Temperature-dependent Evolution Research Articles

Temperature-dependent evolution of synthetic coal-derived graphite fillers and their reinforcement in styrene butadiene rubber composites

This study investigated the structural evolution of synthetic coal-derived graphite (SCG), produced from anthracite through high-temperature treatments ranging from 1000 to 2900 °C, and its reinforcement potential in styrene butadiene rubber (SBR) composites. Upon heating the anthracite to 2000 °C, We observed a gradual structural transformation from an amorphous carbon structure with mixed sp2-sp3 bonding to an ordered sp2-bonded nano-sized graphitic structure. This transformation was accompanied by the evaporation of heteroatom functional groups, an increase in high surface energy site as well as micropore and void structures, and enhanced hydrophobic surface property. Beyond 2000 °C, a flake-like graphite with a larger particle size (average lateral size >10 μm) was gradually formed through lateral and vertical crystalline growth mechanisms. The reinforcing potential of SCG fillers was revealed by incorporating them into SBR and evaluating the properties of the resulting composites. It was found that the tensile strength and 300 % tensile modulus initially enhanced with SCG fillers treated up to 2000 °C, but decreased for fillers treated at 2300 and 2900 °C. On the other hand, storage modulus, tear resistance, and gas permeability consistently improved with fillers treated at higher temperatures. These findings highlight the relationship between the temperature-induced structural evolution of SCG fillers and their reinforcement performance in SBR composites, offering valuable insights for industrial rubber applications, particularly enhancing the performance and sustainability of automotive tire.

Temperature-Dependent Structural Evolution of Coal-Based Graphite During Synthetic Graphitization Process

Temperature-Dependent Structural Evolution of Coal-Based Graphite During Synthetic Graphitization Process

Hydrothermally grown copper cobalt phosphate hydrate nanostars for supercapacitors: Investigation of their charge transfer kinetics

The transition bimetal phosphates are optimistic materials for supercapacitors. In this study, copper cobalt phosphate hydrate ((Cu0.35Co0.65)3(PO4)2·H2O) (CCPH) was deposited on Nickel foam using a hydrothermal method at different reaction temperatures as 120, 150, and 180 °C. X-ray diffraction analysis results in the monoclinic crystal structure of CCPH. The Raman study confirms the presence of the phosphate group. The scanning electron microscopy (SEM) study reveals that the reaction temperature-dependent morphological evolution takes place from nanostars to three dimensional (3D)-porous spongy balls-like structure. The elevating reaction temperature has changed the morphology from nanostars to 3D-porous spongy balls. The electrochemical analysis of the CCPH12 electrode resulted in a specific capacitance of 3390.73 mF/cm2 (518.02 µAh/cm2) at 10 mA/cm2 current density. The charge storage dynamics of the CCPH electrodes were analyzed using power law. The CCPH12 electrode delivered the energy density and power density as 0.142 mWh/cm2 and 2.75 mW/cm2, respectively.

Temperature-dependent ejection evolution arising from active and passive effects in DNA viruses

Recent experiments have demonstrated that the ejection velocity of different species of DNA viruses is temperature dependent, potentially influencing the cellular infection mechanisms of these viruses. However, due to the challenge in quantifying the multiscale characteristics of DNA virus systems, there is currently a lack of systematic theoretical research on the temperature-dependent evolution of ejection dynamics. This work presents a multiscale model to quantitatively explore the temperature-dependent mechanical properties during the virus ejection process, and unveil the underlying mechanisms. Two different assumptions of DNA structures, featuring two or single domains, are used for the early and later stages of ejection, respectively. Temperature is introduced as an influencing variable into the mesoscopic energy model by considering the temperature dependence of Debye length, DNA persistence length, molecular kinetic energy, and other parameters. The results indicate that temperature variations alter the energy landscape associated with DNA structure, leading to the changes in the energy minimum and corresponding DNA structure remaining in the capsid. These changes affect both the active ejection force and passive friction during the DNA ejection, ultimately leading to a significant increase in ejection velocity at higher temperatures. Furthermore, our model supports the previous hypothesis that temperature-induced changes in the size of viral portal pore could dramatically enhance DNA ejection velocity.

