Abstract: We report on the incorporation of SiV centers during hot filament chemical vapor deposition of diamond on top of diamond nanopillars with diameters down to 100 nm. The nanopillars themselves were prepared from nano crystalline diamond films by applying electron beam lithography and inductively coupled plasma reactive ion etching. The optical investigations revealed the presence of ensembles of SiV color centers incorporated during the overgrowth step. (C) 2016 Elsevier B.V. All rights reserved.

Abstract: The morphology and structure of hexagonal graphitic BN (h-BN) powders with graphitization indices GI <5, used as precursors for the synthesis of cubic BN (c-BN) crystals, has been investigated by transmission electron microscopy in diffraction contrast and high resolution. We show that besides the GI, which is a general parameter for controlling the structural quality of h-EN ponders, some other microstructural features strongly influence the synthesis of c-BN. In our opinion, the high reactivity of some h-BN powders results from the presence of some nucleation centers for c-BN, observed at the edges of the h-BN particles. They are formed by a rearrangement of the graphitic (0002) planes by bending back, joining in pairs and forming locally nanoarches (half nanotubes). In these particular places, the nature of bonding locally turns towards sp(3), as in the case of c-BN, (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: Objective. The aim was to evaluate the optical properties, mechanical properties and aging stability of yttria-stabilized zirconia with different compositions, highlighting the influence of the alumina addition, Y2O3 content and La2O3 doping on the translucency. Methods. Five different Y-TZP zirconia powders (3 commercially available and 2 experimentally modified) were sintered under the same conditions and characterized by X-ray diffraction with Rietveld analysis and scanning electron microscopy (SEM). Translucency (n = 6/group) was measured with a color meter, allowing to calculate the translucency parameter (TP) and the contrast ratio (CR). Mechanical properties were appraised with four-point bending strength (n = 10), single edge V-notched beam (SEVNB) fracture toughness (n = 8) and Vickers hardness (n = 10). The aging stability was evaluated by measuring the tetragonal to monoclinic transformation (n = 3) after accelerated hydrothermal aging in steam at 134 degrees C, and the transformation curves were fitted by the Mehl-Avrami-Johnson (MAJ) equation. Data were analyzed by one-way ANOVA, followed by Tukey's HSD test (alpha = 0.05). Results. Lowering the alumina content below 0.25 wt.% avoided the formation of alumina particles and therefore increased the translucency of 3Y-TZP ceramics, but the hydrothermal aging stability was reduced. A higher yttria content (5 mol%) introduced about 50% cubic zirconia phase and gave rise to the most translucent and aging-resistant Y-TZP ceramics, but the fracture toughness and strength were considerably sacrificed. 0.2 mol% La2O3 doping of 3Y-TZP tailored the grain boundary chemistry and significantly improved the aging resistance and translucency. Although the translucency improvement by La2O3 doping was less effective than for introducing a substantial amount of cubic zirconia, this strategy was able to maintain the mechanical properties of typical 3Y-TZP ceramics. Significance. Three different approaches were compared to improve the translucency of 3YTZP ceramics. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Abstract: The dataset together with the corresponding Python scripts and Jupyter notebooks presented in this article are supplementary data for the work presented in Samaee et al., 2019 [1]. The data itself consists of two parts: the simulation data that was used in [1] to analyze the effect of a particular grain boundary on curved dislocations and the precession electron diffraction (PED) strain maps together with post-processed data for analyzing details of the observed dislocation vein structures. Additionally, the complete stress tensor components, which are not shown in [1], have also been included. The data sets are accompanied by Python code explaining the file formats and showing how to post-process the data. (c) 2019 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract: In this paper we review the work related to amorphization under mechanical stress. Beyond pressure, we highlight the role of deviatoric or shear stresses. We show that the most recent works make amorphization appear as a deformation mechanism in its own right, in particular under extreme conditions (shocks, deformations under high stresses, high strain-rates).

Abstract: Water-soluble Pt nanoflowers (NFs) were prepared by a diethylene glycol-mediated reduction of Pt acetylacetonate
(Pt(acac)2) in the presence of polyethyleneimine. Advanced electron microscopy analysis showed that NFs consist of
multiple branches with truncated cubic morphology and different crystallographic orientations. We demonstrate that the
nature of the solvent strongly influences the resulting morphology. The catalytic performance of Pt NFs in 4–nitrophenol
reduction was found to be superior to that of other nanoparticle-based catalysts. Additionally, Pt NFs display good
catalytic reusability with no loss of activity after five consecutive cycles.

