Magnetic and Magneto-Caloric Properties of the Amorphous Fe92−xZr8Bx Ribbons

Magnetic and magnetocaloric properties of the amorphous Fe_92−xZr₈B_x ribbons were studied in this work. Fully amorphous Fe₈₉Zr₈B₃, Fe₈₈Zr₈B₄, and Fe₈₇Zr₈B₅ ribbons were fabricated. The Curie temperature (T_c), saturation magnetization (M_s), and the maximum entropy change with the variation of a magnetic field (−ΔS_m^peak) of the glassy ribbons were significantly improved by the boron addition. The mechanism for the enhanced T_c and −ΔS_m^peak by boron addition was studied.     

Re-Examination of the Microstructural Evolution in Undercooled Co-18.5at.%B Eutectic Alloy

The undercooling (∆T) dependencies of the solidification pathways, microstructural evolution, and recalescence behaviors of undercooled Co-18.5at.%B eutectic alloys were systematically explored. Up to four possible solidification pathways were identified: (1) A lamellar eutectic structure consisting of the FCC–Co and Co₃B phase forms, with extremely low ΔT; (2) The FCC–Co phase primarily forms, followed by the eutectic growth of the FCC–Co and Co₂B phases when ΔT < 100 K; (3) As the ΔT increases further, the FCC–Co phase primarily forms, followed by the metastable Co₂₃B₆ phase with the trace of an FCC–Co and Co₂₃B₆ eutectic; (4) When the ΔT increases to 277 K, the FCC–Co phase primarily forms, followed by an FCC–Co and Co₃B eutectic, which is similar in composition to the microstructure formed with low ΔT. The mechanisms of the microstructural evolution and the phase selection are interpreted on the basis of the composition segregation, the skewed coupled zone, the strain-induced transformation, and the solute trapping. Moreover, the prenucleation of the primary FCC–Co phase was also detected from an analysis of the different recalescence behaviors. The present work not only enriches our knowledge about the phase selection behavior in the undercooled Co–B system, but also provides us with guidance for controlling the microstructures and properties practically.     

Synthesis Method and Thermodynamic Characteristics of Anode Material Li3FeN2 for Application in Lithium-Ion Batteries

Li₃FeN₂ material was synthesized by the two-step solid-state method from Li₃N (adiabatic camera) and FeN₂ (tube furnace) powders. Phase investigation of Li₃N, FeN₂, and Li₃FeN₂ was carried out. The discharge capacity of Li₃FeN₂ is 343 mAh g⁻¹, which is about 44.7% of the theoretic capacity. The ternary nitride Li₃FeN₂ molar heat capacity is calculated using the formula C_p,m = 77.831 + 0.130 × T − 6289 × T⁻², (T is absolute temperature, temperature range is 298–900 K, pressure is constant). The thermodynamic characteristics of Li₃FeN₂ have the following values: entropy S⁰₂₉₈ = 116.2 J mol⁻¹ K⁻¹, molar enthalpy of dissolution Δ_dH_LFN = −206.537 ± 2.8 kJ mol⁻¹, the standard enthalpy of formation Δ_fH⁰ = −291.331 ± 5.7 kJ mol⁻¹, entropy S⁰₂₉₈ = 113.2 J mol⁻¹ K⁻¹ (Neumann–Kopp rule) and 116.2 J mol⁻¹ K⁻¹ (W. Herz rule), the standard Gibbs free energy of formation Δ_fG⁰₂₉₈ = −276.7 kJ mol⁻¹.     

Superionic Solid Electrolyte Li7La3Zr2O12 Synthesis and Thermodynamics for Application in All-Solid-State Lithium-Ion Batteries

