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Ferroelectric polymer-based electrocaloric effect may lead to sustainable heat pumps and refrigeration owing to the large electrocaloric-induced entropy changes, flexible, lightweight and zero-global warming potential. Herein, low-k nanodiamonds are served as extrinsic dielectric fillers to fabricate polymeric nanocomposites for electrocaloric refrigeration. As low-k nanofillers are naturally polar-inactive, hence they have been widely applied for consolidate electrical stability in dielectrics. Interestingly, we observe that the nanodiamonds markedly enhances the electrocaloric effect in relaxor ferroelectrics. Compared with their high-k counterparts that have been extensively studied in the field of electrocaloric nanocomposites, the nanodiamonds introduces the highest volumetric electrocaloric enhancement (~23%/vol%). The resulting polymeric nanocomposite exhibits concurrently improved electrocaloric effect (160%), thermal conductivity (175%) and electrical stability (125%), which allow a fluid-solid coupling-based electrocaloric refrigerator to exhibit an improved coefficient of performance from 0.8 to 5.3 (660%) while maintaining high cooling power (over 240 W) at a temperature span of 10 K. Low-k nanodiamonds are discovered to possess the ability to concurrently enhance the electrocaloric effect, thermal conductivity, and electrical stability of polymeric nanocomposites, providing support for electrocaloric refrigeration. [ABSTRACT FROM AUTHOR]

For perovskite manganites, their colossal magnetoresistance (CMR) requires a large field, which limits their potential applications. In order to uncover the path to achieve low-field CMR, it is crucial to understand the microscopic process of the field driven insulator-to-metal transition (IMT) in manganites. This is particularly true considering the fact that the IMT is of a percolative type, in which the interplay between nucleation and growth of the electronic phase separation domains under magnetic field is not well investigated. In this work, we investigate the magnetic field driven percolative IMT in a model system of La1−x−yPrxCayMnO3 in real space via magnetic force microscopy (MFM). Our experimental observations show unambiguously three stages of the IMT phase transition where domain nucleation and domain growth exhibit distinctly different features in the global initial magnetization measurements. Moreover, MFM reveals that domain growth requires a much lower field than domain nucleation, which provides critical information on how to achieve low-field CMR. It is believed that the exchange field provided by ferromagnetic metallic domains at the boundary with antiferromagnetic insulating domains plays a critical role in assisting the domain growth process. Optimizing such internal exchange fields in manganites is a potential route to achieve CMR without the need of a large external field. [ABSTRACT FROM AUTHOR]

Unique metal–insulator transition behaviors of strongly correlated electronic materials, vanadium dioxide (VO2), and their wide potential applications have gained much attention for investigation. In this research, high‐quality epitaxial films of VO2 (020) are directly grown on fluorophlogopite (001) substrates, and the relationship between phase‐transition temperature and external strains is revealed. After verifying the like‐freestanding property and low intrinsic resistance changing of VO2/fluorophlogopite, variable phase‐transition temperatures under different external strains with a tuning rate of 5.37 K per 0.1% strain are obtained. Based on experimental results and theoretical calculation, it is speculated that lattice constant and bandgap between d// and π * are strongly affected by the external strains, which allow for more effective dynamic modulation of phase‐transition process. This research provides a comprehensive understanding of strain engineering on phase‐transition properties and also broadens the possibility of potential applications of certain optoelectronic devices for strain modulation. [ABSTRACT FROM AUTHOR]

• BNKTT-1La ceramics achieved an excellent bipolar strain of ∼0.44 % and a large unipolar strain of ∼0.439 % at 60 kV/cm. • The unipolar strain of BNKTT-1La ceramics increased significantly to ∼0.895 % at 100 °C. • BNKTT-1La ceramics exhibited excellent fatigue resistance after 105 cycles at 65 kV/cm. Lead-free piezoelectric ceramics [(Na 0.84 K 0.16) 0.5 Bi 0.5 ] 1- x La x Ti 0.985 Ta 0.015 O 3 (BNKTT-100 x La) were synthesized by traditional solid phase reaction. The influences of La3+ doping on ceramic materials' microstructure, ferroelectric, and dielectric properties were investigated systematically. XRD patterns indicated that La3+ fully diffuse into the BNKTT lattice and form a single solid solution. SEM images showed that the surface of all samples was compact and no heterophase appeared. The ferroelectric-relaxor phase transition temperature gradually moved to low temperature with the increase of La3+ doping, which was beneficial to obtain large electro-strain. The maximum unipolar strain of BNKTT-1La ceramics can reach ∼0.439 % at 60 kV/cm corresponding to the inverse piezoelectric coefficient d 33 ∗ of ∼731 pm/V. The strain performance increased significantly to ∼0.895 % at high temperature because the ferroelectric-relaxor phase transition became easier. The BNKTT-1La ceramics showed excellent fatigue resistance after 105 cycles at 60 kV/cm. All these indicated that BNKTT-100 x La ceramics have great application prospects in piezoelectric brakes, strain sensors, and actuators. [ABSTRACT FROM AUTHOR]

In the quest for emerging in-sensor computing, materials that respond to optical stimuli in conjunction with non-volatile phase transition are highly desired for realizing bioinspired neuromorphic vision components. Here, we report a non-volatile multi-level control of VO2 films by oxygen stoichiometry engineering under ultraviolet irradiation. Based on the reversible regulation of VO2 films using ultraviolet irradiation and electrolyte gating, we demonstrate a proof-of-principle neuromorphic ultraviolet sensor with integrated sensing, memory, and processing functions at room temperature, and also prove its silicon compatible potential through the wafer-scale integration of a neuromorphic sensor array. The device displays linear weight update with optical writing because its metallic phase proportion increases almost linearly with the light dosage. Moreover, the artificial neural network consisting of this neuromorphic sensor can extract ultraviolet information from the surrounding environment, and significantly improve the recognition accuracy from 24% to 93%. This work provides a path to design neuromorphic sensors and will facilitate the potential applications in artificial vision systems. Bioinspired neuromorphic vision components are highly desired for the emerging in-sensor computing technology. Here, Ge et al. develop an array of optoelectronic synapses capable of memorizing and processing ultraviolet images facilitated by photo-induced non-volatile phase transition in VO2 films. [ABSTRACT FROM AUTHOR]

