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Abstract: (Sm1− x Yb x )2Zr2O7 (0≤ x ≤1.0) ceramic powders were prepared by chemical-coprecipitation and calcination method, and were pressureless-sintered at 1973K for 10h to fabricate dense bulk materials. (Sm1− x Yb x )2Zr2O7 has a single phase with a pyrochlore or defect fluorite structure, depending mainly upon the Yb content. They are found to be pyrochlores for 0≤ x ≤0.1, and defect fluorites for 0.3≤ x ≤1.0. The electrical conductivity of (Sm1− x Yb x )2Zr2O7 was investigated by complex impedance spectroscopy over a frequency range of 200Hz to 20MHz from 723 to 1173K in air. The measured electrical conductivity obeys the Arrhenius relation. The grain conductivity of (Sm1− x Yb x )2Zr2O7 ceramics gradually increases with increasing temperature. A decrease of about one order of magnitude in grain conductivity is found at all temperature levels when the Yb content increases from x =0.1 to x =0.3. The electrical conductivities of defect fluorite-type materials are lower than those of pyrochlore-type materials in (Sm1− x Yb x )2Zr2O7 system, whereas activation energies for the conduction process increase monotonically as the structure becomes disordered. [Copyright &y& Elsevier]

Abstract: Deuteron spin–lattice relaxation via the motion-dependent part of the electric quadrupole interaction is discussed in partly and fully deuterated ammonium ions of ammonium hexachlorometallates. The dominant motion at temperatures T>50K is normally 120° reorientations of the ammonium ions. In some hexachlorometallates the instantaneous equilibrium directions of the nitrogen–hydrogen vectors make a certain angle Δ with the metal–nitrogen vectors and they appear in groups of six near each metal–hydrogen vector. Each N–D vector jumps between the six directions of one group and this motion (called limited jumps) dominates the deuteron relaxation at lower temperatures. In some samples one direction of each group seems to become more populated than the others when the deuteration degree exceeds a certain value and the ammonium ions become ordered. A model is derived for the relaxation rate in the absence of tunnelling splittings, which includes the effects of reorientations and limited jumps also in the ordered structure, where the limited-jump rate of a N–D vector to the preferred direction, r p, differs from that to the nonpreferred direction, r n. The obtained relaxation rate depends, in addition to the angle Δ, also on the ratio d=r n/r p. The effect of d is discussed and estimates for it are presented on the basis of earlier experiments. The recent model for the deuteron relaxation in NH3D+ ions, including the effect of proton tunnelling, is shortly reviewed. At lowest temperatures the motional rates can be dominated by corresponding incoherent tunnelling and the rate of the incoherent tunnelling contributing to limited jumps is argued to be clearly larger than that of the incoherent tunnelling contributing to approximately 120° rotations. [Copyright &y& Elsevier]

Simultaneous magnetic and martensitic phase transitions in NiMn-based particles embedded in a metallic matrix could be stress-induced by crack propagation, making them candidates as sensory particles in structural health monitoring. For such applications, the particles should be small to maintain matrix properties, but large enough to martensitically transform at desired temperatures, requiring their transformation characteristics to be tailored. Here, the effects of heat treatments on the transformation characteristics of micron-sized Ni 45 Co 5 Mn 36.7 In 13.3 particles are studied to demonstrate such tailorability. It is discovered that martensitic transformation temperatures are proportional to the annealing temperature below the order-disorder (ODO) transition and inversely proportional above it, and an opposite trend is observed for the transformation hysteresis. These findings are in agreement with the bulk behavior, however, a significantly larger hysteresis was found in the particles, which was correlated with crystallite size dependent phenomena, increasing the effective energy barrier to the phase-transition. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: By means of the CALPHAD (CALculation of PHAse Diagram) technique, the In–Pt system was critically assessed. Three solution phases (liquid, face-centered cubic, tetragonal) were described with the substitutional solution model. The compounds In7Pt3, In2Pt, In3Pt2, InPt2 and αIn2Pt3 were treated as stoichiometric compounds. The compounds InPt, In5Pt6, In9Pt13 and βIn2Pt3, which have a homogeneity range, were treated as the formulae (In,Pt)(In,Pt), (In,Pt)5(In,Pt)6, In9(In,Pt)13 and (In,Pt)2(In,Pt)3, respectively. A two-sublattice model (In,Pt)0.25(In,Pt)0.75 is applied to describe the compound InPt3 in order to cope with the order–disorder transition between InPt3 with AuCu3-type structure (L12) and face-centered cubic solution (A1). A set of self-consistent thermodynamic parameters describing the Gibbs energy of each individual phase as a function of composition and temperature for the In–Pt system was obtained. [Copyright &y& Elsevier]

• The as-cast Al 0.3 CoCrFeNi was not a random disordered solid solution. • The thermophysical properties of HEA were affected by nanocrystalline precipitations and atomic order. • The thermal conductivity and lattice thermal conductivity of as-cast HEA show the weak temperature dependence of T−0.47 and T−0.66, respectively. • HEA underwent a disorder-order-disorder transition during the heating process. • NEMD method had a more obvious size effect than EMD, but the result was more accurate when calculating thermal conductivity. In high entropy alloys (HEAs), the nanoscale precipitations and short-range orders affected the material's mechanical properties and brought about changes in the thermal physical properties. As-cast Al 0.3 CoCrFeNi was prepared, and an ideal random disorder HEA model was established by molecular dynamics (MD). The resistivity, thermal conductivity, specific heat capacity and linear expansion coefficient at 300–1100 K were obtained and discussed by experiments and simulations. The intracrystalline segregation was observed in the as-cast HEA. At about 600–800 K, the resistivity growth stagnated, and two exothermic and one downward heat capacity peaks were found in DSC and specific heat, respectively. The metastable structure of as-cast HEA was ordered and a small amount of nano-phase precipitated. When above 800 K, the resistivity increased rapidly, DSC and specific heat appeared endothermic peak and extensive range upward heat capacity peak respectively. The alloy underwent an order-disorder transition accompanied by a small amount of phase decomposition. Phonons were the main force of heat conduction. Thermal conductivity and lattice thermal conductivity show the weak temperature dependence of T−0.66 and T−0.48, respectively. The experimental results, affected by intragranular segregation and ordering, differed from the simulation results at lower temperatures while agreed well with the simulation results at higher temperatures. The order degree on thermodynamic parameters of as-cast HEA during the heating process should be considered in subsequent studies. [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]