Solid-state reaction was used for Li₇La₃Zr₂O₁₂ material synthesis from Li₂CO₃, La₂O₃ and ZrO₂ powders. Phase investigation of Li₇La₃Zr₂O₁₂ was carried out by x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) methods. The thermodynamic characteristics were investigated by calorimetry measurements. The molar heat capacity (C_p,m), the standard enthalpy of formation from binary compounds (Δ_oxH_LLZO) and from elements (Δ_fH_LLZO), entropy (S⁰₂₉₈), the Gibbs free energy of the Li₇La₃Zr₂O₁₂ formation (∆_f G⁰₂₉₈) and the Gibbs free energy of the LLZO reaction with metallic Li (∆_rG_LLZO/Li) were determined. The corresponding values are C_p,m = 518.135 + 0.599 × T − 8.339 × T⁻², (temperature range is 298–800 K), Δ_oxH_LLZO = −186.4 kJ·mol⁻¹, Δ_fH_LLZO = −9327.65 ± 7.9 kJ·mol⁻¹, S⁰₂₉₈ = 362.3 J·mol⁻¹·K⁻¹, ∆_f G⁰₂₉₈ = −9435.6 kJ·mol⁻¹, and ∆_rG_LLZO/Li = 8.2 kJ·mol⁻¹, respectively. Thermodynamic performance shows the possibility of Li₇La₃Zr₂O₁₂ usage in lithium-ion batteries.     

Effect of Nickel as Stress Factor on Phenol Biodegradation by Stenotrophomonas maltophilia KB2

This study focuses on the phenol biodegradation kinetics by Stenotrophomonas maltophilia KB2 in a nickel-contaminated medium. Initial tests proved that a nickel concentration of 33.3 mg·L⁻¹ caused a cessation of bacterial growth. The experiments were conducted in a batch bioreactor in several series: without nickel, at constant nickel concentration and at varying metal concentrations (1.67–13.33 g·m⁻³). For a constant Ni²⁺ concentration (1.67 or 3.33 g·m⁻³), a comparable bacterial growth rate was obtained regardless of the initial phenol concentration (50–300 g·m⁻³). The dependence µ = f (S₀) at constant Ni²⁺ concentration was very well described by the Monod equations. The created varying nickel concentrations experimental database was used to estimate the parameters of selected mathematical models, and the analysis included different methods of determining metal inhibition constant K_IM. Each model showed a very good fit with the experimental data (R² values were higher than 0.9). The best agreement (R² = 0.995) was achieved using a modified Andrews equation, which considers the metal influence and substrate inhibition. Therefore, kinetic equation parameters were estimated: µ_max = 1.584 h⁻¹, K_S = 185.367 g·m⁻³, K_IS = 106.137 g·m⁻³, K_IM = 1.249 g·m⁻³ and n = 1.0706.     

Additive Manufacturing of Magnetostrictive Fe–Co Alloys

Fe–Co alloys are attracting attention as magnetostrictive materials for energy harvesting and sensor applications. This work investigated the magnetostriction characteristics and crystal structure of additive-manufactured Fe–Co alloys using directed energy deposition. The additive-manufactured Fe–Co parts tended to exhibit better magnetostrictive performance than the hot-rolled Fe–Co alloy. The anisotropy energy ΔK₁ for the Fe–Co bulk, prepared under a power of 300 W (referred to as bulk−300 W), was larger than for the rolled sample. For the bulk−300 W sample in a particular plane, the piezomagnetic constant d was large, irrespective of the direction of the magnetic field. Elongated voids that formed during additive manufacturing changed the magnetostrictive behavior in a direction perpendicular to these voids. Magnetic property measurements showed that the coercivity decreased. Since sensors should be highly responsive, Fe–Co three-dimensional parts produced via additive manufacturing can be applied as force sensors.     

Reinforcing Increase of ΔTc in MgB2 Smart Meta-Superconductors by Adjusting the Concentration of Inhomogeneous Phases