Thermo-hydro-mechanical coupling in oil shale: Investigating permeability and heat transfer under high-temperature steam injection

Steam convective heating emerges as a sustainable and effective method for extracting oil shale, where understanding the temperature-dependent evolution of its pyrolytic characteristics, microstructure, and permeability is vital for efficient resource extraction. Through a stress-sensitive micro-CT scanning and a high-temperature and pressure triaxial test apparatus, this research utilizes Balikun oil shale samples to investigate the changes in microstructure and gas production from 20 °C to 550 °C. The study integrates theoretical analysis and numerical simulations to uncover the fundamental connections between internal permeability and heat transfer mechanisms during steam injection. It reveals that oil shale undergoes two critical evolutionary phases: a stability phase below 350 °C, where volatile dispersion occurs, and a rapid increase phase above 350 °C, marked by significant microstructural changes from micro-fractures to extensive through-going fractures due to intense thermal decomposition. This decomposition leads to increased gas production and enhanced thermal fracturing. The threshold temperature is identified at 400 °C, above which the oil shale's mechanical strength and pore pressure increase, leading to decreased volumetric compression until stabilization. These findings demonstrate that higher temperatures enhance fracture connectivity and steam flow, optimizing the heating efficiency in oil shale extraction.

Effect of Micellar Morphology on the Temperature-Induced Structural Evolution of ABC Polypeptoid Triblock Terpolymers into Two-Compartment Hydrogel Network.

We investigated the temperature-dependent structural evolution of thermoreversible triblock terpolypeptoid hydrogels, namely poly(N-allyl glycine)-b-poly(N-methyl glycine)-b-poly(N-decyl glycine) (AMD), using small-angle neutron scattering (SANS) with contrast matching in conjunction with X-ray scattering and cryogenic transmission electron microscopy (cryo-TEM) techniques. At room temperature, A100M101D10 triblock terpolypeptoids self-assemble into core-corona-type spherical micelles in aqueous solution. Upon heating above the critical gelation temperature (T gel), SANS analysis revealed the formation of a two-compartment hydrogel network comprising distinct micellar cores composed of dehydrated A blocks and hydrophobic D blocks. At T ≳ T gel, the temperature-dependent dehydration of A block further leads to the gradual rearrangement of both A and D domains, forming well-ordered micellar network at higher temperatures. For AMD polymers with either longer D block or shorter A block, such as A101M111D21 and A43M92D9, elongated nonspherical micelles with a crystalline D core were observed at T < T gel. Although these enlarged crystalline micelles still undergo a sharp sol-to-gel transition upon heating, the higher aggregation number of chains results in the immediate association of the micelles into ordered aggregates at the initial stage, followed by a disruption of the spatial ordering as the temperature further increases. On the other hand, fiber-like structures were also observed for AMD with longer A block, such as A153M127D10, due to the crystallization of A domains. This also influences the assembly pathway of the two-compartment network. Our findings emphasize the critical impact of initial micellar morphology on the structural evolution of AMD hydrogels during the sol-to-gel transition, providing valuable insights for the rational design of thermoresponsive hydrogels with tunable network structures at the nanometer scale.

A comparison of heat treatment effect on structural and tribological properties of tungsten rich Ni-W and Ni-W-P alloy coatings

In this paper, thick, metallic bright electrodeposited tungsten rich Ni–W–P alloy coatings with two different compositions Ni-36.3wt%W-3.3wt%P (designated as Ni–W–LP) and Ni-19.5wt%W-7.7wt%P (designated as Ni–W–HP) were chosen for comparison of heat-treatment dependent evolution of crystal structure, grain growth, nanohardness and tribological properties with respect to Ni-50.7wt%W coating. The systematic temperature dependent evolution of crystal structure and phases from as-deposited amorphous alloys were mapped using in-situ high temperature GIXRD investigation and peak-broadening analysis. Subsequent variation of nanohardness/microhardess was measured. Detailed tribological investigation of both as-deposited and heat-treated coatings was done by ball-on-plate dry sliding experiment and the observed coefficient of friction and wear data were correlated with measured nanohardness, H/E and H3/E2 ratio and a wear mechanism was proposed based on detailed FESEM investigation of wear scars.

Temperature and time dependent morphological evolution of solution phase synthesized copper oxide nanostructures

Temperature and time dependent morphological evolution of solution phase synthesized copper oxide nanostructures

Ruddlesden-Popper Oxyfluorides La2Ni1-xCuxO3F2 (0 ≤ x ≤ 1): Impact of the Ni/Cu Ratio on the Thermal Stability and Magnetic Properties.

