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Background: We report on the fundamental crystallization kinetics of atomic layer deposited (ALD) TiO2 thin films undergoing a post-deposition anneal (PDA) at low temperatures to probe differences in the as-deposited film microstructure. Methods: The system of study is ALD TiO2 thin films prepared from tetrakis(dimethylamino)titanium(IV) (TDMAT) and water at 120 °C, 140 °C and 160 °C followed by ex situ low temperature annealing at temperatures ranging from 140 °C to 220 °C. All as-deposited TiO2 thin films are amorphous by X-ray diffraction (XRD). Post-deposition annealing (PDA) produces large grain anatase crystals, confirmed by XRD and top-view scanning electron microscopy (SEM). A detailed SEM study is performed to quantify the nucleation and growth kinetics by fitting microstructural data to the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a time-temperature-transformation (TTT) diagram is constructed to summarize the differences in crystallization behavior at different ALD deposition temperatures. Results and conclusions: Fitting microstructural data to the JMAK equation reveals an Avrami exponent close to 3 with continuous nucleation, suggesting two-dimensional, plate-like crystal growth. Applying an Arrhenius relationship to the phase transformation data, the combined activation energy for nucleation and growth is found to be 1.40–1.58 eV atom-1. Nucleation rates are determined, and an Arrhenius relationship is used to calculate the critical Gibbs free energy for nucleation (~1.3–1.4 eV atom-1). As such, nucleation is the rate-limiting step for the amorphous to anatase phase transformation. ALD growth temperature is found to dictate film microstructure with lower deposition temperatures reducing the nucleation rate and leading to larger grain sizes irrespective of PDA conditions. The nucleation rate pre-exponential frequency factor increases with increasing deposition temperature, thereby increasing the likelihood for nucleation. Interestingly, it is this difference in the vibrational modes of the amorphous structure, as indicated by the variation in the nucleation rate pre-exponential frequency factor, that alters the phase transformation rates and not a change in the activation energies for the transformation.

Journal of magnesium and alloys 10(11), 3281-3287 (2022). doi:10.1016/j.jma.2021.08.008, Published by Elsevier, Amsterdam [u.a.]

Hydroxyapatite (HAp) is the major component of all boney tissues in mammals. Because of this omnipresence in the living world, HAp possesses an exceptional biocompatibility. The downside of this omnipresence, however, comes in the form of its mild to moderate biological activities. One means of augmenting these activities involves the doping of HAp with foreign ions. Here, the first synthesis and characterization of HAp doped with germanium ions is being reported. Germanium was deliberately integrated into the crystal lattice of HAp in the form of germanate anions. Approximately two thirds of the germanate ions introduced into the hydrothermal solution got incorporated into the HAp lattice, yielding the approximate stoichiometry of Ca10-x(PO4)5.62+y(GeO3)0.38(OH)2-z. Germanates replaced the phosphates of stoichiometric HAp and induced the expansion of the HAp lattice both along the screw axis of the calcium ion hexagons and in the direction parallel to the basal plane. Simultaneously, the larger size and the triple valency of the germanate ion as compared to the smaller and trivalent phosphates prompted the bond distortion and charge compensation through defect formation, which reduced the crystallinity and increased the microstrain of the HAp lattice. Vibrational spectroscopic analyses corroborated these crystallographic effects by demonstrating the enhanced heterogeneity of the environments surrounding the active modes after germanate ions were incorporated into HAp. Conforming to La Châtelier's principle, this reduction of the crystallographic order increased the capacity of the material for integration of adventitious carbonates. However, the inclusion of germanate ions induced a partial shift of these carbonates to the hydroxyl channel sites, thus decreasing the ratio of the B-type carbonation to the A-type carbonation. Introduced into HAp, germanium acted as a superb regulator of the particle size and morphology, enhancing their fineness and uniformity. Inclusion of germanate ions also increased the electrophoretic mobility and hydrodynamic surface charge density of the particles by reducing their size and by inducing a more stochastic distribution of terminal ionic groups due to the bending of the crystal facets. Overall, the doping of HAp with germanate ions facilitated the production of narrowly dispersed nanorods with a moderately enhanced structural disorder and with a pronounced potential for the biomedical niche. © 2022 The Author(s)

The unveiling of MOF growth mechanism is hampered by the lack of fundamental knowledge about the very early stage of nucleation, especially the form and ratio of molecular species in the solution for crystal growth. Herein, we report the detection of growth species for a series of MOFs with mono-linker, Cu-MOF-2-BDC and Cu-MOF-2-NDC, and two linkers, MTV-MOF-2-(C4H4)x, by high resolution ESI-MS, where a large variety of Cu-containing species are identified unambiguously. The solvent molecules such as H2O, methanol and DMF participate in the formation of these species, other than ethanol. Furthermore, in the growth solution of MTV-MOF-2-(C4H4)x, growth species containing two different organic linkers are observed. The feeding ratio is not the only factor controlling the distribution of growth species for MTV-MOFs, but also the solvent involves in coordination, an aspect usually overlooked previously.

Air moisture is the key issue for perovskites which invades the films and accelerates the damage of devices. Here, polyvinylpyrrolidone (PVP) is introduced to the methylammonium lead iodide (MAPbI3) perovskite precursor to control crystal growth and endow the devices with self-healing ability in a moisture environment. The strong C=Ο⋅⋅⋅Η−Ν hydrogen bonding interactions between PVP and MAPbI3 was confirmed by nuclear magnetic resonance measurements. By introducing hydrogen bonding in the MAPbI3-based PSCs, we form a compact perovskite film of excellent electronic quality with a power conversion efficiency (PCE) of up to 20.32%. Furthermore, the Ο⋅⋅⋅Η−Ν hydrogen bonding interactions at the grain boundaries suppress the decomposition of methylammonium cations and improve the recyclable dissolution-recrystallization of perovskite. As a result, the MAPbI3-PVP based cells exhibited striking moisture stability and self-healing behavior, with negligible decay in efficiency after 500 h of operation in high humidity (65±5% relative humidity) and rapid recovering ability after their removal from the humid environment.