Incorporating with inhomogeneous phases with high electroluminescence (EL) intensity to prepare smart meta-superconductors (SMSCs) is an effective method for increasing the superconducting transition temperature (T_c) and has been confirmed in both MgB₂ and Bi(Pb)SrCaCuO systems. However, the increase of ΔT_c (ΔT_c = T_c ‒ T_cpure) has been quite small because of the low optimal concentrations of inhomogeneous phases. In this work, three kinds of MgB₂ raw materials, namely, ^aMgB₂, ^bMgB₂, and ^cMgB₂, were prepared with particle sizes decreasing in order. Inhomogeneous phases, Y₂O₃:Eu³⁺ and Y₂O₃:Eu³⁺/Ag, were also prepared and doped into MgB₂ to study the influence of doping concentration on the ΔT_c of MgB₂ with different particle sizes. Results show that reducing the MgB₂ particle size increases the optimal doping concentration of inhomogeneous phases, thereby increasing ΔT_c. The optimal doping concentrations for ^aMgB₂, ^bMgB₂, and ^cMgB₂ are 0.5%, 0.8%, and 1.2%, respectively. The corresponding ΔT_c values are 0.4, 0.9, and 1.2 K, respectively. This work open a new approach to reinforcing increase of ΔT_c in MgB₂ SMSCs.     

Building and Breaking Bonds by Homogenous Nucleation in Glass-Forming Melts Leading to Transitions in Three Liquid States

The thermal history of melts leads to three liquid states above the melting temperatures T_m containing clusters—bound colloids with two opposite values of enthalpy +Δε_lg × ΔH_m and −Δε_lg × ΔH_m and zero. All colloid bonds disconnect at T_n+ > T_m and give rise in congruent materials, through a first-order transition at T_LL = T_n+, forming a homogeneous liquid, containing tiny superatoms, built by short-range order. In non-congruent materials, (T_n+) and (T_LL) are separated, T_n+ being the temperature of a second order and T_LL the temperature of a first-order phase transition. (T_n+) and (T_LL) are predicted from the knowledge of solidus and liquidus temperatures using non-classical homogenous nucleation. The first-order transition at T_LL gives rise by cooling to a new liquid state containing colloids. Each colloid is a superatom, melted by homogeneous disintegration of nuclei instead of surface melting, and with a Gibbs free energy equal to that of a liquid droplet containing the same magic atom number. Internal and external bond number of colloids increases at T_n+ or from T_n+ to T_g. These liquid enthalpies reveal the natural presence of colloid–colloid bonding and antibonding in glass-forming melts. The Mpemba effect and its inverse exist in all melts and is due to the presence of these three liquid states.     

Dissection of the high rate constant for the binding of a ribotoxin to the ribosome

Restrictocin belongs to a family of site-specific ribonucleases that kill cells by inactivating the ribosome. The restrictocin–ribosome binding rate constant was observed to exceed 10¹⁰ M⁻¹ s⁻¹. We have developed a transient-complex theory to model the binding rates of protein–protein and protein–RNA complexes. The theory predicts the rate constant as k_a = k_a0 exp(−ΔG_el*/k_BT), where k_a0 is the basal rate constant for reaching the transient complex, located at the outer boundary of the bound state, by random diffusion, and ΔG_el* is the average electrostatic interaction free energy of the transient complex. Here, we applied the transient-complex theory to dissect the high restrictocin–ribosome binding rate constant. We found that the binding rate of restrictocin to the isolated sarcin/ricin loop is electrostatically enhanced by ≈300-fold, similar to results found in other protein–protein and protein–RNA complexes. The ribosome provides an additional 10,000-fold rate enhancement because of two synergistic mechanisms afforded by the distal regions of the ribosome. First, they provide additional electrostatic attraction with restrictocin. Second, they reposition the transient complex into a region where local electrostatic interactions of restrictocin with the sarcin/ricin loop are particularly favorable. Our calculations rationalize a host of experimental observations and identify a strategy for designing proteins that bind their targets with high speed.     

Processing of Waste from Enrichment with the Production of Cement Clinker and the Extraction of Zinc

