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[Display omitted] Shear thickening of multimodal suspensions has proven difficult to understand because the rheology depends largely on the microscopic details of stress-induced frictional contacts at different particle size distributions (PSDs). Our discrete particle simulations below a critical volume fraction ϕ c over a broad range of shear rates and PSDs elucidate the basic mechanism of order–disorder transition. Around the theoretical optimal PSD (relative content of small particles ζ 1 = 0.26), particles order into a layered structure in the Newtonian regime. At the onset of shear thickening, this layered structure transforms to a disordered one, accompanied by an abrupt viscosity jump. Minor increase in large-large particle contacts after the order–disorder transition causes apparent increase in radial force along the compressional axis. Bidisperse suspensions with less regular but stable layered structure at ζ 1 = 0.50 show good fluidity in the shear thickening regime. This work shows that in inertial flows where particle collisions dominate, order–disorder transition could play an essential role in shear thickening for bidisperse suspensions. [ABSTRACT FROM AUTHOR]

Change of conformation or polarization of molecules is an expression of their functionality. If the two correlate, electric fields can change the conformation. In the case of endofullerene single-molecule magnets the conformation is linked to an electric and a magnetic dipole moment, and therefore magnetoelectric effects are envisoned. The interface system of one monolayer Sc2TbN@C80 on hexagonal boron nitride (h-BN) on Ni(111) has been studied. The molecular layer is hexagonally close packedbut incommensurate. With photoemission the polarization and the conformation of the molecules are addressed by the work function and angular intensity distributions. Valence band photoemission (ARPES) shows a temperature-induced energy shift of the C80 molecular orbitals that is parallel to a change in work function of 0.25 eV without charging the molecules. ARPES indicates a modification in molecular conformations between 30 and 300 K. This order–disorder transition involves a polarization change in the interface and is centered at 125 K as observed with high-resolution X-ray photoelectron spectroscopy (XPS). The temperature dependence is described with a thermodynamic model that accounts for disordering with an excitation energy of 74 meV into a high entropy ensemble. All experimental results are supported by density functional theory (DFT). [ABSTRACT FROM AUTHOR]

We investigated pressure-induced order-disorder transition in the B-site-ordered double perovskite oxide La2CoRuO6. La2CoRuO6 crystallized in a double perovskite structure with rock-salt-type B-site ordering of Co2+ and Ru4+ ions in the sample synthesized under ambient-pressure and high-temperature (1373 K) conditions. The ambient-pressure B-site-ordered phase of La2CoRuO6 underwent phase transition from monoclinic to orthorhombic structure by treating high-pressure and high-temperature conditions of 8 GPa and 1373 K. Structure refinement based on the synchrotron X-ray powder diffraction data demonstrates that the B-site cationic ordering was completely destroyed in the high-pressure phase of La2CoRuO6, accompanied by a slight reduction in lattice volume (ΔV = −0.25%). X-ray absorption spectroscopy revealed that the valence states of Co2+ and Ru4+ were retained in the high-pressure phase, indicating that the primary driving force for the pressure-induced order-disorder transition in La2CoRuO6 is the negative PΔV term in the Gibbs free energy. The order-disorder transition pressure in La2CoRuO6 (8 GPa) was lower than that in isoelectronic oxide Y2CoRuO6 (15 GPa), suggesting that the compressibilities of A-site metal ions play a crucial role in the transition. The high-pressure disordered phase of La2CoRuO6 exhibited a short-range magnetic ordering below 22 K because of the absence of the cationic ordering, whereas the ambient-pressure ordered phase exhibited an antiferromagnetic long-range ordering below 25 K. [ABSTRACT FROM AUTHOR]

Schizophyllan is a high molecular weight β‐1,3‐D‐glucan having three β‐1,3‐D‐glucoses and one branched β‐1,6‐D‐glucose in the repeating unit. It dissolves as a triple helix in aqueous solutions but exhibits two separate order‐disorder transitions: a low temperature cooperative order‐disorder transition (CODT) related mainly to the side chains, and a high temperature transition involving triplex dissociation. The branched side chain can be oxidized selectively by periodate oxidation to form a dialdehyde. Subsequent reactions may produce different kinds of derivatives: a dicarboxylated derivative (sclerox), or a Smith‐degraded (reduced dialdehyde) derivative. These derivatives still dissolve in water as trimers but the CODT may be strongly modified, depending on degree of chemical modification. The CODT behavior is analyzed with linear cooperative transition (LCT) theory. These theoretical analyses indicate that only unmodified units of sclerox and Smith degraded derivatives contribute to the transition enthalpy. With increasing degree of chemical modification, the transition curve broadens and the transition temperature shifts to lower temperatures. This happens because contiguous sequences of ordered structures gradually shorten with increasing degree of chemical modification. Dimethyl sulfoxide and imidazole are further employed to investigate solvent effects of CODT for both schizophyllan and the chemically modified derivatives. These compounds are shown to favorably associate with the unmodified units to stabilize the ordered structures. [ABSTRACT FROM AUTHOR]

The stability of solid-solution phases in FCC and BCC lattices was examined in multi-component alloys based on the CALPHAD technique using the compound energy formalism and regular solution model. From the thermodynamic calculations, it was found in ternary systems that the single solid-solution phase became stable around the equiatomic composition where the configurational entropy was the largest value. The transition temperature from the disordered phase to ordered phase(s) or miscibility gap(s) decreased with the increasing number of elements in the system. The order-disorder transition temperature on the FCC lattice was affected by the end member of the ordered phases existing at the equiatomic composition, whereas it was not significant for the order-disorder transition in the BCC lattice. The single solidsolution phase region at equiatomic compositions was affected by variations in the interaction parameters. In multi-component systems, the variations were averaged with increasing the number of elements in the system. This suggests that high-entropy alloys can afford a variety of elements. This study shows that the disordered state can be formed in multicomponent systems around the equiatomic composition and suggests clearly that due to the high-entropy effect, the solution phases are stabilized. [ABSTRACT FROM AUTHOR]

It has been observed that formation of nanoscale interfacial disordered layers adjacent to grain boundaries of highly ordered grains leads to ultrahigh yield strength accompanied by large tensile ductility of the alloy. We propose a theoretical description and formulate criteria of existence of such layers and present strategies of alloy design based on the proposed theory. [Display omitted] [ABSTRACT FROM AUTHOR]

