Variation Of Lattice Parameters Research Articles

Integrated structural and functional analysis of Ba1-xSrxTiO3-Bi0.5Na0.5TiO3 ceramics: Insights into energy storage and electrocaloric performance

This paper reports an extensive investigation on the structural, dielectric, ferroelectric and pyroelectric properties of 0.7Ba1-xSrxTiO3 – 0.3Bi0.5Na0.5TiO3 (x = 0.0, 0.5, 0.6, 0.7) ceramics synthesized via conventional solid-state reaction (SSR) technique. X-ray diffraction data confirms the presence of pure perovskite phase. The variation of lattice parameters with strontium concentration in 0.7Ba1-xSrxTiO3 – 0.3Bi0.5Na0.5TiO3 ceramics were evaluated using the Rietveld refinement of the XRD data. The variation of dielectric permittivity with temperature (ε' ∼ T) shows the diffused phase transition and all the parameters related to the relaxor ferroelectrics (relaxation coefficient, activation energy and freezing temperature) were evaluated. The energy storage properties of the as-prepared ceramics were evaluated using the room temperature PE loop. Amongst the as-prepared ceramics, the composition with x = 0.5 possesses the highest energy storage density of 0.46 J/cm3 with an efficiency of 90 %. The temperature dependent P-E loops were used to study the electrocaloric effect (ECE). The ECE calculations were performed using in-direct method based on Maxwell's thermodynamic relations. A maximum adiabatic temperature change of 0.32 K is achieved at 268 K under a small applied electric field of 25 kV/cm for the ceramic with Sr content x = 0.5. Additionally, electrocaloric responsivity ξmax = 0.13 K mm/kV was also found for the studied ceramics. The above results show that the ceramic 0.7Ba1-xSrxTiO3 – 0.3Bi0.5Na0.5TiO3 with the composition x = 0.5 is a viable lead-free option for application in solid state refrigeration.

Optimizing oxygen transport properties in Al-substituted La0.5Sr0.5Co0.8Fe0.2-xAlxO3-δ (x = 0–0.20) perovskites

In recent years, there has been a surge in the investigation of perovskite-type complex oxides, with a particular focus on La1-xSrxCo1-yFeyO3, renowned for their exceptional mixed ionic-electronic conducting (MIEC) properties. La0.6Sr0.4Co1-yFeyO3 compositions have prominently emerged in this research domain. The hypothesis of enhancing redox stability and mitigating oxygen variations by incorporating trivalent aluminum (Al3+) into the B-site of perovskite structures has gained attention. In this study, single-phase La0.5Sr0.5Co0.8Fe0.2-xAlxO3-δ (x = 0–0.20) perovskite oxides were synthesized using the solution combustion technique. The physicochemical properties of the synthesized materials were thoroughly characterized, including their morphology, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) analysis, oxygen nonstoichiometry, and electrical transport properties. Results revealed lattice parameter variations associated with oxygen nonstoichiometry and B-site cation size, exhibiting a decline up to x = 0.10 followed by an increase. Al-substitution significantly influenced surface morphology, oxygen nonstoichiometry, and electrical conductivity. Notably, La0.5Sr0.5Co0.8Fe0.1Al0.1O3-δ displayed lower electrical conductivity (676 S cm−1 at 300 °C) among the studied oxides. Oxygen nonstoichiometry had a significant impact on oxygen transport parameters, with these perovskites demonstrating improved chemical diffusion coefficient, Dchem (5.5 × 10-5 cm2 s−1), and the oxygen surface exchange coefficient, Kchem (2.32 × 10-5 cm s−1) at 900 °C, suggesting its potential as an oxygen transport membrane. These findings underscore the promising role of Al-substituted perovskite oxides in various advanced applications.

