Lattice Cell Research Articles

A Novel 3D Chiral Metamaterial with Overall Compression‐Twist Properties

Herein, 3D chiral compression‐twist metamaterials represent a novel class of materials capable of converting compression into twist. An isotactic compression‐twist lattice cell (ICTLC), composed of two identical chiral compression‐twist units, is investigated in this paper. By compactly arranging ICTLCs, a 3D chiral metamaterial with overall compression‐twist deformation is achieved. The mechanical properties and deformation mechanisms of the 3D chiral metamaterial are analyzed. The twist angle and the equivalent stress‐strain relationship of the ICTLC are derived based on the deformation of its inclined rods under compression. An analytical solution for the twist angle of the 3D chiral metamaterial under in‐plane compression is also presented. Both experiments and numerical simulations are conducted to verify the compression‐twist performance of the proposed 3D chiral metamaterial. Additionally, the effects of the geometric parameters and the number of the ICTLC on the mechanical behavior and twist performance of the 3D chiral metamaterial are also investigated. The results indicate that, with a constant ratio of longitudinal ICTLC layers to transverse ICTLC rows (and columns), the compressive strength of the metamaterial increases while maintaining efficient compression‐twisting deformation performance as the number of ICTLCs increases. These findings provide insights for the design of metamaterials with enhanced compression‐twist coupling deformation.

Helmets with lattice liners can mitigate traumatic brain injury from impacts

This study explores the effectiveness of architected lattice structures, specifically made of PA12 material, as potential helmet liners to mitigate traumatic brain injuries (TBI), with a focus on rotational acceleration. Evaluating three lattice unit cell topologies (simple cubic, dode-medium, and rhombic dodecahedron), the research builds upon prior investigations indicating that PA12 lattice liners may outperform conventional EPS liners. Employing a high-fidelity finite element male head model and utilizing direct and oblique impact scenarios, mechanical quantities, such as maximum principal strain (MPS) and shear strain, cumulative strain damage measure and intracranial pressure were measured at the tissue level in different brain regions, Results indicate that lattice liners, especially with dode-medium topology, exhibit promising reductions in brain tissue strains. On average, during oblique impacts, less than 1 % of the brain volume experienced an MPS level of 0.4 when the lattice liners were adopted, whereas that percentage was above 70 % with the expandable polystyrene (EPS) foam liners. Pressure-based assessments suggest that lattice liners may outperform EPS liners in oblique impacts, showcasing the limitations of EPS for effective TBI mitigation. Despite certain model limitations, this study emphasizes the need for advancements in helmet technology, particularly in the development of commercial lattice liners using additive manufacturing, to address the limitations of existing EPS liners in preventing rotational consequences of impacts and reducing TBI.

The investigation on the bending fatigue properties of Ti-6Al-4V lattice sandwich structures fabricated EB-PBF

In this study, lattice sandwich structures of Ti-6Al-4V alloy with simple cubic (SC) and rhombic dodecahedron (RD) unit cells were prepared by electron beam powder bed fusion (EB-PBF) technique. Through a combination of finite element simulation and experimental investigation, the effect of lattice cell shape and heat treatment on the bending fatigue performance of these lattice sandwich structures was studied. The results show that the underlying fatigue mechanism of the RD lattice sandwich structure is primarily dominated by cyclic ratcheting of the lattice. In contrast, for the SC lattice sandwich structure, the fatigue mechanism involves an interaction of cyclic ratcheting and fatigue crack initiation and propagation of the lattice. During the cyclic deformation process, the struts of the lattice unit cells in the SC lattice sandwich structure mainly undergo buckling deformation. Under the same bending deformation strain, the struts experience much higher stress in the SC lattice sandwich structure, making them more susceptible to crack initiation and resulting in a quick fatigue failure. Therefore, the fatigue performance of the RD lattice sandwich structure is significantly superior to that of the SC lattice sandwich structure. Heat treatment result in the enhanced plasticity of parent materials of the lattice sandwich structure, leading to improved resistance to cyclic strain accumulation during fatigue processes and an increase in fatigue strength.

