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The conversion of solar energy into H 2 energy by photocatalytic biomass decomposition has become a research hotspot in recent years. In this work, Co 3 S 4 /Zn 0.5 Cd 0.5 S (CS/ZCS) composites with a series of mass ratio were prepared by loading ZCS nanoparticles on the surface of Co 3 S 4 polyhedron, and characterized by many advanced tests. Moreover, their photocatalytic activity of H 2 production were explored by biomass decomposition, like lactic acid (LA) and benzyl alcohol (PhCH 2 OH). When the amount of Co 3 S 4 cocatalyst is 4 wt%, the H 2 production of the composite photocatalyst reaches the highest, which is 17.86 mmol·g−1·h−1 for LA and 20.07 mmol·g−1·h−1 for PhCH 2 OH, much higher than ZCS nanoparticles. Co 3 S 4 cocatalyst as the electrons (e−) trapper of ZCS, enhances the absorption of visible light and improves the migration efficiency of the photogenerated charge carriers (PCCs), thus greatly increasing the photocatalytic H 2 production. This work may play an important role in improving H 2 production from biomass decomposition for metal sulfide. • Co 3 S 4 /Zn 0.5 Cd 0.5 S composite was prepared by self-assembly method. • Co 3 S 4 as the electron trapper were derived from ZIF-67 template. • Photocatalytic H 2 production is generated by biomass decomposition. • The enhanced reasons were analyzed by experimental and theoretical methods. • The mechanism of the charge transfer on Co 3 S 4 / Zn 0.5 Cd 0.5 S is proposed. [ABSTRACT FROM AUTHOR]

Cr 2 O 3 –TiO 2 (CrTiO) composite powders were synthesized via high temperature solid-state reaction method. CrTiO coating with different Cr 2 O 3 content were prepared from plasma spraying using CrTiO composite powders as spraying feed respectively. X ray diffraction analysis (XRD) and scanning electron microscopy (SEM) analysis were taken to characterize the phase components and microstructure, respectively. Electromagnetic parameters (including complex permittivity and complex permeability) of CrTiO coating were characterized and studied through a network vector analyzer. Electromagnetic-wave absorption property of CrTiO coating with different coating thickness were also examined. Results of XRD show that the main composition of the CrTiO composites are TiO 2 and Cr 0.12 Ti 0.78 O 1.34. Complex permittivity and complex permeability of coating increase with the increase of Cr 2 O 3 content, which is ascribed that the enhancement of carrier concentration, relaxation polarization, electron polarization and magnetic polarization etc. Reflectivity results show that the composite coating displays electromagnetic attenuation at 8.2 GHz–12.4 GHz (generally called the X-band) for 15% Cr 2 O 3 content coating with a sample thickness 1.9 mm. The peak value of the reflection loss reaches −10dB can be achieved at 8.2 GHz–10.2 GHz. Moreover, a frequency selective surface (FSS) coupled by a circular element and four square elements is used to further enhanced the microwave absorption performance of coating. The results show that the microwave absorption performance of the absorbing coating mainly depend on the frequency selective surface, Cr 2 O 3 content and thickness of the CrTiO coating. These results imply that CrTiO coating have a potential as microwave absorbing materials for electromagnetism applications. • Electromagnetic parameters of CrTiO ceramic are reported for the first time. • Absorption property of CrTiO ceramic can be improved by frequency selective surface. • Absorbing mechanisms of CrTiO ceramic with frequency selective surface are studied and discussed. [ABSTRACT FROM AUTHOR]

With the development of artificial intelligence, machine learning has a wide range of applications in the field of materials. The sparsity of data on the mechanical properties of high-entropy alloys makes it difficult to balance between the generalizability and interpretability in data-driven predictive models of material properties. A machine learning model was established based on the HEA hardness data of the Al-Co-Cr-Cu-Fe-Ni system, and several modeling features were screened out through a three-step parallel approach. Model ensemble was performed for RandomForest, XGBoost, LightGBM and CatBoost using the stacking ensemble algorithm, and the coefficient of determination(R2) of the model reached 0.93 after a ten-fold cross-validation. The ensemble learning is stable and accurate for predicting HEA hardness value, and is experimentally verified. The model and selected features can also be applied to different HEA systems as well as low hardness CrFeNi MEA. In addition, we further explained the large prediction deviation of MEA in the high hardness region. Further, the effects of HEA composition and phase formation on the hardness of HEA were qualitatively analyzed based on interpretable tools like SHAP values as well as PDP/ICE plots, respectively. Finally, the model not only has the generalization of ensemble learning, but also has certain interpretability. [Display omitted] • Establishing an ensemble learning combining classification and Stacking regression. • Transferable for various HEA and ternary CrFeNi MEA material systems. • Interpretable machine learning approach to analyze the hardening mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electrical properties of K0.5Na0.5NbO3 (KNN) films improved after cobalt (Co) doping. [•] The optimal amount of Co is 2.0mol%. [•] The leakage characteristic of KNN films were investigated. [Copyright &y& Elsevier]