The phase composition and heat conductivity of (ZrO2)0.9(R2O3)0.1 solid solution single crystals have been studied, where R = (Gd, Yb, Sc, Y), (ZrO2)0.9(Sc2O3)0.09(Gd2O3)0.01 and (ZrO2)0.9(Sc2O3)0.09(Yb2O3)0.01. Single crystals have been grown by directional melt crystallization in a cold skull. The phase composition of the crystals has been studied using X-ray diffraction and Raman spectroscopy. The heat conductivity of the crystals has been studied using the absolute steady-state technique of longitudinal heat flow in the 50–300 K range. We show that at a total stabilizing oxide concentration of 10 mol.% the phase composition of the crystals depends on the ionic radius of the stabilizing cation. The (ZrO2)0.9(Sc2O3)0.1 crystals have the lowest heat conductivity in the 50–300 K range while the (ZrO2)0.9(Gd2O3)0.1 solid solutions have the lowest heat conductivity at 300 K. Analysis of the experimental data suggests that the heat conductivity of the crystals depends mainly on the phase composition and ionic radius of the stabilizing cation. Phonon scattering caused by the difference in the weight of the co-doping oxide cation has a smaller effect on the heat conductivity.

Crystallographic analysis of scanning electron microscopy images of small micron-sized single crystals of b.c.c. iron found on the surface of the Moon shows that the deltoidal icositetrahedron faceting behaviour clearly seen is best describable as being from planes of the {229} form. While possibly unexpected given the lack of any report of such faceting in terrestrial and meteoritic b.c.c. iron single crystals, this deltoidal icositetrahedron faceting behaviour can be rationalised straightforwardly in terms of the local chemical conditions which will have been experienced by these crystals while growing from the vapour in the part of the lunar environment from which these samples were obtained.

The first part of this study investigates synthesis protocols to tune the size and the morphology of zeolite L (LTL) crystals using three different glycols. The outcomes clearly demonstrate that the formation of pure LTL phase is greatly facilitated at 150 ºC for 6 days only when using triethylene glycol (TEG) as the co-solvent, verified by powder X-ray diffraction (PXRD). SEM images show that LTL crystals present a cylinder-like structure with an aspect ratio of one. The formation of pure LTL phase is dramatically deteriorated when the synthesis conditions are changed to higher temperature (180 ºC), various synthesis durations (1-3 days) and aging time, and using other co-solvents (ethylene glycol and diethylene glycol). Inspired by published results indicating the interactions between Ge and glycols, I developed three synthesis approaches exploring the feasibility of incorporating germanium (Ge) into LTL framework using TEG in the second part of this study. Moreover, studies report that the incorporation of Ge in zeolite frameworks can enhance zeolites’ catalytic performances. The results from my investigation show that highly crystalline and well-defined LTL crystals are attained at 150 ºC for 3 days. X-ray fluorescence (XRF) shows the presence of Ge in LTL samples, indicating that the incorporation of Ge is very promising using the developed synthesis approaches. The outcomes are expected to be very useful to other researchers in the zeolites research field.

Academy of Finland project (GoldTail (319691) BW) and EARMetal (339979, ML, KY) are greatly acknowledged for funding this research. The RawMatTERS Finland Infrastructure (RAMI) funded by the Academy of Finland and based at Aalto University is also acknowledged. In addition, Zulin Wang would like to acknowledge the financial support from the Chinese Scholarship Council (CSC). The authors would also like to thank Min Chen for his valuable suggestion and discussion. This study investigates the sustainable preparation of Ag/Zn alloys from a simulated zinc process solution (20 ppm Ag, 65 g/L Zn, and 10 g/L H2SO4) via electrodeposition-redox replacement (EDRR) and the electrochemical dealloying behavior of the Ag/Zn alloys. Results indicate that Ag/Zn deposits with diverse compositions and microstructures can be obtained at room temperature without any complexing agents, simply by varying EDRR parameters like deposition time, deposition potential, and redox replacement time. Two types of Ag/Zn intermetallics (Zn0.96Ag0.04 and Ag0.76Zn0.24) were identified by the combination of X-ray diffraction (XRD) and anodic linear sweep voltammetry. Mass-transfer limitations have significant effects on the growth process, and a nucleation-growth mechanism from Ag/Zn particles into dendrites with increased EDRR cycles is introduced: with EDRR parameters favoring mass-transfer limitations (higher overpotentials, longer deposition times, and shorter redox replacement times), a more dendritic morphology of Ag/Zn alloys is achieved. The selective dissolution of Zn (i.e. dealloying) allowed the formation of silver-rich surfaces with an enhanced surface plasmon resonance behavior, which can be readily tuned by EDRR and dealloying parameters. These results highlight the significant potential of the EDRR-dealloying route to produce different types of Ag/Zn alloys and optically functional materials directly from base metal process solutions.