With the prosperity of high entropy alloys, short-range ordering is getting more and more attentions and regarded as the deciding role in the hardening or softening of solid solutions. In this work, the phase stability and mechanical properties of short-range ordered and disordered body-centered cubic (BCC) structures of W-X solid solutions (X = V, Nb, and Ta) are systematically investigated through a combination of first-principles calculation, cluster expansion and quasi-harmonic Debye formula. Based on the calculated heat of formation (Δ H f ), W-X solid solutions show a strong short-range ordering tendency, as those ordered structures have a lower Δ H f than the disordered ones. Generally, short-range ordering results in the decrease of the shear modulus to bulk modulus ratio (G/B) and hardness for W-V and W-Ta systems, while an increase for W-Nb system, manifesting solid-solution softening and hardening effect, respectively. The short-ranged ordered C11 b W 2 X phase exhibits a singularity in mechanical properties characterized by a higher G/B than solid solution phases compared to other ordered phases. The lattice distortion breaks the symmetric W-W bonds and leads to partial covalency in the W 2 X phases. Besides the increased brittleness, this distortion also causes the increase of ideal strength and the reduction of maximum tensile elongation of W 2 X. The effect of short-range ordering and lattice distortion on the hardening or softening of the W-X systems disappears after the order-disorder transition. The W-V and W-Ta phases have higher order-disorder transition temperature than W-Nb phase. Nevertheless, the transition temperature is relatively low in comparison to their melting points, signifying the important role in controlling the solute concentration at lower temperature. [Display omitted] • Strong short-range ordering tendency was found in W-X (V, Nb, Ta) solid solutions. • Solid-solution softening happens in W-V and W-Ta, while hardening in W-Nb systems. • Singularity in mechanical properties occurs in C11 b W 2 X after lattice distortion. • Ideal strength and electronic structure reveal the abnormal brittleness of C11 b W 2 X. • Order-disorder transition temperature of W-Nb is lower than W-V and W-Ta systems. [ABSTRACT FROM AUTHOR]

The L 1 0 -FePt nanocrystals exhibit unique magnetic and catalytic properties, but suffer from the ordering difficulty. The addition of Cu can facilitate the L 1 0 -FePt ordering for some Fe–Pt–Cu alloys, however, the action mechanism is far from being well understood. In this work, a systematic study has been performed to the phase diagrams of the Fe–Pt–Cu system. The isothermal sections at 600 °C, 750 °C and 1000 °C, as well as the partial vertical sections of Fe 50 Pt 50 –Cu 50 Pt 50 and Fe 50 Pt 50 –Cu, were constructed. An emphasis has been paid to the L 1 0 -FePt phase, which has a wide composition range with a solid solubility of Cu up to 40.0 at% at 600 °C. Its order-disorder transition temperature decreases rapidly when deviating from 54 at% Pt, but at different lower rates along (FePt) 100- x Cu x and (Fe 50- x Cu x)Pt 50 with the increase of Cu. The ternary miscibility gap which originates from the Fe–Cu side has been studied by both experimental determinations and thermodynamic calculations. The results indicate that, at certain low temperatures, for instance 300 °C, the metastable miscibility gap can expand even up to 45 at% Pt, entering the L 1 0 -FePt phase region. An ordering transition mechanism of the L 1 0 -FePt phase stimulating by a two-phase separation was thus proposed. For a specially designed disordered Fe–Pt–Cu alloy, a metastable two-phase separation can take place firstly in the annealing process, driving the Cu atoms forming Cu-rich particles, leaving a large number of vacancies in the alloy, and consequently, accelerate the atomic diffusion and stimulate the subsequent L 1 0 ordering transition. These results will provide a new perspective for the composition design of Fe–Pt–Cu catalysts and magnetic recording media. [Display omitted] • Phase diagrams of the Fe–Pt–Cu system were critically determined. • Effects of Cu addition on the order-disorder transition of L 1 0 -FePt were well described. • Ternary miscibility gap of the Fe–Pt–Cu system in both stable and metastable states was established. • An ordering transition mechanism of L 1 0 -FePt phase stimulating by a two-phase separation was proposed for Fe–Pt–Cu alloys. [ABSTRACT FROM AUTHOR]

In this paper, the (Bi 2 O 3) 1–x–y (Tm 2 O 3) x (Yb 2 O 3) y ternary systems were successfully synthesized by the solid–state reaction method under air conditions. All powder compositions were then heat treated for 100 h at 750 °C to allow for partial substitution of dopant cations, Tm3+ and Yb3+, between host Bi3+ cations. Characterizations of fabricated compositions were carried out by XRD, TG and DTA, FPPT, and FE–SEM techniques. Stacked XRD patterns verified that all compositions included solely single–phase peaks, with the exception of Bi 0.92 Tm 0.04 Yb 0.04 O 1.5–δ and Bi 0.88 Tm 0.04 Yb 0.08 O 1.5–δ , whose patterns suggested mixed phases. The DTA curves, depending on temperature, detected the endothermic peaks at around 600 °C, implying that an order–disorder transition occurs in the anion sublattice of the doped crystal. At 700 °C, the conductivity of the Bi 0.88 Tm 0.08 Yb 0.04 O 1.5–δ system was found to be 0.432 S/cm, surpassing the conductivity of a single–doped (Bi 2 O 3) 0.80 (Er 2 O 3) 0.20 system, which had a value of 0.37 S/cm at the same temperature. • The cubic δ-phase with high ion conductivity became stable in the majority of fabricated compositions. • The magnified XRD patterns indicated a peak shift because of doping. • The DTA curves reveal the endothermic peaks at around 600 °C, signifying an order-disorder transition. • The highest conductivity is found to be 0.432 S/cm at 700 °C for the Bi 0.88 Tm 0.08 Yb 0.04 O 1.5–δ composition. • The order-disorder transition is noticeable on the Arrhenius plots at around 600 °C. [ABSTRACT FROM AUTHOR]

Pursuing novel thermal barrier–coating materials with lower thermal conductivity and high‐temperature stability can simultaneously improve the working efficiency and service temperature of a gas turbine. In this study, a series of high‐entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 (RE = La, Nd, Sm, Gd, Dy, and Er) oxides were prepared though solid‐state reaction. Through tuning the rare‐earth cations, an order–disorder transition occurs from certain partially ordered weberite structure (C2221) to disordered defective fluorite structure (Fm3¯$\bar{3}$m). All the high‐entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides possess low thermal conductivity in the range of 0.91–1.34 W m−1 K−1 at room temperature, which can be attributed to increased lattice anharmonicity and disorder, resulting in additional phonon scattering. Herein, we proved that the incorporation of heterovalent cations at B‐sites in high‐entropy A2B2O7 crystals is an effective strategy to reduce the thermal conductivity without compromising the decrease of oxygen vacancy. Moreover, the high‐entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides show the relatively higher thermal expansion coefficients of 10.3–10.7 × 10−6°C−1 and excellent phase stability at elevated temperatures. [ABSTRACT FROM AUTHOR]

The backbone of the Janus double-brush copolymer may break during long-term service, but whether this breakage affects the self-assembled phase state and microphase transitions of the material is still unknown. For the Janus double-brush copolymers with a periodicity in molecular architecture ranging from 1 to 10, the influences of the architectural periodicity on their phase diagrams and order–disorder transitions (ODT) were investigated by the self-consistent mean field theory (SCFT). In total, nine microphases with long-range order were found. By comparing the phase diagrams between copolymers of different periodicity, a decrease in periodicity or breakage along the copolymer backbone had nearly no influence on the phase diagrams unless the periodicity was too short to be smaller than 3. For copolymers with neutral backbones, a decrease in periodicity or breakage along the copolymer backbone reduced the critical segregation strengths of the whole copolymer at ODT. The equations for the critical segregation strengths at ODT, the architectural periodicity, and the volume fraction of the backbone were established for the Janus double-brush copolymers. The theoretical calculations were consistent with the previous theoretical, experimental, and simulation results. [ABSTRACT FROM AUTHOR]

