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In this study, the advanced chemical vapor transport (CVT) method in combination with the quenching effect is introduced for creating molybdenum oxide nanoparticle arrays, composed of the hierarchical structure of fine nanoparticles (NPs), which are vertically grown with a homogeneous coverage on the individual carbon fibers of carbon fiber paper (CFP) substrates. The obtained molybdenum oxide NPs hold a metastable high-temperature γ-Mo4O11 phase along with a stable α-MoO3 phase by the quenching effect. Furthermore, such a quenching effect forms thinner and smaller nanoparticle aggregates by suppressing the growth and coalescence of primary particles. The molybdenum oxide nanoparticle aggregates are prepared using two different types of precursors: MoO3 and a 1:1 (mol/mol) mixture of MoO3 and activated carbon. The results characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy show that the relative amount of α-MoO3 to γ-Mo4O11 within the prepared NPs is dependent on the precursor type; a lower amount of α-MoO3 to γ-Mo4O11 is obtained in the NPs prepared using the mixed precursor of MoO3 and carbon. This processing–structure landscape study can serve as the groundwork for the development of high-performance nanomaterials in various electronic and catalytic applications.

In this paper we report the crystal growth conditions and optical anisotropy properties of Tungsten ditelluride (WTe2) single crystals. The chemical vapor transport (CVT) method was used for the synthesis of large WTe2 crystals with high crystallinity and surface quality. These were structurally and morphologically characterized by means of X-ray diffraction, optical profilometry and Raman spectroscopy. Through spectroscopic ellipsometry analysis, based on the Tauc–Lorentz model, we identified a high refractive index value (~4) and distinct tri-axial anisotropic behavior of the optical constants, which opens prospects for surface plasmon activity, revealed by the dielectric function. The anisotropic physical nature of WTe2 shows practical potential for low-loss light modulation at the 2D nanoscale level.

WOS: 000427715600070, In this work we present physical, electrical and magnetic properties of beta-Fe1.1Se single crystalline alloys produced by chemical vapor transport technique using short (120 h) and long (700 h) heating processes. The best T (c) was obtained from the long time processed samples. Magnetization results showed that samples are typical type-II superconductor. Calculated critical current density values, at zero field, were found to be 1.1 x 10(6) Acm(-2) for long time processed samples at 2 K and indicates strong pinning mechanism and bulk superconducting nature. The zero temperature value of higher upper critical field was calculated to be H (c2)(0) = 244 kOe. Calculated values of coherence length were found between 3.65 and 3.67 nm. Pauli paramagnetic limit, H (P) (0) = 1.84T (c) , is exceeded for both series of samples. Results obtained suggested that the spin-paramagnetic effect possibly the dominant pair-breaking mechanism for both series of samples., Scientific and Technological Research Council of Turkey, TUBITAK [115F278], This work was supported by the Scientific and Technological Research Council of Turkey, TUBITAK (Project Grant No. 115F278).

A comparative analysis of free and bound excitons in the photoluminescence (PL) spectra of CuInS2 single crystals grown by the traveling heater (THM) and the chemical vapor transport (CVT) methods is presented. The values of the binding energy of the A free exciton (18.5 and 19.7 meV), determined by measurements of the spectral positions of the ground and excited states, allowed the Bohr radii (3.8 and 3.7 nm), bandgaps (1.5536 and 1.5548 eV) and dielectric constants (10.2 and 9.9) to be calculated for CuInS2 crystals grown by THM and CVT, respectively. © 2017 Elsevier B.V.

Halide perovskites have many important optoelectronic properties, including high emission efficiency, high absorption coefficients, color purity, and tunable emission wavelength, which makes these materials promising for optoelectronic applications. However, the inability to precisely control large-scale patterned growth of halide perovskites limits their potential toward various device applications. Here, we report a patterning method for the growth of a cesium lead halide perovskite single crystal array. Our approach consists of two steps: (1) cesium halide salt arrays patterning and (2) chemical vapor transport process to convert salt arrays into single crystal perovskite arrays. Characterizations including energy-dispersive X-ray spectroscopy and photoluminescence have been employed to confirm the chemical compositions and the optical properties of the as-synthesized perovskite arrays. This patterning method enables the patterning of single crystal cesium lead halide perovskite arrays with tunable spacing (from 2 to 20 μm) and crystal size (from 200 nm to 1.2 μm) in high production yield (almost every pixel in the array is successfully grown with converted perovskite crystals). Our large-scale patterning method renders a platform for the study of fundamental properties and opportunities for perovskite-based optoelectronic applications.