Abstract: We used the Calphad technique to represent the thermodynamic properties and phase equilibria in the system Fe–Al. Relative to the description accepted in the COST507 project, we improved the representation of the bcc_A2, bcc_B2 and fcc_A1 phases. We conclude that new heat capacity measurements are required for the intermetallic phases FeAl2, Fe2Al5 and FeAl3 to improve a thermodynamic description of this system. New activity measurements for iron are required to improve a thermodynamic description for the bcc_A2 and bcc_B2 phase. [Copyright &y& Elsevier]

Abstract: Oxygen sorption on perovskite-type oxides can be advantageously used for air separation at high temperature. The large heat of oxygen sorption on these oxide sorbents presents a major challenge for the heat management of the high sorption separation process in practical applications. This paper reports a method to minimize the heat effects by taking advantage of an endothermic process of oxygen vacancy order–disorder phase transition accompanying the oxygen sorption process on perovskite-type oxide sorbents. The oxygen sorption isotherms, phase diagram, exothermic heat of oxygen sorption, and endothermic heat of the order–disorder phase transition for were measured by simultaneous TGA/DSC and XRD. The conditions for zero apparent heat of sorption are determined. If the oxygen partial pressure change and adsorption temperature are controlled such that they give an oxygen adsorption amount, which is numerically equal to the ratio of heat of phase transition to heat of oxygen sorption, the net heat released from the oxygen sorption step can be minimized or controlled to be negligible. This strategy for heat effect minimization is demonstrated with the results of TGA/DSC measurements at different operating conditions and air separation by a fixed-bed packed with the perovskite-type oxide sorbent. [Copyright &y& Elsevier]

Abstract: The Ru–Zr system has been critically assessed by means of the CALPHAD technique. Based on the experimental data, the solution phases (liquid, body-centered cubic, hexagonal close-packed) were initially modeled with the Redlich–Kister equation. It was shown that this model had a definite temperature range beyond which the liquid became unstable. To tackle the problem, the solution phases were modeled with a new semi-empirical equation, which was recommended by Kaptay. A two-sublattice model (Ru, Zr)0.5(Ru, Zr)0.5 is applied to describe the compound RuZr in order to deal with the order–disorder transition between body-centered cubic solution (A2) and RuZr with CsCl-type structure (B2). Another two-sublattice model (Ru, Zr)0.6667(Ru, Zr)0.3333 is applied to describe the compound Ru2Zr in order to cope with the order–disorder transition between hexagonal close-packed (A3) and Ru2Zr with MgZn2-type structure (C14). A set of self-consistent thermodynamic parameters of the Ru–Zr system was obtained. [Copyright &y& Elsevier]

Abstract: Boolean networks can be used as simple but general models for complex self-organizing systems. The freedom to choose different rules and structures of interactions makes this model applicable to a wide variety of complex phenomena. It is known that the damage dynamics in annealed Boolean systems should fall in the same universality class of the directed percolation model. In this work we present results about the behavior of this model at and near the critically ordered condition for both the annealed and the quenched versions of the model. Our study concentrates on the way the system responds to a small perturbation. We show that the characteristic correlation time, i.e., the time in which any memory of this perturbation is lost, diverges as one moves towards criticality. Exactly at the critical point, we observe that the time for returning to the natural state after the perturbation follows a power-law distribution. This indicates that most perturbations are quickly restored, while few events may have a global effect on the system, suggesting a mechanism that assures at the same time robustness and adaptability. The critical exponents obtained are in agreement with the values expected for the universality class of mean-field directed percolation both in the annealed and in the quenched Boolean network model. This gives further evidence that annealed Boolean networks may in certain conditions provide a good model for understanding the behavior of regulatory systems. Our results may give insight into the way real self-organizing systems respond to external stimuli, and why critically ordered systems are often observed in Nature. [Copyright &y& Elsevier]

Abstract: By means of CALPHAD (CALculation of PHAse Diagram) technique, the Li–Zn system was critically assessed. Three solution phases (liquid, body-centered cubic, hexagonal close-packed) were modeled with the Redlich–Kister equation. The compound LiZn2 was treated as stoichiometric compound. αLi2Zn3, βLi2Zn3, Li2Zn5 and αLiZn4, which had a homogeneity range, were treated as the formulae Li2(Li,Zn)3, (Li,Zn)2(Li,Zn)3, (Li,Zn)2Zn5 and (Li,Zn)1(Li,Zn)4, respectively. A three-sublattice model (Li,Zn)0.5(Li,Zn)0.5(Va)3 is applied to describe the compound LiZn in order to cope with the order–disorder transition between body-centered cubic solution (A2) and LiZn with NaTl-type structure (B32). Another three-sublattice model (Li,Zn)0.2(Li, Zn)0.8(Va)0.5 is applied to describe the compound βLiZn4 in order to cope with the order–disorder transition between hexagonal close-packed solution (A3) and βLiZn4 with Mg-type structure. A set of self-consistent thermodynamic parameters of the Li–Zn system was obtained. [Copyright &y& Elsevier]