Highlights: [•] Structures of K0.5Na0.5NbO3 (KNN) films hardly change with the thickness. [•] The dielectric constants of films did not monotonously increase with the thickness. [•] The ferroelectric properties of films improved by increasing the thickness. [ABSTRACT FROM AUTHOR]

Abstract: Pyrochlore Bi1.5Zn1.0Nb1.5O7 (BZN) thin films deposited at 650°C under an oxygen pressure of 10Pa by pulsed laser deposition were characterized as a function of zinc amount. The zinc concentration in the thin films was varied using ceramic targets having 0–40mol% excess zinc contents. The X-ray diffraction measurement shows that thin films have a cubic pyrochlore phase structure and a strong preferential orientation of (111) plane. The dielectric properties are investigated as functions of temperature and frequency. Dielectric constant and loss tangent of the thin films both slightly increase with the increase of Zn amount. The thin film with 40mol% zinc exhibits a dielectric constant of 198 and a loss tangent of 0.004 at 10kHz. The dielectric relaxation behavior has been studied by measuring the temperature dependence of dielectric properties. The characteristic temperatures (T m) move to the high temperature with the increase of Zn and gradually approach that of BZN ceramic. Meanwhile, in a wide frequency and temperature range (1kHz–1MHz, −100–150°C), the dielectric constant of the thin films almost keeps unchanged and shows a negative temperature coefficient. Leakage current density of the thin films with 20mol% zinc is approximately three order magnitude lower than that of films with 0mol% zinc at 400kV/cm. The conduction of BZN thin films is controlled by the Schottky emission mechanism and the space-charge-limited current mechanism. [Copyright &y& Elsevier]

Abstract: Bi2Zn2/3Nb4/3O7 thin films were deposited on Pt/TiO2/SiO2/Si(100) substrates at a room temperature under the oxygen pressure of 1–10Pa by pulsed laser deposition. Bi2Zn2/3Nb4/3O7 thin films were then post-annealed below 200°C in a rapid thermal process furnace in air for 20min. The dielectric and leakage current properties of Bi2Zn2/3Nb4/3O7 thin films are strongly influenced by the oxygen pressure during deposition and the post-annealing temperature. Bi2Zn2/3Nb4/3O7 thin films deposited under 1Pa oxygen pressure and then post-annealed at a temperature of 150°C show uniform surface morphologies. Dielectric constant and loss tangent are 57 and 0.005 at 10kHz, respectively. The high resolution TEM image and the electron diffraction pattern show that nano crystallites exist in the amorphous thin film, which may be the origin of high dielectric constant in the Bi2Zn2/3Nb4/3O7 thin films deposited at low temperatures. Moreover, Bi2Zn2/3Nb4/3O7 thin film exhibits the excellent leakage current characteristics with a high breakdown strength and the leakage current density is approximately 1×10−7 A/cm2 at an applied bias field of 300kV/cm. Bi2Zn2/3Nb4/3O7 thin films are potential materials for embedded capacitor applications. [Copyright &y& Elsevier]

Abstract: The PbTe films were deposited onto ITO glass substrate by radio frequency magnetron sputtering. Effect of external direct current electrical field applied between substrate and target on the quality of films was investigated. Stylus surface profile, X-ray diffraction (XRD), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the films. The film thickness was measured by a conventional stylus surface profile. The crystal structure and lattice parameters of films were determined by using XRD. The surface morphology of the films was measured by AFM. The absorption coefficients and optical band gaps of films were found from FTIR. The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated. All the obtained films were highly textured with a strong (200) orientation. With increasing bias voltage to −30V, the property of crystal structure, surface morphology and absorption coefficients and resistivity were improved. However, further increase of substrate bias leads to transformation of the property. [Copyright &y& Elsevier]

