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In situ temperature-dependent crystal structure of lead-free ferroelectric perovskite Ba0.798Ca0.202Zr0.006Ti0.994O3 single crystal was characterized using x-ray diffraction from 170 to 380 K. Three phases were identified at different temperatures of 170, 220, and 298 K, revealing rhombohedral (R3m), orthorhombic (Pmm2), and tetragonal (P4mm) crystal structures, respectively. The change in the bond length and its distortion are reported for both AO12 and BO6 polyhedrons, allowing for the estimation of the spontaneous polarization. The Debye–Waller factor is reported as a function of temperature for A and B-sites. Density-functional theory calculations on the tetragonal phase were performed to obtain information on the distribution of the Ca ions, the local atomic displacements, and the ideal value of the spontaneous polarization of a defect-free crystal at 0 K. We find that Ca prefers to arrange in columnar 2D plates oriented along the tetragonal axis. The Ca ions avoid being next neighbors of Zr; however, the specific arrangement of Ca has only a minor impact on the spontaneous polarization. [ABSTRACT FROM AUTHOR]

Ba 1- x K x (Zn 1/3 Nb 2/3)O 3- x /2 (BKZN, x = 0–0.2) ceramics were prepared by the high-temperature solid-state reaction method. Based on P–V–L theory, Raman vibration spectroscopy and X-ray photoelectron spectroscopy (XPS), this paper investigates the relationship between the internal and external factors of K+ substitution in the Ba(Zn 1/3 Nb 2/3)O 3 (BZN) ceramics and the microwave dielectric properties of the ceramics. X-ray diffraction (XRD) characterisation revealed that all samples were single phase with no impure phases. Replacing Ba2+ with K+ greatly reduced the sintering temperature and optimised the microwave dielectric properties of the ceramics. The dielectric constant (ε r) was closely related to the ion polarizability and density, and inversely proportional to Raman shift of the A 1g (O) peak. The quality factor (Q × f) depended largely on the lattice energy (U b) and the full width at half-maximum (FWHM) of A 1g (O) near 790 cm−1. The temperature coefficient of the resonance frequency (τ f) could be inferred from the bond energy (E b) and oxygen octahedral distortion. Finally, outstanding microwave dielectric properties (ε r = 40.83, Q × f = 71,658 GHz and τ f = 2.52 ppm/°C) were acquired for Ba 0.95 K 0.05 (Zn 1/3 Nb 2/3)O 2.975 ceramics sintered at the optimum sintering temperature (1325 °C) for 4 h. [ABSTRACT FROM AUTHOR]

Utilizing a conventional solid-state reaction procedure, (Al 0.5 Nb 0.5)4+-modified 0.85Bi 0.5 Na 0.5 TiO 3 -0.11Bi 0.5 K 0.5 TiO 3 -0.04BaTiO 3 (BNKT-BT) samples were synthesized. The impact of (Al 0.5 Nb 0.5)4+ on the crystal structure, ferroelectric, dielectric, and AC impedance properties was systematically investigated. The XRD patterns demonstrate that the crystal structures of all samples exhibit typical pseudo-cubic features. According to the XPS, the doping of (Al 0.5 Nb 0.5)4+ reduces the concentration of oxygen vacancies inside the ceramics, which significantly affects the relaxation properties. This substitution successfully triggers a change from a non-ergodic relaxor (NR) state to an ergodic relaxor (ER) state, which is ascribed to the weakening of the pinning effect of the oxygen vacancies on the polar nanoregions (PNRs). The ceramics exhibit an enormous monopolar strain of 0.468 % under 60 kV/cm, accompanied by an inverse piezoelectric coefficient (d 33 *) of 780 pm/V, surpassing the performance of numerous other BNT-based piezoelectric ceramics. After 1×104 switching cycles, the strain value changes slightly, indicating excellent fatigue performance. The considerable strain arises from a reversible transformation of the ER phase to the ferroelectric phase induced by an electric field. This research suggests that (Al 0.5 Nb 0.5)4+-doped BNKT-BT ceramics have good prospects for application in actuators and sensors. • (Al 0.5 Nb 0.5)4+-modified BNKT-BT ceramics were prepared. • Under 60 kV/cm, a large unipolar strain of 0.468 % (d 33 * = 780 pm/V) was obtained. • The phase transition of nonergodic-to-ergodic relaxor was analyzed. [ABSTRACT FROM AUTHOR]

