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Relaxor‐PbTiO3 crystals exhibit excellent piezoelectric properties (d33 > 2000 pC N−1 and k33 > 90%) and thus attractes widespread attention in the past two decades. However, the inevitable segregation of components during the crystal growth results in relatively low‐performance consistency of Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT) crystals, which seriously affects their practical applications. In this work, Nd3+ as A‐site substitution is introduced to improve the uniformity of electromechanical performance of PMN‐PT crystal. The results show that the crystal exhibits a high piezoelectric coefficient of 3000 pC N−1 in rhombohedral phase with a variation of 36%. The electron probe X‐ray microanalyzer indicates that the opposite separation characteristics of Nd3+ and Ti4+ lead to improved uniformity of piezoelectric performance along the crystal boule. The giant piezoelectricity in Nd‐doped PMN‐PT is attributed to the enhanced local structural heterogeneity introduced by doping Nd. Furthermore, the Nd‐doped PMN‐PT crystal shows the rhombohedral‐tetragonal phase transition temperature in the range of 74–87 °C, which indicates that Nd‐doped PMN‐PT crystal can be a promising candidate for the design of advanced piezoelectric transducers. [ABSTRACT FROM AUTHOR]

β‐SiC powders with different particle morphologies were prepared by combustion synthesis in an N2 atmosphere, with carbon black, carbon fiber, graphene, and graphite as carbon sources. With carbon black as the carbon source, single‐phase β‐SiC nanopowder with an average particle size around 20 nm was obtained. From carbon fiber and graphene, SiC fibers and sheets were produced, which were polycrystalline and consisted of lots of nanocrystals with random orientations. It was proposed that the synthesis of SiC occurs by gas–solid reaction and the growth of SiC is confined to the carbon particles. In the controlled growth of SiC, the morphology of the precursor carbon is preserved, offering an opportunity to control the particle morphology of SiC by changing carbon sources. [ABSTRACT FROM AUTHOR]

Promoting crystal growth is of great practical importance in the pharmaceutical industry, especially for manufacturing large crystals. In this work, intensification of crystal growth was investigated by using p-toluamide as a model compound. The crystal habit and the functional groups of different crystal faces of p-toluamide were analyzed from the crystal structure data. The growth rate of the (100) and (011) faces of p-toluamide was systematically measured by single crystal experiments and the effect of additives on crystal growth was evaluated. It was found that different additives could selectively promote the growth of specific crystal faces. Molecular simulation was used to investigate the influence mechanism of additives on (011) crystal face growth. It was revealed that the special promotion effect is due to the fact that the additive molecules repel the solvent molecules which exhibit a stronger inhibiting effect, thus eliminating the negative influence of the solvent on the surface diffusion of p-toluamide. [ABSTRACT FROM AUTHOR]

Due to dielectric permittivity, significant band gap and photo-catalytic activity, BiO has many potential applications in functional material field. Its special properties are determined by the morphology and crystal phase. In this study, the tetrahedron, rod-like and flowerlike BiO powders with α and γ phase were synthesized by chemical precipitation method and the effect of the reaction conditions was studied. The model was designed to illustrate this process. Phase composition, microstructure, and morphology of the powders were investigated by X-ray diffraction and field emission scanning electron microscope. The results suggested that the phases and morphologies of BiO powders were influenced by the surfactant, reaction rate and reactant adding order of the experiment when BiO were synthesized by chemical precipitation method. The mechanism was related with the free energy of the crystal face and the condition of the interface between crystal and liquid phase, which induced the different crystal growth mechanism during the reaction. The results indicated a controlled way to design various BiO for applications. [ABSTRACT FROM AUTHOR]

The smooth 2H–SiC fibers with hexagonal structure and a small amount of tower-like 3C–SiC fibers with face-centered cubic structure were synthesized with a simple catalyst-free method. Specifically, SiC fibers were obtained by thermal treatment of the Si 3 N 4 powder in a graphite crucible at temperature of 1800 °C and pressure of 190 MPa in Ar atmosphere. The synthesized SiC fibers consist of SiC wires with several tens to hundreds of micrometers in length and mostly 200–800 nm in diameter and some SiC whiskers with shorter length of 3–15 μm. The smooth 2H–SiC fibers and rough 2H–SiC fibers with tower-like growth traces grown along [1010] direction, and the tower-like 3C–SiC fibers may grow with orientation attachment patterns along [111] direction. Finally, the vapor-solid growth mechanism and detailed growth process of SiC fibers were discussed. [Display omitted] • The 2H–SiC fibers and a small amount of tower-like 3C–SiC fibers were synthesized. • The crystal growth direction is [1010] for 2H–SiC and [111] for 3C–SiC. • Vapor-solid mechanism dominates in this catalyst-free synthesis process. [ABSTRACT FROM AUTHOR]