Two-dimensional (2D)/quasi-2D perovskite solar cells (PSCs) incorporating organic spacer cations exhibit appealing ambient stability in comparison with their 3D analogs. Most reported organic spacer cations are based on ammonium, whereas formamidinium (FA+) has been seldom applied despite that FA has been extensively used in high-efficiency 3D PSCs. Herein, a novel FA-based organic spacer cation, 4-chloro-phenylformamidinium (CPFA+), is applied in quasi-2D Ruddlesden-Popper (RP) PSCs for the first time, and methylammonium chloride (MACl) is employed to promote crystal growth and orientation of perovskite film, resulting in high power conversion efficiency (PCE) with improved stability. Upon incorporating CPFA+ organic spacer cation and MACl additive, high-quality quasi-2D CPFA2MAn−1Pbn(I0.857Cl0.143)3n+1 (n = 9) perovskite film forms, exhibiting improved crystal orientation, reduced trap state density, prolonged carrier lifetime and optimized energy level alignment. Consequently, the CPFA2MAn−1Pbn(I0.857Cl0.143)3n+1 (n = 9) quasi-2D RP PSC devices deliver a highest PCE of 14.78%. Moreover, the un-encapsulated CPFA-based quasi-2D RP PSC devices maintain ∼ 80% of its original PCE after exceeding 2000 h storage under ambient condition, whereas the 3D MAPbI3 counterparts retain only ∼ 45% of its original PCE. Thus, the ambient stability of quasi-2D RP PSC devices is improved obviously relative to its 3D MAPbI3 counterpart.

The Mg-4.58Gd-0.45Y-0.01Er alloys with different volume fractions of columnar crystals in hard orientation (orientation factor of 〈a〉 basal plane slip system is less than 0.2) were prepared by changing the pulling rate to regulate the crystal growth orientation. Tensile tests were performed on the Mg-4.58Gd-0.45Y-0.01Er alloy at room temperature, and the structure after deformation was investigated by electron backscatter diffraction (EBSD). Subsequently, the strengthening mechanism of columnar crystals in hard orientation was explored. The results show if orientation factors of 〈a〉 basal plane slip system of columnar crystals are all greater than 0.4 (soft orientation), the alloy has low yield strength σs (64 MPa), but great work hardening ability, and ultimate tensile strength σb and elongation δ are 114 MPa and 37.3%, respectively. If orientation factors of 〈a〉 basal plane slip system of columnar crystals are all less than 0.2 (hard orientation), the alloy has high strength (σs, 125 MPa), but poor plasticity (δ, 6.32%). If the “hard orientation” and the “soft orientation” columnar crystals are arranged alternately along the direction perpendicular to the crystal growth, the alloy has both superior strength (σs, 102 MPa) and excellent plasticity (δ, 22.5%) at room temperature. The improved comprehensive mechanical property can be attributed to two factors. On the one hand, the “hard orientation” columnar crystals can prevent the “soft orientation” crystals deforming, so the strength is improved. On the other hand, the “hard orientation” columnar crystals themselves can withstand a certain amount of deformation to retain appropriate plasticity.

The MnO2@ZIF-8 core–shell nanoparticles for highly efficient dye degradation have been synthesized with a green method. ZIF-8 crystals with controlled morphology and size are first synthesized by using peptide to modulate the crystal growth. MnO2 is then coated on ZIF-8 via in situ reaction. The surface MnO2 density can be controlled by the dosage of KMnO4. The MnO2@ZIF-8 nanoparticles work as photocatalyst to degrade rhodamine B in a Fenton-like process, giving a degradation ratio of > 96.0%. The degradation kinetics comply well with the Pseudo-second-order model and the experimental equilibrium data meet the Langmuir model best. The specific hierarchical structure of MnO2@ZIF-8 assures a synergistic enhancement of the catalytic degradation performance from several aspects. First, anchoring of the MnO2 nanoparticles on ZIF-8 allows their well disperse to provide more active surface area. Second, highly porous ZIF-8 can adsorb dye molecules to accumulate them at the surface reactive sites. Third, the MnO2/ZIF-8 nano-heterojunctions enhance charge carrier transfer and accelerate the production of free oxidative radicals. The study demonstrates a green method for fabrication of hierarchical hybrid structures, paving the way for designing novel photocatalysts with potential applications for wastewater treatment.

A liquid carbon-rich SiAlCN precursor is facilely synthetized by hydrosilylation between liquid polyaluminocarbosilane (LPACS) and 1,3,5,7-tetravinyl- 1,3,5,7-tetramethylcyclotetrasilazane {[CH3(CH2 CH2)SiNH]4} (TeVSZ). The structural evolution during the polymer-ceramic conversion process is investigated by various methods. The results show that the main cured mechanism is β-addition on hydrosilylation, although α-addition on hydrosilylation, polymerization of vinyl groups and dehydrocoupling reaction between N–H bonds also occur during the cured process. During the pyrolysis process, dehydrogenation and dehydrocarbonation condensation reactions, transamination reactions occur, leading to formation of a three-dimensional network inorganic structure at 400–800 °C, where part of Al–O bonds convert to Al–N bonds. Then the network inorganic structure undergoes demixing and separation into amorphous SiAlCN(O) phase, where the amorphous turbostratic free carbon phase also form at 800–1200 °C. With demixing and decomposition of the amorphous carbon-rich SiAlCN(O) phase, the crystalline β-SiC and graphitic carbon start to form at about 1400 °C, the crystalline sizes of them both enlarge with increasing temperature. However, the crystal growth of β-SiC is distinctly inhibited due to existence of the rich carbon phase, tiny amounts of Al2O3 and AlN. In addition, a small amount of AlN can promote the formation of α-SiC at 1800 °C.

Cirrus clouds related to transported dust layers were identified on 22 occasions with ground-based polarization lidar from December 2012 to February 2018 over Wuhan (30.5°N, 114.4°E), China. All the events occurred in spring and winter. Cirrus clouds were mostly located above 7.6 km on top of the aloft dust layers. In-cloud relative humidity with respect to ice (RHi) parameters derived from water vapor Raman lidar and from ERA5 reanalysis data were used as criteria to determine the possible ice nucleation regimes. Corresponding to the two typical cases shown, the observed events can be classified into two categories: (1) category A (3 cases), in-cloud peak RHi ≥ 150%, indicating competition between heterogeneous nucleation and homogeneous nucleation; and (2) category B (19 cases), in-cloud peak RHi < 150%, revealing that only heterogeneous nucleation was involved. Heterogeneous nucleation generally took place during cirrus cloud formations in the upper troposphere when advected dust particles were present. Although accompanying low cloud-top temperatures ranging from -51.9 to -30.4°C, dust-related heterogeneous nucleation could contributed to primary ice nucleation in cirrus clouds by providing ice nucleating particle concentrations of 10-3 to 102 L-1. Heterogeneous nucleation and subsequent crystal growth reduced the ambient RHi to be less than 150% by consuming water vapor and thus even completely inhibited homogeneous nucleation.