Multifaceted investigation into the impact of Ga substitution for Al in V[formula omitted]MnAl inverse Heusler alloys

This study investigates the impact of Ga substitution for Al in V2MnAl inverse Heusler alloys, focusing on lattice parameter variations. Despite similar valence electrons, Ga’s distinct size and surface energy prompt questions about its role in alloy characteristics. Experimental synthesis of V2Mn1Al1−xGax alloys (x = 0 to 0.60) reveals crystal parameter changes. Theoretical exploration using density functional theory (DFT) probes how Ga doping at the Al site influences the density of states, altering the half-metallic properties of V2MnAl. Additionally, machine learning, with a dataset of 391 entries, predicts lattice constants based on atomic properties, enhancing our ability to maneuver material characteristics. This multifaceted approach aims to deepen our understanding of Ga’s impact on Heusler alloys, bridging experimental and theoretical realms for comprehensive insights into materials design and behavior.

Strained single crystal high entropy oxide manganite thin films

The ability to accommodate multiple principal cations within a single crystallographic structure makes high entropy oxides (HEOs) ideal systems for exploring new composition–property relationships. In this work, the high-entropy design strategy is extended to strained single-crystal HEO-manganite (HEO-Mn) thin films. Phase-pure orthorhombic films of (Gd0.2La0.2Nd0.2Sm0.2Sr0.2)MnO3 were deposited on three different single-crystal substrates: SrTiO3 (STO) (100), NdGaO3 (110), and LaAlO3 (LAO) (100), each inducing different degrees of epitaxial strain. Fully coherent growth of the thin films is observed in all cases, despite the high degree of lattice mismatch between HEO-Mn and LAO. Magnetometry measurements reveal distinct differences in the magnetic properties between epitaxially strained HEO-Mn thin films and their bulk crystalline HEO counterparts. In particular, the bulk polycrystalline HEO-Mn shows two magnetic transitions as opposed to a single one observed in epitaxial thin films. Moreover, the HEO-Mn film deposited on LAO exhibits a significant reduction in the Curie temperature, which is attributed to the strong variation of the in-plane lattice parameter along the thickness of the film and the resulting changes in the Mn–O–Mn bond geometry. Thus, this preliminary study demonstrates the potential of combining high entropy design with strain engineering to tailor the structure and functionality of perovskite manganites.

Achieving a Deeply Desodiated Stabilized Cathode Material by the High Entropy Strategy for Sodium-ion Batteries.

Manganese-based layered oxides are currently of significant interest as cathode materials for sodium-ion batteries due to their low toxicity and high specific capacity. However, the practical applications are impeded by sluggish intrinsic Na+ migration and poor structure stability as a result of Jahn-Teller distortion and complicated phase transition. In this study, a high-entropy strategy is proposed to enhance the high-voltage capacity and cycling stability. The designed P2-Na0.67Mn0.6Cu0.08Ni0.09Fe0.18Ti0.05O2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g-1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low-cost, high-energy-density cathode materials for sodium-ion batteries.

Achieving a Deeply Desodiated Stabilized Cathode Material by the High Entropy Strategy for Sodium‐ion Batteries

AbstractManganese‐based layered oxides are currently of significant interest as cathode materials for sodium‐ion batteries due to their low toxicity and high specific capacity. However, the practical applications are impeded by sluggish intrinsic Na+ migration and poor structure stability as a result of Jahn–Teller distortion and complicated phase transition. In this study, a high‐entropy strategy is proposed to enhance the high‐voltage capacity and cycling stability. The designed P2‐Na0.67Mn0.6Cu0.08Ni0.09Fe0.18Ti0.05O2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g−1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low‐cost, high‐energy‐density cathode materials for sodium‐ion batteries.

Transmission Electron Microscopic and X-ray Diffraction Based Study of Crystallographic Bibliography Demonstrated on Silver, Copper and Titanium Nanocrystals: State of the Art Statical Review