Fin angles optimization of water-cooled plate-fin heat sink based on anisotropic Darcy–Forchheimer theory

Flat heat sinks are devices for efficient heat dissipation and are important components in manufacturing. For example, in precision glass molding, it is utilized as a cooling plate contributing to improve the quality of the product by reducing residual stress and shape deviation, during the gradual cooling phase. In this study, we attempted to achieve precise temperature design of the cooling plate using variable lattice optimization. Fins allow for controlling the flow direction and achieving efficient heat transfer. Therefore, elliptical cylindrical fins were adopted as lattice unit cells, increasing the design freedom of the flow field. To account for the asymmetric flow field within the unit cell, we introduced an asymmetric tensor for the coefficients of the effective physical properties in the Darcy–Forchheimer equation. The proposed method's effectiveness and validity are discussed through numerical calculations with effective material properties, reproduced detailed shapes, and experimental verification. The optimization aiming to minimize the average temperature yielded a numerical simulation temperature decrease of 24.6 % and an experimental temperature decrease of 14.1 % compared to the benchmark model.

Na+ conductivity of (100−x)Na3PS4−xCa3N2 glass and glass−ceramics

AbstractThe ionic conductivity of Na3PS4 can be improved via the aliovalent substitution of P and S as well as multivalence cation substitution of Na. Although the enhanced ionic conductivities of tetragonal and cubic Na3PS4 have been theoretically and experimentally studied, the dynamics of sodium ions in these systems have been rarely reported. In this study, (100−x)Na3PS4−xCa3N2 (0 ≤ x ≤ 10) glass samples were synthesizing using high‐energy planetary ball‐milling method. These samples were subjected to heat treatment at 280°C for 1 h in an argon atmosphere to obtain glass–ceramic samples. The structures of these samples were characterized via Raman spectroscopy and X‐ray diffraction analysis. The lattice parameter and cell volume of the glass–ceramic samples strongly depended on the x value in (100−x)Na3PS4−xCa3N2 (0 ≤ x ≤ 10). Their ionic conductivities were determined via alternating current electrochemical impedance spectroscopy (EIS). 92Na3PS4−8Ca3N2 glass–ceramics exhibited an ionic conductivity of 8.14 × 10−4 Scm−1 at 25°C. Charge carrier concentration and hopping rate were extracted from the EIS data to determine the ionic conductivities of the samples. The activation energies of DC conductivity and mobile ion formation and migration were also derived from the EIS data to analyze the effect of Ca3N2 doping on the ionic conductivity of the synthesized samples.

Design of vibrational filters based on 3D lattice material elongated structure

This study examines the potential of elongated periodic three-dimensional lattice structures for the design of vibration filters using so-called absolute band gaps. These filters are generally obtained by modifying the total stiffness of the structure, which decreases the propagation velocity of all wave polarisations. With a view to optimisation, we are implementing an original structure consisting of interconnected 3D beams with a sinusoidal accordion shape to control the speed of longitudinal waves. In addition, a central junction in the shape of a deformed cross controls the speed of transverse waves. To calculate the propagation of elastic waves in such structures, we use spectral element methods that take into account the longitudinal, torsional and bending motions of three-dimensional beams. The dispersion curves are obtained by applying the Floquet-Bloch periodicity conditions. They are analysed by a detailed study of the wave motion and polarisation. Finally, the geometrical parameters of the lattice cell are optimised using a genetic algorithm to generate the widest absolute band gap at the lowest frequency.