Abstract: Lead-free ferroelectric (K, Na)NbO3 (KNN) thin films were prepared on Pt/Ti/SiO2/Si substrate by a sol–gel method. Sodium acetate, potassium acetate and niobium pentaethoxide were used as starting metal–organic compounds in KNN precursor solutions. The thermal decomposition of KNN gel was studied by thermal analysis method. Thin films of KNN with a perovskite structure were obtained by pyrolysis at 400°C and rapid thermal annealing at 500–650°C. The KNN thin films showed relatively dense and uniform microstructure with grain size of about 100nm. KNN thin films annealed at 650°C exhibited a dielectric constant of 258 and loss tangent of 0.05, respectively, at 1kHz. A ferroelectric hysteresis loop with a remnant polarization and coercive field of 3.54μC/cm2 and 160kV/cm, respectively, was obtained for the KNN thin film. [ABSTRACT FROM AUTHOR]

Filling Yb atoms into the nanovoid of skutterudites has been long the main strategy to achieve high thermoelectric performance. However, both the ZT and the Yb actual total filling fraction (ATFF) show great discrepancies among the literature. The underlying mechanisms behind such discrepancy still keep mysterious. Here, we theoretically and experimentally study the solid solution and phase transformation in the un-filled, single-filled, and multiple-filled skutterudites from a kinetics perspective. The ZT and ATFF discrepancies are thus explained by the complex reaction process. Our density functional theory calculations indicate that an extraordinarily large energy barrier exists in the solid solution process of Yb atoms in CoSb 3.The introduction of other filling atoms can further reduce the Yb diffusion rate, putting off the overall reaction process. As the reaction progresses, the ATFF first increases sharply and finally keeps constant, representing the complex phase transition behaviors from non-equilibrium microstructures to equilibrium microstructures. Through optimizing the synthesis route, we successfully promote the reaction process to the ultimate limit in the Yb 0.3 Ca 0.1 Al 0.1 Ga 0.1 In 0.1 Co 3.75 Fe 0.25 Sb 12 sample. A remarkable theoretical conversion efficiency of 14.12% is achieved, exhibiting excellent stability and reproducibility as expected. Our results provide an intrinsic understanding of chemical doping from materials science essentials, which is applicable for designing other high-performance functional materials. Image 1 • An extraordinarily large energy barrier exists in the Yb solid solution process. • There is a parabolic relationship between the actual total filling fraction and the reaction time. • It is the complex reaction process that accounts for the discrepancies of the ZT and the actual total filling fraction. • The theoretical conversion efficiency of 14.12% is achieved in the Yb 0.3 Ca 0.1 Al 0.1 Ga 0.1 In 0.1 Co 3.75 Fe 0.25 Sb 12 sample. [ABSTRACT FROM AUTHOR]

A new eutectic high-entropy alloy (EHEA) of Cr 41 CoFeNi was prepared by arc melting technique. The microstructure and corrosion resistance of the Cr 41 CoFeNi EHEA were systematically investigated by EBSD, TEM, EIS and XPS analyses. The results revealed that the Cr 41 CoFeNi EHEA showed a dual-phase structure consisting of BCC phase and FCC phase, and the morphologies displayed the lamellar eutectic and network-shaped eutectic. Compared with 316 L stainless steel, the Cr 41 CoFeNi EHEA exhibited a better anti-corrosion property in 0.5 M H 2 SO 4 solution. This was mainly attributed to the formation of a dense and stable Cr-oxide layer on the surface of Cr 41 CoFeNi EHEA, which retarded further dissolution of the matrix. Moreover, bound water could adsorb metal ions to form a new protective film, which played an important role in improving the corrosion resistance of the Cr 41 CoFeNi EHEA. However, the elemental segregation and chemical potential difference between phases increased the defects in the passive film and accelerated its pitting corrosion of low potential phase. Moreover, the (Co, Fe, and Ni)-enriched FCC structured phase was preferentially eroded. • A novel eutectic high-entropy alloy of Cr 41 CoFeNi(EHEA) was designed and fabricated • The corrosion mechanisms of EHEA and 316 L stainless steel(316 L SS) were clarified • The passive film thickness of EHEA was about 5.3 times greater than that of 316 L SS • The main constituents of passive film on EHEA were Cr-oxide and bound water [ABSTRACT FROM AUTHOR]

