrical characteristics of PSZO thin films.

Inside Cover: Strain Engineering of a MXene/CNT Hierarchical Porous Hollow Microsphere Electrocatalyst for a High‐Efficiency Lithium Polysulfide Conversion Process (Angew. Chem. Int. Ed. 5/2021)

A tensile-strained MXene/CNT porous microsphere was developed by Xin Wang, Zhongwei Chen, and co-workers in their Research Article on page 2371 as an electrocatalyst for high-performance lithium–sulfur batteries. A unique O-Ti-C interface was constructed on the MXene surface through a spray-drying process and heat treatment to produce internal stress, inducing lattice distortion and expansion of the Ti−Ti bonds.

First-Principles Calculation of Defect Properties on Copper Doped KTaO3 Crystal

A first-principles calculation is applied to perform a study of the Cu: KTaO3 system. The defect formation energy, the doping induced lattice distortion and the electronic structure properties have been calculated. The defect formation energy found that Cu is prefer to substitute K (CuK) at corresponding defect charge state +3(), +1() and 0 () with Fermi energy increase; The doping of Cu leads to an obvious distortion of the oxygen octahedron, along with the change of ionic bond characteristics; Further research on electronic structure shows that the doped Cu atom mainly occupies the top of the valence band, resulting in the decrease of the band gap.

Reduced graphene oxide thin layer induced lattice distortion in high crystalline MnO2 nanowires for high-performance sodium- and potassium-ion batteries and capacitors

The large-radius of both K- and Na-ions gives rise to a serious concern towards exploring high-performance electrode materials for potassium ion batteries (KIBs) and sodium ion batteries (SIBs), respectively. Herein, MnO2 nanowires coated with reduced graphene oxide (denoted MnO2@rGO) are demonstrated as excellent anode materials in KIBs and SIBs. The coating of rGO not only facilitates a lattice distortion in the spacing of high crystallinity MnO2 nanowires allowing the faster transfer of K- and Na-ions, but also creates an interfacial structure between rGO and MnO2. Both enhance the electronic conductivity and further protect the nanowires from degradation. As an anode for KIBs and SIBs, the MnO2@rGO nanowires deliver a stable cycling performance with capacity retention of 81.7% over 400 cycles and 75% after 500 cycles, respectively. The potassiation and depotassiation reaction mechanisms are also revealed. Furthermore, the uniqueness of our hybrid designs allows high crystallinity MnO2@rGO nanowires to be used as anodes for both K-ion capacitors (KICs) and Na-ion capacitors (SICs). Considering their easy synthesis, environmental benignity and low cost, MnO2@rGO nanowires are potential anode materials for Na- and K-ion based energy storage devices.

Configurations of V4+ centers in the MoVO catalyst material. A systematic stability analysis of DFT results

The reactivity of a catalyst is in part determined by its geometric and electronic structure. Here we present a model that is able to describe the energy trend of the important oxidation catalyst material MoVO, as obtained from hybrid density functional calculations for various V4+/V5+ configurations. For an exemplary V/Mo occupancy, we systematically examined the universe of all V4+ distributions. The distribution of these V4+ centers, in combination with the induced lattice distortions, plays a key role in determining the stability of the material, entailing energy variations of up to ~140 kJ mol−1 per unit cell. Hence, for this kind of catalyst, it is crucial to account for the V4+ distributions. To this end, we are proposing novel predictive models based on features like the number of Mo centers with two reduced neighbors V4+ and the locations of potentially reducible centers V5+. For the V/Mo occupancy chosen, these models are able to describe the energy variation due to the V4+ distribution with root mean square errors as low as 6 kJ mol−1. Accordingly, catalytically selective sites featuring pentameric units with a single polaron center are among the most of stable configurations. Another aspect of this work is to understand energy contributions of polaron arrangements bracketing Mo centers.