Abstract: The present paper describes the synthesis, characterization, structural refinement and optical absorption behavior of lead tungstate (PbWO4) powders obtained by the complex polymerization method heat treated at different temperatures for 2h in air atmosphere. PbWO4 powders were characterized by X-ray diffraction (XRD), Rietveld refinement, Fourier transform Raman (FT-Raman) spectroscopy and ultraviolet–visible (UV–vis) absorption spectroscopy measurements. XRD, Rietveld refinement and FT-Raman revealed that PbWO4 powders are free of secondary phases and crystallizes in a tetragonal structure. The UV–vis absorption spectroscopy measurements suggest the presence of intermediary energy levels into the band gap of structurally disordered powders. [Copyright &y& Elsevier]

Abstract: Third-harmonic susceptibility has been employed to probe the order–disorder transition of vortex matter of a good-quality sample of MgB2 with random disorder. In the major part of the temperature interval, the measured boundary line can be adjusted by a power-law function, in accordance with theoretical models for the melting of the ordered phase of a 3D vortex-glass. For larger temperatures, however, thermally-induced depinning anticipates disorder, which is also predictable for the vortex matter behavior of a clean system with small amounts of randomly distributed disorder, as is the case of the Mg0.95B2 sample studied here. [Copyright &y& Elsevier]

Abstract: Measurements were made of in situ X-ray diffraction, electrical resistivity, and magnetic susceptibility for a series of newly found ternary alloys CuMPt6 with M=Ti, V, Cr, Mn, Fe, Co, and Ni. They possess, after appropriate heat treatment, the Cu3Au-type ordered structure, though the ordering is not complete for M=Ni. They are fairly good electrical conductor with a specific resistivity of around 6×10–3 ohmm. A general trend has been found in the magnetic property: nonmagnetic–spin-glass-like–ferromagnetic–paramagnetic, with increasing atomic number of M. The alloy with M=Mn, however, is specific among the seven alloys in that it undergoes secondary ordering into the cubic ABC6-type structure and is regarded as a counterpart of the Heusler alloy forming in the bcc systems. [Copyright &y& Elsevier]

Abstract: Time-resolved magneto optical measurements in Bi2Sr2CaCu2O8+δ show oscillatory relaxation of the local magnetization. The oscillatory behaviour is observed in a limited range of temperatures and fields below the vortex order–disorder phase transition line. We ascribe this phenomenon to coupled effects of thermally activated flux creep and annealing of transient disordered vortex states injected into the sample during field increase. [Copyright &y& Elsevier]

The solubility of alkylthiol-coated silver nanoparticles and the energetics of the ligand disordering have been investigated. Calorimetry measurements have provided correlations between the nature of the ligands and the enthalpy of the ligand disordering, which have guided the improvement of nanoparticle solubility and dispersion in organic media. [ABSTRACT FROM AUTHOR]

Abstract: Ordering phenomena in bcc (110) binary thin film intermetallics are studied by a statistical–thermodynamic model. The system is modeled by an Ising approach that includes only nearest-neighbor chemical interactions and is solved in a mean-field approximation. Vacancies and anti-structure atoms are considered on both sublattices. The model describes long-range ordering and simultaneously short-range ordering in the thin film. It is applied to NiAl thin films with B2 structure. Vacancy concentrations, thermodynamic activity profiles and the virtual critical temperature of order–disorder as a function of film composition and thickness are presented. The results point to an important role of vacancies in near-stoichiometric and Ni-rich NiAl thin films. [Copyright &y& Elsevier]

Abstract: We study the spatio-temporal evolution of populations made up from a few tens to thousands of monokinetic repulsive agents moving through a two-dimensional grid. We adopt the behavioral description of agents, in which each agent executes an action following a state automaton. In the first step, the agents follow the repulsion rule of a deterministic automaton. Collective behaviors are calculated from the application of the evolution mechanisms for each individual. We show that, depending on the repulsion law and on the presence of borders, the agents become organized into a square or a condensed hexagonal stationary lattice, which maximizes the potential function of the distribution. Thus, the repulsion may force the condensation to the same site. Then, we study the collective behaviors when the agents are faulty and randomly violate the repulsion law. When the number of agents is small (say, for population involving a few tens of agents), we observe fast and random alternations between the ordered lattice phase and a strongly disorganized state. These alternations are essentially averaged and disappear in the large populations, resulting in a partially ordered homogeneous distribution. [Copyright &y& Elsevier]

Abstract: We present experimental data relating to magnetic field (H) scan rate (dH/dt) dependence in the magnetization (M) hysteresis width across the field regions of the second magnetization peak (SMP) and the peak effect (PE) in weakly pinned crystals of 2H-NbSe2 and Ca3Rh4Sn13. We note that the said dependence is small at the low field end, where individual/small bundle pinning dominates, as well as at the high field end (i.e., above the peak field of the PE), where disordered amorphous state is the stationary state. In between the onset field of the SMP anomaly and the peak field of PE, the scan rate dependence in magnetization data displays a non-monotonic variation. We conjecture that the healing of the transient disordered vortex states injected into a superconducting sample during field ramping process could be responsible for the observed behavior. We believe that the disordering commencing at the onset field of SMP has a window to heal between its peak field () and the onset field () of the PE. A comparison of the scan rate dependence in two different crystals of 2H-NbSe2, one of which displays only the PE phenomenon and the other one that displays both SMP and PE anomalies, show that while enhancement in quenched random pinning invokes the occurrence of SMP anomaly, it slows down the temporal decay of currents across the PE region. [Copyright &y& Elsevier]