Ba[(Zn1-xMgx)1/3Nb2/3]O3(x = 0 ~ 0.9) ceramics were prepared by the traditional solid-phase reaction sintering method. In this paper, the effects of MgO doping on the shrinkage, density, phase composition, crystal structure, microstructure, and microwave dielectric properties of Ba(Zn1/3Nb2/3)O3 (BZN) ceramics were investigated. The phase constituents, crystal structure, and microstructure of the ceramics were studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The results showed that Ba(Zn1/3Nb2/3)O3 as the main phase, and the secondary phase Ba5Nb4O15 was detected with high MgO content (x > 0.3). However, the appearance of secondary Ba5Nb4O15 directly led to the deterioration of the microwave dielectric properties of the samples. Ba[(Zn1–xMgx)1/3Nb2/3]O3 (x = 0.3) ceramics sintered at 1500 °C for 4 h possessed superior dielectric properties: εr = 36.31, Q × f = 111,326 GHz, τf = + 12.1 ppm/°C. Such the ceramics could be used to make dielectric resonators and stable oscillators. [ABSTRACT FROM AUTHOR]

The effect of Na2O-doped on the formation and hydration properties of ye'elimite containing Fe (C4A2.8F0.2$) was focused on this study. A combination of x-ray powder diffraction (XRD), infrared spectrum (IR), differential scanning calorimetry (DSC)-thermogravimetric (TG) analysis, and SEM–EDS were used to investigate the microstructure and morphology of C4A2.8F0.2$ with doping Na2O. Hydration kinetics tests were conducted to study the effect of Na2O on the C4A2.8F0.2$ by the isothermal calorimetry and the electrical conductivity. The results show that Na2O-doped promotes the phase transition of ye'elimite from orthogonal to cubic phase. The amount of Na+ ions substituted for Ca2+ ions reaches the limit doping Na2O with a dosage of 0.8 wt%, and the crystal structure of C4A2.8F0.2$ mineral tends to be stable. When the amount of Na2O is more than 0.8 wt%, the formation of C4A2.8F0.2$ is hindered and its content decreases. Besides, adding Na2O promotes the grain growth of the C4A2.8F0.2$, which doubles its average size, and makes the morphology of C4A2.8F0.2$ change from an egg-like shape to an irregular shape. In addition, the hydration process of C4A2.8F0.2$ doping with Na2O is accelerated, the induction period is significantly shortened or even disappeared, indicating Na2O facilitates the exothermic concentration of C4A2.8F0.2$ hydration. However, the addition of Na2O has no obvious effect on the total hydration heat release of C4A2.8F0.2$. [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]

Benzoylecgonine (BZE) is the major toxic metabolite of cocaine and is responsible for the long‐term cocaine‐induced toxicity owing to its long residence time in humans. BZE is also the main contaminant following cocaine consumption. Here, we identified the bacterial cocaine esterase (CocE) as a BZE‐metabolizing enzyme (BZEase), which can degrade BZE into biological inactive metabolites (ecgonine and benzoic acid). CocE was redesigned by a reactant‐state‐based enzyme design theory. An encouraging mutant denoted as BZEase2, presented a >400‐fold improved catalytic efficiency against BZE compared with wild‐type (WT) CocE. In vivo, a single dose of BZEase2 (1 mg kg−1, IV) could eliminate nearly all BZE within only two minutes, suggesting the enzyme has the potential for cocaine overdose treatment and BZE elimination in the environment by accelerating BZE clearance. The crystal structure of a designed BZEase was also determined. [ABSTRACT FROM AUTHOR]

Reaction of silver nitrate with 2‐aminobenzothiazole (abbreviated as Habt) in methanol at 45°C gave mononuclear complex of formula [Ag (Habt)2]NO3•CH3OH. The structure of the complex was characterized by infrared (IR) spectra, single crystal X‐ray diffraction, and elemental analysis. X‐ray diffraction analysis indicated that the title complex was crystallized in the triclinic crystal system with space group P–1, in which silver(I) ion was coordinated to two 2‐aminobenzothiazole ligands through the benzothiazol nitrogen atom. Theoretical study of the complex was carried out by density functional theory (DFT) B3LYP method. The antimicrobial effects of the ligand and its silver(I) complex were evaluated by bio‐microcalorimetry on the growth of Schizosaccharomyces pombe (S. pombe). Some quantitative metabolic parameters, such as growth rate constant (k), maximum heat power (Pmax), inhibition ratio (I), and half inhibition concentration (IC50), were derived from the metabolic power–time curves of S. pombe growth. The half inhibition concentration (IC50) of the ligand was calculated to be 2.58 × 10−3 mol L−1. The complex could strongly influence the lag phase of S. pombe. [ABSTRACT FROM AUTHOR]