Ruddlesden-Popper oxyfluorides of the substitution series La2Ni1-xCuxO3F2 (0 ≤ x ≤ 1) were obtained by topochemical fluorination with polyvinylidene fluoride (PVDF) of oxide precursors La2Ni1-xCuxO4. The thermal stability and the temperature-dependent unit cell evolution of the oxyfluorides were investigated by high-temperature XRD measurements. The oxyfluoride with x = 0.6 shows the highest decomposition temperature of θdec ∼ 520 °C, which is significantly higher than the ones found for the end members La2NiO3F2 (x = 0) θdec ∼ 460 °C and La2CuO3F2 (x = 1) θdec ∼ 430 °C. The magnetic properties of all La2Ni1-xCuxO3F2 oxyfluorides were characterized by field- and temperature-dependent measurements as well as DFT calculations of the magnetic ground state. An antiferromagnetic ordering was derived for all substitution levels. For the Néel temperature (TN), a nonlinear dependence on the copper content was found, and comparably high values of TN in the region of 200-250 K were observed in the broad composition range of 0.3 ≤ x ≤ 0.8.

Structural and electrical properties of tetragonal tungsten bronze K4Bi2Nb10O30-Ba4Na2Nb10O30 solid solutions across two proximate phase transitions

Tetragonal tungsten bronzes allow for broader compositional engineering compared to perovskites. Here we investigate solid solutions between Ba4Na2Nb10O30 (BNN) and K4Bi2Nb10O30 (KBiN). A transition from orthorhombic to tetragonal symmetry was observed at 30–35 % KBiN. An expansion of the in-plane and a contraction of the out-of-plane parameter were observed with increasing KBiN content. Ferroelectricity, shown by a maximum in permittivity, was observed up to 20–35 % KBiN, while diffuse dielectric behaviour was exhibited from 40 % KBiN. Non-linear P-E loops are evident up to 35 % KBiN, and vaguely present for 40 % KBiN. The most prominent ferroelectric character, assigned by large remanent polarisation and opening of the strain hysteresis response was exhibited at 35 % KBiN. A ferroelastic-paraelastic phase transition between 30 % and 35 % KBiN and a ferroelectric-paraelectric phase transition around ∼40 % KBiN were inferred. Thus, the two distinct phase transitions mimic the temperature dependent structural evolution observed for BNN.

Emergence of two distinct phase transitions in monolayer CoSe2 on graphene

Dimensional modifications play a crucial role in various applications, especially in the context of device miniaturization, giving rise to novel quantum phenomena. The many-body dynamics induced by dimensional modifications, including electron-electron, electron-phonon, electron-magnon and electron-plasmon coupling, are known to significantly affect the atomic and electronic properties of the materials. By reducing the dimensionality of orthorhombic CoSe2 and forming heterostructure with bilayer graphene using molecular beam epitaxy, we unveil the emergence of two types of phase transitions through angle-resolved photoemission spectroscopy and scanning tunneling microscopy measurements. We disclose that the 2 × 1 superstructure is associated with charge density wave induced by Fermi surface nesting, characterized by a transition temperature of 340 K. Additionally, another phase transition at temperature of 160 K based on temperature dependent gap evolution are observed with renormalized electronic structure induced by electron-boson coupling. These discoveries of the electronic and atomic modifications, influenced by electron-electron and electron-boson interactions, underscore that many-body physics play significant roles in understanding low-dimensional properties of non-van der Waals Co-chalcogenides and related heterostructures.Graphical

Morphological, structural and electronic properties of zinc oxide nano structures deposited on ZnO substrate layer – A theoretical perspective