Exploring the Impact of Elevated Pressure on the Structural Dynamics of TlInS2 Crystal (I): A First-Principles Investigation with XRD, Raman, and Hirshfeld Topology

The structural dynamics of Thallium Indium Disulfide (TlInS2) crystal under elevated pressures were comprehensively investigated using a combination of X-ray diffraction (XRD), Raman spectroscopy via first-principles calculations, and Hirshfeld surface (HS) analysis. This study aims to elucidate pressure-induced modifications in the crystal structure and their associated properties of TlInS2 crystal. The findings reveal significant structural transformations as pressure increases, with XRD patterns indicating lattice compression and a critical transition from semiconductor to conductor at pressure P=6.25GPa [42]. The calculations predict a reduction in bond lengths, specifically S1-In1 and S1-Tl2, alongside a corresponding decrease in lattice parameters and unit cell volume. Raman spectroscopy corroborates these changes through shifts in phonon modes. The HS analysis provides further insights into pressure-dependent alterations in intermolecular interactions, revealing changes in voids and surface characteristics. The data gained from TlInS2's structural behavior under pressure, contributing to the optimization of its functional properties for pressure-tunable applications in high-performance electronic and optoelectronic devices.

Structure, microstructure, and ESR properties of concentration-dependent Zn1-xMnxO nanoparticles

In this study, the estimated stress, strain, and crystallite sizes of different Mn-doped ZnO nanoparticles were calculated using the Williamson-Hall method and compared with the values obtained from the Debye-Scherrer formula. Moreover, defects, and magnetic properties of Mn-doped ZnO nanoparticles at different concentrations were investigated. The sol-gel method was used to synthesize nanoparticles. The X-ray diffraction and Rietveld analysis results confirm that the desired structure is formed and that no secondary phase is present up to an Mn concentration of x=0.2. In and out of plane lattice parameters, cell volumes, bond length, atomic locality, and dislocation density (δ) were clarified. The grain size of the concentration-dependent samples was provided by scanning electron microscope. Photoluminescence (PL) spectra exhibited ultraviolet emission along with a broad band encompassing violet, blue, and red regions, attributed to defect-related and excitonic emissions. These emissions were notably influenced by synthesis conditions and doping elements and ratios. Electron spin resonance properties of the concentration-dependent samples were analyzed to figure out the g-factor through line widths of pike-to-pike (ΔHPP) of ESR spectra. Mn-doped ZnO nanoparticles exhibited ferromagnetism at room temperature.

A review of structural diversity design and optimization for lattice metamaterials

Metamaterials are a type of groundbreaking engineered materials with unique properties not found in natural substances. Lattice metamaterials, which have a periodic lattice cell structure, possess exceptional attributes such as a negative Poisson’s ratio, high stiffness-to-weight ratios, and outstanding energy dissipation capabilities. This review provides a comprehensive examination of lattice metamaterials. It covers their various structures and fabrication methods. The review emphasizes the crucial role of homogenization methods and multi-scale modeling in assessing metamaterial properties. It also highlights the advancement of topology optimization through advanced computational techniques, such as finite element analysis simulations and machine learning algorithms.

The novel Zn-doped hexagonal perovskite Ba7In6Al2O19: electrical conductivity and hydration

The novel phase Ba7In5.9Zn0.1Al2O18.95 with hexagonal perovskite structure was obtained by solid-state technique. The substitution of In3+ by the Zn2+ leads to the expansion of the lattice parameters and cell volume. It was established that the investigated sample is capable of water incorporation from the gas phase; the degree of hydration reaches 1.42 mol H2O, which is significantly higher than that for the undoped phase (0.41 mol H2O). This is a result of the expansion of the hexagonal layer that facilitates the placement of OH–-groups. The oxide-ion and proton conductivities for the doped Ba7In5.9Zn0.1Al2O18.95 sample were higher than those for the undoped composition, Ba7In6Al2O19, by 0.50 and 0.75 orders of magnitude (500 °C), respectively. The new phase Ba7In5.9Zn0.1Al2O18.95 demonstrates the predominant protonic conductivity at Т ≤ 500 °C and pH2O = 1.93·10−2 atm.