For instance, by employing a tripodal bis(benzimidazole) ligand bis((1-methylbenzimidazol-2-yl)methyl)amine(MeIDB) and its derivative as the main ligand, a series of nickel and copper complexes were synthesized which allow a systematic investigation of a biomimetic chemistry [[8]]. Comment Multi-benzimidazole ligands have been often used in the synthesis of various metal-organic complexes or modelling the biomimetic coordination environment around the enzymatic active site [[7]]. However, up to now the detailed crystallization properties of MeIDB has been not reported which can be helpful for the design of various multifunctional compounds due to its central acyclic -CH SB 2 sb -N-CH SB 2 sb - linkage moiety, making the ligand possess various steric arrangements. [Extracted from the article]

Three tungsten powder samples—one coarse grained (c-W; grain size: 1 µm–3 µm) and two nanocrystalline (n-W; average grain sizes: 10 nm and 50 nm)—are investigated under nonhydrostatic compression in a diamond anvil cell in separate experiments, and their in situ X-ray diffraction patterns are recorded. The maximum microscopic deviatoric stress in each tungsten sample, a measure of the yield strength, is determined by analyzing the diffraction line width. Over the entire pressure range, the strength of tungsten increases noticeably as the grain size is decreased from 1 µm–3 µm to 10 nm. The results show that the yield strength of tungsten with an average crystal size of 10 nm is around 3.5 times that of the sample with a grain size of 1 µm–3 µm. [ABSTRACT FROM AUTHOR]

The ADP/ATP carrier (AAC) is a transporter responsible for the equal molar exchange of cytosolic ADP and ATP synthesized within mitochondrial matrix across the mitochondrial membrane. Its primary structure consists of three homologous repeats, and each repeat contains a conserved motif that is shared by all members of the mitochondrial carrier family (MCF). Although these MCF motif residues cluster together in the crystal structure of AAC, detailed analyses on the interactions among the motif residues are still limited. In the present study, all-atom molecular dynamics (MD) simulations of up to 10 μs have been carried out on AAC, and interactions and structural dynamics of the MCF motif residues have been specifically investigated. Our simulations have revealed: i) a very asymmetrical electrostatic network at the bottom of the pocket of apo AAC, ii) the asymmetrical interactions between the Pro kink region and the [YWF][KR] G motif in three repeats, iii) the role of the conserved Arg residues in stabilizing the C-ends of the odd-numbered helices, iv) the structural change of the [YWF][KR] G motif and its potential involvement in substrate translocation process. Our results highlight the asymmetry of the MCF residues in the three repeats, which might contribute to the ability of the carriers to transport the asymmetrical substrates. Our observations provide microscopic basis for further research on the translocation mechanism of mitochondrial carriers. • An asymmetrical electrostatic network forms at the bottom of the pocket of apo AAC. • Pro kink-[YWF][RK]G interactions, between the first and the second part of MCF sequence motif, are asymmetrical in the three AAC repeats. • The three capping Arg residues are important in stabilizing the odd-numbered helices. • Structural change of the [YWF][RK]G portion of second part of AAC sequence motif is observed. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) are known to have high strength, but poor ductility. Prior studies have shown that plasticity in MG can be enhanced by significantly reducing their dimension to nanoscale. Here we show that, via the introduction of certain types of crystalline/amorphous interfaces, plasticity of MG can be prominently enhanced as manifested by the formation of ductile “dimples” in a 2 μm thick amorphous CuNb film. By tailoring the volume fraction and architecture of crystalline/amorphous multilayers, tensile fracture surface of MG can evolve from brittle featureless morphology to containing ductile dimples. In situ micropillar compression studies performed inside a scanning electron microscope show that shear instability in amorphous layers can be inhibited by interfaces. The mechanisms for improving plasticity and fracture resistance of MG via interface and size effect are discussed. [ABSTRACT FROM AUTHOR]

The control of thermal expansion of solid compounds is intriguing but remains challenging. The effect of guests on the thermal expansion of open-framework structures was investigated. Notably, the presence of guest ions (K+) and molecules (H2O) can substantially switch thermal expansion of YFe(CN)6 from negative ( αv=−33.67×10−6 K−1) to positive ( αv=+42.72×10−6 K−1)-a range that covers the thermal expansion of most inorganic compounds. The mechanism of such substantial thermal expansion switching is revealed by joint studies with synchrotron X-ray diffraction, X-ray absorption fine structure, neutron powder diffraction, and density functional theory calculations. The presence of guest ions or molecules plays a critical damping effect on transverse vibrations, thus inhibiting negative thermal expansion. An effective method is demonstrated to control the thermal expansion in open-framework materials by adjusting the presence of guests. [ABSTRACT FROM AUTHOR]