To further improve the comprehensive performances of conventional nitramine energetic crystals hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX), and 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20), especially their thermal stability and safety properties, is the main pursue in the field of energetic materials. Enlightened by means of the composition of attachment proteins from mussels, this research demonstrates that polydopamine (PDA) self‐polymerization could be used to prepare core‐shell structure energetic composites by surface coating technology. The results reveal that energetic crystal cores are mostly well‐coated by PDA more than 6 h; the combined characteristics of explosives and PDA indicating the main interface interaction force is hydrogen bonding. Moreover, the optimal polymorph of HMX (β) and CL‐20(ε) are maintained in the preparation process. Besides, another interesting phenomenon can be observed that the polycrystalline phase transition of endothermic and the decomposition temperature of exothermic peak for energetic crystals have been increased evidently, benefitting from the heat resisting of PDA layer. Moreover, thermal decomposition has been studied and calculated under different heating rates. Furthermore, the impact sensitivity of the PDA modified composites obtained is tested as well and decreased by 2–4 times compared with pristine energetic crystals. Therefore, this fabrication strategy in this study would provide a potential application of energetic@PDA in high‐strength and high‐energy propellants. [ABSTRACT FROM AUTHOR]

The unique electronic structure and crystal structure driven by external pressure in transition metal tellurides (TMTs) can host unconventional quantum states. Here, the discovery of pressure‐induced phase transition at ≈2 GPa, and dome‐shaped superconducting phase emerged in van der Waals layered NbIrTe4 is reported. The highest critical temperature (Tc) is ≈5.8 K at pressure of ≈16 GPa, where the interlayered Te–Te covalent bonds form simultaneously derived from the synchrotron diffraction data, indicating the hosting structure of superconducting evolved from low‐pressure two‐dimensional (2D) phase to three‐dimensional (3D) structure with pressure higher than 30 GPa. Strikingly, the authors have found an anisotropic transport in the vicinity of the superconducting state, suggesting the emergence of a "stripe"‐like phase. The dome‐shaped superconducting phase and anisotropic transport are possibly due to the spatial modulation of interlayer Josephson coupling. [ABSTRACT FROM AUTHOR]

Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3 (NBT-6.5BT) is systematically investigated via in situ Raman spectroscopy. The pressure dependence of phonon modes up to 30 GPa reveals two characteristic pressures: one is at around 4.6 GPa which corresponds to the rhombohedral-to-tetragonal phase transition, showing that the pressure strongly suppresses the coupling between the off-centered A- and B-site cations; the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure ∼13–15 GPa with certain degree of order-disorder transition, evidenced by the abnormal changes of intensity and FWHM in Raman spectrum. [ABSTRACT FROM AUTHOR]

A series of novel Bi 0.38 Na 0.38 Sr 0.24 Ti (1- x) (Mn 1/3 Nb 2/3) x O 3 lead-free ceramics (BNST-100 x MN) were designed and fabricated. The dielectric, ferroelectric, energy-storage, electrostrain properties, and impedance performance of these materials were systematically investigated. A large strain response under low driving electric field was obtained that benefits from the enhanced relaxor-to-ferroelectric phase transition. The optimum piezoelectric stain coefficient d 33 * of 930 pm/V (under 40 kV/cm) was achieved in BNST-1MN composition. The substitution by MN dopant gave rise to a homogeneous micro-morphology with small grains that gave rise to an enhanced high breakdown strength (BDS). Slim and slanted ferroelectric hysteresis was obtained by introducing a larger amount of MN, and hence the BNST-2MN ceramic exhibits a high energy-storage density of 1.30 J/cm3 at 110 kV/cm, accompanied with an excellent fatigue-free behavior. The dielectric response exhibited a stable high temperature dielectric property with low dielectric loss. These results indicate that BNST-100 x MN ceramics are promising candidates for the actuator and energy storage applications. [ABSTRACT FROM AUTHOR]

Abstract Lead lanthanum zirconate stannate titanate (PLZST) antiferroelectric materials have been intensively studied in the last few decades due to their adjustable phase transition and outstanding performance. Despite the strong interest it has drawn, there is a lack of study of domain structure evolution in antiferroelectric materials with morphotropic phase boundary (MPB) composition, which is of great importance for understanding the phase transition between ferroelectric and antiferroelectric phase. PLZST single crystals with the composition in the MPB region were grown by the flux method in this work. We presented the direct evidence that rhombohedral ferroelectric and tetragonal antiferroelectric phase coexist in the as-grown single crystals. The evolution of phase structure and domain morphology during the temperature-induced phase transition was observed by in situ optical visualization, accompanied by a broadening depolarization response. An enhanced broadening pyroelectric response with a wide temperature window was detected. A modified Ginzburg-Landau-Devonshire theory was employed to elucidate the structural and physical origin of the broadening thermal depolarization. It is anticipated that a further understanding of the phase transition behavior in PLZST single crystals may be helpful in developing novel ferroelectrics and antiferroelectrics with MPB compositions. [ABSTRACT FROM AUTHOR]

Abstract A series of novel lead-free (1- x)(0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3)- x Sr 0.8 Bi 0.1 □ 0.1 Ti 0.8 Zr 0.2 O 2.95 (SBTZ) ceramics were prepared via a traditional solid state sintering method. The ferroelectric, dielectric, AC impedance and fatigue properties were systematically studied. The introduction of V O and V A decreased the stability of ferroelectric phase, facilitated field-induced relaxor to ferroelectric transition and resulted in pinched and sloped P - E curves. The dielectric properties indicated that the relaxor phase of prepared ceramics was gradually dominated and the temperature of phase transition (T F-R) went downwards to room temperature with the increase of SBTZ. Therefore, a giant unipolar strain of 0.494% with a normalized strain d 33 * of 706 pm/V was obtained at x = 0.06. The AC impedance spectra of x = 0.06 ceramics revealed that its capacitance mechanism was derived from bulk effect. In addition, the stable fatigue resistance properties implied that the prepared ceramics were promising candidates for strain sensors and actuators. [ABSTRACT FROM AUTHOR]

Radial electric ( E )-field induced periodic polarization rotation from orthorhombic (O) to M C -type monoclinic (M C ) phase in Pb(Mg 1/3 Nb 2/3 )O 3 -0.34PbTiO 3 (PMN-0.34 PT) single crystals has been studied by in situ polarized light microscope. The piezoelectric coefficient ( d 33 ∗ ) and dielectric permittivity ( ε 33 T / ε 0 ) were 1800 pm/V and 5100, respectively, for [100]-oriented M C samples, almost three times of those in [011]-oriented O phase crystals. The domain structure evolution from 1O to 4M C was confirmed based on the optical extinction rules and permissible domain configurations. Moreover, the phase transition sequences of [100]- and [011]-poled PMN-0.34 PT crystals were M C —Tetragonal (T)—Cubic (C) and O—T—C upon heating, respectively. Our findings suggest that the phase stability of this crystals is associated with the orientation of applied field and radial E- field can serve as a general strategy to get fundamental insights into large piezoelectric activity and anisotropic phase stability in ferroelectric single crystals. [ABSTRACT FROM AUTHOR]