The work investigates the deposition of zinc and oxygen atoms on a Zinc terminated ZnO substrate, maintaining their stoichiometric ratio (O:Zn) at 0.8, under varying incident energies (0.5 eV and 5 eV) and temperatures (300 K and 700 K) using the ReaxFF potential in Molecular Dynamics (MD) simulation. The study explores the impact of deposition conditions on growth mechanisms, film morphology, and structural parameters such as Radial Distribution Function (RDF) and Coordination Number (CN). RDF analysis highlights disordered atomic arrangements and diverse bonding configurations within the film, with CN showing deviations from perfect crystalline ZnO, indicating non-uniform, non-crystalline, and nano behaviour. Post-heating the films to temperatures approaching the ZnO melting point results in enhanced crystallinity, as evidenced by distinct, dominant, and multiple RDF peaks. Density Functional Theory (DFT) approach of the deposited structures elucidates the formation of ZnO nanoclusters-(ZnO)3 and (ZnO)4 and investigates their electronic structure properties. DFT analysis of the post-heated films reveals the formation of ZnO monomers (ZnO), indicating an approaching crystalline behaviour, yet the films exhibit non-epitaxial and non-uniform characteristics. DFT calculations were instrumental in validating the observed structural behaviours in the deposited films. The study underscores the significance of stoichiometric ratio in film deposition and demonstrates the temperature-dependent evolution of structural properties towards crystallinity, shedding light on the intricate dynamics of ZnO film growth offering tailored control over film properties for enhanced performance in practical applications such as optoelectronics and gas sensing.

Magnetic hyperfine interactions of probe 57Fe atoms within the hexagonal manganite ScMnO3

Here we present the Mössbauer study of the combined magnetic and electrical hyperfine interactions of the probe 57Fe nuclei localized in the hexagonal manganite ScMnO3. The hyperfine interactions were measured in the temperature range where ScMnO3 demonstrates spin ordering: 15 K <T <TN (∼ 130 K). By analyzing the hyperfine parameters of 57Fe nuclei, we evaluated the oxidation state of the iron ions, their local crystal environment, and the orientation of the magnetic moments μFe in the structure of ScMn0.99657Fe0.004O3 at T <<TN. The temperature-dependent evolution of Zeeman structures in Mössbauer spectra was analyzed using the stochastic relaxation model, and indicates the presence of frustration of the superexchange interactions Fe3+−O−Mn3+. The temperature dependence of the hyperfine magnetic field Bhf(T) was described using critical indices, whose values reflect the reduced dimensionality of the magnetic system under study. It was shown that the observed sharp temperature-dependent change of the quadrupole shift of the Zeeman structure components may be attributed to the spin reorientation process, resulting in antiferromagnetism with a weak ferromagnetic component.

A thermoplastic clay constitutive model with temperature dependent evolution of stress anisotropy

This paper presents a thermomechanical constitutive model that captures temperature dependent evolutions of preconsolidation stress and stress anisotropy in normally consolidated and lightly overconsolidated saturated clays. Following a non-associative flow rule, the model was formulated to account for the rate of evolution of stress anisotropy as a function of temperature. A temperature-dependent rotational hardening parameter was introduced and calibrated employing a simple optimization algorithm for four different clays. The developed model was further implemented in a finite element (FE) analysis software for use in boundary value problems. Success of such numerical implementation and predictive performance of the constitutive model was further verified through FE simulations of drained and undrained triaxial tests on saturated clays at reference and elevated temperature. FEA results obtained from these simulations agreed very well with test data reported in the literature.

Enhanced magnetic anisotropy and its thermal stability in obliquely deposited Co-Film on the nanopatterned substrate

The deliberate manipulation of magnetic anisotropy through controlled adjustments to surface and interface morphology has become important due to its potential applications in spintronics and magnetic memory devices. In the present work, oblique angle deposition (OAD) at 65° to the surface normal on a rippled substrate, keeping nanopatterns on the SiO2 substrate perpendicular to the OAD projection, has been used to induce in-plane uniaxial magnetic anisotropy (UMA) and its thermal stability in cobalt (Co) thin film. Prior to film preparation, the patterned substrate of wavelength 68 ± 4 nm and amplitude 3.4 ± 0.2 nm was prepared separately using a low-energy ion beam erosion (IBE) process. Grazing incidence small-angle X-ray scattering (GISAXS) and magneto-optical Kerr effect (MOKE) techniques have been used for film characterization. While GISAXS provided information about film structure and morphology, MOKE provided information about magnetic properties, thus making it possible to correlate the temperature-dependent evolution of morphology with that of UMA in the film. A clear anisotropy in the growth of Co film is found to result in strong UMA. Unlike previous studies, which typically observe a reduction in UMA strength with thermal annealing, the present work demonstrates a 31 % increase in UMA strength after annealing up to 200 °C, underscoring the importance of oblique angle deposition on nano-rippled substrates for achieving high UMA and ensuring its thermal stability up to moderate temperatures. The appearance of large UMA and its unusual temperature dependence is understood in terms of the shadowing effects and column coalescence, resulting in more robust shape anisotropy. This work provides insights into morphological anisotropy, elucidating the interplay of shadowing effects, shape anisotropy, and dipolar interactions within interacting column and ripple structures. This method gives rise to morphology-induced anisotropy, which can also be applied to other ferromagnetic films to enhance the magnetic anisotropy and ensure thermal stability.