• α-DyGa 3 single crystals were grown by the self-flux method. • The Néel temperature of α-DyGa 3 was determined to be T N ~ 7.2 K. • The magnetic structure of α-DyGa 3 is collinear antiferromagnet with k = (1/2, 0, 1/2). We have succeeded in growing α -DyGa 3 single crystals by the self-flux method and determined its magnetic structure by neutron powder diffraction. α -DyGa 3 crystallizes in the rhombohedral SrSn 3 -type structure (R 3 ̅ m , #166, hR 48), and the magnetic sublattice is comprised of staggering layers of triangular lattice of Dy. Magnetic ordering occurs below T N ~ 7.2 K with the magnetic propagation vector k = (1/2, 0, 1/2), results in an alternating stripe antiferromagnetic structure in the ab -plane described by the magnetic space group C C 2/ c (BNS #15.90, origin at (0, 0, 0)). At 3.5 K, the magnetic moment is 5.72(12) μ B per Dy3+. The Dy3+ spins are lying in basal plane and perpendicular to the b -axis. [ABSTRACT FROM AUTHOR]

Future piezo-(ferro-)electric devices, in particularly the transducers with the miniaturized size require materials with thickness in micrometer scale, which limit the utilization of bulk materials due to the difficulty of thinning. Modified composite sol-gel methods turns out to be a powerful approach to fabricate thick piezo-(ferro-)electric oxide films with thicknesses of several micrometers, which satisfy the requirements of devices particularly transducers. We report the preparation of the lead-free (Bi 0·5 Na 0.5) 1- x Ba x TiO 3 -Bi 0.5 Na 0·5 TiO 3 (BNBT x %-BNT, x = 0, 0.05, 0.06, 0.07) 0–3 composite ferroelectric thick films using a modified composite sol-gel technique. The impacts of the composition of the powders and the thickness of films on the structural and electrical properties of BNBT x %-BNT composite thick films have been in-depth investigated. The dielectric, ferroelectric and piezoelectric properties of the films strongly depend on the composition of the ferroelectric powders. The most excellent electrical properties are found in BNBT6-BNT films, which have the phase at morphotropic phase boundary. These results indicate that the BNBT x %-BNT 0–3 composite thick films are a highly promising lead-free piezoelectric material for piezo-(ferro-)electric device applications like high-frequency transducers. • A modified composite sol–gel technique can be used to prepare lead-free thick films in micrometers. • The properties of the composite films are highly dependent on the ferroelectric powder (filler). • A relative constant of 1079 and remnant polarization of 21.6 μC/cm2 are obtained in the composite films. [ABSTRACT FROM AUTHOR]

We report doping at B-Site in TmFeO 3 with In3+ ion of varying concentration (x = 0.02, 0.05, 0.07, 0.1) to explore the effect of In3+ ion substitution on structural, magnetic and vibrational properties. XRD study revealed that all the synthesized samples exhibit distorted perovskite orthorhombic (Pbnm) crystal symmetry. The immediate observable effect was an increase in lattice parameters with increasing doping up from x = 0.0 to 0.1 as evidenced by diffraction peaks shifted towards lower angle. Spin reorientation transition (Γ 4 →Γ 2) in all prepared samples occurs at temperature (∼85–92 K) to be a process involving the continuous rotation of Fe3+ spins. M-H curves display the coexistence of weak ferromagnetism and antiferromagnetic ordering at all the measured temperatures with reduction in coercive field and remanence values. Varied magnetic behaviors were observed in this series of compounds, which are believed to be associated with the different interactions of Fe and rare earth ions. The occurrence of two-magnon and two-phonon modes in Raman spectra at temperature around 100 K attributed to spin-reorientation transition exhibited by TmFe 1-x In x O 3. This might be unambiguous evidence for spin-phonon coupling in the prepared compounds. The coupling and possible presence of two phonon and magnon pair scattering and other energy carriers have been used to explain several recently discovered thermally driven spin transport phenomena. • XRD data reveals that samples TmFe 1-x In x O 3 possess the orthorhombic structure (Pbnm). • Spin reorientation transition (Γ 4 → Γ 2) arises at temperature between 85 and 92 K. • M-H curves display the coexistence of weak ferromagnetism and antiferromagnetic ordering • Evidences for spin-phonon coupling are also comes from Raman spectra of In-doped TmFeO 3. • Orthoferrites are very attractive option to fulfill the demand of miniaturization data storage and spintronics devices. [ABSTRACT FROM AUTHOR]