Transient flow structures in a continuous casting mold can strongly influence the slag entrainment in liquid steel and the bubbles capture in the initial solidified shell, both of which are associated with the quality of the final product. This paper presents a numerical study of the turbulent flow with a top free surface in the continuous casting mold at a meso-scale level by a three-dimensional combined approach of Free Surface Lattice Boltzmann Method and Large Eddy Simulation (FSLBM-LES). The validity of the model is verified by the good agreement between the calculated results and the measurements from various water experiments in terms of the flow velocity and free surface profile. The mathematical model is then used to reveal the transient and spatiotemporal asymmetric characteristics associated with the transient flow field and the free surface fluctuation, although the steady state operation is considered during the continuous casting process. The results show that the locations of the jets of liquid steel from the two out ports of the Submerged Entry Nozzle (SEN) always fluctuate alternatively within a certain range, and periodically deviate from the design angle of the SEN within the same time period. The oscillating behavior of the jets promotes the asymmetric flow patterns and multi-scale vortices at both sides of the SEN. By introducing the Q-criterion in the results analysis, the formation, development, and shedding of the coherent structure (CS) of the turbulent flow are quantitatively characterized. The interaction between the transient flow patterns and the fluctuations of the top free surface as well as the evolution of the transient profile and velocities of the free surface are also demonstrated. The results obtained from the current study suggest that the FSLBM-LES model offers a promising way to study the complex flows and related transfer phenomena in the continuous casting process. [ABSTRACT FROM AUTHOR]

Three new Sb-based antiferromagnetic oxychlorides: MnSb2O3(OH)Cl (1), FeSb2O3(OH)Cl (2), and CoSb2O3(OH)Cl (3) have been synthesized by using hydrothermal reaction methods. Their crystal structures are isostructural and incorporate two types of structural units: sphenoid SbO4 polyhedra and M2O8Cl2 (M = Mn, Fe, Co) dimers, that share edges forming a two dimensional (2D) MSb2O3(OH)Cl network. The neutral MSb2O3(OH)Cl 2D layers are arranged from ABAB-type for compounds 1 and 2 to AA′B′B-type for 3 with smaller cation radii. Magnetic measurements show that 1 belongs to an antiferromagnetic material, while 2 and 3 have weak ferromagnetic properties with unsaturated ferromagnetism originating from spin-canting below the transition temperature. In addition, the optical absorption band gaps were determined to be 3.8, 2.4, and 3.6 eV for 1, 2, and 3, respectively. This work demonstrates that utilizing both halide ions and lone-pair elements simultaneously in one structure is a feasible and practical route to reduce framework connectivity in order to synthesize new low-dimensional oxyhalides. [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]

C15H13N5O9Zn2, monoclinic, P21/n (no. 14), a = 6.7739(13) Å, b = 14.160(3) Å, c = 18.506(4) Å, β = 97.908(4)°, V = 1758.1(6) Å3, Z = 4, Rgt(F) = 0.0597, wRref(F2) = 0.1125, T = 298(2) K. [ABSTRACT FROM AUTHOR]

Multiferroic Bi 1−x Sm x FeO 3 (x = 0.00–0.05) ceramics were prepared by a conventional solid-state reaction method, and effects of Sm 3+ ions on crystal structure, magnetic and dielectric properties were investigated. TGA-DSC studied the synthesis process of pure BiFeO 3 sample and confirmed the synthesis temperature was about 825 °C. For all samples, they were rhombohedral distorted perovskite structure of R-3c space group. Lattice constants and particle sizes decreased based on the data of XRD and Rietveld refinement. Morphologies of the samples were determined with Scanning Electron Microscopy proving the grain to be shrinkage. With increasing of Sm 3+ ions, saturation magnetization of Bi 0.97 Sm 0.03 FeO 3 material at 5000 Oe was about 1.5 times larger than that of pure BiFeO 3 , while the coercivity increased from 87.3 Oe to 121.3 Oe. In a wide range frequency from 1 MHz to 1.6 GHz, dielectric constant kept a stable value. With Sm 3+ increasing, dielectric constant increased from 27 to 46, while dielectric loss kept a low value. [ABSTRACT FROM AUTHOR]

Seven new cadinane-type sesquiterpenoids ( 1 – 7 ) were isolated from the rhizomes of Stahlianthus involucratus . The planar structures of 1 – 7 were elucidated on the basis of extensive spectroscopic and HRMS data. The absolute configuration of 1 was determined by the single-crystal X-ray diffraction, whereas those of C-9 in 3 , C-9 in 4 , C-6 in 6 , and the 1,2-diol in 7 were deduced via the CD data of the in situ formed [Rh 2 (OCOCF 3 ) 4 ] complex, and Mo 2 (OAc) 4 -induced CD analysis, respectively. [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]