Tau-borides (Mnx{Ru,Os,Ir}1-x)23B6: X-ray single crystal and TEM data, physical properties

Investigation (electron microprobe and X-ray powder and single crystal diffraction analyses) of the phase relations in the Mn-rich corner (> 45 at% Mn) of the systems Mn-{Ru,Os,Ir}-B, prompted in all three systems a ternary compound with formula (Mnx{Ru,Os,Ir}1-x)23B6. For the systems Mn-Ru-B, Mn-Ir-B phase equilibria have been determined at 950°C (Ru), 900°C (Ir) revealing in both cases a small homogeneity region at constant B-content (Mn1-xRux)23B6 (0.29 < x < 0.37); (Mn1-xOsx)23B6 (0.33 < x < 0.37), as well as (Mn1-xIrx)23B6 (0.29 < x < 0.34). The crystal structure of the three compounds was determined from single crystal and X-ray powder intensity data analyses to be isotypic with the Cr23B6-type (so-called tau-phase, space group Fm3¯m, No. 225). In all cases Mn atoms fully occupy the 4a site (0,0,0) at the origin of the unit cell. For the 8c site (¼,¼,¼) we observed a random distribution of Mn1-x(PM)x with decreasing PM content (PM stands for a platinum group metal atom) going from Ru to Os and Ir, where Mn atoms fully occupy 8c. Whereas the remaining sites (48h, 32f) show various ratios of the two metal species, boron atoms fully occupy the centers (24e site) of the Archimedean metal atom antiprisms. A transmission electron microscopic study confirms the absence of superstructures related to these metal atom disorder, thus Mn and PM atoms randomly share their sites. The latter is well reflected in the behavior of the electrical resistivity of these compounds, which is dominated by disorder scattering. For (Mn0.6{Ru,Os}0.4)23B6, temperature dependent dc magnetization studies reveal distinct antiferromagnetic-like anomalies at TN ≅ 72 K and 114 K, respectively. Low field dc and ac magnetic susceptibility data of (Mn0.7Ir0.3)23B6 display a distinct ferromagnetic-like transition at TC = 280 K, consistent with a pronounced specific heat anomaly and a rather continuous temperature dependent evolution of magnetic anisotropy effects. Mechanical properties (hardness) characterize the tau phases among rather hard and brittle intermetallics (about 5–6 GPa).

Damage recovery stages revisited: Thermal evolution of non-saturated and saturated displacement damage in heavy-ion irradiated tungsten

Establishing the correlation between damage recovery and temperature in nuclear materials is vital to understanding material property degradation. Among the handful of topics related, one long-standing concern is the differences in damage recovery caused by different initial defect concentrations, with respect to ranges below and beyond the damage saturation limit. In this study, the temperature dependence of damage recovery has been comprehensively elucidated for pure tungsten, irradiated with 6 MeV copper ions at room temperature (RT), up to 0.05 dpa (non-saturated damage, n-SD) and 0.6 dpa (saturated damage, SD), and followed by isochronal annealing. Coupled transmission electron microscopy and Doppler broadening positron annihilation spectroscopy characterizations provided a full-probe-range picture of defect evolution. The varied initial defect concentrations caused retaining differences in damage recovery, but no substantial influence on temperature-dependent defect evolution. Moderate and dramatic damage recovery were identified below 973 K and above 1123 K in n-SD and SD tungsten, respectively. Most strikingly, nano-sized voids were confirmed at 473 K in both samples. Annealing at 1873 K saw the complete removal of defects in n-SD tungsten, but survival of a few dislocations via void pinning in SD tungsten. Full damage recovery in SD tungsten was projected to be ∼2000 K. The current revisit of damage recovery stages demonstrated the significance of encompassing scenarios of non-saturated and saturated defect concentrations. Accordingly, four damage recovery stages were redefined for heavy-ion irradiated tungsten, namely stage I (20 K–RT), stage II (RT–653 K), stage III (653–1123 K), and stage IV (1123–2000 K).