Single-phase high-entropy alloys with compositionally disordered elemental arrangements have excellent strength, but show a serious embrittlement effect with increasing strength. Precipitation-hardened high-entropy alloys, such as those strengthened by L12-type ordered intermetallics, possess a superior synergy of strength and ductility. In this work, we employ first-principles calculations and thermodynamic simulations to explore the atomic interactions and order–disorder transitions in FeCoNiAl1−xTix high-entropy alloys. Our calculated results indicate that the atomic interactions depend on the atomic size of the alloy components. The thermodynamic stability behaviors of L12 binary intermetallics are quite diverse, while their atomic arrangements are short-range in FeCoNiAl1−xTix high-entropy alloys. Moreover, the order–disorder transition temperatures decrease with increasing Ti content in FeCoNiAl1−xTix high-entropy alloys, the characteristics of order–disorder transition from first-principles calculations are in line with experimental observations and CALPHAD simulations. The results of this work provide a technique strategy for proper control of the order–disorder transitions that can be used for further optimizing the microstructure characteristics as well as the mechanical properties of FeCoNiAl1−xTixhigh-entropy alloys. [ABSTRACT FROM AUTHOR]

Order–disorder transitions are widely explored in various vortex structures in condensed matter physics, that is, in the type‐II superconductors and Bose–Einstein condensates. In this study, the ordering of the polar vortex phase in [Pb(Zr0.4Ti0.6)O3]n/(SrTiO3)n (PZT/STO) superlattices is investigated through phase‐field simulations. With a large tensile substrate strain, an antiorder vortex state (where the rotation direction of the vortex arrays in the neighboring ferroelectric layers are flipped) is discovered for short‐period PZT/STO superlattice. The driving force is the induced in‐plane polarization in the STO layers due to the large tensile epitaxial strain. Increasing the periodicity leads to antiorder to disorder transition, resulting from the high energy of the head‐to‐head/tail‐to‐tail domain structure in the STO layer. On the other hand, when the periodicity is kept constant in short‐period superlattices, the order–disorder–antiorder transition can be engineered by mediating the substrate strain, due to the competition between the induction of out‐of‐plane (due to interfacial depolarization effect) and in‐plane (due to strain) polarization in the STO layer. The 3D ordering of such polar vortices is still a topic of significant current interest and it is envisioned that this study will spur further interest toward the understanding of order–disorder transitions in ferroelectric topological structures. [ABSTRACT FROM AUTHOR]

The order-disorder transitions (ODT) of core-shell bottle brush copolymer and its structural isomers were investigated by dissipative particle dynamics simulations and theoretically by random phase approximation. Introducing a chain topology parameter λ which parametrizes linking points between M diblock chains each with N monomers, the degree of incompatibility at ODT ( (χ N) ODT ; χ being the Flory–Huggins interaction parameter between constituent monomers) was predicted as a function of chain topology parameter (λ) and the number of linked diblock chains per bottle brush copolymer (M). It was found that there exists an optimal chain topology about λ at which (χ N) ODT gets a minimum while the domain spacing remains nearly unchanged. The prediction provides a theoretical guideline for designing an optimal copolymer architecture capable of forming sub-10 nm periodic structures even with non-high χ components. [ABSTRACT FROM AUTHOR]

Unexpected inversion‐symmetry breaking was observed in the order–disorder phase transitions of [M(acac)2(abco)2] (1; M=Co2+, 2; Ni2+, acac−=2,4‐pentanedionato, abco=1‐azabicyclo‐[2.2.2]‐octane=quinuclidine) during heating. The isostructural, transition‐free complexes [M(acac)2(cabco)2] (3; M=Co2+, 4; Ni2+, cabco=3‐chloro‐1‐azabicyclo‐[2.2.2]‐octane=3‐chloroquinuclidine) were also studied for comparison. Complexes 1 and 2 crystallized in ordered phases in the centrosymmetric I2/m space group at 100 K, whereas they crystallized in disordered phases in the non‐symmetric I2 space group at 300 K. The 60° step rotation disordering of the abco ligands was observed in the electron density maps of 1 and 2, which was consistent with the transition enthalpies estimated by differential scanning calorimetry (DSC). Gradual phase transitions were observed for 1 and 2 by DSC and powder X‐ray diffraction (PXRD) at approximately 225 K. The inversion‐symmetry disordering was likely induced by the local pseudo‐symmetry of the abco ligands, increasing from trigonal to hexagonal and the increased steric repulsion pathways among them. [ABSTRACT FROM AUTHOR]

In this work, we study a model of asymmetric two-component lattice fermion system at half-filling, where particles of both species (distinguishable by, e.g., spin) can interact only via nearest-neighbor repulsion W. The analysis is performed on the Bethe lattice using the Hartree-Fock-type mean-field approximation, which is rigorous in the limit of high dimensions. At sufficiently low temperatures, both antiferromagnetic and charge orders (related to inhomogeneous distribution of particles with both spins) coexist in the system. We find that an order-disorder continuous transition occurs with increasing temperature. The transition temperature depends on the ratio t↑/t↓ of the hopping amplitudes of both fermion species (i.e., the asymmetry of the model). For fixed W, it is the biggest if one component is localized (e.g., t↑ = 0), and it decreases to its minimal value for the same hopping amplitudes (t↑ = t↓). Moreover, it increases with W for fixed t↑/t↓. Dependencies of order parameters with model parameters and temperature are also presented. [ABSTRACT FROM AUTHOR]

The ongoing electrification and miniaturization increase the quality demands on solder joints. A bottleneck for solder joint reliability can be the intermetallic Cu6Sn5 phase, which undergoes a phase transition, implying a volume change in a relevant temperature range. There are contradicting reports on the sign and magnitude of this volume change, which possibly implements stresses and cracks in solder joints. To clarify the characteristics of the phase transition, different samples were manufactured by applying industrial-like standards and isothermal heat treatments around the predicted phase transition temperature. Using x-ray diffraction, a coexistence of ordered η′ and disordered η was detected in samples treated at 438–445 K. The lattice parameters show that the volume of the disordered η phase is approximately 0.64–0.65% smaller than the one of the ordered η′ phase. A comparison with order–disorder transitions in structurally related phases shows that the volume change based on order–disorder transitions is normally of opposite sign and around 0.1–0.2%. Therefore, an effect of different compositions is considered responsible for the volume change. Adopting the exact composition Cu6Sn5 (Cu1.20Sn) for the η′ phase, it was estimated, based on density functional theory calculations from the literature, that the coexisting η phase assumes lower Cu content of Cu1.171Sn at 438 K and Cu1.174Sn at 445 K. In contrast, the lattice parameters of η′, generated at different temperatures, imply a largely temperature-independent composition of Cu1.20Sn. This leads to adjustments of the Cu-Sn phase diagram. [ABSTRACT FROM AUTHOR]

The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A1 (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (TC = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin–phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order–disorder transition in LiTaO3. [ABSTRACT FROM AUTHOR]

The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A1 (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (TC = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin–phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order–disorder transition in LiTaO3. [ABSTRACT FROM AUTHOR]