High-pressure synthesis, crystal structure and anisotropic thermal/compressive behaviors of pseudo-ternary (V,Cr,Mo)P4

Pseudo-ternary CrP4-type (V,Cr,Mo)P4 was successfully synthesized at the conditions of 4 GPa and 900 °C by using a large volume multi-anvil-type press. SEM-EDS and STEM analyses revealed that the synthesized pseudo-ternary (V,Cr,Mo)P4 contains almost equimolar amounts of transition metals. The lattice parameters and unit cell volume of (V,Cr,Mo)P4 yield the average value of its end-members. The low-temperature (133 K–333 K) in-situ synchrotron XRD measurements demonstrated that the c-axis showed the highest coefficient of thermal expansion, followed by the b-axis and the a-axis. These thermal behaviors are the same as the binary end-members and pseudo-binary (V,Cr)P4. While from the high-pressure (P < 10 GPa) in-situ synchrotron XRD measurements, it was found that (V,Cr,Mo)P4 showed no phase transition and compression behaviors in which the c-axis was more compressible than the other two axes (b and a) and the b-axis was slightly compressible more than the a-axis. The zero-pressure bulk modulus of 106 (1) GPa and 122.1 (7) GPa were obtained for (V,Cr)P4 and (V,Cr,Mo)P4, respectively. MoP6 octahedral is highly distorted in comparison with VP4 and CrP4, thus the incorporation of MoP4 greatly yields incompressible behaviors of CrP4-type phosphides with respect to temperature and pressure.

Comprehensive analysis of organic dye doped metal-coordinated single crystals: A study of structural, optical, thermal, dielectric, piezoelectric and mechanical characteristics

Organic dye can induce positive changes in optical, mechanical and electrical properties of semi-organic single crystals. Single crystals of pure and 0.01 mol% SSY dye doped ZTS are grown from a slow evaporation solution technique. The structural properties of pure and SSY-dyed ZTS crystals are characterized using SCXRD and PXRD, confirming the maintenance of crystallinity and incorporation of dye molecules within the host lattice of ZTS crystal. Both ZTS crystals belong to orthorhombic crystal system with space group Pca21. The refined lattice parameters and cell volume of present pure ZTS crystal are a = 11.1723 Å, b = 7.7989 Å, c = 15.5357 Å, α = β = γ = 90°, V = 1353.6762 Å3. The intensity of all Raman peaks in ZTS is enhanced by the incorporation of dye. Optical spectroscopic UV–visible and photoluminescence techniques highlight the comparative studies of light absorption, energy bandgap, optical constants and fluorescence emission. An increment of 0.05 eV in optical bandgap is observed in dyed ZTS. The dielectric properties with variation in frequency range (23 Hz–10 MHz) at different temperature range (30–100 °C) are evaluated through impedance spectroscopy, showing an increase in dielectric constant around 15 % and reduction in dielectric loss, indicating potential for improved performance in electronic applications. A significant enhancement is observed in the piezoelectric coefficient (d33) in dyed ZTS single crystals. The d33 value of ZTS is increased from 2.75 to 2.95 pC/N by the doping of organic dye. Vickers micro-hardness tester is used to know the mechanical strength through micro-indentation, which illustrated an increase in the hardness nature of dyed ZTS single crystals. These findings provide a foundation for the future development of ZTS-based materials for technological applications, offering a promising route for the advancement of functional materials in the domain of piezoelectric and optoelectronic technologies.

Co and F co-doping to augmenting the electrochemical performance of P2-type sodium lithium manganese oxide for sodium ion battery

P2-type sodium lithium manganese oxide is recognized as one of the most promising cathode materials for sodium-ion batteries (SIBs). However, its practical application has been hindered by poor cycling performance and limited rate capacity. In this study, we successfully co-doped cobalt (Co) and fluorine (F) into P2-type sodium lithium manganese oxide, resulting in the enhanced material CoF-NLM, which significantly improves its electrochemical performance. The CoF-NLM material exhibits several advantageous characteristics: (i) a notable increase in lattice constant and lattice cell volume, which facilitates the intercalation and deintercalation of sodium ions within its bulk structure; (ii) an enhanced surface morphology that promotes better contact between the electrode and the electrolyte; and (iii) an increased Mn3+/Mn4+ ratio, which enhances the number of active transition metal centers available for electrochemical reactions. As a result, the CoF-NLM sample demonstrates exceptional electrochemical performance, boasting a specific capacity of 135.51 mAh/g at a current density of 8 mA g−1 and maintaining an impressive 92.69 % capacity retention after 100 cycles. This study conclusively demonstrates that ion doping is a highly effective strategy for enhancing the electrochemical performance of cathode electrode materials in SIBs; paving the way for the development of high-energy, high-power SIBs that can meet the demands of next-generation energy storage applications.