Abstract: Previous work by Honma et al. suggested that there is an order–disorder transition around 1090°C in Ti–Ni alloys, but its existence has not been confirmed by independent investigation. In the present work, various techniques including TG-DTA, resistance measurement and TEM were employed to detect the possible signs of such a transition. We found interestingly that when strong measures were taken to prevent sample oxidation, no sign for order–disorder transition was detected; but when the sample was allowed to be oxidized during measurement, we did find a clear DTA peak at 1118°C. With SEM-EPMA analysis this peak was identified as originating from a eutectic reaction in the oxidation-affected layer, where selective oxidation of Ti causes significant enrichment of Ni and hence drives the oxidation-affected layer into the eutectic regime. Therefore, our results disprove the existence of “order–disorder transition” in the B2 portion of the Ti–Ni phase diagram. [Copyright &y& Elsevier]

Abstract: Order–disorder transition (ODT) behavior in eicosylated polyethyleneimine (PEI20C) comblike polymer obtained by grafting n-eicosyl group on polyethyleneimine backbone was systematically investigated by the combination of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy as well as solid-state high resolution nuclear magnetic resonance (NMR) spectroscopy. DSC investigations showed two obvious transitions, assigned to the transitions (1) from orthorhombic to hexagonal and (2) from hexagonal to amorphous phase, respectively. These transitions are induced by the variations of alkyl side chain conformation and packing structure with temperature changing, which consequently lead to the destruction of original phase equilibrium. The ODT behavior can also be confirmed by spectroscopic methods like WAXD, FTIR and NMR. The ordered structure and the transition behavior of the alkyl side chains confined by the PEI backbone are obviously different from those of pristine normal alkanes. The transition mechanism of ODT and the origin of the phase transition behavior in PEI20C comblike polymer were discussed in detail in this paper. [Copyright &y& Elsevier]

Abstract: Thermodynamic modeling and optimization of the Gd–Mg, Mg–Y, Gd–Y binary systems and the Gd–Mg–Y ternary system have been critically carried out by means of the CALPHAD (CALculation of PHAse Diagrams) technique. The solution phases (liquid, body-centered cubic, and hexagonal close-packed) are modeled with the Redlich–Kister equation. The Compound Energy Model has been used to describe the thermodynamic functions of the intermetallic compounds in these systems. The compounds Mg2Y, Mg5Gd, Mg3Gd, Mg2Gd and Mg24Y5 in the Gd–Mg–Y system have been treated as the formulae (Mg, Y)2(Gd, Mg, Y), Mg5(Gd, Y), Mg3(Gd, Y), Mg2(Gd, Y) and Mg24(Gd, Mg, Y)4Y, respectively. A model (Gd, Mg, Y)0.5(Gd, Mg, Y)0.5 has been applied to describe the compound MgM formed by MgGd and MgY in order to cope with the order–disorder transition between the body-centered cubic solution (A2) and MgM with CsCl-type structure (B2) in the Gd–Mg–Y system. A set of self-consistent thermodynamic descriptions of the Gd–Mg–Y system have been obtained. The projection of the liquidus surfaces and the entire reaction schemes for the Gd–Mg–Y system have been constructed. [Copyright &y& Elsevier]

This work reports the study of Bi4V2–xBaxO11–1.5x (0.02≤ x≤0.50) series, which is a potential source of solid electrolytes to apply in oxygen sensors. X-ray powder diffraction was used to point out the formation of major ionic conductive phases and minor ones. The modifications of vanadate substructure were probed, at short range, by Fourier-transform infrared spectroscopy. Differential scanning calorimetry evidenced the formation of tetragonal γ phase, which can be ionic conductive, for x=0.14. [ABSTRACT FROM AUTHOR]

Abstract: The Ru–Sc system has been critically assessed by means of the CALculation of PHAse Diagram (CALPHAD) technique. The solution phases (liquid, body-centered cubic (bcc) and hexagonal close-packed(hcp)) were modeled with the Redlich–Kister equation. The intermetallic compounds Ru3Sc5, RuSc2, Ru4Sc11, Ru13Sc57 and Ru7Sc44 were treated as stoichiometric. The compound Ru2Sc, which has a homogeneity range, was modeled using two sublattices (Ru,Sc)2Sc. A two-sublattice model (Ru,Sc)0.5(Ru,Sc)0.5 was applied to describe the intermediate B2 compound RuSc with CsCl-type structure in order to cope with the order–disorder transition in the Ru–Sc system. Using this model, the ordered B2 compound RuSc and the disordered Sc-rich solution bcc are described by a single Gibbs energy function. A set of self-consistent thermodynamic parameters of the Ru–Sc system was obtained. [Copyright &y& Elsevier]

Abstract: It is usually believed that there is an order–disorder transition at 1090°C in binary Ti–Ni alloys, as Honma et al. reported previously. The presence or absence of such transition is very important, because the result may greatly affect the martensitic transformation behavior, and the associated shape memory characteristics. In the present paper, we question whether such transition really exists or not. One of the difficulties in such experiments, including the work of Honma et al., lies in the fact that Ti can be easily oxidized at such high temperatures, which complicates the alloy behavior greatly and may lead to erroneous interpretation of experimental data. After doing carefully designed experiments on this point, we did not find any differential thermal analysis peak up to the melting temperature, or any drastic change in electrical resistance in a wide temperature region including 1090°C, which is the characteristic of order–disorder transition. These observations lead to the conclusion that such order–disorder transition does not exist in Ti–Ni binary shape memory alloys. [Copyright &y& Elsevier]