Through high-pressure, small-angle neutron scattering (SANS) and a random-phase approximation (RPA) theory based on a molecular model, we investigate the origin of the pressure responsiveness of a phase-segregating deuterated polystyrene-block-poly (2-ethyl hexyl acrylate) (d PS- b -PEHA) copolymer melt for use as a material for low-energy processing. The SANS intensities for the copolymer were measured over a temperature range at applied pressures between 0.1 and ∼83 MPa. The copolymer exhibited an order-disorder transition (ODT) and revealed baroplasticity, where its ODT was suppressed upon pressurization as Δ T O D T / Δ P ≈ -15.8 K/100 MPa to ease subsequent processing. Theory predicts that a disparity in the self interactions ε j j 's (Δ ε j j = ε P S − ε P E H A ) or a disparity in the compressibilities between blocks precisely yields the observed Δ T O D T / Δ P. The effective Flory-Huggins χ is argued to consist of the conventional enthalpic χ H and entropic χ S coming from Δ ε j j mediated by the copolymer bulk modulus. Pressure strengthens χ H due to densification, whereas the augmented bulk modulus reduces χ S. The diminution of χ S is shown to be the source of baroplasticity. Image 104 • Pressure response of a phase-segregating diblock copolymer melt is probed via high pressure small-angle neutron scattering. • Baroplasticity in the copolymer melt is investigated through a RPA theory combined with a molecular equation of state. • Observed baroplasticity is caused by disparity in self energies and the suppression of entropic part of c upon pressurization. [ABSTRACT FROM AUTHOR]

In this paper, Ce–Ho–Tb co–doped Bi 2 O 3 compositions were developed using the solid–state reaction method under atmospheric conditions. The XRD patterns confirm the stability of the cubic δ–phase in Ho and Tb–rich compositions but not in the Ce–rich ones, which consist of mixed phases, such as α and β. Peak shifting is additionally apparent in the magnified XRD diagram of primary peaks regarding the (111) diffraction plane, suggesting that the structural features change with doping. At 700 °C, the highest conductivity is found to be 0.30 S/cm for the composition 8Ce4Ho4Tb, and it is comparable to the single–doped (Bi 2 O 3) 0.80 (Er 2 O 3) 0.20 system at the same temperature. The FE–SEM images show the aggregation, particularly in images of Ce–rich compositions, implying that large cations have difficulty penetrating the lattice. The porosity over the surface is dense, particularly for Tb–rich compositions, indicating a decline in conductivity with doping. The cubic δ–phase of Bi 2 O 3 crystal, an excellent ion conductor, is capable of being stabilized at room temperature in Ho-rich compositions. Arrhenius plots of conductivity clearly show that the content ratios of 1:2:1, which is a specific ratio, play a key role in achieving the highest conductivity stable Bi 2 O 3 electrolytes. [Display omitted] • A high ion conductor, δ-Bi 2 O 3 phase was effectively stabilized in Ho and Tb-rich compositions. • The highest conductivity was determined to be 0.30 S/cm, which is greater than 20ESB electrolyte. • In several compositions, the order-disorder transition on the Arrhenius plots is noticeable. • The FE-SEM pictures revealed a local aggregation on the surface, particularly in the Ce-rich specimens. [ABSTRACT FROM AUTHOR]

Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics were synthesized using conventional solid-state reaction. The effect of densification annealing treatments on microstructures and microwave dielectric properties of Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics have been investigated. The ordered of B-site zirconolite structures were obtained after a long-time annealing. The order-disorder transition contributes to enhance the microwave dielectric properties of Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics. The ceramics sintered at 980 °C exhibit a large permittivity of 75 and a Qf value of 3000 GHz. The most efficient annealing treatment which induced a≈100% improvement of Qf value was obtained in the samples annealed at 890 °C for 24 h, while the permittivity remain stable. As the annealing temperature increased to 930 °C, the Qf value abruptly decreased. The microwave dielectric properties of Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics are affected by the enhancement of cation order and the reduction of crystal defect. An excellent microwave dielectric properties Qf ≈ 6300 GHz, ε ≈ 76 and τ f  ≈ 189 ppm/°C was obtained when the ceramic was annealed at 890 °C for 24 h. [ABSTRACT FROM AUTHOR]

The relation between metal order-disorder and magnetic properties in the solid solution Hf 1– x Ti x MnSb 2 (0 ≤  x  ≤ 1) with the NiAs structure is investigated. The synchrotron X-ray diffraction studies have revealed that two-dimensional (2D) metal-ordered structure in HfMnSb 2 persists up to x  = 0.15, though its degree of metal order decreases with x . Although the NiAs-like phase is not formed for 0.2 ≤  x  ≤ 0.3, a metal disordered phase appears for x  ≥ 0.4. A conical spin order is only found in the metal-ordered region and is fairly robust against partial cation disorder, while the completely metal-disordered region is a ferromagnetic state, providing firm evidence that the presence/absence of metal order essentially defines the ground state. Neutron depolarization measurement for HfMnSb 2 suggests possible successive phase transitions. [ABSTRACT FROM AUTHOR]

The crystal structure and dielectric properties of TiO2-modified Ca[(LiNb)Sn]O microwave ceramics are investigated in the present paper. The crystal structure is probed by XRD patterns and their Rietveld refinement, results show that a single perovskite phase is formed in TiO2-modified Ca[(LiNb)Sn]O ceramics with the crystal structure belonging to the orthorhombic Pbnm 62 space group. Raman spectra results indicate that the -site order-disorder structure transition is a key point to the dielectric loss of TiO2-modified Ca[(LiNb)Sn]O ceramics at microwave frequencies. After properly modified by TiO2, the large negative temperature coefficient of Ca[(LiNb)Sn]O ceramic can be compensated and the optimal microwave dielectric properties can reach = 25.66, = 18,894 GHz and TCF = −6.3 ppm/C when sintered at 1170C for 2.5 h, which manifests itself for potential use in microwave dielectric devices for modern wireless communication. [ABSTRACT FROM AUTHOR]

Schizophyllan and scleroglucan are water-soluble polysaccharides having repeating units consisting of three β-1,3-linked glucose residues in the main chain and a single β-1,6-linked glucose residue as the side chain. This polysaccharide dissolves as a triple helix in an aqueous solution and shows a cooperative order-disorder transition between the side chain and solvent molecules while retaining the triple helical conformation. Periodate and subsequent chlorite oxidations selectively modify the side chain glucose to provide the corresponding dicarboxylate units. Optical rotation measurements and differential scanning calorimetry were performed on carboxylated schizophyllan/scleroglucan (‘sclerox’) samples to investigate the effects of the degree of carboxylation on the order-disorder transition in deuterium oxide with 0.1 M NaCl. The transition curves for the sclerox samples are strongly dependent on the degree of carboxylation. The modified side chains cannot take the ordered structure, resulting in a reduction of the transition enthalpy. The transition temperature for carboxylated schizophyllan becomes lowered and the transition curve broadens with increasing the degree of carboxylation. The permanent disordered units are included in a trimer by the carboxylation to inhibit a long sequence of the ordered units. [ABSTRACT FROM AUTHOR]