The poling effect on the [011]-oriented (1− x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 (PMN- xPT) single crystals across the morphotropic phase boundary ( MPB) was studied. The dielectric and piezoelectric properties were investigated as a function of the poling field. Domain structure evolutions during the poling process were recorded. In the unpoled PMN- xPT phase diagram, an apparent rhombohedral (R)-tetragonal (T) phase boundary exists. With room-temperature poling, the structure transformation sequence strongly depends on the composition. The crystal experiences a direct transition to the 2R/2T domain state in the rhombohedral or tetragonal phase field beyond the MPB region, whereas within the MPB zone it is hard to achieve the 2R/2T engineered configuration although the initial state is either rhombohedral or tetragonal as well. The piezoelectric responses of the MPB·PMN- xPTs are extraordinary weak ( d33 ~ 250 pC/N), in contrast to the [011]-oriented multidomain PMN- xPTs with ultrahigh-piezoelectric coefficient ( d33 > 1000 pC/N). We demonstrate that a slight composition variation near the MPB will significantly influence the domain evolution route and piezoelectricity for the [011]-oriented PMN- xPT crystals. We also confirm the feasibility to realize the 2R/2T engineered domain configuration for the [011]-oriented MPB crystals, which will extend the desired portion of the Bridgeman-grown boules with optimal piezoelectric properties. [ABSTRACT FROM AUTHOR]

M-type barium hexaferrite (BaM) thin films with different structures ( d s100 : single-layer 100 nm thick film; d s200 : single-layer 200 nm thick film; d b200 : bilayer 200 nm thick film, where the thickness of each layer is 100 nm and the total film thickness is 200 nm) were deposited on (001) sapphire (Al 2 O 3 ) substrate by radio frequency (RF) magnetron sputtering. Effects of different structures on the crystallographic, morphological, magnetic properties and stress were investigated in details. For the structure of d s100 , BaM film processes platelet-like grains, which shows excellent magnetocrystalline anisotropy and large squareness ratio S ⊥ (0.62). For the structure of d s200 , there are a lot of acicular grains. Thus, the c-axis in-plane oriented and/or randomly oriented grains induce poor magnetocrystalline anisotropy. For the structure of d b200 , the platelet-like grains dominate the microstructure. Both squareness ratio S ⊥ (0.67) and coercivity H c⊥ (98.6 kA/m) of the d b200 show the highest values among the three kinds of the film structures. In addition, with the increase of film thickness from 100 nm to 200 nm, the stress in film decreases gradually. Compared with the other structures, the bilayer 200 nm thick film ( d b200 ) obtains the smallest stress. [ABSTRACT FROM AUTHOR]

In this work, we synthesized the Co-Ti-substituted barium ferrite materials (Ba(CoTi)FeO) by sol-gel method (S1) and solid-state method (S2). The phase formation, structural and magnetic properties of both samples were investigated separately. Differential scanning calorimeter and thermo-gravimetric analysis curves showed changes in energy and weight with respect to temperatures during the sintering process-from room temperature to 1200 °C at a rate of 10 °C per min. X-ray diffractometer patterns indicate that both samples, with Co-Ti ions substitution, had single phase of M-type barium ferrite, and no clear structural changes or formation of second phase was observed. Grain size and shape of samples were exhibited in SEM images, from which S1 showed more regular-shaped particles than S2. Magnetic hysteresis loops of the samples were measured using a vibrating sample magnetometer and showed similar saturation magnetization ( M) and coercivity ( H). M and H are mainly determined by electron magnetic moment, ion occupation and particle size. Microwave absorption properties of the samples were characterized by a microwave vector network analyzer in the frequency range of 0.5-18 GHz. In terms of complex magnetic permeability, dielectric permittivity, maximum reflection loss, resonance peak and bandwidth, there were remarkable differences between two samples. We suggested that these different characteristics originate from the variation in particles size, surface state and oxygen vacancies, which determined the interfacial polarization and related microwave absorption performance of the samples. [ABSTRACT FROM AUTHOR]

In this article, high-quality single domain SmBCO bulks have been successfully produced in the air by top seeded infiltration and growth (TSIG) method, with a new solid phase of (Sm 2 O 3 + xBaCuO 2 ) and liquid phase of (Y 2 O 3 + 6CuO + 10BaCuO 2 ), x = 0.9, 1.0, 1.1, 1.2, 1.3 and 1.4. The results show that the onset critical temperature (T c-onset ) of the SmBCO bulks increases with the increasing of x, because the substitution of Sm on Ba site in Sm 1+x Ba 2−x Cu 3 O 7 crystal is reduced by the BaCuO 2 addition; the T c-onset have reached 96 K when x = 1.4. The amount and the size of Sm211 particles of the single domain SmBCO bulks decreases with the increasing of BaCuO 2 addition x. All of the critical current density (J c ), levitation force and trapped field of the samples are increasing from 1.08 × 10 5 A/cm 2 , 38.47 N and 0.2330 T to 1.66 × 10 5 A/cm 2 , 44.34 N and 0.2680 T when x increases from 0.9 to 1.2, and then decreases to 0.83 × 10 5 A/cm 2 , 37.94 N and 0.2085 T with the increasing of x from 1.2 to 1.4 respectively, the largest J c of 1.66 × 10 5 A/cm 2 , levitation force of 44.34 N and trapped field of 0.2680 T are reached at the optimal value of x = 1.2. This result provides a very important way to fabricate high-quality single domain SmBCO bulks in air. [ABSTRACT FROM AUTHOR]