A new high-pressure phase of BiAlO 3 is predicted by first-principles calculations. The new phase belongs to the orthorhombic system with the space group Pnma . At pressure of about 12.6 GPa, a ferroelectric-to-paraelectric phase transition occurs between the R3c and Pnma phases for BiAlO 3 . The calculated lattice parameters, elastic constant and elastic modulus of R3c -BiAlO 3 are in good agreement with experimental and theoretical data. Phonon dispersion relation and elastic constant calculations indicate that the predicted Pnma phase is dynamically and mechanically stable. The analysis of electronic structures reveals the ionic-covalent and ionic bonding between the O Bi and O Al atoms in Pnma -BiAlO 3 , respectively. This study gives a fundamental understanding of the structural transformation in BiAlO 3 . [ABSTRACT FROM AUTHOR]

The electrocaloric effect (ECE) of Mn doped Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PIN-PMN-PT:Mn) single crystals with particular emphasis on the impact of crystallographic orientations and phase transitions were investigated systematically. Orientation-dependent phase transitions have been demonstrated by the dielectric and strain behaviors. Intriguingly, the negative ECE of – 0.02 °C and – 0.002 °C were obtained firstly in [001]-oriented PIN-PMN-PT:Mn crystals near the rhombohedral→tetragonal phase transformation and in [011]-oriented crystals near the rhombohedral→orthorhombic phase transformation, respectively. However, only the positive ECE was found in [111]-oriented crystals near the tetragonal→rhombohedral phase transition. Additionally, the maximum ECE temperature changes calculated in [001]-, [011]- and [111]-oriented crystals were 0.33 °C, 0.46 °C and 0.38 °C, respectively. Our results suggest that the negative ECE is attributed to electric field-induced phase transitions, whose critical field decreases with the increase of temperature. The phase transition-mediated coexistence of positive and negative effects in the relaxor-ferroelectric single crystals is beneficial to enhance the efficiency of the solid-state cooling devices. [ABSTRACT FROM AUTHOR]

For rhombohedral (R) Pb(In1/2Nb1/2)O3-PbZrO3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ( PIN- PZ- PMN- PT) relaxor single crystal, high temperature-insensitive behaviors under different external stimuli were observed (remnant polarization Pr from 30°C to 180°C and piezoelectric strain d33* from 30°C to 116°C). When electric field E ≥ 50 kV/cm in the case of an activation field Ea = 40-50 kV/cm was applied, it was found that the domain switching was accompanied by a phase transition. The high relaxor nature of the R phase PIN- PZ- PMN- PT was speculated to account for the large Ea and high piezoelectric response. The short-range correlation lengths [ABSTRACT FROM AUTHOR]

The (Na0.484Bi0.456Ba0.06)Ti0.97Nb0.03O3 − xLi+ ( x = 0, 0.005, 0.01, 0.015) lead-free piezoelectric ceramics are prepared by conventional solid-state reaction technique. X-ray diffraction and surface scanning electron microscope images confirm the pure perovskite structure of sintered ceramics. Electric field and composition-dependent strain behavior are investigated. The highest bipolar strain of 0.47% is achieved at x = 0.01 with the applied electric-field of 70 kV cm−1, and the corresponding normalized strain ( [ABSTRACT FROM AUTHOR]

Eucalyptus species are widely planted for reforestation in subtropical China. However, the effects of Eucalyptus plantations on the regional water use remain poorly understood. In an age sequence of 2-, 4- and 6-year-old Eucalyptus plantations, the tree water use and soil evaporation were examined by linking model estimations and field observations. Results showed that annual evapotranspiration of each age sequence Eucalyptus plantations was 876.7, 944.1 and 1000.7 mm, respectively, accounting for 49.81%, 53.64% and 56.86% of the annual rainfall. In addition, annual soil evaporations of 2-, 4- and 6-year-old were 318.6, 336.1, and 248.7 mm of the respective Eucalyptus plantations. Our results demonstrated that Eucalyptus plantations would potentially reduce water availability due to high evapotranspiration in subtropical regions. Sustainable management strategies should be implemented to reduce water consumption in Eucalyptus plantations in the context of future climate change scenarios such as drought and warming. [ABSTRACT FROM AUTHOR]

The anisotropic domain structures and local piezoresponse of rhombohedral Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 single crystals with high ferroelectric phase transition temperature ( TFE-FE≥120°C) were systematically investigated by vector piezoresponse force microscopy. The typical size of labyrinthine domain pattern for [001] C sample was in the range of 100-200 nm, revealing its relaxor feature. While the [011] C sample exhibited ordered ribbon-shaped domain pattern with preferential alignment along <011> direction since the modulation effect of polar nanoregions. For [111] C sample, it had messy and featureless domain patterns. For as-grown crystal, the incorporation of Zr4+ cation in Pb(Mg1/3Nb2/3)O3-PbTiO3 system resulted in that the long-range coulomb interactions of the charged ions in the short range order regions were weakened, leading to an increased relaxor feature. Concurrently, the incorporation of Zr4+ cation enhanced the Pb-B repulsion intensity, resulting in an improved TFE-FE. Temperature-dependent properties of as-grown crystal exhibited good temperature stability from 30 to 120°C, indicating it is a promising material for actuator and ultrasonic transducer applications. [ABSTRACT FROM AUTHOR]

In this paper, we calculate the strong decays of heavy-light states, namely, the charmed meson and the charm-strange meson. The method we adopt is the reduction formula, PCAC relation and low energy theorem, following which, the transition amplitudes are calculated. The wave functions of the heavy mesons involved are achieved by solving the instantaneous Bethe-Salpeter equation. As the OZI-allowed two-body strong decays give the dominant contribution, they can be used to estimate the total widths of mesons. Our results are: and . The ratios of branching ratios of two main channels are and , respectively. [ABSTRACT FROM AUTHOR]