This paper presents studies on the processing of enrichment tailings as a component of a raw mixture in order to obtain cement clinker, with simultaneous distillation of zinc. Thermodynamic studies were carried out in the temperature range of 600–1600 °C using the software application “HSC Chemistry 6” developed by the metallurgical company Outokumpu (Finland). As a result of the conducted studies, we found that zinc contributes to the intensification of mineral formation of cement clinker. In particular, it was found that the formation of belite is possible in the temperature range from 990.7 to 1500 °C with Gibbs energy values of −0.01 and −323.8 kJ (which is better than the standard process by −11.4 kJ), respectively; the formation of alite is possible in the temperature range from 982.9 to 1500 °C with Gibbs energy values of −0.05 and −402.1 kJ (better than the standard process by −11.4 kJ), respectively; the formation of tricalcium aluminate is thermodynamically possible in the temperature range from 600 °C at ΔG_T^o = −893.8 kJ to 1500 °C at ΔG_T^o = −1899.3 kJ (better than the standard process by −1570.1 kJ), respectively; and the formation of four calcium aluminoferrite is possible in the temperature range from 600 °C at ΔG_T^o = −898.9 kJ to 1500 °C at ΔG_T^o = −1959.3 kJ (better than the standard process by −1570.2 kJ), respectively, with simultaneous distillation of zinc into a gaseous state for its further capture.     

Thermoelectric Oxide Modules (TOMs) for the Direct Conversion of Simulated Solar Radiation into Electrical Energy

The direct conversion of concentrated high temperature solar heat into electrical energy was demonstrated with a series of four–leg thermoelectric oxide modules (TOM). These temperature stable modules were not yet optimized for high efficiency conversion, but served as proof-of-principle for high temperature conversion. They were constructed by connecting two p- (La_1.98Sr_0.02CuO₄) and two n-type (CaMn_0.98Nb_0.02O₃) thermoelements electrically in series and thermally in parallel. The temperature gradient ΔT was applied by a High–Flux Solar Simulator source (HFSS) which generates a spectrum similar to solar radiation. The influence of the graphite layer coated on the hot side of the Al₂O₃ substrate compared to the uncoated surface on ΔT, P_max and η was studied in detail. The measurements show an almost linear temperature profile along the thermoelectric legs. The maximum output power of 88.8 mW was reached for a TOM with leg length of 5 mm at ΔT = 622 K. The highest conversion efficiency η was found for a heat flux of 4–8 W cm^-2 and the dependence of η on the leg length was investigated.     

Computing protein stabilities from their chain lengths

New amino acid sequences of proteins are being learned at a rapid rate, thanks to modern genomics. The native structures and functions of those proteins can often be inferred using bioinformatics methods. We show here that it is also possible to infer the stabilities and thermal folding properties of proteins, given only simple genomics information: the chain length and the numbers of charged side chains. In particular, our model predicts ΔH(T), ΔS(T), ΔC_p, and ΔF(T) —the folding enthalpy, entropy, heat capacity, and free energy—as functions of temperature T; the denaturant m values in guanidine and urea; the pH-temperature-salt phase diagrams, and the energy of confinement F(s) of the protein inside a cavity of radius s. All combinations of these phase equilibria can also then be computed from that information. As one illustration, we compute the pH and salt conditions that would denature a protein inside a small confined cavity. Because the model is analytical, it is computationally efficient enough that it could be used to automatically annotate whole proteomes with protein stability information.     

Magnetic Anisotropy and Microstructure in Electrodeposited Quaternary Sn-Fe-Ni-Co Alloys with Amorphous Character

Sn-Fe-Ni-Co quaternary alloys, in the composition range of 37–44 at% Sn, 35–39 at% Fe, 6–8 at% Ni and 13–17 at% Co, were prepared by direct current (DC) and pulse plating (PP) electrodeposition. The alloy deposits were characterized by XRD, ⁵⁷Fe and ¹¹⁹Sn conversion electron Mössbauer spectroscopy, SEM-EDX and magnetization measurements. XRD revealed the amorphous character of the quaternary alloy deposits. The dominant ferromagnetic character of the deposits was shown by magnetization and Mössbauer spectroscopy measurements. Room temperature Mössbauer spectra showed minor paramagnetic phases, where their occurrences (~3–20%) are correlated to the electrodeposition parameters (J_dep from −16 to −23 mA/cm² for DC, J_pulse from −40 to −75 mA/cm² for PP), the composition and the saturation magnetization (~52–73 emu/g). A considerable difference was found in the magnetization curves applying parallel or perpendicular orientation of the applied fields, indicating magnetic anisotropy both in DC and pulse plated alloy coatings.     