In this contribution, tracking control designs using output feedback are presented for a two-phase Stefan problem (SP) arising in the modeling of the vertical gradient freeze process. The two-phase SP, consisting of two coupled free boundary problems, is a vital part of many crystal growth processes due to the temporally varying spatial extent of the solid and liquid domains during growth. After discussing the special needs of the process, collocated and flatness-based state feedback designs are carried out. The quality of the provided approximations and the performance and robustness against parameter uncertainties of the open- and closed-loop control setups are analyzed in several simulations.

Piezo-/ferroelectrics are essential materials for electromechanical sensors and actuators and energy harvesters in a wide range of technological applications. The demand for piezo-/ferroelectric materials with high Curie temperature (TC) arises from numerous emerging applications such as downhole oil and gas explorations, automobiles, petrochemistry, metallurgy, and nuclear energy and aerospace industries, in which the electromechanical devices have to operate at elevated temperatures. However, it is a long-standing challenge to simultaneously obtain high piezoelectricity and high TC. Recently, significant progress has been made on bismuth-based piezo-/ferroelectric single crystals (BPSCs) which show excellent piezoelectric performance and high TC, proving to be a promising family of novel materials for high-temperature electromechanical applications. In this highlight, we review the recent progress in BPSCs with focus on materials design, crystal growth, physical properties, crystal chemistry, and complex domain structures. In addition, the future perspectives of BPSCs are discussed.

Perovskite solar cells (PSC) capable of open-circuit voltage (VOC) over 1.5 V was fabricated based on a formamidinium lead-bromide (FAPbBr3) perovskite absorber film prepared by sequential deposition procedure using dimethylsulfoxide (DMSO) and tetramethylenesulfoxide (TMSO) mixed solvent. A PbBr2 film formed from a precursor PbBr2 solution with the DMSO–TMSO mixed solvent was reacted with FABr to convert into FAPbBr3 film. The mixed solvent-based PbBr2 film exhibits as an amorphous-like phase containing a PbBr2–TMSO complex, which led to formation of an FAPbBr3 film possessing high crystallinity and uniform thick absorber layer compared with the pristine PbBr2 film prepared by pure DMSO solvent. With a bandgap of 2.1 eV, FAPbBr3-based PSCs prepared by the solution process with PbBr2–TMSO complex exhibited high VOC up to 1.55 V and power conversion efficiency of 7.8% on the device fabrication using a Li-treated mesoporous TiO2 as electron transport layer with 5 x 5 mm2 cell active area.

The influence of alkali metals (Na, K, Cs, Li and Rb) doping on the properties and crystal growth of tris(thiourea)zinc(II)sulphate crystals by slow evaporation solution growth technique at 30 °C has been investigated. Each metals as dopant incorporate into the crystal lattice even at its low concentrations is well confirmed by energy dispersive X – ray spectroscopy (EDS). In the powder X –ray diffraction (XRD), high intense peaks are observed for all doped specimens due to stress developed in the crystal because of doping when compared to pure one. Single crystal XRD reveals a nominal increase in the cell parameter values of the doped samples compared to pure. Presence of each alkali metal quantitatively is confirmed by inductively coupled plasma (ICP) technique. It is interesting to observe the enhancement of fluorescence intensity of pure ZTS by the dopant in the photoluminescence (PL) spectra. The grown crystals are also characterized by FT-IR, UV-V is and TG/DSC methods. The second harmonic generation (SHG) efficiency, an essential character required for the single crystals to identify the non-linear optical (NLO) property, was performed by kurtz powder technique.

We measured barium attachment and detachment fluxes from and to barite crystal surfaces in solutions with [Ba]/[SO4] ratios from 0.06 to 52. The doping of 137Ba in the initial experimental solutions enabled us to measure unidirectional fluxes near solubility equilibrium (Q/K ≈1.0) in batch reactors. Both attachment and detachment fluxes increase with [Ba]/[SO4] ratios. As expected, since the solutions were near solubility equilibrium ( S I ≈ 0.0 n ), the attachment and detachment fluxes were nearly equal. The experimental data can be fit accurately using the Zhang and Nancollas (1998) (ZN98) process-based AB crystal growth model, which describes crystal growth and dissolution through nucleation and propagation of kink sites. Simultaneous fitting step velocity data of Kowacz et al. (2007) significantly reduced the number of non-uniqueness solutions. The remarkable fit implies that barite recrystallization at room temperature near equilibrium and moderate supersaturation occurs via ion-by-ion addition and removal, rather than the formation of amorphous precursors or aggregation of particles. The model is best fit using different detachment frequencies for Ba and SO4, suggesting the ZN98 assumption that detachment frequencies should be the same for the constituent ions does not apply to barite. Based on experimental data and model fitting, Ba attachment and detachment fluxes at a fixed saturation state increase with [Ba]/[SO4] ratios monotonically. This has potentially significant implications for interpreting isotope and trace element cycling in natural environments.

Good quality single crystal of p-fluorobenzyl ammonium dihydrogen phosphate [PFBADP], a compound has been successfully grown from aqueous solution by slow evaporation solution growth method. The crystal system and lattice parameters are confirmed by the single crystal X-Ray diffraction analysis. An optical absorption study on the sample shows that the material is well suitable for optical applications. The functional groups of the compound are confirmed qualitatively by FT-IR spectral analysis. The photoluminescence studies indicate that the grown crystals have a green fluorescence emission. Dielectric studies have been carried out for the grown crystal and the results were discussed in detail.