A recently investigated Ti–24 at.% Nb–2 at.% Zr alloy was cold-rolled with reductions of 75% and 95%, and the resulting materials were heat-treated under the same conditions. The two types of specimens obtained through this procedure show the same phase composition. Precipitation of an isothermal ω phase leads to some improvement in the properties of the 75%-rolled specimens. The 95%-rolled and subsequently heated specimens exhibit different performances compared to the 75%-rolled samples heated under the same processing conditions. The stress-induced martensitic transformation is inhibited in the 95%-rolled specimens, owing to the combined effects of the isothermal ω phase and texture. The Ti–24 at.% Nb–2 at.% Zr alloy shows open circuit potential and corrosion behavior similar to commercially pure Ti. The corrosion resistance of the alloy is reduced upon precipitation of the ω phase, owing to an unstable passive film. [ABSTRACT FROM AUTHOR]

The domain configuration was reengineered with a modified poling procedure for the [011]-poled single-domain PMN-0.35PT crystals located at the morphotropic phase boundary. As a consequence, the dielectric constant εr at room temperature was significantly enhanced by more than 10 times to about 18 000, extremely higher than the reported (1 - x)Pb(Mg1/3 Nb2/3)O3-xPbTiO3 ferroelectric crystals. Besides, the decreasing rate of the dielectric constant (dεr/dT) was about 300/K with a temperature coefficient (α) of 1.7%/K, comparable to the BST materials for dielectric bolometer applications. The ferroelectric phase transition behavior was investigated to establish the poling procedure and a thermal hysteresis of about 25°C was indicated across the room temperature for the orthorhombic-tetragonal phase transition, which contributed to the revolution of the domain pattern. [ABSTRACT FROM AUTHOR]

The pressure-induced phase transformation from B3 to B1 structures in ZnS using first-principle projector-augmented wave method is studied. To understand the nature and driving force behind the transition, the interesting properties in both phases, including enthalpy, phonon dispersion curves and elastic constants, are systematically investigated. The results show that the calculated transition pressure is within the range of 16.33 GPa to 19.04 GPa, which is in good agreement with the available experimental and theoretical data. The transition process can be viewed as the appearance and disappearance of very slight lattice distortion accompanied by the movement of Zn and S atoms along the [111] crystallographic axis. The physical driving force of the B3–B1 phase transition is confirmed to be a coupling effect between the mechanical instability of B3 phase under pressure and the softening acoustic phonon mode resulting from the pressure-induced lattice deformation. For B1 phase, it is further predicted that a new phase transition takes place at about 59.9 GPa. [ABSTRACT FROM AUTHOR]

A perovskite single crystal of the quaternary system PIN–PZ–PMN–PT, with rhombohedral (R) symmetry (3m) and a size of 10 × 10 × 6 mm3, was successfully grown by a slow cooling method, which had a high rhombohedral-to-tetragonal (T) ferroelectric (FE) phase transition temperature (TR–T = 129 °C). The introduction of In3+ and Zr4+ enhanced the repulsion intensity between Pb2+ and B-site cations in the ABO3 lattice and increased the energy difference ΔET–R, resulting in an improved FE phase transition temperature compared to the PMN–PT binary system single crystals. The evolution of domain configuration induced by both electric field and temperature was studied for the [001]C PIN–PZ–PMN–PT single crystal by using a polarized light microscope. Star porphyritic domains with short-range order before poling and stripe domains with long-range order after poling were observed, respectively, confirming the typical relaxor domain configurations of the R phase. Fine domain walls induced by temperature for the poled [001]C sample were responsible for the high piezoelectric property. Furthermore, minor ferroelectric property variations (ΔPmax ＜ 6%, ΔPr ＜ 10%) were observed at the temperature range from 20 °C to 140 °C, indicating the good thermal stability of the quaternary system PIN–PZ–PMN–PT single crystal. [ABSTRACT FROM AUTHOR]

The phase structure in the as-grown PMN-0.36 PT single crystal was studied and the temperature-induced domain evolution was investigated using a polarized light microscope ( PLM). The crystal is identified to be MC type monoclinic based on the PLM results and tends to transform to cubic (C) phase directly through polarization rotation. The MC phase is metastable below Curie temperature ( TC), but prone to tetragonal phase upon electric field poling or high-temperature annealing. We suppose that the formation of the MC phase structure is associated with the strain gradient originated from Ti4+ segregation and the special MC-C phase transformation style is mediated by the corresponding residual ferroelastic strain stored within the as-formed domain structure. [ABSTRACT FROM AUTHOR]

Ferroelectric thin films have exhibited great potential in electrocaloric (EC) solid-state refrigeration due to large adiabatic temperature changes. However, current research on the EC effect of ferroelectric thin films mainly focuses on (001)-oriented thin films, while the EC response in different oriented thin films has yet to be systematically investigated. In this work, combining thermodynamic energetic and entropy analyses, a nonlinear thermodynamic approach has been generalized to investigate the EC response modulated by misfit strain in different oriented epitaxial ferroelectric (1- x)Pb(Mg 1 / 3 Nb 2 / 3)O 3 − x PbTiO 3 [(1- x)PMN- x PT] thin films. The effects of the chemical composition x , the misfit strain u m and the film orientation on the phase diagrams, phase transition temperatures and EC response in (1- x)PMN- x PT thin films are examined. It is found that different oriented thin films possess obviously different phase structures, phase boundaries and phase transition temperatures, resulting in different EC responses. The excellent EC response appears around the tetragonal-paraelectric (Te c -PE) phase boundary for (001)-oriented thin films, orthorhombic-paraelectric (O a a -PE) phase boundary for (110)-oriented thin films, and rhombohedral-paraelectric (R a a a -PE) phase boundary for (111)-oriented thin films under compressive misfit strain, due to the large change in polarization. The maximum adiabatic temperature change Δ T shifts to a higher operating temperature when the composition x increases, due to the shifting of the ferroelectric–paraelectric phase boundary towards the higher temperature. Good agreement with experimental data is observed. The results also indicate that (001)-oriented thin films are beneficial to EC cooling at higher temperature, (111)-oriented thin films are beneficial to EC cooling at lower temperature, and (110)-oriented thin films are beneficial to EC cooling at medium temperature, suggesting that the EC response in ferroelectric thin films can be modulated by misfit strain via growing thin films in an appropriate orientation. These insights offer an alternative way to modulate the EC response in ferroelectric thin films. [ABSTRACT FROM AUTHOR]