Thermal-Mechanical Coupling Performance of Heat-Resistant, High-Strength and Printable Al-Si Alloy Antisymmetric Lattice Structure.

The unsatisfactory mechanical performance at high temperatures limits the broad application of 3D-printed aluminum alloy structures in extreme environments. This study investigates the mechanical behavior of 4 different lattice cell structures in high-temperature environments using AlSi12Fe2.5Ni3Mn4, a newly developed, heat-resistant, high-strength, and printable alloy. A novel Antisymmetric anti-Buckling Lattice Cell (ASLC-B) based on a unique rotation reflection multistage design is developed. Micro-CT (Computed Tomography)and SEM (Scanning Electron Microscope) analyses revealed a smooth surface and dense interior with an average porosity of less than 0.454%. Quasi-static compression tests at 25, 100, and 200°C showed that ASLC-B outperformed the other 3 lattice types in load-bearing capacity, energy absorption, and heat transfer efficiency. Specifically, the ASLC-B demonstrated a 51.56% and 44.14% increase in compression load-bearing capacity at 100 and 200°C compared to ASLC-B(AlSi10Mg), highlighting its excellent high-temperature mechanical properties. A numerical model based on the Johnson-Cook constitutive relationship revealed the damage failure mechanisms, showing ASLC-B's effectiveness in preventing buckling, enhancing load-transfer efficiency, and reducing stress concentrations. This study emphasizes the importance of improving energy absorption and mechanical performance for structural optimization in extreme conditions. The ASLC-B design offers significant advancements in maintaining structural integrity and performance under high temperatures.

Influence of electron and hole doping on structural, Magnetic, and magnetocaloric properties of Ba2FeMoO6 double perovskite

The impact of Sm3+ and Ag+ doping at the Ba2+ site on the structural, magnetic, and magnetocaloric properties of Ba2FeMoO6 (BFMO) double perovskite was compared. Samples were synthesized using the sol–gel method. Rietveld refinement patterns of samples Ba2-xAxFeMoO6 (A=Sm, Ag, x = 0.0, 0.025) showed all samples had cubic structures with Fm-3 m space group and no impurity. The lattice parameters and unit cell of the Ba1.975Sm0.025FeMoO6 (BSFMO), and Ba1.975Ag0.025FeMoO6 (BAFMO) samples decreased compared to the parent sample. X-ray photoelectron spectroscopy confirmed that Fe and Mo ions were mixed valence for all samples. The results of magnetization versus temperature (M−T) showed an increase for BSFMO and a decrease for BAFMO samples under an external magnetic field of 0.05 T. The magnetic study indicated a decrease in the transition temperature for BSFMO (∼303 K) and an increase for BAFMO (∼321 K) to compare with the parent sample (∼310 K). The maximum value of magnetic entropy changes (ΔSMmax)of the BFMO, BSFMO, and BAFMO samples at H=3 T obtained 0.92 Jkg-1K−1, 0.75 Jkg-1K−1, and 0.39 Jkg-1K−1, respectively, and the second-order magnetic phase occurred around the transition temperature. For BFMO, BSFMO, and BAFMO, the relative cooling power (RCP) is 34.48 J/kg, 32.25 J/kg, and 21.97 J/kg, respectively. The second-order magnetic phase transition occurred around the transition temperature for all samples using the energy criterion as well as the universal curve method. In addition, we used Widom’s law to determine the critical exponent of the samples, which provides a new thermodynamic method to determine the magnetic phase transition. The results of the magnetocaloric effect indicate that although the maximum entropy changes and relative cooling decrease with doping Ag and Sm ions, they have a wide temperature range of magnetic entropy changes compared to the pristine sample, which can be candidates for magnetic cooling.