Abstract: This study describes the influence of annealing temperature on the structure and luminescence properties of KGd1-xEux(MoO4)(2) (0 <= x <= 1). Compounds with the general formula (A ', A '')(n)[(W, Mo)O-4](m) are investigated as luminescent materials for photonic applications such as phosphor-converted LEDs (light-emitting diodes). Herein, the KGd0.8Eu0.2(MoO4)(2) light-rose crystal was grown by the Czochralski technique. Moreover, three polymorphs of KGd1-xEux(MoO4)(2) were present in the 923-1223 K range of annealing temperatures under ambient pressure: a triclinic alpha-phase, a disproportionately modulated monoclinic beta-phase and an orthorhombic gamma-phase with a KY(MoO4)(2)-type structure. The different behaviors of KGd(MoO4)(2) and KEu(MoO4)(2) were revealed by DSC studies. The number and the character of phase transitions for KGd1-xEux(MoO4)(2) depended on the elemental composition. The formation of a continuous range of solid solutions with the triclinic alpha-KEu(MoO4)(2)-type structure and ordering of K+ and Eu3+/Gd3+ cations were observed only for alpha-KGd1-xEux(MoO4)(2) (0 <= x <= 1) prepared at 923 K. The structures of gamma-KGd1-xEux(MoO4)(2) (x = 0 and 0.2) were studied using electron diffraction and refined using the powder X-ray diffraction data. The luminescence properties of KGd1-xEux(MoO4)(2) prepared at different annealing temperatures were studied and related to their different structures. The maxima of the D-5(0) -> F-7(2) integral emission intensities were found under excitation at lambda(ex) = 300 nm and lambda(ex) = 395 nm for triclinic scheelite-type alpha-KGd0.6Eu0.4(MoO4)(2) and monoclinic scheelite-type beta-KGd0.4Eu0.6(MoO4)(2) prepared at 1173 K, respectively. The latter shows the brightest red light emission among the KGd1-xEux(MoO4)(2) phosphors. The maximum and integral emission intensity of beta-KGd0.4Eu0.6(MoO4)(2) in the D-5(0) -> F-7(2) transition region is similar to 20% higher than that of the commercially used red phosphor Gd2O2S:Eu3+. Thus, beta-KGd0.4Eu0.6(MoO4)(2) is very attractive for application as a near-UV convertible red-emitting phosphor for LEDs.

Abstract: Crystal structure prediction is the holy grail of crystal engineering and is key to its ambition of driving the formation of solids based on the selection of their molecular constituents. However, this noble quest is hampered by the limited predictability of the incorporation of solvent molecules, first and foremost the ubiquitous water. In this context, we herein report the structure of four methylene blue cyanometallate phases, where anions with various shapes and charges influence the packing motif and lead to the formation of differently hydrated structures. Importantly, water molecules are observed to play various roles as isolated fillings, dimers, or an infinite network with up to 13 water molecules per repeating unit. Each crystal structure has been determined by single-crystal X-ray diffraction and evaluated with the aid of Hirshfeld surface analysis, focussing on the role of water molecules and the hierarchy of different classes of interactions in the overall supramolecular landscape of the crystals. Finally, the collected pieces of evidence are matched together to highlight the leading role of MB stacking and to derive an explanation for the observed hydration diversity based on the structural role of water molecules in the crystal architecture.

Abstract: A copper(II) hexafluoroacetylacetonate (1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, hfa) adduct with N,N,N¡ä,N¡ä-tetramethylethylenediamine (TMEDA) [Cu(hfa)2¡¤TMEDA] is used for the first time as precursor for the chemical vapor deposition (CVD) of copper oxide nanosystems. The syntheses are carried out under both O2 and O2+H2O reaction atmospheres on Si(100) substrates, at temperatures ranging between 250 and 550 ¡ãC. Subsequently, the interrelations between the preparative conditions and the system composition, nanostructure, and morphology are elucidated by means of complementary analytical techniques [Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron and X-ray excited auger electron spectroscopies (XPS and XE-AES), glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM)]. The obtained data revealed a gradual transformation from Cu2O, to Cu2O + CuO, to CuO nanosystems upon increasing the deposition temperature from 250 to 550 ¡ãC under both growth atmospheres. Such a phenomenon was accompanied by a progressive morphological evolution from continuous films to 1D hyperbranched nanostructures. Water vapor introduction in the deposition environment enabled to lower the deposition temperature and resulted in a higher aggregate interconnection, attributed to a higher density of nucleation centers.