PbS nano-microcrystals were prepared from Pb(OAc)2·3H2O and sulfur in a solution without any surfactant using the solvothermal process. Different morphologies, mainly including polyhedron microcrystals and sphere-like assemblies, were characterized using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). PbS nano-microcrystals with cubic crystal structure were detected using X-ray diffraction (XRD), electron diffraction (ED) and high resolution transmission electron micrograph (HRTEM) techniques. The optical properties were investigated by ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence spectroscopy (PL). The UV-vis absorption peaks of PbS exhibited a large blue-shift and the PL spectra had a strong and broad emission bands centered at 408 nm. The crystal growth mechanism of PbS was also discussed. [ABSTRACT FROM AUTHOR]

Abstract: ZnO/Ag composite nanoarrays were obtained using Fe–Co–Ni foil as substrate via a novel solution method in large scales. The structure, composition, morphology and optical properties of the synthesized ZnO/Ag nanoarrays were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and ultraviolet–visible (UV–vis) absorption measurement. The properties of surface-enhanced Raman scattering and photocurrent of the ZnO/Ag nanoarrays were also investigated in detail. It was shown that Ag nanoparticles were successfully grown on the surface of ZnO nanoarrays. Comparing to pure ZnO nanoarrays, the ZnO/Ag composite nanoarrays have been proved to be a versatile substrate for enhanced surface-enhanced Raman scattering for common organic molecules and obvious photocurrent multiplication effect. [Copyright &y& Elsevier]

Abstract: This paper presents an investigation on the synthesis and characterization of ZnO–Ag core–shell nanocomposites. ZnO nanorods were employed as core material for Ag seeds, and subsequent nucleation and growth of reduced Ag by formaldehyde formed the ZnO–Ag core–shell nanocomposites. The ZnO–Ag nanocomposites were annealed at different temperature to improve the crystallinity and binding strength of Ag nanoparticles. The morphology, microstructure and optical properties of the ZnO–Ag core–shell nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible (UV–vis) absorption and photoluminescence measurement. It was demonstrated that very small face-center-cubic Ag nanoparticles were coated on the surface of ZnO nanorods. The ultraviolet absorption and surface plasmon absorption band of ZnO–Ag core–shell nanocomposites exhibited some redshifts relative to pure ZnO nanorods and monometallic Ag nanoparticles. The coating of Ag nanocrystals onto the ZnO nanorods completely quenched the photoluminescence. These observations reflected the strong interfacial interaction between ZnO nanorods and Ag nanoparticles. The effect of Ag coating thickness on the morphology and optical properties of ZnO–Ag core–shell nanocomposites was also investigated. Moreover, the growth mechanism of ZnO–Ag core–shell nanocomposites was also proposed and discussed in detail. [Copyright &y& Elsevier]

Relaxor ferroelectric-based Pb(Mg1/3Nb2/3)O3-32PbTiO3 (PMN-32PT) single crystal was prepared by using the vertical Bridgman method at the optimized condition and the thermal stability with temperature under different conditions was analyzed through the differential scanning calorimetry (DSC) and the thermal gravity analysis (TGA). The phases were identified by XRD. DSC/TGA results of the as-grown PMN-32PT crystal indicated that PMN-32PT crystals was stability before melting in the sealed conditions while kept instability in the temperature higher than 900°C in the open system; the melting point of PMN-32PT was 1302.1°C in sealed condition while reduced to 1282.9°C in open system due to the evaporation of PbO and the transformation into pyrochlore phases. [ABSTRACT FROM AUTHOR]

The relaxor-based ferroelectric single crystals Pb(In1/2Nb1/2)O3- Pb(Mg1/3Nb2/3)O3-PbTiO3 were grown successfully using the vertical Bridgman technique. The crystals were spontaneously nucleated and induced to grow by the seed respectively, with diameter of Ø25-40 mm and length of 80-170 mm. The [001]-oriented wafers of as-grown crystals showed the excellent electrical characterizations (ε∼5500, tanδ∼1.35%, d33 ∼1900pC/N, k33∼0.9). Both the higher rhombohedral-tetragonal phase transition temperature (Tr/t ∼100-120°C) and Curie temperature (Tc ∼170-200°C) enlarged the operating temperature range of the devices. The crystals had the stable time dependence of piezoelectric properties. Therefore, the successful growth and high performance made the crystal be a promising candidate for the ultrasonic applications. [ABSTRACT FROM AUTHOR]

Two polymorphs formulated as [Ru(H2biim)3]SO4(H2biim = 2,2′-biimidazole) have been solvothermally synthesized through changing the pH value of the reaction solution in an identical solvent at 120 °C. The α-[Ru(H2biim)3]SO4(1) crystallizes in the monoclinic space group P21/cwith a= 8.1802(9) , b= 21.293(2) , c= 15.2116(14) , β= 121.357(4)°, Z= 4. The β-[Ru(H2biim)3]SO4(2) crystallizes in a chiral space group I41with a= 12.6267(10) , c= 14.244(2) , Z= 4. Complex 1assembles into homochiral (Δ and Λ), (6,3) honeycomb two-dimensional layers, which further alternately stack in racemic, hydrogen-bonded networks, whereas 2is a chiral, (10,3)-b3-D network. Thus 1and 2are topological isomers. Importantly, their formations are much dependent on the pH value of the reaction solution. The data observed in this study seem to suggest that the diverse hydrogen bonding modes between the sulfate and H2biim ligand identified here play a crucial role in the formation of the polymorphs and topological isomers. The powder XRD patterns and infrared spectra also provide valuable information in the diagnosis of the polymorphs. [ABSTRACT FROM AUTHOR]