(Pb0.97La0.02)(Zr xSn0.89− xTi0.11)O3 ( x = 0.60, 0.62, 0.64, 0.66, 0.68, 0.70, 0.72, and 0.74) ceramics with the compositions in tetragonal antiferroelectric (AFE) region, near the morphotropic phase boundary, were prepared by using the conventional solid-state reaction process. Their electric field-induced phase transitional behaviors, composition- and temperature-dependent dielectric, depolarization, and pyroelectric properties were investigated systematically. The AFE to ferroelectric phase switching field EA-F decreased with increasing x, while depolarization temperature Td increased with a linear relationship of Td = 842 x-483. Enhanced pyroelectric coefficient with a value of 12.1 μC/cm2/K was obtained at 88°C for the ceramics with x = 0.68, which was four times larger than the reported values. Composition-dependent pyroelectric response over 24°C-140°C was realized by changing x from 0.60 to 0.74. The results also suggested that the enhanced pyroelectric response near Td was accompanied by a release of large Pr, caused by an induced ferroelectric to AFE phase transition. [ABSTRACT FROM AUTHOR]

Temperature-dependent domain configurations were studied for both unpoled and poled [110]C-oriented 0.63Pb(Mg1/3Nb2/3)O3–0.37PbTiO3 (PMN–0.37PT) single crystals by polarized light microscopy (PLM). Combining the dielectric properties and the domain configurations upon heating, it was found that the temperature-induced phase transition in the unpoled [110]C-oriented PMN–0.37PT single crystal followed the tetragonal (T) → cubic (C) sequence. However, under an electric (E) field of 10 kV cm−1 along the [110]C direction, a single domain orthorhombic (O) phase was induced. The E field-dependent domain structures were observed in situ under PLM, which verified that the T phase turned to O phase when an E field of 10 kV cm−1 was applied along the [110]C direction. Upon subsequent heating, the phase transition followed the O → T → C sequence. The O–T discontinuous phase transition led to a remarkable change in the dielectric coefficient and strain with increasing temperature. The strain at 45 °C (0.148%) was 2.2 times larger than that at room temperature (0.068%), accompanied by a tremendous piezoelectric coefficient (UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/ ~1645 pm V−1). [ABSTRACT FROM AUTHOR]

Hydrodynamic behaviors of multiple supersonic jets, especially their coalescence, are of paramount importance to effective design and operation of the oxygen lance in steelmaking basic oxygen furnace (BOF) but not well understood. This paper presents a numerical study on the coalescence of supersonic jets from the multi-nozzle oxygen lance at a practical Mach number by a compressible and non-isothermal computational fluid dynamics model. The model is firstly validated and then used to study the effects of key variables (i.e. ambient temperature and arrangement of nozzles including inclination angle and number) on coalescence behavior under various operational conditions. The results show that the jets prefer to deviate from their own nozzle axes and tend to coalescence with decreasing ambient temperature/nozzle inclination angle or increasing nozzle number. The attenuations of the velocity and dynamic pressure at the jet centerline are delayed with the increase of ambient temperature or the decrease of nozzle number/inclination angle. The critical condition where the jets are free from interaction is identified with increasing nozzle inclination angle, and the critical value is 258 for the four-nozzle lance considered. The simulation results are then used to estimate the cavity shape and splashing modes in BOFs. [ABSTRACT FROM AUTHOR]

The reactions of 4-(dimethylamino)pyridine (DMAP) and metal chloride in dilute hydrochloric acid yield two four-coordinate complexes, 1 (DMAP + )(FeCl 4 − ) and 2 (DMAP + ) 2 (CoCl 4 2 − ). The differential scanning calorimetry (DSC) measurements, temperature-dependent dielectric properties and variable-temperature single-crystal X-ray diffraction analyses of compound 1 confirmed the reversible isostructural phase transition with the same space group P 2 1 / n (No. 14) at 298 K and 373 K. The temperature-dependent single crystal structural analyses of compound 1 reveal the distinct and synchronous molecular motions of both the cationic and anionic moieties, where the orientational changes of organic cations and the order–disorder transformations of FeCl 4 − anions are mainly responsible for dielectric properties of compound 1 . The variable-temperature structure analyses and the variable-temperature PXRD measurements reveal that compound 2 undergoes a reversible structural phase transition at around 381 K. The space groups of compound 2 change from triclinic P -1 in room temperature phase (RTP) to monoclinic C 2/ c in high temperature phase (HTP), accompanied by thermal and dielectric anomalies. [ABSTRACT FROM AUTHOR]

Tetramethylphosphonium dichromate ([(CH3)4P]2[Cr2O7], 1) undergoes a reversible phase transition at around 221 K. The results of the variable-temperature single-crystal X-ray structural analyses and the rotational potential energy calculations suggest that the phase transition is probably related to the order-disorder transition of the [Cr2O7]2- anion. The change of the space group from Pa-3 at room temperature to Pbca at low temperature is reflected in the peak-like dielectric response. Tetraethylphosphonium trichromate ([Et4P]2[Cr3O10], 2) crystallizes in the monoclinic space group P21/c at room temperature. Upon cooling and heating, the step-like dielectric anomalies observed at around 270 K indicate a reversible phase transition. Moreover, the rotational potential energy calculations certify the potential motion of the [Cr3O10]2- anion, being related to the phase transition. These findings open a new approach to the design of complexes that show phase transitions coupled with unusual dielectric properties. [ABSTRACT FROM AUTHOR]

The piezoelectric properties of BaTi 1− x Zr x O 3 are investigated by first-principles calculations with virtual crystal approximation. The total energy, piezoelectric coefficient, elastic property and Born effective charge as a function of Zr doping level x of BaTi 1− x Zr x O 3 are calculated in order to reveal the property of its polymorphic phase boundaries. Our results show that the polymorphic phase boundaries of BaTi 1− x Zr x O 3 exist only in the range of x =0.077–0.088, which is coincident with the available experimental observation. And a high piezoelectric coefficient d 33 at x =0.08 is shown in the tetragonal and orthorhombic BaTi 1− x Zr x O 3 . It is found that this high piezoelectric activity at the polymorphic phase boundaries is due to the flat free energy profile of BaTi 1− x Zr x O 3 . Moreover, as can be seen in our calculations, the enhancement of structural instability and Ti–O covalent bonding is responsible for the enhancement of piezoelectricity of BaTi 1− x Zr x O 3 . This study gives a fundamental understanding of polymorphic phase boundaries in BaTi 1− x Zr x O 3 , and may further serve the improvement of piezoelectric response in BaTi 1− x Zr x O 3 from the application point of view. [ABSTRACT FROM AUTHOR]