In this work the Cu/Zn order-disorder transition in Cu 2 ZnSnS 4 kesterites on Wyckoff positions 2c and 2d was investigated by a structural and electronic analysis in theory and experiment. For experimental investigations stoichiometric samples with different Cu/Zn order, annealed in the temperature range of 473–623 K and afterwards quenched, were used. The optical gaps were determined using the Derivation of Absorption Spectrum Fitting (DASF) method. Furthermore, the order-disorder transition was examined by DFT calculations for a closer analysis of the origins of the reduced band gap, showing a good agreement with experimental data with respect to structural and electronic properties. Our studies show a slight increase of lattice parameter c in the kesterite lattice with increasing disorder. Additionally, a reduced band gap was observed with increasing disorder, which is an effect of newly occurring binding motifs in the disordered kesterite structure. [ABSTRACT FROM AUTHOR]

A Rietveld analysis of neutron powder diffraction patterns obtained in situ during temperature scans shows that Fe 2 VAl crystallizes at room temperature in the fully ordered L 2 1 structure and transforms at 1080 °C and at 1190 °C into partially disordered B 2 and fully disordered A 2 variants respectively. The low temperature stability of the L 2 1 structure as well as the two high temperature L 2 1 → B 2 → A 2 transitions are theoretically predicted by a combination of ab-initio (electronic structure and phonons) and thermodynamic calculations performed on special quasi-random structures. Pronounced cold work effects and the pre-transitional antisite defects which are observed respectively at 25 °C under mechanical stress and at high temperature (above 800 °C), appear to be generic effects in the family of Heusler alloys. [ABSTRACT FROM AUTHOR]

In this work a series of stoichiometric Cu 2 ZnSnS 4 (CZTS) samples annealed at different temperatures in the range of 473–623 K were investigated. The temperature dependence of the Cu/Zn-order-disorder behavior was analyzed by neutron powder diffraction measurements. Cu fully occupies the 2a and Sn the 2b position within the whole temperature range. For Zn and the remaining Cu on sites 2d and 2c, a clear change from ordered to disordered kesterite structure is found. The critical temperature T c for this Landau-type second order transition was determined as 552±2 K. It was found that in Cu 2 ZnSnS 4 very long annealing times are necessary to reach equilibrium at low temperatures. [ABSTRACT FROM AUTHOR]

The conductivity plots of the disc-shaped pallet samples are almost linear, consistent with the Arrhenius equation, and an increase in total dopant concentration leads to a decrease in conductivity. [Display omitted] • High–temperature conductivity tests (>700 °C) can have an impact on the cubic δ–phase stability. • To achieve highest conductivity, the dopant concentration should be kept as low as possible. • The order–disorder transition was observed in the samples 5Tb10Gd5Sm and 5Tb5Gd15Sm. • The highest conductivity was found to be 0.07 S/cm at 750 °C with a dopant content ratio of 2:1:1. In this study, the effects of a triple doping strategy on the microstructure and electrical conductivity of Tb–Gd–Sm co–doped Bi 2 O 3 systems were investigated. The XRD patterns generated after the conductivity measurements confirm that high–temperature conductivity tests (>700 °C) can help to stabilize the cubic δ–phase by creating a secondary annealing effect. At about 730 °C, the phase transition (α → δ) is noticeable on both the DTA curve and the conductivity plot of the sample 5Tb5Gd5Sm. The order–disorder transition is recognizable in samples 5Tb10Gd5Sm and 5Tb5Gd15Sm, resulting in two distinct conductivity regions. At 750 °C, the sample 10Tb5Gd5Sm has the highest conductivity of 0.0758 S/cm as well as the lowest activation energy of 0.27 eV. [ABSTRACT FROM AUTHOR]

The phase behavior in relatively low-molecular-weight poly( ε -caprolactone)-poly(butadiene) diblock copolymers (PCL-PB) were investigated using small angle X-ray scattering (SAXS). The temperature dependence of χ was determined from the curve fitting of SAXS profiles using random phase approximation in the disordered state. The phase diagram for PCL-PB was constructed. Generally, according to Fredrickson-Helfand theory, the product ( χN ) ODT , where N is the degree of polymerization and χ is the Flory–Huggins interaction parameter at the order-disorder transition temperature, is considered to be shifted toward upper side in phase diagram due to the existence of fluctuation. However, in PCL-PB, the significant increase of ( χN ) ODT was not apparently observed. In order to compare ( χN ) ODT values with theoretical and many experimental studies, we calculated ( χN ) ODT which was obtained from 19 earlier reports. We picked out 69 samples which formed lamellae morphology and had nearly symmetric composition. In the region of relatively low-molecular-weight, it was found that the increase of ( χN ) ODT was not clearly seen in the almost all of investigated articles. [ABSTRACT FROM AUTHOR]

Abstract: Based on the amorphization of zeolites, an order–disorder transition method was used to prepare silica glass via Spark Plasma Sintering (SPS). In order to get a better understanding about the mechanism of amorphization induced by SPS, the intermediate products in this process were prepared and characterized by different characterization techniques. X-ray diffraction and High-energy synchrotron X-ray scattering show a gradual transformation from ordered crystal to glass. Local structural changes in glass network including Si–O bond length, O–Si–O bond angle, size of rings, coordination were detected by Infrared spectroscopy and 29Si magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. Topologically ordered, amorphous material with a different intermediate-range structure can be obtained by precise control of intermediate process which can be expected to optimize and design material. [Copyright &y& Elsevier]

The Fe−Pt intermetallic nanocrystals exhibit good chemical stability, unique magnetic and catalytic properties, but suffer from the ordering difficulty. It has been found that the addition of Au can promote the disorder-order transitions, but the mechanism is far from being well understood. In this work, the phase equilibria and phase transformations of the Fe−Pt−Au alloys have been experimentally investigated and thermodynamically analyzed. The results show that the driving forces for both the L 1 0 _FePt and L 1 2 _FePt 3 ordering are so weak that the homogeneous nucleation in the disordered fcc matrix is difficult, while a heterogeneous nucleation mechanism on the pre-existed phase boundary is preferred. On the other hand, there exists a metastable ternary miscibility gap between αAu and fcc-FePt or fcc-FePt 3 , and accordingly, when Au content is properly designed in the spinodal region, the enrichment of Au can take place spontaneously throughout a fcc Fe−Pt−Au structure during annealing. The segregation of αAu in the Fe−Pt−Au alloys can further accelerate the diffusion of Pt and Fe atoms, facilitate the nucleation of the ordered L 1 0 _FePt and L 1 2 _FePt 3 phases, and stimulate the ordering process. These results correlate the Au addition with the ordering of Fe−Pt intermetallics and further the magnetic and catalytic properties, and it is thus expected to provide guidance for a rational alloy design of Fe–Pt–Au materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• A reversible redox-induced order-disorder transition (ODT) is discovered. • A 10-component single-phase ordered pyrochlore oxide is stable at 1600 °C in air. • Reduction at 1600 °C induces an ODT to form single-phase disordered fluorite oxide. • Re -oxidation at 1600 °C reverses the ODT to form single-phase ordered pyrochlore. • In-situ neutron diffraction reveals the mechanism of oxygen vacancy induced ODT. This study discovers a reversible order-disorder transition (ODT) in a 10-component compositionally complex ceramic, (Nd 0.15 Pr 0.15 Dy 0.8 Ho 0.8 Er 0.8 Ti 0.2 Yb 0.1 Hf 0.1 Zr 0.1 Nb 0.8)O 7-δ , induced via annealing in oxidized vs. reduced environments at 1600 °C. Notably, the 10-cation oxide remains a homogenous single-phase high-entropy solid solution before and after the ODT in the pyrochlore vs. fluorite structure that can be quenched. In-situ neutron diffraction reveals the oxygen vacancy formation and atomic displacement during this ODT. This study reveals a new pathway to induce ODT via a redox transition to tailor the properties of compositionally complex fluorite-based oxides. [Display omitted] [ABSTRACT FROM AUTHOR]