0.36BiScO 3 -0.64PbTiO 3 (0.36BS-0.64PT) piezoelectric ceramics with high Curie temperature and good piezoelectric properties comparable to commercial PZT ceramics were fabricated through traditional solid-state reaction method. Microstructural morphology, phase transition, and electrical properties of 0.36BS-0.64PT ceramics were investigated systematically. A high temperature single element ultrasonic transducer was designed and fabricated using this ceramic. The temperature stability of the piezoelectric, and acoustic properties of the transducer was investigated in detail. It was found that the 0.36BS-0.64PT based transducer can maintain reasonably good performance at temperatures as high as 200 °C. The center frequency was found around 4 MHz and changed slightly with the temperature from 30 °C to 200 °C. The −6 dB bandwidth was found over 12% at 200 °C. The results show that the 0.36BS-0.64PT ceramics have great potential for high-temperature ultrasonic transducer applications. [ABSTRACT FROM AUTHOR]

A series of DyFe 1- x In x O 3 ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1) polycrystalline samples have been prepared by the conventional solid reaction methods. The crystal structures, refined by the Fullprof, are found to be orthorhombic for 0 ≤ x ≤ 0.6 and hexagonal in the case of 0.7 ≤ x ≤ 1. The lattice constants are changed by the In ions doping, and a huge distortion of the magnetic sublattice was induced. The magnetization versus temperature curves are obtained for all the samples, at the temperature between 3 K and 300 K. The pure DyFeO 3 sample undergoes a spin reorientation transition at around 50 K, whereas the doped In 3+ ions significantly modify the phase transition. We reveal that such substitution retained the spin reorientation transition effect for x ≤ 0.8. We develop a formalism based on the molecular theory, giving explanation of the changes in the spin-reorientation temperature induced by the In-doping. Then, by performing density functional theory (DFT) calculation, we analyzed the magnetic phases for the hexagonal compounds. Furthermore, our findings indicate a type of Γ′ 4 - Γ′ 2 transition exists in the hexagonal Fe-In magnetic systems which directly point to a quasi-2 dimensional magnetic order. [ABSTRACT FROM AUTHOR]

In this study, ZnO thick films suitable for high frequency focused ultrasonic transducers with high piezoelectric properties, and low tensile stress were prepared by DC magnetron sputtering. The ZnO films were analyzed in detail by X-ray diffraction and scanning electron microscope. The sputtering growth process of ZnO films was optimized by improving the structural zone models (SZM). Based on the optimized process, a focused ultrasonic transducer, with a fused quartz acoustic lens structure, was fabricated by sputtering the ZnO thick films. The finite element method was used to complete the design, simulation, and evaluation of the transducer. Test results show that there was no crack in the piezoelectric layer of the transducer. The transducer had a center frequency of 50 MHz, with a high − 6 dB bandwidth of 119%. • The structural zone models suitable for pure metal sputtering were modified. • ZnO thick films with low tensile stress and high piezoelectric performance were prepared based on the modified models. • A 50 MHz ultrasonic transducer with a high – 6 dB bandwidth (119%) was fabricated based on the optimized ZnO thick film. [ABSTRACT FROM AUTHOR]

Strongly correlated electron systems are an excellent platform for functional materials. Here, we present a strong magnetic effect in the Eu3+-doped TmFeO 3 single crystal, where half of the Tm3+ sites are replaced by Eu3+ dopants in the orthorhombic lattice of TmFeO 3 (Tm 0.5 Eu 0.5 FeO 3). We demonstrated by combining the dc -magnetic susceptibility χ(T) as well as magnetization isotherm M (H), that the temperature dependent magnetization results under tiny change in magnetic field (H) shows the evidence for the formation of such remarkable effects due to Tm3+ substituted with Eu3+ ion in TmFeO 3. Interestingly, Eu3+ doping protects the antiferromagnetic (AFM) spin-reorientation transition along crystallographic c -axis as observed by a sharp transition at T SR = 90 K, similar as parent TmFeO 3. Further, an external applied field (H) of 500 Oe is enough to fully suppress the spin-reorientation transition in Eu3+ doped TmFeO 3. We emphasize that the transition from almost free-state of Tm3+ spin to AFM state changes by 90 K at such low magnetic field. Experimentally observe significant changes in terms of shift in the magnetic transition (SRT) under an applied very low magnetic field due to Eu3+ doping in TmFeO 3 lattice is truly robust effect. [Display omitted] • Interesting magnetic effect in the Eu3+-doped TmFeO3 single crystal. • Single crystals were grown using a four-mirror optical-floating zone furnace. • Spin-reorientation transition in TmFeO3 is found to be at TSR = 93 K at an applied field H = 100 Oe. • External applied field of 500 Oe is enough to fully suppress the spin-reorientation transition in Eu3+ doped TmFeO 3. • Eu3+ ions in TmFeO 3 are playing important role which significantly enhances the spin-lattice correlations. [ABSTRACT FROM AUTHOR]