This statistical review compares the crystallographic structures of functional nanocrystals composed of silver (Ag), copper (Cu) and titanium (Ti) using transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. TEM provides high-resolution imaging to directly visualize individual nanoparticles' size, internal shape and crystallinity. Statistical analysis quantifies variations in lattice parameters, crystal structure, size distributions, phase compositions, lattice strains, preferred orientation and lattice volume of these three crystalline nanomaterials. The review highlights the complementary roles of TEM and XRD in comprehensive Ag, Cu and Ti nanocrystalline materials characterization. The crystallographic functional parameters of Ag were 2θ= 38.1° (111), 44.3° (200) and 64.4° (220); for Cu crystal 43.3° (111), 50.4° (200), 74.1° (220), 89.9° (311) and 95.1° (222) and 35.1° (100), 38.4° (002), 40.2° (101), 53.0° (102), 63.0° (103), 70.7° (110), 76.2° (112), 82.3° (201) demonstrated for Ti nanocrystals. The crystallographic predominant plane or Miller indices were also revealed by selected area electron diffraction (SAED) on TEM. The FCC structure of Ag and Cu is shown in larger lattice volumes compared to the HCP structure of Ti and prefer oriented. The degree of crystallinity of Ti, Cu and Ag nanocrystalline materials was observed at 90.0%, 98.0% and 100.0% respectively. This quantitative comparison provides valuable insights into the structural property relationships in these nanocrystals, enabling rational design strategies for optimizing their performance in various functional applications.

Influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate single crystal

This report presents investigation on influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate (LAM) single crystal for the first time. Single crystals of LAM were grown at different pH by solution growth method by allowing slow evaporation of solvent. Crystal grown at pH 6.4 grows slowly as compare to other crystals grown at other pH values. The slight variation in lattice parameters of grown crystals has been confirmed by powder X-ray diffraction study. FT-IR study confirms the presence of functional groups of LAM in all grown crystals. Influence of pH on optical quality of crystals has been discussed. The crystal grown at pH 5.4 has maximum optical transparency and shows 2 and 20 % more transmission than crystals grown at pH 4.4 and 6.4, respectively. Other optical parameters like cutoff wavelength (λmax), band gap (Eg), linear refractive index (n), reflectance, extinction coefficient (k), electrical susceptibility (χ), optical conductivity(σop), electrical conductivity (σel) and Urbach energy (Eu) of all crystals have been evaluated from transmission data. The LAM crystal grown at pH 6.4 show high values of third order nonlinear optical parameters, as compare to other grown crystals, that attest its suitability for applications like higher harmonic generation, optical switching, optical limiting and other photonic applications over other grown crystals. Thermal stability of the grown crystals has been attested by TG-DTA study.

Manganese substitution effect on physical properties of sol-gel derived DyFeO3 orthoferrite

A simple composite DyFe(1-x)MnxO3 (x = 0, 0.1, 0.3, 0.5) powders were successfully prepared by the sol–gel method. The effect of Mn modification on the structure, thermal and phase transition behaviour of DyFeO3 orthoferrite was investigated. Mn modification didn't show any structural change and all the samples confirmed the pure orthorhombic phase with Pbnm space group. However, a contradicting trend in the variation of lattice parameters were observed due to the presence of mixed oxidation state of Dy, Fe and Mn in the sample leading to oxygen vacancies. The presence of mixed oxidation state was confirmed through X-ray photoemission spectra (XPS). Scanning electron microscopy (SEM) and Williamson Hall (WH) plot confirmed a decrease in particle sizes with increasing Mn concentration leading to an increase in the specific surface area which suggested an inhibition of grain growth with Mn modification. The defects-initiated change in physical behaviour in terms of structural, thermal, microstructural and dielectric are analyzed and discussed in detail.

Epitaxial growth and magnetic properties of Mn5(SixGe1-x)3 thin films

Structural and magnetic properties of Mn5(SixGe1-x)3 thin films were investigated. Ferromagnetic Mn5Ge3 and anti-ferromagnetic Mn5Si3 thin films have been synthesized and characterized as these compounds exhibit interesting features for the development of spintronics. Here, Mn5(SixGe1-x)3 thin films were grown on Ge(111) substrates by co-deposition using molecular beam epitaxy. Crystalline thin films can be produced with controlled Si concentrations ranging from 0 to 1. The thin films were relaxed by dislocations at the interface with the substrate. A lattice parameter variation was observed as the Si content increased, which is comparable to previous works done in bulk. Reflection high-energy electron diffraction diagrams and X-ray diffraction profiles showed that lattice parameters a and c are shrinking and that the surface roughness and crystallinity degrade as the Si amount increases. Magnetometric measurements revealed a ferromagnetic behavior for all Si concentrations. The measured average ferromagnetic moment per manganese atom decreased from 2.33 to 0.05 μB/Mn atom. No ferro to anti-ferromagnetic transition was observed contrary to the bulk Mn5(SixGe1-x)3 compound.