Atomic ordering in bcc and hcp TiAl+Mo alloys near equiatomic TiAl composition is investigated by different ab initio tools. We show that small addition of Mo, about 5 at. %, is enough to make bcc alloys with more than 50 at. % of Ti stable with respect to the hcp alloys. Moreover, such alloying also leads to stabilizing the B2 ordered structure with respect to its B2 2 modification, which is the bcc-based ground state structure of binary TiAl. The site preference of Mo in the B2 and B19 ordered alloys is investigated by different methods: in the dilute limit, using the transfer energy formalism; in concentrated alloys, from the total energies of disordered and partially ordered alloys in the mean-field coherent potential approximation; and from Monte Carlo simulations. These methods produce consistent results for the B2 phase predicting a strong preference of Mo to Al sublattice. The site preference of Mo in the B19 phases varies from a weak preference for Al sites in the single impurity calculations to a quite strong preference for Ti sites in the mean-field approximation and finally to a strong Al preference in Monte Carlo simulations. Mo alloying dramatically increases the order–disorder transition temperatures in bcc and hcp Al-deficient Ti 0.5 Al 0. 5 − x Mo x alloys. • The system shows long-ranged and strong composition-dependent effective interactions. • Mo shows a strong preference for the Al site in the B2 structure. • Adding a small amount of Mo in bcc Ti-rich compositions stabilizes the B2 phase. • The ordered phase of hcp binary TiAl is the B19 structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of fluorination on VPLi cathode investigated for the first time. • V4+ content is ranged from 16.3% to 23.8%. • VF 4 and Li 3 VF 6 converted into LiVP 2 O 7 increasing specific capacity. • The charge transfer from Li to O contributed to the cycle stability. Vanadium-based amorphous materials are an emerging category of lithium ion battery cathodes with high specific capacity and high voltage performance. In this study, we investigated the effect of fluorination on the performance of an amorphous vanadium-phosphorus-lithium (VPLi) cathode for lithium ion battery applications. Results show that the fluorinated product consists Li 3 VF 6 and VF 4 nanocrystals embedded in an amorphous phase when the V4+ content was in the range of 16.3% to 23.8%. VPFLi has an optimal specific capacity of 344.3 mAh g−1 in the first cycle and 269.7 mAh g−1 after 200 cycles at a current of 50 mA g−1 within the voltage range of 1.5–4.2 V. VPLi has an amorphous structure, and the reversible V4+/V5+ lithiation process corresponds to the conversion between V 2 O 5 and Li 2 V 2 O 5 during the charge–discharge cycle. Compared to VPLi, VF 4 and Li 3 VF 6 crystals were found to convert into LiVP 2 O 7 in VPFLi, which led to the increased specific capacity. Simulation based on density functional theory show that fluorine for oxygen has led to the movement of Fermi level moves towards the edge of the conduction band. Charge mostly transferred from Li to O which contributed to the improved cathode stability. This study provides a new perspective towards selecting novel cathode for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The influence of high-pressure (HP) treatment (300–600 MPa) on the rheological behavior of xanthan gum (XG) dispersions was studied at ambient temperature. The pressure-treated samples were thereafter isothermally heated in situ in a rheometer to include the thermal effect on the oscillatory rheology. The main objective of this work was to study the influence of three independent variables, namely concentration (0.75, 1 and 1.25%), pressure (0.1, 300 and 600 MPa), and temperature (40, 55 and 70 °C) on the maximization of the oscillatory rheological moduli (G′, G″ and η*) of xanthan gum using central composite design (CCD) method. The developed quadratic regression model indicated that all the linear, two quadratics (concentration and temperature), and two interactions (concentration-pressure and concentration-temperature) terms were significant (P < 0.05) for oscillatory moduli (R 2 = 0.99) and insignificant lack-of-fit. The mechanical rigidity produced by the pressure was higher than the thermally treated xanthan, which needs further in-depth structural analysis to confirm the pressure-assisted order-disorder transition. Both the time-pressure and time-temperature superposition principles were fitted well for the HP-treated xanthan dispersions. [Display omitted] • Rheology of High-pressure-treated xanthan gum were investigated using RSM design. • The concentration and temperature influenced the oscillatory moduli significantly. • Pressure-temperature resulted in a higher rigidity than the thermally-treated dispersions. • The pressure assisted higher moduli could be associated with the order-disorder transition. • The superposition principle fitted well for both the pressure and temperature with frequency. [ABSTRACT FROM AUTHOR]

Order-disorder transition of 1-adamantane-methanol compound at 271 K has been studied by Raman spectroscopy as function temperature. The assignment of all frequencies modes in the experimental spectrum have been realized by the calculated frequencies and intensities with LanL2DZ basis sets. The all O H vibrations modes are identified, the evolution of the Raman spectrum as function of temperature prove the change of these modes near the T c transition. The thermal coefficient (γ) determined in two phases and the decrease of the activation energy with the increase of the temperature indicates the structural transformation attributed to an order-disorder phase transition. [ABSTRACT FROM AUTHOR]

• A series of single-phase duodenary high-entropy oxides are synthesized. • An order-disorder transition occurs with changing composition. • Increased modulus-to-thermal conductivity ratios from the rule of mixture. • Unexpected increases in Young's modulus at low doping levels. • Temperature-dependence reveals ultralow glass-like thermal conductivity. Improved thermomechanical properties have been reported for various high-entropy oxides containing typically five metal cations. This study further investigates a series of duodenary (11 metals + oxygen) high-entropy oxides by mixing different fractions of a five-cation fluorite-structured niobate and a seven-cation pyrochlore (both containing Yb) with matching lattice constants. Nine compositions of duodenary high-entropy oxides have been examined. All of them exhibit single high-entropy phases of either disordered fluorite or ordered pyrochlore structure. An order-disorder transition (ODT) is evident with changing composition, accompanied by a reduction in thermal conductivity (k). In comparison with the ODT criteria developed from ternary oxides, these duodenary oxides are more prone to disorder, but the ODT is still controlled by similar factors (but at different thresholds). Interestingly, there are abrupt increases in Young's modulus (E) at low mixing concentrations near both endmembers. The E / k ratios are increased, in comparison with both endmembers. This study suggests a new route to tailor high-entropy ceramics via controlling cation ordering vs. disordering. [Display omitted] [ABSTRACT FROM AUTHOR]