We present the analysis of a family of nanotubes (NTs) based on the quaternary misfit layered compound (MLC) YxLa1–xS-TaS2. The NTs were successfully synthesized within the whole range of possible compositions via the chemical vapor transport technique. In-depth analysis of the NTs using electron microscopy and spectroscopy proves the in-phase (partial) substitution of La by Y in the (La,Y)S subsystem and reveals structural changes compared to the previously reported LaS-TaS2 MLC-NTs. The observed structure can be linked to the slightly different lattice parameters of LaS and YS. Raman spectroscopy and infrared transmission measurements reveal the tunability of the plasmonic and vibrational properties. Density-functional theory calculations showed that the YxLa1–xS-TaS2 MLCs are stable in all compositions. Moreover, the calculations indicated that substitution of La by Sc atoms is electronically not favorable, which explains our failed attempt to synthesize these MLC and NTs thereof., A.E. acknowledges the support by Act 211 Government of the Russian Federation, Contract No. 02.A03.21.0006. The support of the Israel Science Foundation (Grant No. 7130970101), Irving and Cherna Moskowitz Center for Nano and Bio-Nano Imaging, and the Perlman Family Foundation and the Kimmel Center for Nanoscale Science (Grant No. 43535000350000) is greatly acknowledged. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through Project Grant MAT2016-79776-P (AEI/FEDER, UE) and from the European Union H2020 program “ESTEEM3” (823717). S.H. acknowledges funding by the German Research Foundation (HE 7675/1-1). I.P. is the incumbent of the Sharon Zuckerman Research Fellow Chair.

Averievite-type compounds with the general formula (MX)[Cu5O2(TO4)], where M = alkali metal, X = halogen and T = P, V, have been synthesized by crystallization from gases and structurally characterized for six different compositions: 1 (M = Cs; X = Cl; T = P), 2 (M = Cs; X = Cl; T = V), 3 (M = Rb; X = Cl; T = P), 4 (M = K; X = Br; T = P), 5 (M = K; X = Cl; T = P) and 6 (M = Cu; X = Cl; T = V). The crystal structures of the compounds are based upon the same structural unit, the layer consisting of a kagome lattice of Cu2+ ions and are composed from corner-sharing (OCu4) anion-centered tetrahedra. Each tetrahedron shares common corners with three neighboring tetrahedra, forming hexagonal rings, linked into the two-dimensional [O2Cu5]6+ sheets parallel to (001). The layers are interlinked by (T5+O4) tetrahedra (T5+ = V, P) attached to the bases of the oxocentered tetrahedra in a “face-to-face” manner. The resulting electroneutral 3D framework {[O2Cu5](T5+O4)2}0 possesses channels occupied by monovalent metal cations M+ and halide ions X−. The halide ions are located at the centers of the hexagonal rings of the kagome nets, whereas the metal cations are in the interlayer space. There are at least four different structure types of the averievite-type compounds: the P-3m1 archetype, the 2 × 2 × 1 superstructure with the P-3 space group, the monoclinically distorted 1 × 1 × 2 superstructure with the C2/c symmetry and the low-temperature P21/c superstructure with a doubled unit cell relative to the high-temperature archetype. The formation of a particular structure type is controlled by the interplay of the chemical composition and temperature. Changing the chemical composition may lead to modification of the structure type, which opens up the possibility to tune the geometrical parameters of the kagome net of Cu2+ ions.

Black phosphorus, an emerging layered material, exhibits promising applications in diverse fields, ranging from electronics to optics. However, controlled synthesis of black phosphorus, particularly its few-layered counterparts, is still challenging, which should be due to the unclear growth mechanism of black phosphorus. Here, taking the most commonly used Sn-I assisted synthesis of black phosphorus as an example, we propose a growth mechanism of black phosphorus crystals by monitoring the reactions and analyzing the as-synthesized products. In the proposed mechanism, Sn24P19.3I8 is the active site for the growth of black phosphorus, and the black phosphorus crystals are formed with the assistance of SnI2, following a polymerization-like process. In addition, we suggest that all Sn-I assisted synthesis of black phosphorus should share the same reaction mechanism despite the differences among Sn-I containing additives. Our results shown here should shed light on the controlled synthesis of black phosphorus and facilitate further applications of black phosphorus.

Vertically aligned N-doped ZnO microrods with a hexagonal symmetry were fabricated via the chemical vapor transport with abundant N2O as both O and N precursors. We have demonstrated the suppression of the zinc interstitial-related shallow donor defects and have identified the zinc vacancy-related shallow and deep acceptor states by temperature variable photoluminescence in O-rich growth environment. Through spatially resolved cathodoluminescence spectra, we found the luminescent inhomogeneity in the sample with a core-shell structure. The deep acceptor-isolated VZn and the shallow acceptor VZn-related complex or clusters mainly distribute in the shell region.

Shubnikov-de-Haas oscillations were studied under high magnetic field in Bi$_2$Se$_3$ nanostructures grown by Chemical Vapor Transport, for different bulk carrier densities ranging from $3\times10^{19}\text{cm}^{-3}$ to $6\times10^{17}\text{cm}^{-3}$. The contribution of topological surface states to electrical transport can be identified and separated from bulk carriers and massive two-dimensional electron gas. Band bending is investigated, and a crossover from upward to downward band bending is found at low bulk density, as a result of a competition between bulk and interface doping. These results highlight the need to control electrical doping both in the bulk and at interfaces in order to study only topological surface states., 6 pages, 4 figures

An unprecedentedly stable CH3NH3PbI3 film synthesized by a modified chemical vapor transport method is demonstrated. The results show that the crystal structure, light absorption, and device efficiency do not degrade after storing for 100 d in air with 40% relative humidity, while the conventional solution‐processed perovskites are usually stable for less than 20 d in similar conditions.