Abstract: The two Mg–RE systems, Mg–Tb and Mg–Yb, have been critically assessed by means of the CALculation of PHAse Diagram (CALPHAD) technique. The solution phases (liquid, body-centered cubic, face-centered cubic and hexagonal close-packed) were modeled with the Redlich–Kister equation. The intermetallic compounds Mg24Tb5 and Mg5Tb were treated as stoichiometric. The compounds, Mg2Tb and Mg3Tb in Mg–Tb system and Mg2Yb in Mg–Yb system, which have a homogeneity range, were modeled using two sublattices Mg2(Mg, Tb), Mg3(Mg, Tb) and (Mg, Yb)2(Mg, Yb), respectively. A three-sublattice model (Mg, Tb)0.5(Mg, Tb)0.5Va3 was applied to describe the intermediate B2 compound (MgTb) in order to cope with the order–disorder transition in the Mg–Tb system. A set of self-consistent thermodynamic parameters of the Mg–Tb and the Mg–Yb system was obtained, respectively. [Copyright &y& Elsevier]

Abstract: Structure evolution of pyrochlore titanates Y2Ti2O7 and Gd2Ti2O7 at high pressure was investigated with Raman and X-ray diffraction methods. Pressure-induced order–disorder transitions are found in titanate pyrochlores. The cations and anions in Y2Ti2O7 began to be disordered at pressures above 50 GPa and the structure changes from pyrochlore (Fd-3m) to defect fluorite structure (Fm-3m) A4O7. This transition is not stable in Gd2Ti2O7, and amorphization proceeds at pressure above 32 GPa. [Copyright &y& Elsevier]

Abstract: We have investigated microdomain structures of novel block copolymers, poly(p-tert-pentyloxyvinylbebzene-b-p-vinylphenol) and poly(p-tert-pentyloxy-vinylbebzene-b-p-vinylphenol-b-p-tert-pentyloxyvinylbebzene) with small-angle X-ray scattering (SAXS). We analyzed SAXS profiles of the block copolymers in their ordered state with paracrystal theory, and found that the block copolymers formed the lamella structures in the order of 1nm with long-range order. We estimated the lower-limit size of the microdomain structure by analyzing the order–disorder transition of the block copolymer solutions and explored that we can attain 7.6nm by decreasing the molecular weight of block copolymers. [Copyright &y& Elsevier]

Abstract: Low temperature scanning tunneling microscopy (LT-STM) studies have been performed on the LT-cleaved and the chemically etched surface of YBa2Cu3O y single crystals. We find that the vortex structure can be observed on the chemically etched surface of YBa2Cu3O y as a function of temperature and magnetic field. At low magnetic fields, we observed a slightly distorted triangular lattice, which is attributed to the Bragg-glass phase. The triangular lattice transforms into a disordered structure in high magnetic fields above the order–disorder transition H ∗(T). We observed that the disordered vortices form small clusters comprising 5- and 7-fold coordination pairs. These microscopically determined vortex structures are in good agreement with the vortex matter phase diagram derived from the macroscopic measurements, thus providing the evidence of the field-driven transition in the vortex solid phase of YBa2Cu3O y . [Copyright &y& Elsevier]

Abstract: We have investigated effects of magnetic field on transformation temperatures of a pure iron specimen and selection of variants formed by martensitic transformation in an Fe–31.2Pd (at.%) alloy single crystal and disorder–order transition in a CoPt single crystal. Following results are obtained: (i) the equilibrium temperature of austenite to ferrite transformation in the pure iron specimen increases by about 7K when a magnetic field of 10T is applied, and the result is discussed on the basis of the Clausius–Clapeyron equation; (ii) the rearrangement of martensite variants driven by magnetic field is confirmed to occur in the Fe–31.2Pd (at.%) ferromagnetic shape memory alloy, and the behavior is discussed quantitatively by introducing magnetic shear stress acting across the twinning plane; (iii) single variant of L10-type ordered phase in a CoPt is obtained by ordering heat-treatment under a magnetic field. [Copyright &y& Elsevier]

Abstract: We have studied the order–disorder phase transitions of FCC alloy thin films in the (001) direction using the mean-field method. Surface field is used to describe the surface effects such as surface segregation. All the different types of the phase diagrams of alloy thin films under the surface field are calculated. It is shown that the order–disorder phase transitions of alloy films are much more complex than those of bulk due to the combined effects of surface field and finite size confinement. The main features of phase diagrams are as follows: (1) for the thin films with even number layers, there are some middle-temperature phases due to the anti-phase boundary phenomena induced by the surface field, which leads to more complex phase behavior than those of odd number layer films. (2) For the quasi-two-dimensional thin films with odd number layers, there is an phase which does not show order–disorder phase transition with the increase of temperature due to the finite size of film. (3) For the thin films with both even and odd number layers, there are some critical points in the phase diagrams. [Copyright &y& Elsevier]