We report temperature-induced spin reorientation and magnetization jump effects in the rare earth (RE) orthoferrite Ho 0.5 Pr 0.5 FeO 3 single crystal. The single crystal of about 6 mm in diameter and 50 mm in length was successfully grown by optical floating zone method. Both X-ray diffraction and Laue photograph confirmed the homogeneity and high quality of the crystal. Magnetic properties of Ho 0.5 Pr 0.5 FeO 3 single crystal are studied over a wide temperature range from 2 to 300 K. Spin reorientation transition from Γ 2 to Γ 4 phase is observed in the temperature range of 75–90 K. At lower temperature, the Ho 0.5 Pr 0.5 FeO 3 shows an abrupt jump of magnetization along the a -axis, which occurs only in the field-cooling process, and is sensitive to external applied magnetic field. By analyzing the jump temperature and magnitude of the magnetization, we conclude that it is caused by the spin reversal of the rare earth ions. The isothermal magnetization versus field hysteresis loop measurements along a axis explain the spin configuration variation from 3 K to 60 K. [ABSTRACT FROM AUTHOR]

• Z-type hexaferrite Sr 3 Co 2 Fe 23.04 Al 0.96 O 41 single crystal was grown by the Na 2 CO 3 -Fe 2 O 3 flux method. • The magnetization increases with two steps to saturation at 300 K, implying the existence of a spiral magnetic phase. • The magnetoelectric coupling effect occurs near room temperture. • The intensity of the electric polarization changes without any decay at 200 K under the oscillating magnetic field. We have grown Z-type hexaferrite Sr 3 Co 2 Fe 23.04 Al 0.96 O 41 single crystal with a little Al3+ ion doping on the Fe3+ ion sites by the Na 2 CO 3 -Fe 2 O 3 flux method. The magnetic properties and magnetoelectric (ME) coupling effects were investigated systematically. With Al3+ ion doping, the transverse conical magnetic phase could be maintained up to 359 K under small magnetic field (H). The magnetization increases with two steps to saturation at 300 K as shown in the M - H curve, implying the existence of a spiral spin order. The ME coupling effects occur near room temperture. Besides, the sign of the electric polarization (P) is independent of the H and the intensity of the electric polarization changes without any decays at 200 K under the oscillating magnetic field. Both of them are crucial for device application, such as information storage devices and non-volatile memory. [ABSTRACT FROM AUTHOR]

• Y-type hexaferrites Ba 0.5 Sr 1.5 Mg 1.6 Co 0.4 Fe 12 O 22 single crystals is synthesized by flux method. • The direction of the applied magnetic field is crucial for its spin configurations. • The non-zero P occurred at zero magnetic fields and reversible by applied fields. • The reversible P induced by the in-plane H is observed below 150 K. Multiferroic Y-type hexaferrites are single-phase compounds in which the electric polarization (P) is induced by a low magnetic field (H). In this study, Y-type hexaferrite Ba 0.5 Sr 1.5 Mg 1.6 Co 0.4 Fe 12 O 22 single crystal was synthesized using Na 2 CO 3 -Fe 2 O 3 flux. Their structural, magnetic, and magnetoelectric properties were investigated. The different transition temperatures between the H ⊥ c and H // c configurations showed that the direction of the applied H was important for the spin configurations. The M - H loops exhibited that the field-induced transitions could occur at room temperature (RT). A first-order magnetic phase transition around 250 K was unveiled from the Arrott plots. The P was non-zero at zero H below 50 K. By studying the magnetic field dependence of the dielectric properties at selected temperatures, a magnetoelectric phase diagram exhibiting the evolution of the spin-induced ferroelectric order with the H ab and temperature (T) was revealed. The magnetoelectric phase diagram showed that the polarization was reversed by the magnetic fields below 150 K where the H -induced ferroelectric order was maintained in a zero magnetic field. [ABSTRACT FROM AUTHOR]