Three analogue N-heterocyclic complexes, 1-propyl-1-methylpiperidinium perchlorate (1, [PMpip][ClO4]), 1-cyanomethyl-1-methylpiperidinium perchlorate (2, [CMpip][ClO4]), and 1-cyanomethyl-1-methylmorpholinium perchlorate (3, [CMmor][ClO4]) are identified as phase transition materials displaying switchable dielectric behaviors. Despite the common [ClO4]− anion and the closely related cations, compound 1 crystallizes in the orthorhombic space group P212121, but compounds 2 and 3 belong to the monoclinic space group P21/n with distinct cell dimensions. Compounds 1, 2 and 3 undergo reversible phase transitions around 199, 387 and 416 K, respectively, accompanied by notable step-like dielectric anomalies which could be switched by the phase transition and be tuned in distinct dielectric states. The respective dielectric constants in the high dielectric states are 1.2, 2.2 and 3.2 times that in the low dielectric states for compounds 1, 2 and 3. Generally, these differences in the phase transitions and dielectric properties are caused by the distinct molecular structures and hydrogen-bonding conformations resulting from the structural variations in the side-chain and the ring structure. [ABSTRACT FROM AUTHOR]

In this paper, Co-Ti ions co-substituted M-type barium ferrite materials [Ba(CoTi)FeO, x = 1.15, 1.20, 1.25 and 1.30] were synthesized by solid-state reaction method. The ferrites, with sintering at 1,200 °C for 4 h, all exhibit the single phase M-type barium ferrite structure. However, there are obvious differences on properties among different amounts of Co-Ti substitution, basing on the same phase formation of M-type barium ferrites. With x increasing from 1.20 to 1.25, magnetic properties, including saturation magnetic flux density ( B), residual magnetic flux density ( B), initial permeability ( μ), saturation magnetization ( M), coercivity ( H) and Q-factor, have an obvious change. This is attributing to that Co and Ti occupancies at different sites in the barium ferrite crystalline structure bring the change of magnetocrystalline anisotropy. The appropriate content of Co-Ti substitution makes the magnetocrystalline anisotropy transform from uniaxial to planar anisotropy. Meanwhile, this difference also is confirmed by Raman spectroscopy. The spectra are recorded from 200 to 3,200 cm in the room temperature. The occupancy of Co and Ti ions on the Fe sites causes difference in intensity and Raman bands, which also corroborate the changes of Co-Ti occupation and magnetocrystalline anisotropy from another perspective. [ABSTRACT FROM AUTHOR]

(1 − x )[Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 (65/35)]– x PbZrO 3 (PMN–PT–PZ) ceramics near morphotropic phase boundary with 0 ≤ x ≤ 0.10 were synthesized via the conventional solid-state reaction method. X-ray diffraction and variable temperature dielectric property characterization indicated that the rhombohedral to tetragonal phase transition temperature ( T rt ) increased linearly with the increase of PZ constant. The composition and temperature dependence of their ferroelectric and pyroelectric properties were also investigated. The results showed that there appeared mutation for remnant polarization, coercive field, as well as pyroelectric coefficient at the temperate range near T rt , which was ascribed to the reorientation of dipoles caused by the rhombohedral–tetragonal phase transition. [ABSTRACT FROM AUTHOR]

The field dependence of ferroelectric hysteresis loop and polarization reversal of 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNT-6BT) ferroelectrics at room temperature and 110 °C are investigated. The variation of the hysteresis area suggests three stages of the polarization reversal at the two temperatures, where the first and third stage can be scaled as power law relationships, and the second stage shows non-linear functions. Distinct features in the two temperatures indicate the differences between the domain structures and their external field responses. The reversible field-induced phase transition from relaxor phase to ferroelectric phase at 110 °C plays a key role in getting the large strain. [ABSTRACT FROM AUTHOR]

[Display omitted] • The bandgap variation of h -BAlN and w -BAlN with Al composition were calculated. • The preferentially formed BAlN alloys will convert from h -BAlN to w -BAlN when Al exceeds 18.7%. • A comprehensive bandgap variation of BAlN was obtained when considering the phase transition. • h -BAlN and w -BAlN films were prepared by magnetron co-sputtering technique and the phase transition was observed. • The bandgap variation of BAlN films in experiments can be well explained by DFT calculations. BAlN is a promising ultrawide bandgap semiconductor, but systematic studies of its bandgap are scarce. Here, bandgap engineering of BAlN containing the phase transition factor (from hexagonal to wurtzite structures) has been investigated by DFT calculations and verified experimentally. The calculated bandgap bowing parameter of hexagonal BAlN (h -BAlN) is 2.29 eV, while the bandgap bowing parameters of wurtzite BAlN (w -BAlN) are −4.09 eV and 2.48 eV in the B-rich and Al-rich regions, respectively. Meanwhile, calculations indicate that BAlN preferentially forms w -BAlN at Al composition above 18.7%. So, the bandgap variation of BAlN is divided into three regions based on Al composition: h -BAlN (0–18.7%), B-rich w -BAlN (18.7%–50%), Al-rich w -BAlN (50%–1), and each has its own trend. Experimentally, h -BAlN and w -BAlN films were prepared by magnetron co-sputtering technique and the phase transition was observed in X-ray diffraction (XRD) patterns. h -BAlN shows a typical triangular morphology and the Raman and XRD peaks are located at 1371 cm−1 and 44.3°, tending to (1 0 1) h -BN. w -BAlN has a "needle-felt" surface with Raman and XRD peaks at 656 cm−1 and 35.9°, tending to (0 0 2) w -AlN. The experimental bandgap variation of BAlN shows a "W" shape, which can be well explained by the calculation results. [ABSTRACT FROM AUTHOR]

Lead-free ceramics (1- x)NaNbO3- xLiTaO3 were synthesized by an ordinary solid-state reaction method. Rietveld analysis reveals that the crystal structure changes from one orthorhombic phase with Pbcm space group to another orthorhombic phase with P2221 space group when increasing x. The morphotropic phase boundary between two different orthorhombic symmetries is formed at 0.14 < x < 0.18. Excess LiTaO3 causes an abnormal grain growth behavior. The pure NaNbO3 presents four current peaks in the I- E loop, indicating electric-field-induced transitions. A low LiTaO3 doping induces ferroelectricity in the initially antiferroelectric (AFE) NaNbO3. Enhanced ferroelectricity is obtained at x = 0.02-0.12. The addition of LiTaO3 makes the ceramics undergo a transition from an antiferroelectricity dominant to a ferroelectricity dominant phase state. The optimum d33, kp, Qm, and Pr values of 46 pC/N, 18.3%, 1333, and 27.1 μC cm−2 are obtained when x equals 0.12, and the ceramic exhibits good temperature stability because of its high TC. [ABSTRACT FROM AUTHOR]