Influence of cationic doping at different sites in NaNbO3 on the photocatalytic degradation of methylene blue dye

The present study presents the preparation of Nb-based perovskite with different cationic dopants (potassium and vanadium) for the catalytic photodegradation of methylene blue (MB) dye. For the preparation of powder samples, chemical route followed by heat treatment (at 800 °C) was adopted and X-ray diffraction confirmed the phase formation. Furthermore, scanning electron microscopy (SEM/EDX) and X-ray photoelectron spectroscopy supported the successful incorporation of dopants in NaNbO3 lattice. Furthermore, the induced lattice distortion and resulted optical modification were determined by uniform strain model and UV–visible spectroscopy, respectively. As a result of inclusion of dopants, photodegradation of MB dye under household CFL exposure has been studied in detail by considering the different dye concentrations (1, 5, and 10 mg/L). Doping at both sites (A and B) in NaNbO3 exhibited better photocatalytic efficiency (34%) in 5 h of illumination as compared to single cation-doped systems which can be associated to the higher content of lattice defects (as charge trap centers), reduced optical band gap and oxygen vacancies. Furthermore, intraparticle diffusion model suggested that low concentration of dye solution exhibited surface diffusion mechanism, while higher concentration followed boundary layer diffusion mechanism for the photodegradation of MB dye.

Preparation of Y3+-doped BiOCl photocatalyst and its enhancing effect on degradation of tetracycline hydrochloride wastewater

Abstract Novel, visible light-sensitive photocatalysts of yttrium-doped bismuth oxychloride (Y–BiOCl) were successfully fabricated through consecutive solvent-based and thermal processes. Several characterization strategies were employed to analyze the morphologies, chemical properties, and photocatalytic performances of the catalysts. Compared to pure BiOCl, Y–BiOCl catalysts displayed superior photocatalytic capability for visible light-induced tetracycline hydrochloride (TC) removal. Photocatalytic activity was maximized at 15-wt% Y-doping, with the resulting Y–BiOCl catalyst achieving 90.3% TC removal efficiency within only 60 min, as well as high stability and reusability. Y3+ was discovered to displace Bi3+ in the BiOCl lattices, inducing lattice distortion and thereby raising the concentration of oxygen holes and defects. Y3+-doping also narrowed the bandgap of BiOCl and significantly decreased the bandgap energy, thereby decreasing the photocarrier recombination rate and enhancing photocatalytic activity. The main accomplishment of this study was the development of a promising photocatalytic material for removing organic compounds from wastewater.

Atomic Pt with Trapped Interstitial F in PtCo Nanosheets for Zinc-Air Batteries

Platinum group metals (PGMs) based materials are currently dominantly used as oxygen reduction/evolution reaction (ORR/OER) catalysts in many emerging renewable energy devices such as Zn-air batteries (ZABs) because of their favorable surface electronic structures for electrocatalytic reactions. Most recently, atomic PGMs anchored on the conducting supports have been recognized as the most effective way to improve the utilization efficiency of PGMs and reduce the catalyst cost. However, traditional synthetic approaches to atomic catalysts, such as wet impregnation and atomic layer deposition, still have a long way to be optimized for industrial mass production. In this work, we designed a scalable and repeatable synthesis of atomic Pt in the alloyed platinum cobalt (PtCo) nanosheets by combining bottom-up electrodeposition and top-down fluorine-plasma (F-plasma) etching treatments. The interstitial F atoms trapped in the alloyed PtCo crystal structure induce lattice distortion which plays a crucial role in stabilizing the atomic Pt on the surface of catalyst (denotes as SA-PtCoF) by balancing surface free energy. Moreover, the proposed SA-PtCoF nanosheets are additive-free catalysts with abundant active sites and high surface areas, which show significant advantages over powder catalysts for ZAB due to the suppressed catalyst deactivations. Benefiting from the catalyst-support interactions and synergistic effects of SA-PtCoF, an unprecedented ZAB performance (power density of 125 mW cm-2, capacity of 808 mAh gZn -1, cycle life over 240 h) is achieved, superior to commercial Pt/C@RuO2 and other state-of-the-art ORR/OER catalysts.

Amorphous WO3 induced lattice distortion for a low-cost and high-efficient electrocatalyst for overall water splitting in acid

An amorphous WO3 induced lattice distortion strategy leads to only 2 wt% Ir for efficient overall water splitting in acid.