The main condition for elimination of growth striations is the formation of standing waves in the melt for damping of convection. The formation of standing waves between the crucible bottom and the solid-liquid interface suppresses convection in the melt and eliminates growth striations in single crystals. Growth striations in InSb and GaAs single crystals were eliminated after the ultrasound was switched on at frequencies of 0.65 MHz and 0.15 MHz in their melts with the Rayleigh numbers 0.18×105 and 0.2×105, respectively. The ultrasound intensity was determined from a model experiment with similar conditions to crystal growth using a light cut method. The model experiments demonstrated formation of standing waves above the waveguide with a piezo transducer after switching on the ultrasound that attended appearance of a dome on a liquid surface. The dome dimensions on the liquid surface were used for calculation of the ultrasound intensity. The calculated ultrasound intensity was 0.85 Wcm-2. It was found that the growth striations disappeared a certain time after switching the ultrasound on, which can be explained by the formation time of standing waves and properties of the melt. The time intervals between switching the ultrasound on and the elimination of striations in grown InSb and GaAs single crystals were measured using the experimental images with the striation elimination, and were 10 s and 22 s, respectively. The controlled formation of ultrasonic standing waves in the melt in crystal growth eliminates growth striations, and this technique can be used for the industrial application.

L-Tyrosine Zinc Carbonate (LTZC) a semi-organic nonlinear optical single crystal has been grown by slow evaporation solution technique. The lattice parameters of the grown crystals are found out by single crystals X- ray diffraction technique. The modes of vibrations of different functional groups present were identified by using Fourier Transform Infrared (FTIR) spectroscopic analysis. The UV–Visible optical absorption spectrum shows that the crystal has high transmission with lowest UV cutoff wavelength of 230 nm. The calculated band gap of LTZC crystal was found to be 5.13 eV. Dielectric constant and dielectric loss for various frequencies and temperatures were performed on LTZC crystal and the results were discussed in detail. The frequency dependence of ac conductivity for different temperatures was studied. The photoconductivity studies confirm that the crystal LTZC has negative photo conducting nature. The mechanical and thermal properties of the grown crystals have been studied. Surface morphological changes are observed in the grown LTZC crystal. The Non-linear optical second harmonic generation conversion efficiency of LTZC was determined using Q-switched Nd: YAG laser. The second harmonic generation conversion efficiency of LTZC is 2.12 times that of KDP.

Graphical abstract, Highlights • Nano-silver synthesized via solution evaporation method with octahedral crystal structure and crystallite size of 28 to 39 nm. • Irregular and non-uniform surface morphology. • Different functional on the surface of nano-silver included CH, CH2, OH, alkyne, and an alkyl halide. • Nano-silver synthesized at 70 °C and a dose of 3.0 g/L caused effective inhibition of E. coli., The modulation of antimicrobial properties of nanomaterials can be achieved through various physical and chemical processes, which ultimately affect subsequent properties. In this study, the antibacterial potential of nano-silver was investigated at 0.5, 1.0, 2.0, and 3.0 g/L, and its differential temperature synthesis was achieved at 20, 50, and 70 °C using the solvent evaporation method. Nano-silver particles exhibited FCC (octahedral) crystalline structure with crystallite sizes ranging between 28 and 39 nm calculated using XRD analysis. Moreover, irregular and non-uniform surface morphology was evident from SEM micrographs. The UV–Vis absorbance spectrum of nano-silver exhibited wave maxima at 433 nm, while the FTIR analysis depicted different modes of vibration indicating the CH, OH, C≡C, C-Cl, and CH2 functional groups attached to the surface. Lastly, nano-silver caused prominent inhibition (12.5 mm) in the Escherichia coli growth, particularly at 70 °C synthesis temperature and 3.0 g/L dose. It is concluded that both the nano-silver crystal growth temperature and dose contributed substantially to bacterial growth inhibition linked with subsequent size, shape-dependent properties.

The effects of pH of the reaction solution and the concentration of phosphoric acid on the crystal growth behavior of LaPO4 crystallites were investigated and the mechanical properties of rare-earth phosphates were compared. As a result, the concentration of phosphoric acid of 10% was beneficial to the crystal growth of LaPO4 nanocrystalline. When the pH value of the reaction solution was 2, the size of LaPO4 crystallites increased gradually with the increasing reaction temperature, and the smallest crystallite size of 43.27 nm was obtained after heat-treatment at 1000 °C. Simultaneously, the activation energy for crystal growth of LaPO4 nanocrystalline was relatively lower (26.82 kJ mol−1). With the decreasing radii of rare-earth ions, the hardness, Young's modulus and fracture toughness of the bulk rare-earth phosphates exhibited a reduced tendency, resulted from the increase of porosity under the same preparation process.

Crystal growth promotion for CuGaSe2 (CGSe) photovoltaic absorber by silver (Ag)-addition is demonstrated, enhancing device performance for wide-gap CGSe solar cells. By introducing Ag precursor, the grain size in the polycrystalline CGSe films deposited by the three-stage process is increased, and a residual Ga2Se3 phase during the growth is suppressed. Photoluminescence intensity is enhanced with Ag-addition, indicating reduced non-radiative recombination, which is related to the suppression of Ga2Se3 phase and reduction of undesirable deep defect levels. For the Ag-alloyed CGSe solar cells, Urbach energy defined from the sub-gap tail in exponential external quantum efficiency is monotonically reduced from 25.5 to 21.1 meV, suggesting the improvement of CGSe bulk quality by Ag-alloying. Open-circuit voltage is enhanced since carrier recombination in Ag-alloyed CGSe bulk is suppressed. Short-circuit current density is also enhanced as carrier collection efficiency is improved by widened depletion width due to the reduction of carrier concentration by Ag-alloying. On the other hand, excess Ag-addition leads to increased series resistance and deterioration of the built-in potential in the solar cells due to the reduced carrier concentration in the Ag-alloyed CGSe absorber. Finally, the conversion efficiency is maximized to 5.3% at [Ag] / ([Ag] + [Cu]) ratio of 0.07 for the Ag-alloyed CGSe solar cells. These findings will help the performance enhancement for the wide-gap CGSe solar cells.