Abstract: Within the framework of the quasi-harmonic approximation, the thermodynamic properties and the phase transition of ThO2 from the cubic structure to the orthorhombic structure are studied using the first-principles projector-augmented wave method. The vibrational contribution to Helmholtz free energy is evaluated from the first-principles phonon density of states and the Debye–Grüneisen model. The calculated results reveal that at ambient temperature, the phase transition from the cubic phase to the orthorhombic phase occurs at 26.49GPa, which is in agreement with the experimental and theoretical data. With increasing temperature, the transition pressure decreases almost linearly above room temperature. The predicted heat capacity and linear thermal expansion coefficient of cubic ThO2 are in good consistence with the experimental data. By comparing the experimental results with the calculation results from the first-principles and Debye–Grüneisen model, it is found that the thermodynamic properties of ThO2 are depicted well by the first-principles phonon treatment after including the an-harmonic correction to quasi-harmonic free energy. [Copyright &y& Elsevier]

Abstract: For spinal-fixation applications, implants should have a high Young’s modulus to reduce springback during operations, though a low Young’s modulus is required to prevent stress shielding for patients after surgeries. In the present study, Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) with a low Young’s modulus was modified by adding Cr to obtain a higher deformation-induced Young’s modulus in order to satisfy these contradictory requirements. Two newly designed alloys, TNTZ–8Ti–2Cr and TNTZ–16Ti–4Cr, possess more stable β phases than TNTZ. These alloys consist of single β phases and exhibit relatively low Young’s moduli of <65GPa after solution treatment. However, after cold rolling, they exhibit higher Young’s moduli owing to a deformation-induced ω-phase transformation. These modified TNTZ alloys show significantly less springback than the original TNTZ alloy based on tensile and bending loading–unloading tests. Thus, the Cr-added TNTZ alloys are beneficial for spinal-fixation applications. [Copyright &y& Elsevier]

The first-principles projector-augmented wave method employing the quasi-harmonic Debye model, is applied to investigate the thermodynamic properties and the phase transition between the trigonal R3c structure and the orthorhombic Pnma structure. It is found that at ambient temperature, the phase transition from the trigonal R3c phase to the orthorhombic Pnma phase is a first-order antiferromagnetic-nonmagnetic and insulator-metal transition, and occurs at 10.56 GPa, which is in good agreement with experimental data. With increasing temperature, the transition pressure decreases almost linearly. Moreover, the thermodynamic properties including Grüneisen parameter, heat capacity, entropy, and the dependences of thermal expansion coefficient on temperature and pressure are also obtained. [ABSTRACT FROM AUTHOR]

Abstract: In the four-wave mixing process, since the intensity of the generated coherence field is related closely to the third-order nonlinear susceptibility. With the help of a Hamiltonian approach, we obtain the expression of third-order nonlinear susceptibility χ (3), and the special relation between χ (3) and the nonlinear conversion coefficient. They are very useful to analyze the phase mismatch due to the Kerr effect and linear refraction contributions, which affect the maximum conversion efficiency under the condition taking account into pump field depletion. The investigative results show that energy conversion efficiency from the weak idler field to the generated field may exceed 100% when the phase mismatch induced by linear refraction is compensated, though the phase mismatch contribution from the Kerr effect can not be compensated simultaneously. Moreover, the conversion efficiency of the photon numbers fast reaches a plateau value. [Copyright &y& Elsevier]

LaCaSrMnO (0 ≤ x ≤ 0.3) (LCSMO) is a thermochromic material. The material can show a phase transition from ferromagnetic-metal to paramagnetic-insulator under the appropriate doping level ( x). In this paper, LCSMO compounds were synthesized by a conventional solid-state reaction method. The normal emissivity and the spectral reflectance of LCSMO with different doping levels ( x) are experimentally investigated. Based on the spectral reflectance data, the optical constants (refractive index n and extinction coefficient k) are calculated by using Kramers-Kronig (K-K) relations. Then, the emissivity changing mechanism is discussed. The experimental results show that the emissivity of LCSMO increases with increasing temperature. For the samples with x = 0.1 and 0.15, their emissivity has a sudden change in the vicinity of the phase transition temperature T. [ABSTRACT FROM AUTHOR]

Abstract: 10mol% Pb(Fe1/2Nb1/2)O3 (PFN) modified Pb(Mg1/3Nb2/3)O3–PbZr0.52Ti0.48O3 (PMN–PZT) relaxor ferroelectric ceramics with compositions of (0.9− x)PMN–0.1PFN–xPZT (x =0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9) were prepared. X-ray diffraction investigations indicated that as-prepared ceramics were of pure perovskite phase and the sample with composition of x =0.8 was close to morphotropic phase boundary (MPB) between rhombohedral and tetragonal phase. Dielectric properties of the as-prepared ceramics were measured, and the Curie temperature (T c) increased sharply with increasing PZT content and could be higher than 300°C around morphotropic phase boundary (MPB) area. At 1kHz, the sample with composition of x =0.1 had the largest room temperature dielectric constant ɛ r =3519 and maximum dielectric constant ɛ m =20,475 at T m, while the sample with composition of x =0.3 possessed the maximum dielectric relaxor factor of γ =1.94. The largest d 33 =318pC/N could be obtained from as-prepared ceramics at x =0.9. The maximum remnant polarization (P r =28.3μC/cm2) was obtained from as-prepared ceramics at x =0.4. [Copyright &y& Elsevier]

Abstract: Rhombohedral–tetragonal ferroelectric structural phase transition temperature (T R−T), far below the Curie temperature (T c) in lead magnesium niobate–lead titanate (PMN–PT) relaxor ferroelectric single crystal, heavily restricts its further applications either as a sensor or transducer. To overcome this shortcoming, lead zirconate (PZ) was introduced into the PMN–PT pseudo-binary system to increase T R−T via the morphotropic phase boundary (MPB) composition design and optimization. According to the PMN–PT–PZ pseudo-ternary phase diagram, various compositions have been selected to discuss the relations between their phase structural transition and piezoelectric properties in the PMN–PT–PZ pseudo-ternary system. X-ray diffraction (XRD) investigation indicates clearly that PMN–PT–PZ ceramics with MPB compositions experience a typical structural phase transition process from rhombohedral phase to tetragonal phase. Remnant polarization (P r=33.4μC/cm2) and piezoelectric coefficient (d 33=1050pC/N) were obtained at the (001) cut PMN–PT–PZ single crystal. T R−T was increased up to 120°C by measuring its dependence of dielectric constant on temperature. [Copyright &y& Elsevier]