Study on the Magnetocaloric Effect of Room Temperature Magnetic Refrigerant Material La0.5Pr0.5(Fe1−xCox)11.4Si1.6 and the Effect Arising from Co Doping on Its Curie Temperature

The arc-melting method was adopted to prepare the compound La_0.5Pr_0.5(Fe_1−xCo_x)_11.4Si_1.6 (x = 0, 0.02, 0.04, 0.06, 0.08), and the magnetocaloric effect of the compound was investigated. As indicated by the powder X-ray diffraction (XRD) results, after receiving 7-day high temperature annealing at 1373 K, all the compounds formed a single-phase cubic NaZn₁₃ crystal structure. As indicated by the magnetic measurement, the most significant magnetic entropy change |∆S_M(T)| of the sample decreased from 28.92 J/kg·K to 4.22 J/kg·K with the increase of the Co content under the 0–1.5 T magnetic field, while the Curie temperature T_C increased from 185 K to the room temperature 296 K, which indicated that this series of alloys are the room temperature magnetic refrigerant material with practical value. By using the ferromagnetic Curie temperature theory and analyzing the effect of Co doping on the exchange integral of these alloys, the mechanism that the Curie temperature of La_0.5Pr_0.5(Fe_1−xCo_x)_11.4Si_1.6 and La_0.8Ce_0.2(Fe_1−xCo_x)_11.4Si_1.6 increased with the increase in the Co content was reasonably explained. Accordingly, this paper can provide a theoretical reference for subsequent studies.     

Misfit-Strain Phase Diagram,Electromechanical and Electrocaloric Responses in Epitaxial PIN–PMN–PT Thin Films

xPb(In_1/2Nb_1/2)O₃-(1−x−y)Pb(Mg_1/3Nb_2/3)O₃−yPbTiO₃ (PIN–PMN–PT) bulks possess excellent electromechanical coupling and dielectric properties, but the corresponding epitaxial PIN–PMN–PT thin films have not yet been explored. This paper adopts a nonlinear thermodynamics analysis to investigate the influences of misfit strains on the phase structures, electromechanical properties, and electrocaloric responses in epitaxial PIN–PMN–PT thin films. The misfit strain–temperature phase diagram was constructed. The results reveal that the PIN–PMN–PT thin films may exist in tetragonal c-, orthorhombic aa-, monoclinic M-, and paraelectric PE phases. It is also found that the c-M and aa-PE phase boundaries exhibit a superior dielectric constant ε11 which reached 1.979 × 10⁶ with u_m = −0.494%, as well as the c-M phase boundary showing a large piezoelectric response d₁₅ which reached 1.64 × 10⁵ pm/V. In comparison, the c-PE and M-aa phase boundaries exhibit a superior dielectric constant ε₃₃ over 1 × 10⁵ around um = 0.316% and the piezoelectric response d₃₃ reached 7235 pm/V. The large electrocaloric responses appear near the paraelectric- ferroelectric phase boundary. These insights offer a guidance for experiments in epitaxial PIN–PMN–PT thin films.     

Temperature-memory polymer actuators

Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔT_m) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures T_acts of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter T_sep in a nearly linear correlation. The temperature T_sep divides ΔT_m into an upper T_m range (T > T_sep) forming a reshapeable actuation geometry that determines the skeleton and a lower T_m range (T < T_sep) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors.     

Modulation of Structure and Optical Property of Nitrogen-Incorporated VO2 (M1) Thin Films by Polyvinyl Pyrrolidone