Temperature-dependent evolution of micromagnetic structure of B20-type Fe1-xCoxGe studied by Mössbauer spectroscopy

The non-collinear magnetic structures hosted in magnets with broken central inversion symmetry, some of which are topologically non-trivial, have unique physical properties and application prospects. This paper presents a detailed study of the temperature evolution of the micromagnetic structures of B20-type Fe1-xCoxGe (x = 0, 0.05, 0.10) polycrystalline samples using 57Fe Mössbauer spectroscopy. We take the relatively weak electric quadrupole interaction as a perturbation of the hyperfine magnetic interaction to obtain the distribution of the hyperfine magnetic field Hhf (φ) in the plane perpendicular to the magnetic propagation vector ks. It is found that the geometric features of Hhf (φ) are sensitive to the relative orientation of ks regarding the electric field gradient at the iron nucleus, as well as to the spin texture. The temperature dependence of Hhf (φ) provides a distinct signal of first-order phase transition when ks shifts from [100] to [111]. The doping of cobalt atoms leads to out-of-plane component and in-plane component aggregation of the neighboring iron magnetic moments. These results are instructive for understanding the dynamical behavior of spiral magnets with long-periods.

Control of temperature dependent viscosity for manufacturing of Bi-doped active fiber

Bi-activated photonic materials are promising for various applications in high-capacity telecommunication, tunable laser, and advanced bioimaging and sensing. Although various Bi-doped material candidates have been explored, manufacturing of Bi heavily doped fiber with excellent optical activity remains a long-standing challenge. Herein, a novel viscosity evolutional behavior mediated strategy for manufacturing of Bi-doped active fiber with high dopant solubility is proposed. The intrinsic relation among the evolution of Bi, reaction temperature and viscosity of the glass system is established. Importantly, the effective avenue to prevent the undesired deactivation of Bi during fiber drawing by tuning the temperature dependent viscosity evolution is built. By applying the strategy, for the first time we demonstrate the success in fabrication of heavily doped Bi active fiber. Furthermore, the principal fiber amplifier device is constructed and broadband optical signal amplification is realized. Our findings indicate the effectiveness of the proposed temperature dependent viscosity mediated strategy for developing novel photonic active fiber, and they also demonstrate the great potential for application in the next-generation high-capacity telecommunication system.

Evolution of the pseudogap temperature dependence in YBa2Cu3O7–δ films under the influence of a magnetic field

The evolution of the temperature dependence of the pseudogap Δ*(T) in optimally doped (OD) YBa2Cu3O7–δ (YBCO) films with the superconducting critical temperature Tc = 88.7 K under the influence of a magnetic field B has been studied in detail. It has been established that the shape of Δ*(T) for various B over the entire range from the pseudogap opening temperature T* to T01, below which superconducting fluctuations occur, has a wide maximum at the BEC-BCS crossover temperature Tpair, which is typical for OD films and untwinned YBCO single crystals. T* was shown to be independent on B, whereas Tpair shifts to the low-temperature region along with the increase in B, while the maximum value of Δ*(Tpair) remains practically constant regardless of B. It was revealed that as the field increases, the low-temperature maximum near the 3D-2D transition temperature T0 is blurred and disappears at B &amp;gt; 5 T. Moreover, above the Ginzburg temperature TG, which limits superconducting fluctuations from below, for B &amp;gt; 0.5 T, a minimum appears on Δ*(T) at Tmin, which becomes very pronounced with a further increase in B. As a result, the overall value of Δ*(T) decreases noticeably most likely due to the pair-breaking effect. A comparison of Δ*(T) near Tc with the Peters–Bauer theory shows that the density of fluctuating Cooper pairs actually decreases from ⟨n↑n↓⟩ ≈ 0.31 at B = 0 to ⟨n↑n↓⟩ ≈ 0.28 in the field of 8 T. The observed behavior of Δ*(T) around Tmin is assumed to be due to the influence of a two-dimensional vortex lattice created by the magnetic field, which prevents the formation of fluctuating Cooper pairs near Tc.