Abstract: To elucidate the relationship between transport properties and phase transformations in mixed-conducting oxides, Sr0.9Ca0.1Co0.89Fe0.11O3− δ (SCCFO) and SrCoO3− δ (SCO) were chosen as the model materials and have been investigated in detail. Oxygen permeation measurements verified that both oxides are well permeable to oxygen at elevated temperatures, e.g., at 900°C during a cooling procedure, oxygen permeation rates as large as 1.5 and 2.0mL/min/cm2 could be obtained with disk-shaped SCCFO and SCO membranes of thickness 1.5mm, respectively. But when cooled to critical temperatures, the oxygen permeability of these kinds of oxides diminished sharply, which could be recovered by increasing the temperature again to certain values. Abrupt changes on electrical conductivity were also observed for both oxides around the same region of temperature as that of oxygen permeability. As indicated by high-temperature X-ray diffraction and thermal analysis, the SCCFO and SCO systems undergo phase transformation between a low-temperature orthorhombic brownmillerite structure (B) or a hexagonal 2H-type structure (H) and a high-temperature cubic perovskite structure (C), respectively. The present results suggest the observed abrupt changes in transport properties versus temperature are attributed to such phase transformation, which may be directly associated with the order–disorder transition of oxygen vacancies. Moreover, compared to the B/C transformation that mainly involves an order–disorder transition on the oxygen sublattice, the H/C one necessarily also involves the cooperative long-range reorganization on the cation sublattice. Therefore it occurs at a higher temperature and absorbs more heat quantity than those of B/C transformation. [Copyright &y& Elsevier]

Abstract: Ba2(In1−x R x )2O5 (x =0, 0.05, 0.1; R=Sc, Lu, Yb, Y, Dy, Gd, Sm) were synthesized by a solid-state reaction method, and all the prepared samples were confirmed to be a single phase by XRD. The lattice volume increased with increasing ionic radius of the substituents, and the slope in the plot of the lattice volume against the ionic radius was changed around the ionic radius of Y3+ or Dy3+. The order–disorder transition temperatures of oxygen vacancies of all the prepared samples were determined by electrical conductivity measurement. The transition temperatures of the samples substituted by larger (or smaller) ions in the ionic radius than In ion were larger (smaller) than that of un-substituted Ba2In2O5, probably due to the preferred site of substituent to either octahedral InO6 site or tetrahedral InO4 site. [Copyright &y& Elsevier]

The phase equilibria among the face-centered cubic (fcc), body-centered cubic (bcc), and βMn phases at 800, 900, 1000, 1100, and 1200 °C were examined by electron probe microanalysis (EPMA), and the A2/B2 and B2/D03 ordering temperatures were also determined using the diffusion couple method and differential scanning calorimetry (DSC). The critical temperatures for the A2/B2 and B2/D03 ordering were found to increase with increasing Mn content. Thermodynamic assessment of the Fe−Mn−Al system was also undertaken with use of experimental data for the phase equilibria and order-disorder transition temperatures using the CALPHAD (Calculation of Phase Diagrams) method. The Gibbs energies of the liquid, αMn, βMn, fcc, and ε phases were described by the subregular solution model and that of the bcc phase was represented by the two-sublattice model. The thermodynamic parameters for describing the phase equilibria and the ordering of the bcc phase were optimized with good agreement between the calculated and experimental results. [ABSTRACT FROM AUTHOR]

Abstract: The aggregation of rod–flexible ABA and BAB triblock (A was rod block and repulsive with block B) copolymers in a thin film was studied as a function of varying the rigidity (η) and the length of the rod block by Monte Carlo simulation. The rigidity of block A was defined as η = R c/R max in this study. R c was the end-to-end distance below which the conformation of the block was not allowed, whereas R max was the longest end-to-end distance that the block could be. If η =0 the block was flexible, whereas if η =1 the block was a straight rod. The simulation results showed that the ABA triblock copolymer film were likely to form lamella structure with increasing the rigidity (η) of block A. The lamellas were parallel each other and perpendicular to the film surface. However, the aggregation of BAB triblock copolymers tended to change from lamella to cylinder structure with increasing the rigidity (η) of block A. Typical lamella and cylinder co-exist structure was obtained at η =0.504 for the BAB copolymer film. On the other hand, the simulation results indicated that the film changed from disorder to order, then to disorder structure with increasing the relative length of B block for both ABA and BAB copolymer films. Well ordered lamella for ABA copolymer and well ordered cylinder for BAB copolymer structures could be obtained when the composition of block B is around 50%. [Copyright &y& Elsevier]

Abstract: Heat capacities of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) were measured by differential scanning calorimetry in the temperature range 280–820K and 280–660K, respectively. PbBi12O19(s) and ϕ-Pb5Bi8O17(s) showed order–disorder transitions whose onset temperatures are 520K and 700K, respectively. The measured heat capacities of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) as a function of temperature are expressed as: Enthalpy increments, entropies and Gibbs energy functions were derived from the measured heat capacity data. [Copyright &y& Elsevier]

Abstract: Oxygen ion conduction in the Aurivillius phases Bi2Sr2(Nb or Ta)2(Ga or Al)O11.5 has been evaluated in detail. High-temperature X-ray diffraction studies, coupled with differential scanning calorimetry, electron microscopy, and conductivity measurements were used to clearly demonstrate that Bi2Sr2(Nb x Ta1−x )2(Ga y Al1−y )O11.5 with x =0, 1 and y =0, 0.5, and 1 form only multiphase specimens. The origin of the previously observed fast ion conduction is a result of interconnected Bi2O3 grains that undergo a high-temperature phase transformation to the δ-Bi2O3 polymorph. The Aurivillius phase component of the multiphase specimens does not demonstrate any type of order–disorder transformation, however, the phase transformations of the Bi2O3 are clearly observed using high-temperature diffraction and calorimetry. [Copyright &y& Elsevier]