VO₂, as a promising material for smart windows, has attracted much attention, and researchers have been continuously striving to optimize the performance of VO₂-based materials. Herein, nitrogen-incorporated VO₂ (M1) thin films, using a polyvinylpyrrolidone (PVP)-assisted sol–gel method followed by heat treatment in NH₃ atmosphere, were synthesized, which exhibited a good solar modulation efficiency (ΔT_sol) of 4.99% and modulation efficiency of 37.6% at 2000 nm (ΔT_{2000 nm}), while their visible integrated transmittance (T_lum) ranged from 52.19% to 56.79% after the phase transition. The crystallization, microstructure, and thickness of the film could be regulated by varying PVP concentrations. XPS results showed that, in addition to the NH₃ atmosphere-N doped into VO₂ lattice, the pyrrolidone-N introduced N-containing groups with N–N, N–O, or N–H bonds into the vicinity of the surface or void of the film in the form of molecular adsorption or atom (N, O, and H) filling. According to the Tauc plot, the estimated bandgap of N-incorporated VO₂ thin films related to metal-to-insulator transition (E_g1) was 0.16–0.26 eV, while that associated with the visible transparency (E_g2) was 1.31–1.45 eV. The calculated E_g1 and E_g2 from the first-principles theory were 0.1–0.5 eV and 1.4–1.6 eV, respectively. The Tauc plot estimation and theoretical calculations suggested that the combined effect of N-doping and N-adsorption with the extra atom (H, N, and O) decreased the critical temperature (τ_c) due to the reduction in E_g1.     

Magnetic and Magnetostrictive Behaviors of Laves-Phase Rare-Earth—Transition-Metal Compounds Tb1−xDyxCo1.95

The magnetic morphotropic phase boundary (MPB) was first discovered in Laves-phase magnetoelastic system Tb–Dy–Co alloys (PRL 104, 197201 (2010)). However, the composition-dependent and temperature-dependent magnetostrictive behavior for this system, which is crucial to both practical application and the understanding of transitions across the MPB, is still lacking. In this work, the composition-dependence and temperature-dependence of magnetostriction for Tb_1−xDy_xCo_1.95 (x = 0.3~0.8) are presented. In a ferrimagnetic state (as selected 100 K in the present work), the near-MPB compositions x = 0.6 and 0.7, exhibit the largest saturation magnetization M_S and the lowest coercive field H_C; by contrast, the off-MPB composition x = 0.5, exhibits the largest magnetostriction, the lowest M_S, and the largest H_C. Besides, a sign change of magnetostriction is observed, which occurs with the magnetic transition across the MPB. Our results suggest the combining effect from the lattice strain induced from structure phase transition, and the influence of the MPB on magnetocrystalline anisotropy. This work may stimulate the research interests on the transition behavior around the MPB and its relationship with physical properties, and also provide guidance in designing high-performance magnetostrictive materials for practical applications.     

Influence of Cu Content on Structure,Thermal Stability and Magnetic Properties in Fe72−xNi8Nb4CuxSi2B14 Alloys

The effect of substitution of Fe by Cu on the crystal structure and magnetic properties of Fe_72−xNi₈Nb₄Cu_xSi₂B₁₄ alloys (x = 0.6, 1.1, 1.6 at.%) in the form of ribbons was investigated. The chemical composition of the materials was established on the basis of the calculated minima of thermodynamic parameters: Gibbs free energy of amorphous phase formation ΔG^amorph (minimum at 0.6 at.% of Cu) and Gibbs free energy of mixing ΔG^mix (minimum at 1.6 at.% of Cu). The characteristic crystallization temperatures T_x1onset and T_x1 of the alpha-iron phase together with the activation energy E_a for the as-spun samples were determined by differential scanning calorimetry (DSC) with a heating rate of 10–100 °C/min. In order to determine the optimal soft magnetic properties, the wound cores were subjected to a controlled isothermal annealing process in the temperature range of 340–640 °C for 20 min. Coercivity Hc, saturation induction Bs and core power losses at B = 1 T and frequency f = 50 Hz P_10/50 were determined for all samples. Moreover, for the samples with the lowest Hc and P_10/50, the magnetic losses were determined in a wider frequency range 50 Hz–400 kHz. The real and imaginary parts of the magnetic permeability µ′, µ″ along with the cut-off frequency were determined for the samples annealed at 360, 460, and 560 °C. The best soft magnetic properties (i.e., the lowest value of Hc and P_10/50) were observed for samples annealed at 460 °C, with Hc = 4.88–5.69 A/m, Bs = 1.18–1.24 T, P_10/50 = 0.072–0.084 W/kg, µ′ = 8350–10,630 and cutoff frequency at 8–9.3 × 10⁴ Hz. The structural study of as-spun and annealed ribbons was carried out using X-ray diffraction (XRD) and a transmission electron microscope (TEM).