Two magnesium silicate fluorides, Mg5(SiO4)2F2 (compound 1) and Mg3SiO4F2 (compound 2), have been successfully synthesized by solid-state reactions for the first time. Compound 1 crystallizes in the space group P21/c (no. 14) of the monoclinic system, whereas the latter belongs to the space group Pnma (no. 62) of the orthorhombic system. As for the crystal structure, compound 1 can be described on the basis of a “framework” made by Mg1O4F2 and Mg2O5F octahedra forming many rings, in which the Mg3 and Si atoms reside. Compound 2 can also be described as the rings created by Mg2O4F2 octahedra, in which the Mg1 and Si atoms reside. Thermal analysis and the infrared spectrum of compound 1 were measured. In addition, the UV-Vis-NIR diffuse-reflectance spectrum exhibits that the relatively wide band gap is about 5.32 eV for compound 1, which is consistent with the theoretical value. The band structure and linear optical properties of title compounds are also theoretically calculated. [ABSTRACT FROM AUTHOR]

A cadmium-thiocyanate complex, poly[(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κ4 N)octakis-μ2-thiocyanato-κ8 N: S;κ8 S: N-tricadmium(II)], [Cd3(C8H14N3)2(NCS)8] n, was synthesized by the reaction of 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, there are two independent types of CdII cation (one on a centre of inversion and one in a general position) and both are in distorted octahedral coordination environments, coordinated by N and S atoms from different ligands. Neighbouring CdII cations are linked together by thiocyanate bridges to form a two-dimensional network. Hydrogen-bonding interactions are involved in the formation of a three-dimensional supramolecular network. [ABSTRACT FROM AUTHOR]

Catalyst-free autocatalyzed dehydrative N-alkylation reactions of 2-aminobenzothiazoles, 2-aminopyrimidines, and 2-aminopyrazine with primary and secondary alcohols have been achieved for efficient, practical, and green synthesis of the versatile heteroaryl amine derivatives. These reactions were interestingly induced by structure-dependent tautomeric equilibria of the heteroaryl amines via MPV–O transfer hydrogenation of the imino tautomers by alcohols to give aldehydes as the key initiating step. [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]

BaTiO3 (BTO) nanoparticles (NPs) with various sizes from 6 to 210 nm were synthesized by a one-step hydrothermal method. The powder X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) display the formation of highly crystalline BTO NPs with a narrow size distribution. The size effect of BTO NPs on crystal structures and thermal expansion was investigated according to refined high-temperature XRD data obtained through a full-profile Rietveld method. These results show that unit cell volume (UCV) drastically increases and tetragonality (the c/a ratio) decreases as the size of BTO NPs is reduced. The coefficients of thermal expansion (CTE) of different BTO NPs reveal that the size dependence of positive thermal expansion of BTO mainly results from the ferroelectrostriction of the tetragonal phase. Through further analysis, we find that the mixed phase of tetragonal and cubic BTO may be a core/diffused shell structure which changes with decreasing NP size. Furthermore, it is speculated that the core/shell structure or tetragonality disappears when the size of BTO NPs is reduced to about 12 nm. The value is in accordance with the obtained results through the study of the change of Raman spectra and the ratio of c/a with the size of BTO NPs as well as with the reported reasonable results in the range of 5–16 nm. [ABSTRACT FROM AUTHOR]

A new tetrazole-metal supramolecular compound, di-μ-chlorido-bis(trichlorido{1-[(1 H-tetrazol-5-yl-κ N2)methyl]-1,4-diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd2(C8H16N6)2Cl8], has been synthesized and structurally characterized by single-crystal X-ray diffraction. In the structure, each CdII cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1-[(1 H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the CdII cations into one-dimensional ribbon-like N-H...Cl hydrogen-bonded chains along the b axis. An extensive hydrogen-bonding network formed by N-H...Cl and C-H...Cl hydrogen bonds, and interchain π-π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three-dimensional supramolecular network. [ABSTRACT FROM AUTHOR]