Abstract: Recently, half-metallic properties have been extensively investigated from theoretical and practical viewpoints. In the present study, the phase equilibria, A2/B2 and B2/L21 order–disorder transition, and ferromagnetic/paramagnetic transition in the Co-rich portion, that is, in the vicinity of half-metallic composition, for Co–Cr–Ga system were examined by electron probe microanalysis (EPMA), differential scanning calorimetric (DSC) measurement, and transmission electron microscope (TEM). The compositions of the γ (A1; fcc-Co), α (A2; bcc-Cr), β (B2; CoGa), ɛ (A3; hcp-Co), and σ (D8b) phases in equilibrium, the critical compositions corresponding to the A2/B2 continuous order–disorder transition, and the critical temperatures of the B2/L21 order–disorder transition and the paramagnetic/ferromagnetic transition in the L21 phase region have been determined. It has been confirmed that the β single-phase region at 1000°C exists in a wide composition range, and the B2/L21 order–disorder transition temperature is higher than that of the Co–Cr–Al system. Furthermore, it has been disclosed that the phase stability of the CoGa B2 phase, estimated from the Bragg–Williams–Gorsky (BWG) calculation as a linear extrapolation of the continuous order–disorder transition temperatures, is lower than that of CoAl. [Copyright &y& Elsevier]

Abstract: The effect of addition of layered silicate on the order–disorder transition of poly[styrene-b-(ethylene-propylene)-b-styrene] (SEPS) block copolymer in the block copolymer/paraffin oil/layered silicate nanocomposite gels was investigated by means of differential scanning calorimetry (DSC) and modulated DSC (MDSC). The addition of layered silicate has significant influences on the order–disorder transition and the phase structure of the block copolymer. With increasing layered silicate, the order–disorder transition temperature of the block copolymer decreased. The addition of layered silicate reduced the ordering level of the block copolymer. MDSC results revealed that the order–disorder transition is a glass transition-like process. A thermal event related to the ordering process, which took place in the preparation of the sample and hid in the specimen, has been revealed by MDSC first time. [Copyright &y& Elsevier]

Abstract: Investigations on the manganese substituted lithium ferrites reveal the strong influence of manganese ions on the ordering of Li+ cations in the spinel-type crystal lattice. We present the effect of Mn3+ substitution in the LiFe5−x Mn x O8 (0≤ x ≤1) samples on the order–disorder phase transition and on the thermal expansion of their spinel lattices. Synchrotron X-ray measurements have been performed in the temperature range 10–300K and 300–1173K. The diffraction experiments were carried out at the DESY-HASYLAB high-resolution powder diffractometer (beamline B2). The transition from ordered (cubic primitive, P4 1 32) to disordered (face centred cubic, Fd3m) structure was observed with the increasing Mn3+ content. [Copyright &y& Elsevier]

Abstract: Changes of the composition of the first, second, and third atomic layers of (001)-oriented AuCu3 crystal having the bulk order–disorder transition at Tc =663K were determined with the use of Auger peak heights for Au and Cu M23VV transitions recorded with the retarding field analyzer for the incidence angle of the primary electron beam equal to 8° and 60°, for the sample temperature ranging from 400 to 1000K. The relative atomic concentration of gold in the first atomic layer (Au1) remains almost constant from 630K (Au1≈0.47) to 900K (Au1≈0.45). Above 900K the decrease is much faster and Au1 approaches 0.35 at 1000K. The relative atomic concentration of gold in the second atomic layer (Au2) remains constant and equal to about 0.17 from 630 to 900K. Above 900K it increases up to 0.31 at 1000K. However, a large systematic error is possible in Au2 determination. No specific changes of Au1 and Au2 are observed in the vicinity of the bulk order–disorder transition temperature Tc . The relative atomic concentration of gold in the third atomic layer Au3 starts to decrease in the vicinity of Tc and this decrease lasts up to 900K. The presented results are compared with the theoretical and experimental literature data. Apart from some common general trends, appreciable quantitative differences are indicated. [Copyright &y& Elsevier]

Abstract: The magnetic properties and phase stability of half-metal-type Co2Cr1−x Fe x Ga alloys were investigated by differential scanning calorimetry (DSC), in a superconducting quantum interference device (SQUID) magnetometer and in a vibrating sample magnetometer (VSM), and by transmission electron microscopy (TEM). It was found that the L21-type single-phase is obtainable for the entire concentration of x and that the value of the saturation magnetic moment M s at 4.2K in the lower composition range of x is in agreement with the generalized Slater–Pauling line, while it is rather larger than the generalized Slater–Pauling line above x =0.6. The Curie temperature T c monotonically increases, whereas the transition temperature from the L21- to B2-type phase is almost constant at 1082±13K with increasing x. [Copyright &y& Elsevier]

This work reports the room-temperature stabilization of the Bi4V2-xFexIIO11-1.5x γ ‘ phase, a promising ionic conductive material that finds application in solid oxide fuel cell and oxygen sensor devices. The Fe(II) cation proved to be a better stabilizer than Fe(III), which was previously used, since a lower substitution degree of V5+ is needed for the former. Powder X-ray diffraction, Fourier-transform infrared spectroscopy and differential scanning calorimetry were used in these experiments. [ABSTRACT FROM AUTHOR]

Abstract: The present work attempts to assess the influence of the order phenomenon on the soft magnetic properties of Fe–Si alloys in a wide concentration range. Alloys with Si content up to 7.6wt% were prepared. Heat treatments including annealing at different temperatures ranging from 500 up to 1100°C and water quench were carried out in order to develop different states of order. 57Fe Mössbauer spectroscopy was used to evaluate and quantify the degree of order. Concerning magnetic properties, total losses and permeability were measured. Results show that magnetic properties are mainly influenced by two factors: stresses induced during quenching and atomic order phenomena. The former deteriorates them as the quenching temperature is increased while the latter becomes more appreciable as the Si content is higher. [Copyright &y& Elsevier]