Fabrication and magnetic performance of rare-earth dysprosium doped Ca-Mg hexaferrite nanoparticles

In this research, dysprosium-substituted M-type Ca-Mg hexaferrites are successfully fabricated via sol–gel combustion technique, employing a nominal composition of Ca0.5Mg0.5Fe12-xDyxO19 (x = 0.0, 0.04, 0.08, 0.12, and 0.15). Analysis of XRD patterns reveals exclusive peaks corresponding to the M-type hexaferrite, with no indications of additional phases, underscoring the high purity and crystalline integrity of the synthesized material. The Rietveld refinement is used to evaluate lattice parameters ’a’ and ’c’ along with the cell volume ’V ’ using the distinct iron sites. Notably, a discernible upward trend in both lattice constants and cell volume emerged with the gradual introduction of dysprosium Dy+3 ion. Hexaferrite phase formation was also confirmed through the ‘c/a’ ratio which lies below the critical value of 3.98. Synthesized samples shows a composite surface morphology with adherent clusters of small crystals and well-formed individual crystals. VSM analysis suggests, remarkable results, particularly at the x = 0.15 doping level, which exhibits the highest magnetic parameters, including Ms = 32.13 emu g−1, Mr = 20.34 emu g−1, and Hc = 1.418 kOe. These results suggest that the synthesized samples hold promise as suitable contenders for optimizing recording media, offering the potential for improved data storage performance.

The thermal expansion of Ti-substituted CaAl12O19

CaAl12O19, which can incorporate Ti as both Ti3+ and Ti4+ (charge coupled substitution with Mg2+), is one of the first minerals to condense from a gas of solar composition and is used as a ceramic. It is variously known as hibonite, calcium hexaluminate (CaO.6Al2O3), and CA6. The lattice parameters and unit cell volumes of Ti-substituted hibonite (P63/mmc) with the formulae CaAl11.8Ti3+0.2O19 and CaAl9.8Ti3+0.54Mg0.83Ti4+0.83O19 were determined as a function of temperature from ~ 10 to 275 K by neutron powder diffraction. The thermal expansion is highly anisotropic with the expansion in c a factor of ~ 5 greater than that in a. The change in a is approximately equal for the two compounds whereas the change in c is almost 50% larger for CaAl11.8Ti3+0.2O19. CaAl11.8Ti3+0.2O19 also exhibits negative thermal expansion between 10 and 70 K. The change in unit cell volume with temperature of both compositions is well described by a two term Einstein expression. The large change in c is consistent with substitution of Ti onto the M2 and M4 sites of the R-block structural unit.

Influence of Rare-Earth Doping Content and Type on Phase Transformation and Transport Properties in Highly Doped CeO2.

Rare-earth doped CeO2 materials find extensive application in high-temperature energy conversion devices such as solid oxide fuel cells and electrolyzers. However, understanding the complex relationship between structural and electrical properties, particularly concerning rare-earth ionic size and content, remains a subject of ongoing debate, with conflicting published results. In this study, we have conducted comprehensive long-range and local order structural characterization of Ce1-xLnxO2-x/2 samples (x ≤ 0.6; Ln = La, Nd, Sm, Gd, and Yb) using X-ray and neutron powder diffraction, Raman spectroscopy, and electron diffraction. The increase in the rare-earth dopant content leads to a progressive phase transformation from a disordered fluorite structure to a C-type ordered superstructure, accompanied by reduced ionic conductivity. Samples with low dopant content (x = 0.2) exhibit higher ionic conductivity in Gd3+ and Sm3+ series due to lower lattice cell distortion. Conversely, highly doped samples (x = 0.6) exhibit superior conductivity for larger rare-earth dopant cations. Thermogravimetric analysis confirms increased water uptake and proton conductivity with increasing dopant concentration, while the electronic conductivity remains relatively unaffected, resulting in reduced ionic transport numbers. These findings offer insights into the relationship between transport properties and defect-induced local distortions in rare-earth doped CeO2, suggesting the potential for developing new functional materials with mixed ionic oxide, proton, and electronic conductivity for high-temperature energy systems.