To elucidate the crystal growth process of hematite in high-temperature lead-free multicomponent alkali borosilicate glass, which is essentially important to control the color of red overglaze enamels, frit and hematite mixture is heat-treated and subjected to microscopic observations. Hematite particles slightly grew due to sintering at low temperature. Once the glass matrix formed near the softening point of frit, hematite dissolved into glass fluid. Hematite crystal growth concomitantly ensued with decrease in the number of hematite particles via Ostwald ripening as the temperature increased. The grown particles exhibited an anisotropic morphology with straight outlines reflecting crystal planes, the morphology of which is completely different from those grown by sintering and particles prior to heating. These results suggest that comprehensive understanding of frit and hematite from the perspectives of glass science and chemistry as well as powder technology are important to truly control the color of red overglaze enamels.

In this study, various concentrations of the large-sized cation iodide, namely, phenylethylammonium iodide (PEAI), incorporated in lead iodide (PbI2) solid films react with heated methylammonium io...

Mechanisms of growth and dissociation, growth rates, and morphology of gas hydrates of methane, carbon dioxide, and two CH4:CO2 mixtures (80:20 and 30:70 nominal concentration) were studied using using high resolution images and very precise temperature control. Subcooling and a recently proposed mass transfer-based driving force were used to analyze the results. When crystal growth rates did not exceed 0.01 mm/s, all systems showed faceted, euhedral crystal habits at low driving forces. At higher driving forces and growth rates, morphologies were different for all systems. These results solve apparent contradictions in literature about the morphology of hydrates of methane, carbon dioxide, and their mixtures. Differences in the growth mechanism of methane-rich and carbon dioxide-rich hydrates were elucidated. It was also shown that hydrate growth of methane, carbon dioxide, and their mixtures proceed via partial dissociation of the growing crystal. Temperature gradients were used to dissociate hydrates at specific locations, which revealed a most interesting phenomenon: On dissociation, carbon dioxide-rich hydrates propagated onto the bare substrate while drawing water from the opposite side of the sample. Furthermore, it was shown that an abrupt change in morphology common to all systems could be correlated to a change in the slope of growth rate data. This change in morphology was explained by a shift in the crystal growth mechanism.

The hydrothermal reaction has been applied popularly to prepare special nano-/micro-morphology materials with the typical characterized of low cost and high yield. Nevertheless, it is difficult to control the morphology and scale of crystal growth purely by the necessary reactants and simply changing the reaction conditions. This paper investigated the one-step hydrothermal method to prepare MoS2 by adjusting the crucial factors of temperature as well as surfactant content. In the deficiency of surfactant, MoS2 powders grew in two ways: deposition as microsphere and longitudinally into nanorods. As the temperature rising, the layer-by-layer order of product should be better, but the transverse growth was intense and the layer thickness was further thickening. Inversely, uniform and individual spherical micro-flowers of MoS2 can be modulated by the surfactant, which expanded available surface active sites and relieved large internal stress during cycling. Moreover, to further improve its performance, carbon recombination is essential in a variety of strategies.

Deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals are key materials in creating tunable deep-UV lasers for frequency conversion technology. However, practical application of the sole usable crystal, KBe2 BO3 F2 , has been hindered by the high toxicity of beryllium and its layering tendency in crystal growth. Herein, we report a beryllium-free deep-UV NLO material NaSr3 (OH)(B9 O16 )[B(OH)4 ] (NSBOH), synthesized by a covalent bond modification strategy under hydrothermal conditions. Moisture-stable NSBOH exhibits strong second-harmonic generation (SHG) at 1064 nm (3.3 × KH2 PO4 ) and 532 nm (0.55 × β-BaB2 O4 ), both amongst the largest powder SHG responses for a deep-UV borate, with good phase-matchability and a short wavelength cutoff edge (below 190 nm). NSBOH possesses a 3D covalent anionic [B9 O19 ]∞ honeycomb-like framework with no layering. The Sr2+ and Na+ ions, residing in the cavities of the anionic framework, act as templates for the assembly and favorable alignment of NLO-active groups, resulting in an optimal balance between strong SHG activities and wide UV transparency. These merits indicate NSBOH is a very attractive candidate for deep-UV NLO applications.

Crystallization often proceeds in media with rich chemical compositions. In pursuit of insight into how foreign compounds interact with the structures and dynamics that comprise crystal growth, we ...

This article considers the hydrodynamic problem of an oblique flow of a viscous incompressible fluid around the tip of a dendritic crystal. Approximate analytical solutions of Oseen's hydrodynamic equations are obtained in 2D and 3D cases using special curvilinear coordinates. It is shown that the projections of the fluid velocity change significantly with a change in the flow slope and Reynolds number. The theory developed in this work has a limiting transition to the previously known solutions for the rectilinear (without tilt) fluid flow around a dendrite. © 2021 John Wiley & Sons, Ltd. Russian Foundation for Basic Research, РФФИ: 20-08-00199; Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2020-0057 This work contains two parts, theoretical and numerical. The first of them was supported by the Russian Foundation for Basic Research (project no. 20-08-00199). The second part was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FEUZ-2020-0057).