The work reports a comprehensive study of the Seebeck coefficient, electrical resistivity and heat capacity of CuCrS2 in a wide temperature range of 100–740 K. It was shown that the value of the Seebeck coefficient is significantly affected by the sample treatment procedure. The order-to-disorder (ODT) phase transition was found to cause a metal-insulator transition (MIT). It was established that the ODT diminishes the Seebeck coefficient at high temperatures (T > 700 K). The DFT calculations of the CuCrS2 electronic structure showed that the localization of copper atoms in octahedral sites makes the band gap vanish due to the MIT. The decrease of CuCrS2 electrical resistivity in the ODT temperature region corresponds to the MIT. [ABSTRACT FROM AUTHOR]

Coordination chemistry, inversion symmetry breaking, molecular rotation, order-disorder transition Keywords: coordination chemistry; inversion symmetry breaking; molecular rotation; order-disorder transition EN coordination chemistry inversion symmetry breaking molecular rotation order-disorder transition 3889 3889 1 02/26/21 20210224 NES 210224 B A kind of "street art lab-journal" on a graffiti wall b is depicted in the cover image. Cover Feature: Inversion Symmetry Breaking in Order-Disorder Transitions of Globular Ligands Coordinating to Cobalt(II) and Nickel(II) Bisacetylacetonato Complexes During Heating (Chem. Eur. J. 12/2021). [Extracted from the article]

• A novel data-driven approach to study the thermodynamics of HEAs is introduced. • Accurate effective Hamiltonians are obtained, with test errors less than 0.1 mRy. • Two major order-disorder transitions are identified and their origin are revealed. • Possible explanation to the temperature dependence of strength and ductility in HEAs. High entropy alloys (HEAs) are a series of novel materials that demonstrate many exceptional mechanical properties. To understand the origin of these attractive properties, it is important to investigate the thermodynamics and elucidate the evolution of various chemical phases. In this work, we introduce a data-driven approach to construct the effective Hamiltonian and study the thermodynamics of HEAs through canonical Monte Carlo simulation. The main characteristic of our method is to use pairwise interactions between atoms as features and systematically improve the representativeness of the dataset using samples from Monte Carlo simulation. We find this method produces highly robust and accurate effective Hamiltonians that give less than 0.1 mRy test error for all the three refractory HEAs: MoNbTaW, MoNbTaVW, and MoNbTaTiW. Using replica exchange to speed up the MC simulation, we calculated the specific heats and short-range order parameters in a wide range of temperatures. For all the studied materials, we find there are two major order-disorder transitions occurring respectively at T 1 and T 2 , where T 1 is near room temperature but T 2 is much higher. We further demonstrate that the transition at T 1 is caused by W and Nb while the one at T 2 is caused by the other elements. By comparing with experiments, the results provide insight into the role of chemical ordering in the strength and ductility of HEAs. [ABSTRACT FROM AUTHOR]

Photoluminescence spectroscopy of Cr3+ shows considerable potential for probing local cation arrangement in MgAl 2 O 4 spinel while undergoing order-disorder phase transition. The PL spectrum consists of R peaks (caused by ordered PL centers) and N peaks (caused by disordered PL centers). The peak dominating in the PL spectra dramatically switched from R peaks to N peaks around 850 °C and showed rather few changes above 900 °C. We defined the percent ratio of the integrated area of N peaks to the total integrated area under all peaks as a parameter to monitor the degree of disordering. This parameter can quantitatively indicate the variation of neighboring atom arrangement around Cr3+ during the order-disorder transition. A thermodynamic model based on this spectroscopic parameter can be built, and we can model the transition with an activation energy of 254 ± 49 kJ/mol. This study also attempted to determine the ability to restore the ordering of heated spinels by annealing them at 650 °C up to 8 days. Our results clearly indicated that the spectra cannot be fully restored back to the ordered state within our experimental time span, thus makes PL spectroscopy a reliable method to distinguish natural spinel from heated ones. • Photoluminescence spectroscopy. • Local order-disorder transition of MgAl2O4: Cr3+. • New parameter. • Spectroscopic model. [ABSTRACT FROM AUTHOR]

In the process of heating, atomic thermal motion causes an increase in Cu or Zn anti-sites and the degree to which atoms randomly occupy sublattices. The disordered solid solution can be separated into partially disordered and fully disordered solid solutions, and the transition from a fully ordered structure to a fully disordered structure of the solid solution should occur as an evolutionary process of atoms that randomly occupy sublattices to different degrees. In this paper, the concept of "disorder degree" is proposed, and a pseudo-atomic lattice inversion potential method is used to simulate the order to disorder transition of CuZn solid solution. The potential parameters can be obtained using density functional theory (DFT) calculation and Chen's lattice inversion method. The results indicate that the lattice distortion exhibits a quadratic relationship in which the disorder degree weakens the cohesive energy in the order-disorder transition process. The calculated vibrational entropy difference between the fully ordered B 2 and fully disordered A 2 CuZn solid solution is 0.24 k B /atom. Furthermore, a new pseudo-atom γ -(Zn or Cu) system is built to calculate the thermodynamic properties of a non-stoichiometry Cu-Zn alloy system, and the results show that the vibrational entropy, specific heat capacity, and bulk modulus exhibit an approximately linear change with Zn concentration. The vibrational entropy and bulk modulus are sensitive to the phase transition, and the slope mutation facilitates the determination of the phase boundary. The order-disorder transition of the solid solution can be treated as an evolutionary process of atoms that randomly occupy sublattices to different degrees. Image 1 [ABSTRACT FROM AUTHOR]

High-temperature Raman spectroscopic study of order-disorder transition in Pentaerythritol [C(CH 2 OH) 4 is reported. The changes in the Raman spectra with increasing temperature have been followed up to ≈503 K. We observe several changes in the spectra including merging of modes, appearance of new modes and sudden change in the slope of the frequency vs temperature curve at ≈ 452 K. In addition, sudden enormous broadening of almost all the modes are noted at ≈ 452 K indicating order-disorder transition of first order in nature. The transition has been found to be completely reversible. • PET, a hydrogen bonded solid, is known for its immense applications in thermal energy storage systems. • A detailed Raman scattering high temperature study on PET revealed significant changes in the spectrum. • Behaviour of the hydrogen bonds responsible for an order disorder transition at around 452 K was observed and reported. [ABSTRACT FROM AUTHOR]

Electron Paramagnetic Resonance is a spectroscopic technique which, in combination with site-directed spin-labeling, provides structural and dynamic information about proteins in conditions similar to those of their physiological environment. The information is sequence-resolved, as it is based on probing the local dynamics of a paramagnetic label incorporated as a side chain of a selected amino acid. EPR does not impose a limit on the size of the protein or protein complex, as long as it is amenable to site-directed mutagenesis, and is able to obtain reliable distance distributions between two or more labels (identical or different).. The mean value, width and shape of distance distributions, as well as their dependence upon the state of the protein or interactions with physiological partners, provide insight into order-disorder transitions and the roles of protein flexibility. The main potentialities and limitations of the technique are revised and illustrated with examples of proteins for which order-disorder play an important role. • Electron Paramagnetic Resonance reports on local protein flexibility and disorder. • Site-Directed Spin-Labeling and EPR are used to assess back-bone dynamics. • DEER obtains distance distributions between spin labels in disordered proteins. • Changes in EPR spectra inform about order-disorder transitions in proteins. • Integrating data and modeling tools provide structural and dynamic models for IDPs. [ABSTRACT FROM AUTHOR]