A copper(II) Schiff-base complex [CuL·2MeOH·HO] was prepared by reaction of the ligand [HL = N, N′- o-phenylene-bis(3-methoxysalicylideneimine)] and Cu(OAc)·HO in methanol at 328.15 K. X-ray diffraction analysis revealed that the title complex was crystallized in the triclinic crystal system with space group P-1, in which copper(II) ion was located in the NO ligand binding sites. According to two designed thermochemical cycles, the dissolution enthalpies of relevant substances of two reactions in the calorimetric solvents were determined by a solution-reaction isoperibol calorimeter, respectively. Combined with some other auxiliary thermodynamic data, the standard molar enthalpies of formation of the ligand and the complex were calculated to be: $$ \Delta_{\text{f}} H_{\text{m}}^{\theta } $$ [HL(s), 298.15 K] = −(384.2 ± 9.10) kJ mol and $$ \Delta_{\text{f}} H_{\text{m}}^{\theta } $$ [CuL·2MeOH·HO (s), 298.15 K] = −(1072.6 ± 9.2) kJ mol. [ABSTRACT FROM AUTHOR]

The title compound, (C20H20P)[Cd(C2N3)3], consists of ethyltriphenylphosphonium (EtPh3P+) cations filling voids in a three-dimensional anionic cadmium dicyanamide network. In the structure, each CdII atom is connected to six neighbouring CdII atoms through six separate dicyanamide ligands, forming cube-shaped cages. The three-dimensional anionic network encloses a solvent-accessible void space of 1851 Å3, amounting to 69.3% of the unit-cell volume. Each cage accommodates only one EtPh3P+ cation. [ABSTRACT FROM AUTHOR]

Thermochromic films are prepared on the substrate of yttria stabilized zirconia by radio frequency magnetron sputtering technique. Crystalline structure and surface morphology are characterized. Characterization result shows that the films are of perovskite structure exhibiting a dense and smooth surface morphology. Composition analysis is performed and the result indicated that the element composition of films can be adjusted to close its stoichiometric ratio by controlling the oxygen flow ratio. Temperature-dependent reflectivity and emissivity are studied. Reflectivity spectra show that the film undergoes a transition from a metallic state to a non-metallic state with increasing temperature. Emissivity of the films is large above the transition temperature and it decreases sharply below the temperature. The emissivity increment at 97–373 K can approach 0.39 by controlling sputtering pressure, working gas and film thickness. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic ceramics of BiFeO3- BaTiO3- Bi0.5 Na0.5 TiO3 have been prepared by a conventional ceramic technique. The microstructure, multiferroic, and piezoelectric properties of the ceramics have been studied. The ceramics sintered at 1000°C for 2 h possess a pure perovskite structure and a morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.02. After the addition of Bi0.5 Na0.5 TiO3, two dielectric anomalies are observed at high temperatures ( Tm ~ 510°C-570°C and T2 ~ 720°C). The phase transition around Tm becomes wider gradually with increasing x. The ferroelectricity, piezoelectricity, and ferromagnetism of the ceramics are significantly improved after the addition of Bi0.5 Na0.5 TiO3. High resistivity (~1.3 × 109 Ω·cm), strong ferroelectricity ( Pr = 27.4 μC/cm2), good piezoelectricity ( d33 =140 pC/N, kp = 31.4%), and weak magnetic properties ( Mr =0.19 emu/g) are observed. [ABSTRACT FROM AUTHOR]

The one- and two-dimensional polymorphic cadmium polycarboxylate coordination polymers, catena-poly[bis[μ2-2-(2-methyl-1 H-benzimidazol-1-yl)acetato-κ3 N3: O, O′]cadmium(II)], [Cd(C10H9N2O2)2] n, and poly[bis[μ2-2-(2-methyl-1 H-benzimidazol-1-yl)acetato-κ3 N3: O, O′]cadmium(II)], also [Cd(C10H9N2O2)2] n, were prepared under solvothermal conditions. In each structure, each CdII atom is coordinated by four O atoms and two N atoms from four different ligands. In the former structure, two crystallographically independent CdII atoms are located on twofold symmetry axes and doubly bridged in a μ2- N: O, O′-mode by the ligands into correspondingly independent chains that run in the [100] and [010] directions. Chains containing crystallographically related CdII atoms are linked into sheets viaπ-π stacking interactions. Sheets containing one of the distinct types of CdII atom are stacked perpendicular to [001] and alternate with sheets containing the other type of CdII atom. The second complex is a two-dimensional homometallic CdII (4,4) net structure in which each CdII atom is singly bridged to four neighbouring CdII atoms by four ligands also acting in a μ2- N: O, O′-mode. A square-grid network results and the three-dimensional supramolecular framework is completed by π-π stacking interactions between the aromatic ring systems. [ABSTRACT FROM AUTHOR]