Pure and sodium-containing lanthanum oxymolybdates were synthesized as polycrystalline samples and single crystals. The compounds have been characterized by several methods including SEM, inductive...

Controlling the crystal growth of perovskites by using additives is one of the effective ways to improve the performance of perovskite solar cells (PSCs). The effect of adding cobalt acetate on the crystal growth of perovskite and the performance of fully screen-printable hole-transport material (HTM)-free mesoporous PSCs with carbon electrode has been investigated. We found that addition of cobalt acetate to the perovskite precursor solution could efficiently increase the perovskite crystal size and improve the crystallinity and light absorption of perovskite films. PSCs fabricated with 4 mg/mL cobalt acetate added achieved the highest device performance, with open-circuit voltage of 0.96 V, short-circuit current density of 23.51 mA cm−2, fill factor of 0.66, and power conversion efficiency of 14.89%. The analysis results suggest that the improved device performance can be attributed to a decrease of nonradiative recombination and an increase of the charge recombination resistance with the addition of cobalt acetate.

Hagihara K., Nakano T.. Control of Anisotropic Crystallographic Texture in Powder Bed Fusion Additive Manufacturing of Metals and Ceramics—A Review. JOM, https://doi.org/10.1007/s11837-021-04966-7., Additive manufacturing (AM) enables the production of complex, net-shape geometries. Additionally, in AM of metal and ceramics, which has received less attention, the microstructure and texture of the product can be arbitrarily controlled by selecting appropriate process parameters, thereby enabling unprecedented superior properties. This paper discusses recent progress pertaining to texture evolution mechanisms and control methods, with an emphasis on selective laser melting. One of the unique characteristics of AM is that the texture can be varied as a function of position within the product by controlling the scan strategy. The transient behavior of the texture and the factor used to control it via the scan strategy are discussed. In addition, the texture evolution behavior of face- and body-centered cubic as well as noncubic materials is discussed. The importance of the crystallographic “multiplicity” of the preferential crystal growth direction is described to understand the evolution behavior of the texture in such materials.

Atomically precise Ag nanoclusters provide an ideal platform to correlate the structure and electrocatalytic performance at the atomic level. Herein, we report the fabrication of homoleptic alkynyl-protected Ag15(C≡CtBu)12+ (abbreviated as Ag15) nanocluster and its electrocatalytic properties toward CO2 reduction reaction. Crystal structure analysis reveals that, Ag15 possesses a body-centered-cubic (BCC) structure with an Ag@Ag8@Ag6 metal core configuration. Interestingly, we found that, Ag15 can adsorb CO2 in air and spontaneously self-assembled into one-dimensional linear material during the crystal growth process. Furthermore, Ag15 can convert CO2 into CO with a faradaic efficiency of ~95.0% at -0.6 V and a maximal turnover frequency of 6.37 s-1 at -1.1 V along with excellent long-term stability. Finally, density functional theory calculations disclosed that, Ag15(C≡CtBu)11+ with one alkynyl ligand stripping off from the intact cluster can expose the uncoordinated Ag atom as the catalytically active site for CO formation.

Penta-twinned metal nanowires are finding widespread application in existing and emerging technologies. However, little is known about their growth mechanisms. We probe the origins of chloride- and alkylamine-mediated, solution-phase growth of penta-twinned Cu nanowires from first-principles using multiscale theory. Using quantum density functional theory (DFT) calculations, we characterize the binding and surface diffusion of Cu atoms on chlorine-covered Cu(100) and Cu(111) surfaces. We find stronger binding and slower diffusion of Cu atoms on chlorinated Cu(111) than on chlorinated Cu(100), which is a reversal of the trend for bare Cu surfaces. We also probe interfacet diffusion and find that this proceeds faster from Cu(100) to Cu(111) than the reverse. Using the DFT rates for hopping between individual sites at Ångstrom scales, we calculate coarse-grained, interfacet rates for nanowires of various lengths─up to hundreds of micrometers─and diameters in the 10 nm range. We predict nanowires with aspect ratios of ∼100, based on surface diffusion alone. We also account for the influence of a self-assembled alkylamine layer that covers most of the {100} facets, but is absent or thin and disordered on the {111} facets and in an "end zone" near the {100}/{111} boundary. With an end zone, we predict a wide range of nanowire aspect ratios in the experimental ranges. Our work reveals the mechanisms by which a halide─chloride─promotes the growth of high-aspect-ratio nanowires.

With the increased demand for controlled deterministic growth of III–V semiconductors at the nanoscale, the impact and interest of understanding defect formation and crystal structure switching becomes increasingly important. Vapor–liquid–solid (VLS) growth of semiconductor nanocrystals is an important mechanism for controlling and studying the formation of individual crystal layers and stacking defects. Using in situ studies, combining atomic resolution of transmission electron microscopy and controlled VLS crystal growth using metal organic chemical vapor deposition, we investigate the simplest achievable change in atomic layer stacking–single twinned layers formed in GaAs. Using Au-assisted GaAs nanowires of various diameters, we study the formation of individual layers with atomic resolution to reveal the growth difference in forming a twin defect. We determine that the formation of a twinned layer occurs significantly more slowly than that of a normal crystal layer. To understand this, we conduct thermodynamic modeling and determine that the propagation of a twin is limited by the energy cost of forming the twin interface. Finally, we determine that the slower propagation of twinned layers increases the probability of additional layers nucleating, such that multiple layers grow simultaneously. This observation challenges the current understanding that continuous uniform epitaxial growth, especially in the case of liquid-metal assisted nanowires, proceeds one single layer at a time and that its progression is limited by the nucleation rate.