Abstract: Strongly c-axis oriented ZnO nanorod arrays were grown on Si(100) by plasma enhanced-chemical vapor deposition (PE-CVD) starting from two volatile bis(ketoiminato) zinc(II) compounds Zn[(R′)NC(CH3)═C(H)C(CH3)═O]2, with R′ = -(CH2)xOCH3 (x = 2, 3). A systematic investigation of process parameters enabled us to obtain the selective formation of ZnO nanorods with tailored features, and provided an important insight into their growth mechanism. The morphology, structure, and composition of the synthesized ZnO nanosystems were thoroughly analyzed by field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDXS), glancing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Photoluminescence (PL) measurements were carried out to gain information on the optical properties. Specifically, one-dimensional (1D) ZnO architectures could be grown on Si(100) substrates at temperatures as low as 200−300 °C and radio frequency (RF)-power values of 20 W, provided that a sufficiently high mass supply to the growth surface was maintained. To the best of our knowledge, the present work reports the mildest preparation conditions ever appeared in the literature for the PE-CVD of ZnO nanorods, a key result in view of potential large-scale technological applications.

Abstract: Hexagonal boron nitride nanowall thin films were deposited on Si(100) substrates using a Ar(51%)/N-2(44%)/H-2(5%) gas mixture by unbalanced radio frequency sputtering. The effects of various target-to-substrate distances, substrate temperatures, and substrate tilting angles were investigated. When the substrate is close to the target, hydrogen etching plays a significant role in the film growth, while the effect is negligible for films deposited at a farther distance. The relative quantity of defects was measured by a non-destructive infrared spectroscopy technique that characterized the hydrogen incorporation at dangling nitrogen bonds at defect sites in the deposited films. Despite the films deposited at different substrate tilting angles, the nanowalls of those films were found to consistently grow vertical to the substrate surface, independent of the tilting angle. This implies that chemical processes, rather than physical ones, govern the growth of the nanowalls. The results also reveal that the degree of nanowall crystallization is tunable by varying the growth parameters. Finally, evidence of hydrogen desorption during vacuum annealing is given based on measurements of infrared stretching (E-1u) and bending (A(2u)) modes of the optical phonons, and the H-N vibration mode.

Abstract: High purity porous ZnO nanopyramids with controllable properties are grown on their tips on
Si(100) substrates by means of a catalyst-free vapor phase deposition route in a wet oxygen
reaction environment. The system degree of preferential [001] orientation, as well as
nanopyramid size, geometrical shape and density distribution, can be finely tuned by varying the
growth temperature between 300 and 400°C, whereas higher temperatures lead to more compact
systems with a three-dimensional (3D) morphology. A growth mechanism of the obtained ZnO
nanostructures based on a self-catalytic vapor-solid (VS) mode is proposed, in order to explain
the evolution of nanostructure morphologies as a function of the adopted process conditions. The
results obtained by a thorough chemico-physical characterization enable to get an improved
control over the properties of ZnO nanopyramids grown by this technique. Taken together, they
are of noticeable importance not only for fundamental research on ZnO nanomaterials with
controlled nano-organization, but also to tailor ZnO functionalities in view of various potential
applications.

Abstract: Liquid metal embrittlement (LME) induced quasi-brittle fracture characteristics of a 9Cr–1Mo ferritic–martensitic steel (T91) after fatigue cracking in lead–bismuth eutectic (LBE) have been investigated at various length scales. The results show that the LME fracture morphology is primarily characterized by quasi-brittle translath flat regions partially covered by nanodimples, shallow secondary cracks propagating along the martensitic lath boundaries as well as tear ridges covered by micro dimples. These diverse LME fracture features likely indicate a LME mechanism involving multiple physical processes, such as weakening induced interatomic decohesion at the crack tip and plastic shearing induced nano/micro voiding in the plastic zone.