Abstract: A stable polarized diode end-pumped [100]-cut Nd:YAG laser, passively Q-switched by a [001]-cut Cr4+:YAG saturable absorber, has been developed. The dependences of output characteristics in different directions of Cr4+:YAG crystal were investigated. The experiment demonstrated that in comparison with conventional [111]-cut Nd:YAG rod, stable output with high polarization extinction ratio was achieved by using the [100]-cut Nd:YAG as the laser crystal. The extinction ratio was 500:1 and the stability was 96.5%. [Copyright &y& Elsevier]

Two alkylimido derivatives of hexamolybdate, (Bu4N)2[Mo6O18(≡N- o-COOCH3C6H4)] ( 1) and (Bu4N)2[Mo6O18(≡N- o-COOCH2CH3C6H4)] ( 2), were synthesized in high purity and good yields by the reaction of [(C4H9)4N]4[α-Mo8O26] and methyl anthranilate or ethyl- o-aminobenzoate hydrochloride with N, N′-dicyclohexylcarbodiimide (DCC) as a dehydrating agent in dry acetonitrile solution, which were characterized by elemental analyses, IR, UV/Vis, and 1H NMR spectroscopy as well as ESI-MS, and single-crystal X-ray diffraction study. Compound 1 crystallizes in the monoclinic space group P21/ n with one-dimensional chain structure via intramolecular hydrogen bond. Compound 2 also crystallizes in the monoclinic space group P21/ n with dimer structure by intramolecular hydrogen bonds and π-π interactions between the pairs of cluster anions. [ABSTRACT FROM AUTHOR]

Abstract: A series of N-heterocyclic carbene (NHC) silver complexes derived from N-ferrocenylmethyl-N′-(pyridylmethyl)imidazolium iodides have been synthesized, which show remarkable structural diversity. Reaction of N-ferrocenylmethyl-N′-(2-pyridylmethyl)imidazolium iodide with Ag2O yielded stair-like NHC–Ag complexes, whose assembly modes significantly depended on experimental conditions. Reaction of N-ferrocenylmethyl-N′-(4-pyridylmethyl)imidazolium iodide with Ag2O yielded a chain NHC–Ag complex with a repeating 16-membered macrocyclic unit. However, similar reaction of N-ferrocenylmethyl-N′-(3-pyridylmethyl)imidazolium iodide with Ag2O only gave a dimeric NHC–Ag complex through bridging iodide. In these NHC–Ag complexes, 2- and 4-pyridyl-substituted NHCs act as bridging bidentate ligands through the pyridyl nitrogen and carbene carbon atoms, while 3-pyridyl-substituted NHC only acts as a monodentate ligand through the carbene carbon atom. An I/Cl exchange reaction was observed upon recrystallization of these NHC silver iodides in CH2Cl2. These NHC–Ag complexes exhibited highly effective catalytic activity in the three-component coupling reaction of alkyne, aldehyde and amine to generate propargylamines. [Copyright &y& Elsevier]

This work reports a detailed structural study by synchrotron x-ray diffraction of several sets of thick YBa2Cu307 layers. The samples represent recent advances in flux-pinning design, containing various concentrations of artificial pinning centers: (i) BaZr03 nanorods, (ii) BaZr03 nanoparticles, and (iii) Y2O3 nanoparticles. A statistical analysis was performed in order to separate the effects of defect-induced and intrinsic pinning. We report a statistically significant correlation between the orthorhombic distortion of the YBCO matrix and the pinning strength. Our result implies that the in-plane ordering of oxygen ions in the chain positions accounts for approximately 60% of the pinning force. The strain-induced pinning mechanism analysis, based on the Eshelby model of elastically strained composites, predicts that small YBCO grain size is a critical component of a strong pinning architecture that can enable critical current density values approaching the depairing limit. [ABSTRACT FROM AUTHOR]

Abstract: Antiferroelectric (Pb, La) (Zr, Sn, Ti)O3 (PLZST) single crystals have been successfully grown by flux method using PbO–PbF2–B2O3 as the flux. The obtained crystals are pale yellow in color and translucent. Domain structures, dielectric constants and optical transmission measurements have been performed on the 〈001〉-oriented PLZST single crystals. Two types of domains, namely, 90° and 180° domains, are observed. The extinction of 90° domains at P/A: 0° reveals a tetragonal structure in the crystal. The sequence of phase transitions from antiferroelectric to ferroelectric and then paraelectric has been established with increasing temperature. According to the modified Curie–Weiss relationship, the PLZST crystal is in an intermediate state between normal and relaxor antiferroelectrics. The broad optical transparent region (from 0.4 to 7.0μm) and high optical transmittance (up to 65%) indicate that PLZST crystals are promising for optical uses. [Copyright &y& Elsevier]