High-temperature behaviour of fluorcarletonite, KNa4Ca4Si8O18(CO3)4(F,OH)⋅H2O, from the Murun Alkaline Complex, Russia, appraised by experimental and theoretical methods

AbstractThe thermal behaviour of fluorcarletonite, KNa4Ca4Si8O18(CO3)4(F,OH)⋅H2O, from the charoitites of the Severny district at the Malyy Murun massif, Murun complex, NW Aldan Shield, Siberia, Russia, has been investigated in order to understand the temperature-induced changes in the crystal structure of this rare silicate. The study has been carried out combining in situ high-temperature single-crystal X-ray diffraction (T range 25–550°C), ex situ high-temperature Fourier-transform infrared spectroscopy (25–700°C) and ab initio calculations. An increasing trend of lattice parameters and cell volume was observed in the 150–550°C temperature range, when the mineral underwent a progressive dehydration process. At 550°C ~40% water loss was detected. If compared with the fluorcarletonite structure at room temperature, the partially dehydrated fluorcarletonite shows: the same space group (P4/mbm); increased distances between the oxygens of the H2O molecules (O11w and O12w) and their Na-centred octahedral cations (Na1 and Na2, respectively); distortion of the four- and six-member tetrahedral rings of the double silicate layer. The dehydration process mainly involves the oxygen at the O11w site which has a different local environment with respect to the oxygen at the O12w site. At T &gt; 600°C, the complete dehydration is accompanied by deprotonation of the OH groups substituting for the F atoms and by the collapse of the structure when the CO2 is released. The adopted approach allowed definition of the temperature thresholds at which modifications occur in the fluorcarletonite crystal structure when subjected to controlled heating conditions. Our findings contribute to assessment of stability, reactivity and, more generally, the thermal behaviour of sheet silicates with fluorcarletonite-like topology.

Investigating the effects of hydrostatic pressure on the physical properties of cubic Sr3BCl3 (B = As, Sb) for improved optoelectronic applications: A DFT study

This article explores changes in the structural, electronic, elastic, and optical properties of the novel cubic Sr3BCl3 (B = As, Sb) with increasing pressure. This research aims to decrease the electronic band gap of Sr3BCl3 (B = As, Sb) by applying pressure, with the objective of enhancing the optical properties and evaluating the potential of these compounds for use in optoelectronic applications. It has been revealed that both the lattice parameter and cell volume exhibit a declining pattern as pressure increases. At ambient pressure, analysis of the band structure revealed that both Sr3AsCl3 and Sr3SbCl3 are direct band gap semiconductors. With increasing pressure up to 25 GPa the electronic band gap of Sr3AsCl3 (Sr3SbCl3) reduces from 1.70 (1.72) eV to 0.35 (0.10) eV. However, applying hydrostatic pressure enables the attainment of optimal bandgaps for Sr3AsCl3 and Sr3SbCl3, offering theoretical backing for the adjustment of Sr3BCl3 (B = As, Sb) perovskite's bandgaps. The electron and hole effective masses in this perovskite exhibit a gradual decrease as pressure rises from 0 to 25 GPa, promoting the conductivity of both electrons and holes. The elastic properties are calculated using the Thermo-PW tool, revealing that they are anisotropic, ductile, mechanically stable, and resistant to plastic deformation. Importantly, these mechanical properties of both compounds are significantly enhanced under pressure. Optical properties, including the absorption and extinction coefficients, dielectric function, refractive index, reflectivity, and loss function, were calculated within the 0–20 eV range under different pressure conditions. The calculated optical properties highlight the versatility and suitability of Sr3AsCl3 and Sr3SbCl3 perovskites for pressure-tunable optoelectronic devices.