We present real-time study of pristine graphene sandwiched in a homogeneous polymer matrix and its phase transition where the graphene membrane irreversibly scrolls and folds above the polymer’s glass temperature. Tubular structures tend to form by curling up from edge defects of graphene and roll along its surface. A single-layer can also fold into two- or three-layer stacks and the overlapping between layers extends along the membrane surface to enlarge up to micrometer sizes. Further, oxidized graphene does not show such reactivity at even higher temperatures, indicating that the intrinsic thermal instability of pristine graphene in the polymer matrix is the origin of the transition. [ABSTRACT FROM AUTHOR]

Abstract: A powder metallurgy technology was developed to prepare Ti50Cu23Ni20Sn7 bulk metallic glasses (BMGs). Firstly, amorphous powder was prepared by mechanical alloying (MA) method successfully after being milled for 30h. Phase transformation of the as-milled powder was characterized by X-ray diffraction (XRD). Morphology of the as-milled amorphous powder was observed by scanning electron microscopy (SEM). Onset temperature of glass transformation and onset temperature of crystallization (T x and T g) of the as-milled amorphous powder were evaluated by differential scanning calorimeter (DSC). Secondly, the as-milled amorphous powder was then consolidated by spark-plasma sintering (SPS) method into a specimen with the shape of cylindrical stick, with a diameter and height of about 20 and 10mm, respectively. The SPS experiment was conducted under a pressure of 500MPa at a heating rate of 40K/min, sintering and holding for 1min at the temperature of 763K. It was confirmed that the as-milled powder is of fully amorphous however the consolidated specimen shows to be an amorphous matrix with partial crystallization. Compressing strength, Young''s modulus, micro-hardness, friction and density of the consolidated specimen are about 975MPa, 121GPa, 13GPa, 0.12 and 6599kg/m3, respectively. Fractograph of the specimen appears to be shear fracture and very few defects can be seen from the picture of SEM. [Copyright &y& Elsevier]

Abstract: Piezoelectric ceramics with compositions of (0.90−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3–0.10PbZrO3, , 0.31, 0.34, 0.37, 0.40 and 0.43, were prepared using the conventional columbite precursor method, and their structural phase transformation and piezoelectric behaviors near the morphotropic phase boundary (MPB) have been systematically investigated as a function of PbTiO3 content. X-ray diffraction (XRD) results demonstrate that the structure of the ceramics experiences a gradual transition process from rhombohedral phase to tetragonal phase with the increasing of PbTiO3 content, and that compositions with –0.40 lie in the MPB region of this ternary system. A Raman spectra investigation of the ceramic samples testified to the transformation process of rhombohedral phase to tetragonal phase by comparing the relative intensities of tetragonal E(2TO1) mode and rhombohedral phase Rh mode. The structure information was also correlated to the parabola change of the piezoelectric constant; the maximum piezoelectric constants were obtained near the MPB region. [Copyright &y& Elsevier]

Abstract: This study focuses on the numerical model simulation of stress and temperature fields of carburized specimens with different carbon content during the quenching process. In the models the coupling between thermal field, phase transformation field and stress field was considered. The changes of the thermomechanical parameters of the material, as a function of carbon content and thermal field, were considered in the stress simulations. The residual stress fields of 20CrMnTi specimens with different carbon content of 0.8% and 1.0% were measured using an X-ray stress analyzer. Finite element model (FEM) was built for simulating the residual stress field after quenching. Meanwhile, the temperature and stress fields during quenching were simulated. The measured and simulated results are in good agreement. [Copyright &y& Elsevier]

To raise mechanical strength of metallic materials, methods such as grain refinement and amorphization are usually utilized but sacrifice plasticity. Strength and plasticity are largely dictated by dislocation-defect interactions in crystalline materials and by shear banding in metallic glasses, depending significantly on the length scales of microstructural features. Here we report on the evolution of microstructures and multistage phase transformations from micro/nanocrystalline to an entirely amorphous structure, realized by tailoring the composition of Cr in co-sputtered Al 1 00 -x Cr x (x = 0–25 at%) alloys. The associated Cr segregation caused the formations of different dual-phase nanocomposites. In-situ micromechanical experiments revealed that the flow stress of Al–Cr alloys can reach 2.4 GPa and the deformation behaviors varied drastically with Cr composition. This study established the mechanistic connection between the Cr composition-dependent evolution of microstructure and ultrahigh strength as well as plasticity, and revealed the benefits of building nanocomposites through a multistage phase transformation to improve the plasticity of nanocrystalline and amorphous materials. • Cr segregates at grain boundaries in Al–Cr alloys with a wide compositional range. • The segregation enables multistage phase transformation: FCC-Al 7 Cr-amorphous. • Microstructure-dependent flow stress could reach 2.4 GPa for Al alloys. • Nanocomposites could improve plasticity of nanocrystalline and amorphous materials. • Mechanistic connection between property and microstructure is established. [ABSTRACT FROM AUTHOR]

• The deformation mechanisms of nanotwinned Al/Ti multilayers were investigated by using in situ micropillar compression tests. • Nanotwinned Al/Ti multilayers exhibit flow stress up to 2.4 GPa and good work hardening capability. • Deformation induced stacking faults and HCP-to-FCC phase transformation were revealed in Ti. • Molecular dynamics simulations elucidate the mechanisms of deformation induced phase transformation in Ti. Nanotwinned Al/Ti multilayers have exhibited size-dependent microstructure evolution and high strength. However, their deformation mechanisms are less well understood. In this work, we investigated the deformation mechanisms of nanotwinned Al/Ti multilayers with FCC/HCP layer interfaces by using in situ micropillar compression tests. Nanotwinned Al/Ti multilayers exhibit compressive strength up to 2.4 GPa and good work hardening capability. Post-compression TEM analyses reveal high-density stacking faults and the HCP-to-FCC phase transformations in Ti. Molecular dynamics simulations elucidate the mechanisms of deformation induced phase transformation in Ti and the influence of collective movement of partial dislocations on the deformability of Al/Ti multilayers. [ABSTRACT FROM AUTHOR]