Structural and Electrical Properties of Li Substituted Mg Nano Ferrites: Prepared by Citrate-gel Auto Combustion Method

LixMg1−xFe2O4 where x=0.0to0.5with0.1 nano ferrites were synthesized by citrate gel auto combustion. Using a field-emission scanning electron microscope (FE-SEM) and the X-ray diffraction technique, their structural and topographical studies were examined. The prepared nano ferrites’ single-phase cubic spinel along the Fd3m space group is confirmed by the structural investigation. The synthesized samples were found to have a crystalline size of 20–26 nm, as determined by the Debye–Scherrer formula. Lattice parameter variation observed for the samples indicates dopant atoms into a crystal lattice can also lead to changes in the lattice constant. FE-SEM images revealed the clear grain and grain boundaries with agglomerated structure and it varied between 33.6 nm-24.4 nm. Two bands observed in Fourier transform infrared spectroscopy illustrates the M-O band in tetrahedral and octahedral sites. Dielectric parameters of the sample observed by LCR meter. Single semicircle behavior observed in impedance spectra. Dielectric constant and dielectric loss decreased as increasing frequency explained by Koop’s theory of mechanism. AC conductivity increasing trend observed with frequency, mobility of charge carrier active at high frequency domain.

A structural-thermodynamic model of the (U1-zPuz)O2+δ solid solution

Thermodynamic mixing properties of the (U1−zPuz)O2+δ fluorite solid solution are modelled by taking into account the dependence of the δ parameter on the chemical potential of O2. Simultaneously, the model is made consistent with phase separation data that are relevant for the hypo-stoichiometric domain. An ion-packing approach is used to describe the variation in the lattice parameter as functions of z and δ. The linking of the ion-packing and thermodynamic models allows predicting the lattice parameter variation across the miscibility gap. The constructed diagrams provide means for estimating equilibration temperatures of biphasic assemblages from X-ray diffraction data.Graphical abstract

Direct observations of dynamic and reverse transformation of Ti-6Al-4V alloy and pure titanium

This paper focused on the characterization and mechanism of the dynamic transformation from the alpha to beta phase during the hot deformation of Ti-6Al-4V alloy and pure titanium. The investigation employed in-situ neutron diffraction and atomistic simulations for a comprehensive understanding of the process. Dynamic transformations were observed during deformation of the Ti-6Al-4V alloy and pure titanium below the beta-transus temperatures (temperatures at which (alpha + beta) / alpha → beta). In the dynamic transformation of Ti-6Al-4V, the lattice parameters of the beta phase continuously increased during deformation in the tensile and transverse directions, a trend inconsistent with the behavior of flow stress. The anomalous variations in lattice parameters were attributed to element diffusion (i.e. a decrease in vanadium content in beta phase). During isothermal holding after unloading, the in-situ neutron diffraction results for Ti-6Al-4V and pure titanium indicated a sluggish reverse transformation from the beta to alpha phase. The mechanism of dynamic transformation was explored through in-situ neutron diffraction and atomistic simulations, which revealed twofold effects of deformation on dynamic transformation. Firstly, deformation led to a significant rise in the Gibbs energy of the alpha phase relative to the beta phase, expanding the beta phase region and diminishing the alpha phase region. Secondly, deformation lowered the energy barriers associated with dynamic transformation, facilitating the activation of dynamic transformation more readily than in the equilibrium state before deformation.