The γ-cyclodextrin polymer (γ-CDP) and carboxymethyl-γ-cyclodextrin polymer (CM-γ-CDP) cross-linked both by epichlorohydrin were investigated via dielectric spectroscopy over the frequency range 0.1–100 kHz and the temperature ranges 122.0–472.4 K and 123.6–460.3 K, respectively. The γ-CDP reveals a thermally reversible transformation of some normal hydrogen bonds to flip-flop type at T trans = 199.1 K, whereas the CM-γ-CDP doesn't show any transformation of hydrogen bonds. Both systems present in the lnσ vs 1/T plot two linear parts following the Arrhenius equation. In the case of γ-CDP, the first linear part during cooling (a) has activation energy E α = 0.41 eV and during heating (b) has E α = 0.42 eV in the range 259.7–310.0 K. The second linear part (c) in the range 316.5–357.1 K has E α = 0.36 eV. The corresponding values of CM-γ-CDP are E α = 0.32 eV (a), E α = 0.33 eV (b) in the range 242.1–295.1 K and E α = 0.91 eV (c) in the range 307–366.1 K. The linear parts (a) and (b) of both polymers are related to the accumulation of protons in the grain-boundary regions as it is depicted in the Cole-Cole plots. The linear part (c) is related to the proton migration from the grain-boundary region to the electrodes and the dehydration process taking place. The ac-conductivity of CM-γ-CDP is considerably higher than that of γ-CDP as the partial hydrogen replacement of some hydroxyl groups by carboxymethyl moiety, renders numerous protons more flexible to move along the hydrogen-bonded network, contributing to the conductivity. Both systems after the dehydration process, presented a newly-formed hydrogen bonded network due to the reorientation of hydrogen bonded chains at T > 397.0 K for γ-CDP and T > 420.9 K for CM-γ-CDP. Image 1035280 • Water-diffusion influence on proton conduction. • Attenuation and regeneration of stable H-bonded network. • Carboxymethylation eliminates the order-disorder transition and increases the proton conduction. [ABSTRACT FROM AUTHOR]

According to the available experimental phase equilibrium relations, thermochemical properties and the experimentally observed ageing precipitation sequence from literatures, the thermodynamic re-modeling and re-assessment of the Mg–Gd binary system have been carried out by means of CALPHAD (CALculation of PHAse Diagram) technique. The metastable phases, including GP zones (D0 19 -type) and Mg 7 Gd intermediate, are described by the models (Gd,Mg%) 0.75 (Gd%,Mg) 0.25 and (Gd,Mg%) 0.875 (Gd%,Mg) 0.125 , respectively, in order to deal with the order-disorder transitions between the ordered phases GP zones (D0 19 -type)/Mg 7 Gd intermediate and the disordered solid solution HCP_A3(Gd,Mg). With the considerations of the influences of elastic strain energies and interface energies on the thermodynamic driving forces, the effective driving forces for the precipitates to nucleate are calculated to match the ageing precipitation sequence, α(Mg) SSSS (supersaturated solid solution)→ GP zones (D0 19 -type)→ β′(c-bco, Mg 7 Gd)→ β 1 (D0 3 , Mg 3 Gd)→ β(fcc, Mg 5 Gd). A set of the self-consistent thermodynamic parameters has been obtained. The present calculations of the phase diagram, the thermochemical properties, and the precipitation driving forces of the typical Mg–Gd alloys with x (Gd) = 0.01819 and 0.0318 at 498 K, are not only well consistent with the reported experimental data but also in a satisfactory agreement with the precipitation sequence in the early stage of ageing observed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Image 1 • Metastable GP zones (D0 19 -type)/Mg 7 Gd are considered as the ordered phases of α(Mg). • Stable and metastable phases of Mg–Gd system are re-assessed by CALPHAD technique. • Thermodynamic and effective nucleation driving forces for precipitation are calculated. • Interface and elastic strain energies are treated as resistances of precipitation. • The precipitation sequence can be well predicted by the effective driving forces. [ABSTRACT FROM AUTHOR]

(Nd 1– x Y x) 2 Zr 2 O 7 solid solutions have been prepared by solid phase method. The influence of yttrium content on the structure and electrical performance has been explored. The crystal structure is characterized by X-ray diffraction and Raman spectroscopy. The morphology is investigated by scanning electron microscopy. The electrical property is analyzed by electrochemical impedance spectroscopy measurement. (Nd 1– x Y x) 2 Zr 2 O 7 solid solutions exhibit a single-phase structure except that NdYZr 2 O 7 shows a biphasic structure. As yttrium content x raises from 0 to 1, the order degree of (Nd 1– x Y x) 2 Zr 2 O 7 solid solutions decreases gradually, and the structures of solid solutions transform from ordered pyrochlore-type structure to disordered defect fluorite-type structure. (Nd 1– x Y x) 2 Zr 2 O 7 solid solutions are dense, and the relative densities are over 94%. The total conductivity of Nd 2 Zr 2 O 7 is greatly enhanced by doping yttrium at the Nd-site in 823–1073 K. The total conductivity achieves 5.2 × 10−3 S cm−1 at 1073 K for (Nd 0.6 Y 0.4) 2 Zr 2 O 7 , which is the highest valve of (Nd 1– x Y x) 2 Zr 2 O 7 solid solutions. • (Nd 1– x Y x) 2 Zr 2 O 7 show a single-phase structure except for NdYZr 2 O 7. • Order-disorder transition takes place in (Nd 1– x Y x) 2 Zr 2 O 7 solid solutions. • The total conductivity of Nd 2 Zr 2 O 7 can be improved by doping Y 2 O 3. • (Nd 0.6 Y 0.4) 2 Zr 2 O 7 has the highest conductivity at 1073 K in (Nd 1– x Y x) 2 Zr 2 O 7 system. [ABSTRACT FROM AUTHOR]

Cu2MnSnS4 shares several promising properties with the widely investigated Cu2ZnSnS4 for photovoltaic applications such as containing only earth abundant and non‐toxic elements, and suitable absorption characteristics for absorber materials. Thin film Cu2MnSnS4 samples with various cation compositions are co‐sputtered reactively followed by a high temperature anneal. Formation of Cu2MnSnS4 and co‐existence of several secondary phases is verified by XRD and Raman. Our investigation of the crystal structure based on first‐principles DFT confirms that stannite crystal structure is preferred over kesterite, although, further verification considering cation disorder is needed. The direct band gap of Cu2MnSnS4 is calculated as 1.52 eV (1.62 eV) for stannite (kesterite), which coincides with the range of the measured band gaps from spectrophotometry of 1.42–1.59 eV. After further annealing treatments below 240 °C, the absorption shows reversible changes: the band gap blue‐shifts and the Urbach tail energy is reduced. It is concluded that, just like Cu2ZnSnS4, disorder also occurs in Cu2MnSnS4. The implications of our findings are discussed and related to the current understanding of cation disorder in Cu2ZnSnS4 and related compounds. Furthermore, for the first time first‐principles DFT investigations are presented for the thiospinel Cu2MnSn3S8 which is observed experimentally as a secondary phase in Sn‐rich Cu2MnSnS4 thin films. [ABSTRACT FROM AUTHOR]