Abstract: This paper reports the mechanochemical synthesis and the structural and microstructural characterization of three titanates, Ti2O7 (, Gd and Dy), with a pyrochlore-like structure. Starting from stoichiometric mixtures of elemental oxides TiO2 and O3, single-phase samples of highly disordered pyrochlores were obtained after milling. Differential thermal analysis of the as prepared powders showed in every case the presence of a single exothermic event at temperatures close to 800 °C. The evolution of the structure and microstructure of these highly-disordered pyrochlores with temperature was studied by combining XRD and IR and Raman spectroscopies. On heating, both the cation and anion arrays in Y2Ti2O7 and Dy2Ti2O7, order by two independent processes. The exothermic events observed in DTA have their origin in the ordering of the anion sublattice, whereas cation ordering progress smoothly with temperature. Gadolinium titanate, Gd2Ti2O7, behaves differently to the other two compounds studied concerning the cation sublattice: no evidence of cation disorder is observed, even in the just-milled sample. [Copyright &y& Elsevier]

Abstract: The Li+ diffusion and phase behavior of the lithium-doped poly(ethylene glycol) distearate were studied by 7Li NMR, DSC, and polarized-light optical microscopy. The spectra for highly Li+-doped samples (oxygen-to-lithium ratio y≤9) show 7Li quadrupolar powder patterns even at temperatures above the melting point, what is attributed to reduced segmental mobility due to local ordering. These patterns disappear above y-dependent temperatures, when the samples undergo order–disorder transitions, as determined recently by SAXS. Similar effect is observed in the behavior of the diffusion coefficient versus temperature, where the curve slopes increase by a factor ∼2 above the order–disorder transition. Additionally, when the temperature is fixed at 50 °C and the oxygen-to-lithium ratio is changed from 5 to 16, the ordered phase is observed only for samples with y<9, and below this y value a strong decrease in the 7Li diffusion coefficient is observed. The order present in samples with y≤9 at 50 °C decreases the segmental mobility and reduces the conductivity, which is directly confirmed by the 7Li NMR diffusion coefficient measurements. [Copyright &y& Elsevier]

Abstract: Simultaneous DSC-TGA measurements were conducted on a perovskite-type oxide, La0.1Sr0.9Co0.9Fe0.1O3−δ, when it was subject to a sudden change of oxygen activity in the gas environment (from 1.3×10−4 to 0.21 atm) at constant temperature. The DSC-TGA and XRD results show occurrence of synergetic thermal effects for exothermic oxygen sorption and endothermic oxygen vacancy order to disorder transition for the perovskite-type oxide in response to the sudden increase of oxygen activity in a large temperature range (350–800 °C). The perovskite-type ceramic transforms from the ordered (brownmillerite) to disordered (perovskite type) structure as temperature increases. The order to disorder phase transition temperature decreases with decreasing oxygen nonstoichiometry or increasing oxygen partial pressure, with the maximum transition temperature at 857.9 °C. The apparent heat measured for the perovskite-type ceramic sample during the oxygen sorption process changes from endothermic to exothermic one as temperature increases from 350 to 800 °C. The endothermic heat for phase transformation and exothermic heat for oxygen sorption for the perovskite-type oxide were estimated at 59.8 J/g and −180.5 kJ/mol, respectively, from the DSC-TGA measurements. [Copyright &y& Elsevier]

The decomposition and formation of ordered phases in steels with 5 to 6.5 %Si were investigated by a combined analysis of TEM and electrical resistivity measurements in order to determine the optimal heat treatment conditions for removal of ordered phases. TEM diffraction pattern study revealed that B2 ordered phase in 6.5 %Si steel was sufficiently dissolved by heat treatment at 850 °C for 1 h, and then rapidly re-formed during cooling. The critical cooling rate, above which the suppression of B2 phase formation was possible, increased rapidly with Si content higher than 5.6%. DO3 phase appeared only in the case of as-cast samples containing Si content as high as 6.5%. The measurement of electrical resistivity change during the heat treatment showed that the atomic movement was substantially spurred above 800 °C, resulting in an active order-disorder transition. The removal of solidification segregation is necessary to reduce the amount of B2 ordered phase in the as-cast or hot-rolled state, to lower the heat treatment temperature for dissolution of B2 ordered phase, and to shorten the heat treatment time. [ABSTRACT FROM AUTHOR]

Abstract: The ionic conductivity of the α-AgI-stabilized composite and homogeneous glass of AgI–Ag2O–MoO3 system was measured in the temperature range from 100 to 340 K. The α-AgI-stabilized composite type-B shows the progressive change of activation energy at 273 K, which is attributed to the order–disorder transition in the α-AgI crystal. The conductivity of glass exhibits the bending in wide temperature range, which was analyzed by Vogel–Tamman–Fulcher equation. The calculated value is in excellent agreement with the experimental data. [Copyright &y& Elsevier]

The title compound crystallizes in the space group P21/c with the following unit cell dimensions: a=7.885(2) Å, b=25.937(2) Å, c=11.059(5) Å, β=91.067(2)°, Z=4. The examination of the structure shows a layer arrangement perpendicular to the b axis: planes of β phenylethylammonium cations [C6H5(CH2)2NH3]2+ alternate with planes of [Cd0.75Hg0.25Br4]2- tetrahedra. The cohesion of the atomic arrangement is ensured by hydrogen bonding (N&z.sbnd;H…Br) and Van der Waals contacts. DSC and Raman spectroscopy measurements were carried out and reveals a transition at T=347 K. This transition display an order–disorder mechanism involving mainly conformational changes of the organic chain [C6H5(CH2)2NH3]2+ coupled with distortion of the (Cd/Hg)Br4 tetrahedra. The transitional behavior and the crystal dynamics will be discussed and compared with those found in the literature for homologous compounds. [Copyright &y& Elsevier]