Wurtzite ZnO as a multifunctional material is attractive due to the ferroelectricity and piezoelectricity; Cubic MgO is also a very useful insulator oxide for applications in emerging electronics. Using the volume matching condition, we construct a stable 1 × 1 ZnMgO superlattice alternating along the crystallographic c -direction. We then calculate the electronic, ferroelectric and piezoelectric properties of the ZnMgO superlattice through density-functional theory. It is found that the epitaxial tensile strain can effectively reduce the polarization barrier without significantly reducing the polarization, increase the piezoelectric constant e 33 and soften the elastic constant C 33. In addition, the piezoelectric modulus d 33 is enhanced by about 4 times, and the electromechanical coupling coefficient k 33 is nearly doubled at 4% strain. • Mechanically and dynamically stable ZnO/MgO superlatticeis an outstanding ferroelectric and piezoelectric material. • Epitaxial tensile strain can effectively reduce the polarization barrier, increase piezoelectric response and the electromechanical coupling coefficient in the atomistic superlattice. [ABSTRACT FROM AUTHOR]

In this work, a fully-B2 microstructure was obtained in a Ti–40Al–8Nb (at. %) alloy by water-quenching from the single β phase region, and the decomposition behavior of the fully-B2 microstructure during annealing at 800 °C was investigated. Results showed that the fully-B2 microstructure was thermodynamically unstable and numerous lath-liked α 2 phases precipitated from the B2 matrix following the Burgers orientation relationships after annealing for 3 min. With the increase of isothermal holding time, these lath-liked α 2 phases transformed into ultra-thin (α 2 +γ) lamellar structures with a lamellar spacing of 4 nm. Due to the perpendicular decomposition of the α 2 lamellar and coarsening of the γ lamellar, ω 0 and γ phases formed in the lamellar structures. Besides, the decomposition of the B2 phase directly into fine γ and ω 0 particles was also observed and the orientation relationships among these three phases were (1–10) B2 //(1-1-1) γ //(11–20) ω0 and [111] B2 //[01-1] γ //[0001]ω 0. After tempering for 3000 min, the growth of the γ and ω 0 phases occurred, leading to a ω 0 +γ+B2 microstructure with phase size of 300–500 nm. • A fully-B2 microstructure was obtained in a β-quenched Ti–40Al–8Nb alloy. • Phase precipitation of the fully-B2 microstructure during aging was studied. • A submicron microstructure composed of ω 0 , γ and B2 phases was produced in S-3000. • Two precipitation processes of the ω 0 and γ phases were observed. [ABSTRACT FROM AUTHOR]

We report the low field spin switching and spin reorientation transition in rare earth orthoferrite PrFeO 3 single crystal grown by optical floating zone method. Applied magnetic fields can regulate the spin switching in a quite wide range of temperatures. The effective magnetic moments of Fe3+ and Pr3+ sublattices undergo parallel to antiparallel configurations in field-cooled-cooling processes, which produce an abrupt drop in magnetization at low temperatures. The reverse spin switching show a magnetization recovering jump at a rather higher temperature in the field-cooled-warming regime, even above 300 K under very low fields. These intriguing magnetic phase transitions are due to the intrinsic 3 d -4 f electron interactions between Fe3+ and R 3+ sublattices, which dominate the interesting magnetic behaviors in R FeO 3. In particular, PrFeO 3 shows a great sensitivity to weak field even at room temperature, which makes it a controllable candidate for potential application in spintronic devices by using very low field. Finally, we summarize the spin configuration diagram of the R FeO 3 family. • We grow high quality PrFeO3 single crystal by optical floating zone method.. • We observed firstly the spin reorientation in PrFeO3 under very low field.. • We observed the spin switching at low temperatures in field-cooled-cooling processes.. • The reverse spin switching is observed firstly in field-cooled-warming processes in R FeO3 system.. • We consummate the spin configurations and magnetic phase diagram of R FeO3 family. [ABSTRACT FROM AUTHOR]