Defect-induced improved structural and electrical properties of Gd-Sr co-doped ceria for solid oxide fuel cell applications

Compositions of Ce1-x-yGdxSryO2-δ (x = 0.1, 0.2, and y = 0.025, 0.05, 0.075) are prepared using the sol-gel auto combustion method. The as-prepared powders are calcined at 500 °C for 2 h, followed by pelletization and sintering at 1450 °C for 4 h. Phase identification, defect distribution, microstructural analysis, and conductivity are examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy and impedance spectroscopy, respectively. A single crystalline phase is formed, and the lattice parameter variation with dopant concentration exhibits anomalous behavior. All the samples show relative densities higher than 92 %. The partial liquid phase sintering is also observed. In co-doped samples, the doping of 10 % Gd with 2.5 % Sr exhibits the highest conductivity, i.e., 1.20 × 10−2 S cm−1 at 600 °C. The developed materials are used in anode-supported cell testing. It shows a maximum power density of 112.7 mW cm−2 and a current density of 288.7 mA cm−2 at 600 °C with wet hydrogen and air on the anode and cathode side, respectively.

A Computational exploration of the electronic, mechanical, and magnetic properties of Co2A1−xBxAl full heusler alloys (A, B = Cr, Mn, and Fe)

An investigation of the structural, mechanical, electronic, magnetic, and thermomagnetic properties of Co2A1−xBxAl full Heusler alloys (where A, B = Cr, Mn, and Fe, and x ranges from 0 to 1.0) has been carried out using density functional theory (DFT) and Monte Carlo simulations. The investigation reveals small variations in lattice parameters and elastic modulus across the different compositions. The band gaps, calculated using modified Becke-Johnson (mBJ) potential, are found to be approximately 1.4 eV for Co2CrAl and Co2MnAl, while a lower band gap of 0.8 eV is observed for Co2FeAl, which also exhibits the highest total magnetic moment of 5 μB. The doped structures display band gaps and magnetic moments that are intermediate to the pure compounds. The Fe-Co exchange interaction is identified as the most robust, significantly contributing to the high Curie temperatures in Fe-containing compounds, reaching up to 1120 K in the Co2FeAl alloy. Furthermore, the study underscores the strategic use of atomic substitution as an effective approach to manipulating key properties of these Heusler alloys. The ability to modulate band gaps, magnetic moments, and Curie temperatures through atomic substitution offers a promising pathway for optimizing these materials for specific technological applications, aligning with the needs of advanced functional devices.

Unveiling electronic structure and magnetic properties of AFe2O4 (A = Co, Ni, Zn, and Mg): Synergizing experimentation with DFT investigation

This study presents the synthesis of nano-crystalline spinel ferrites AFe2O4 (A = Co2+, Ni+2, Zn+2, and Mg+2), through the sol-gel method, yielding crystallite sizes ranging from 12 to 28 nm. The variation in IR and Raman spectra due to M-O-M bonding supports the variation in lattice parameters. The magnetization measurements revealed that CoFe2O4 has a high saturation magnetization of ∼55 emu/g and coercivity of ∼1350 Oe, while ZnFe2O4 exhibited saturation magnetization value of ∼8 emu/g and coercivity of ∼16 Oe. In addition, the electronic structure calculated using DFT, which corroborated the antiparallel alignment of Fe ions in the tetrahedral and octahedral sites, validating the measured magnetic moments. Notably, the CoFe2O4 ferrite exhibited a higher squareness ratio than other ferrites, signifying its suitability as a magnetic material for audio-video recording.

Influence of shock waves on bifunctional nickel particles: Enhancing magnetic properties and supercapacitor applications

In the present study, shock-wave impact experiments were conducted to investigate the structural properties of nickel metal powder when exposed to shock waves. Both X-ray diffractometry and scanning electron microscopy were used to evaluate the structural and surface morphological changes in the shock-loaded samples. Notably, the experimental results revealed variations in lattice parameters and cell structures as a function of the number of shock pulses and the increasing volume. The transition occurred from P2 (100 shocks) to P3 (200 shocks). Remarkably, P5 (400 shocks) exhibited attempts to return to its initial state, and intriguingly, P4 displayed characteristics reminiscent of the pre-shock condition. Additionally, significant morphological changes were observed with an increase in shock pulses. Magnetic measurements revealed an increase in magnetic moment for P2, P3, and P4, but a return to the original state was observed for P5. Moreover, the capacitance exhibited an upward trend with increasing shock pulses, except for P5, where it experienced a decline. These findings underscore the significant impact of even mild shock waves on the physical and chemical characteristics of bifunctional nickel particles. This research sheds light on the potential applications of shock wave-induced structural changes in enhancing the magnetic properties and supercapacitor performance of nickel particles.