Abstract: Vertically aligned carbon nanotubes (VACNTs) were directly grown on carbon fabric (CF) using the controllable injection chemical vapor deposition without the pretreatment of the surface of CF. Electrochemical characterization indicated that VACNT/CF electrodes achieved a relative high specific capacitance of 75Fg−1 at a current density of 1Ag−1 due to large specific surface area and low contact resistance. The specific capacitance still remained 63Fg−1 at a high current density of 100Ag−1 with the retention of 84%, which far exceeded other carbonaceous materials. This excellent rate capability of VACNT/CF electrodes was attributed to large mesopore size, three-dimensional hierarchical architecture and aligned pathway, facilitating the diffusion of electrolyte ions. In addition, the area-normalized capacitance of VACNT/CF electrodes was improved remarkably by prolonging the growth time of CNT. [Copyright &y& Elsevier]

Abstract: Ag@AgBr core–shell nanowires have been synthesized in large quantities via a redox reaction between Ag nanowires and FeBr3 in solution at room temperature. The effect of the molar ratio of Fe:Ag on the formation and optical absorption of the Ag@AgBr core–shell nanowires was systematically studied. The results showed that Ag nanowires were converted into Ag@AgBr core–shell nanowires and finally into AgBr nanorods with the increase of the molar ratio of Fe:Ag. At the same time, the optical absorption of Ag nanowires decreased gradually and disappeared finally. In addition, the growth mechanism of the Ag@AgBr core–shell nanowires was also discussed in detail. [Copyright &y& Elsevier]

Bi 2 O 3 /YSZ (Y 2 O 3 -stabilized ZrO 2 ) composite powders for solid electrolytes application were synthesized by chemical co-precipitation method. The effects of raw material ratios and temperatures on the properties of the composite powders were studied. The morphology, crystal structure and phase composition of the composite powders were characterized by means of field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results showed that the Bi 2 O 3 /YSZ composite powders could be fabricated by chemical process, and the composite powders with different shapes were prepared when the ratio of raw materials or temperature changed. The one-dimensional rod-like Bi 2 O 3 particles were obtained when the content of Bi 2 O 3 was above 10 mol% or the heating mechanism was changed. And the growth mechanism of Bi 2 O 3 in the synthesis process was studied. The oriented attachment with interaction of Ostwald ripening was the possible growth mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Relaxor ferroelectric-based Pb(Mg1/3Nb2/3)O3–32PbTiO3 (PMN–32PT) single crystal growth and thermal analysis were reported. The as-grown PMN–32PT crystal was determined by XRD to be a single phase with rhombohedral structure at room temperature. The Curie temperature was in the range of 137–146°C with ferroelectric rhombohedral to tetrahedral phase transition temperature of 92–118°C. The piezoelectric coefficients were about 2000pC/N with longitude electromechanical coupling factors about 0.93. DSC/TGA analysis of the as-grown PMN–32PT crystal indicated that the melting point of PMN–32PT was 1302.1°C in sealed condition while reduced to 1282.9°C in open system due to the evaporation of PbO and the transformation into pyrochlore phases. [Copyright &y& Elsevier]

A Pb(In 1/2 Nb 1/2)O 3 –Pb(Mg 1/3 Nb 2/3)O 3 –PbTiO 3 relaxor ferroelectric single crystal with a 5" diameter and 145 mm length was grown by the modified Bridgman method. The composition distribution of the crystal boule was investigated. The result showed that the PbTiO 3 contents increased along the growth direction, which means that compositional segregation existed, and the effective segregation coefficient was simulated to be 0.84, which is close to that of 3" single crystal. The horizontal composition distribution in the crystal demonstrated that the solid-melt interface of the 5" single crystal was serious convex during crystal growth and was caused by the nonuniform radial thermal field of the large melt. The dielectric, piezoelectric, ferroelectric properties and domain structures were measured to investigate the effect of the composition change along the crystal growth direction. Based on the domain structure and electrical performance, the crystal boule was divided into rhombohedral, morphotropic phase boundary and tetragonal regions. It was found that the optimal piezoelectric coefficient d 33 of the 5" single crystal was more than 2000 pC/N. This work provided positive information for large sized single crystal growth of a relaxor ferroelectric single crystal. • The 5'' diameter by 145 mm long of PIN-PMN-PT crystal along [110] direction was grown by the modified Bridgeman method. • The compositions of single crystal samples along the crystal growth direction and horizontal direction were measured for compositional segregation and horizontal component distribution effect of 5 inches single crystal growth. • The dielectric, piezoelectric and ferroelectric properties of [001] C samples along the crystal growth direction were investigated. Considering the performance of all samples, the crystal in the rhombohedral phase near MPB are suitable for engineering applications. [ABSTRACT FROM AUTHOR]