Densification and grain growth of UO2 and MnO-UO2 during pressureless sintering

Large-grain UO2 has attracted much attention due to its advantage of suppressing fission gas release by reducing the specific surface area of grain boundaries. In this study, a single grain growth additive MnO is selected to modify UO2 by conventional pressureless sintering method. The effect of MnO modification on UO2 densification and grain growth at temperatures between 1200 and 1700 °C was investigated in detail. 0.5 wt%MnO-UO2 pellets can reach nearly 95% T.D. when sintered at 1200 °C for 24 h. An average grain size greater than 300 µm can be obtained at 1700 °C for 24 h. A series of sintering experiments were designed and conducted to verify the specific mechanism of MnO on the grain growth of UO2. The classical grain growth kinetics indicates that the grain growth exponent of MnO modified UO2 in the early stage is 3, which corresponds to the lattice diffusion under pore control, while that of UO2 is 2 and conforms to the grain boundary migration control. The SEM results show that there is solute segregation of MnO at the grain boundaries, followed by nucleation of lamellar structure in the form of piles and plates on the boundaries after high temperature treatment and traces of liquid phase in some region. Diffusion sintering experiments show that the mechanism of MnO-promoted UO2 grain boundary migration is based on solid phase diffusion. The XRD results of UO2 modified with different amounts of MnO demonstrate that the growth degree of UO2 grains can be related to the variation of lattice parameters resulted from the MnO modification. This is due to the enhanced mobility of UO2 grain boundaries because of the large distortion of surrounding lattice caused by Mn modification. These results can provide new ideas for the manufacture of UO2 ceramic fuels.

Isostructural phase transition in Tb2Ti2O7 under pressure and temperature: Insights from synchrotron X-ray diffraction

Tb2Ti2O7, a pyrochlore system, has garnered significant interest due to its intriguing structural and physical properties and their dependence on external physical parameters. In this study utilizing high-brilliance synchrotron X-ray diffraction, we conducted a comprehensive investigation of structural evolution of Tb2Ti2O7 under external pressure and temperature. We have conclusively confirmed the occurrence of an isostructural phase transition beyond the pressure of 10 GPa. The transition exhibits a distinct signature in the variation of lattice parameters under pressure and leads to changes in mechanical properties. The underlying physics driving this transition can be understood in terms of localized rearrangement of atoms while retaining the overall cubic symmetry of the crystal. Notably, the observed transition remains almost independent of temperature. Our findings offer insights into the distinctive behaviour of the isostructural phase transition in Tb2Ti2O7.

Electronic properties of MnO(110) film grown on Cu (111)

In this study, we investigated MnO thin films grown on Cu(111) using a soft x-ray and UV based spectroscopy, low energy electron diffraction (LEED), scanning tunneling (STM) and scanning transmission electron microscopy (STEM). MnO thin film assumes (110) preferential plane orientation organized in different spatial domains to better adapt to Cu(111) surface and an in-plane/out-of-plane lattice parameter variation up to 11% with respect to bulk counterpart originating a sizeable XLD signal at Mn L2,3 edges. The formation of oxidized Cu region during the MnO thin film growth is not avoidable due to the copper reactivity to oxygen and at the interface the coexistence of MnO islands alternated with Cu2O regions was observed by STM. Mn 2p and Mn 3s core level photoemission line shapes present a slight change in multiplet peak relative intensity with respect bulk MnO counterpart due to the role of Cu substrate in the core level relaxation process. The photon energy dependent photoemission spectra of valence band discriminate the MnO states and indicate a weak influence of the substrate once the film thickness is reduced to 1 nm. These findings open new route in the tuning oxide thin film properties.