In the last decade, organic-inorganic perovskite solar cells (PSCs) have had tremendous success, raising their power conversion efficiency from 3.8% in 2009(T, A, K, & Y, 2009) to >25.6% (Li et al., 2021). Perovskite material is newly emergent, third-generation solar cells, it generally refers to any composite that has structure like that of calcium titanium oxide (CaTiO2). It has a general formula ABX­3, where A refers to an organic compound, B is an inorganic and X represents the halides. In this research, a Hybrid-Formamidinium Bismuth Bromide Perovskite solar cell (FABi2Br9) was synthesized via a novel crystal growth process and subjected to characterization for determining its optoelectronic properties for solar cells application. The x-ray diffraction (XDR) results revealed the crystal hexagonal structure of FABi2Br9, the crystal sizes were obtained and it gives an excellent size (74nm) for light absorption material. The bandgap was determined using ultraviolet-visible spectroscopy (U.V vis) which was found to be 1.80eV which is within the required range for an absorbing layer in a solar cell architecture. Nuclear magnetic resonance (NMR) and was used to identify the organic content purity of the composite. In conclusion, FABi2Br9 was found to be pure with excellent optoelectronics properties that can readily be used as an absorbent layer in perovskite solar cells architecture

Halide perovskite single crystals (HPSCs) provide a unique platform to study the optoelectronic properties of such emerging semiconductor materials, while the temperature induced crystal growth method often has an increased solute integration speed and/or unavoidable solute consumption, resulting in a soaring or slumping crystal growth rate of HPSCs. Here, we developed a universal and facile solvent-volatilization-limited-growth (SVG) strategy to finely control the crystal growth rate by the fine-control-valve for high quality crystal grown through solution processes. The grown HPSCs by SVG method exhibited a record low trap density of 2.8 × 108 cm−3 and a high charge carrier mobility-lifetime product (μτ product) of 0.021 cm2/V, indicating the excellent crystal quality. The crystal surface defects were further passivated by oxygen suppliers as Lewis base, which led to a reduction of surface leakage current by two times when using for low dose rate X-ray detection. Such HPSC X-ray detector displayed a high sensitivity of 1274 µC/(Gyair cm2) with a lowest detectable dose rate of 0.56 μGyair/s under 120 keV hard X-ray. Further applications including alloy composition analysis and metal flaw detection by HPSC detectors were also demonstrated, which not only shows the bright future for product quality inspection and non-destructive materials analysis, but also paves the way for growing high quality single crystals and fabricating polycrystalline films.

An active pharmaceutical ingredient is currently produced in a traditional batch antisolvent crystallization process. Although well-established, this process lacks flexibility to control the crystal size distribution (CSD). Therefore, a new process was developed to enable the control of the CSD according to different specifications. This new process was implemented in continuous in a planar oscillatory flow crystallizer (planar-OFC). In this work, the main goal was to enable the production of small crystals to meet very specific formulation requirements and, simultaneously, promote the aggregation of these small particles to optimize the filtration operation. First, the operating conditions were optimized for continuous operation. Then, the planar-OFC was divided into two spatially independent sections, the nucleation zone (where nucleation is dominant) and the crystal growth zone (where crystal growth is dominant), so as to control the CSD as a function of the residence time in each zone. In particular, the formation of aggregates could be promoted by increasing the residence time in the nucleation zone. Ultimately, the planar-OFC was able to produce smaller particles with significantly narrower CSDs than the traditional batch process. This is particularly important when small particle sizes are required, thus reducing manufacturing time and operating costs.

In this work, three Nitrogen-functionalized graphene (NGs): amino-graphene (G-NH2), graphene-ethanolamine (G-EA), and graphene ethylenediamine (G-EDA) have been synthesized and tested as hole transport layers (HTL) for perovskite solar cells (PSCs) applications. Among the evaluated graphene-based derivatives, the PSCs fabricated with graphene-ethylenediamine (G-EDA) showed best power conversion efficiency of 12.9%. The enhanced PCE of G-EDA based PSCs as compared to other NGs are attributed to the uniform coverage, faster hole transportation, and a template for larger perovskite crystal growth. Moreover, the PCE of the PSCs fabricated with G-EA and G-EDA based HTLs remain stable even after 200 h of light-soaking.

Bi3+/Te4+ co-doped Cs2SnCl6 with dual emission spectrum (i.e., 450 and 575 nm) was achieved by a modified solution method, which can overcome the phase separation in the previous method for Cs2SnCl6 crystal growth. The two emission peaks arising from the two dopants Bi3+ and Te4+ have distinct photoluminescence (PL) lifetimes. Thus, the control of dopant ratio or PL delay time will regulate the PL intensity ratio between 450 and 575 nm peaks leading to adjustable emission color. The energy transfer between the two emission centers, which is confirmed by the optical spectra and PL lifetime, has a critical distance around 7.8 nm with a maximum of 50% transfer efficiency. The Bi3+/Te4+ co-doped Cs2SnCl6 with superior stability in water and aqua regia was fabricated into a single-phase white light-emitting diode. In the meantime, various luminescent heterostructures were obtained by epitaxial Cs2SnCl6 crystal growth with different dopants, which can broaden the study of composition engineering in halide perovskites.

This paper is devoted to the mathematical modeling of a combined effect of directional and bulk crystallization in a phase transition layer with allowance for nucleation and evolution of newly born particles. We consider two models with and without fluctuations in crystal growth velocities, which are analytically solved using the saddle-point technique. The particle-size distribution function, solid-phase fraction in a supercooled two-phase layer, its thickness and permeability, solidification velocity, and desupercooling kinetics are defined. This solution enables us to characterize the mushy layer composition. We show that the region adjacent to the liquid phase is almost free of crystals and has a constant temperature gradient. Crystals undergo intense growth leading to fast mushy layer desupercooling in the middle of a two-phase region. The mushy region adjacent to the solid material is filled with the growing solid-phase structures and is almost desupercooled. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons, Ltd. Russian Science Foundation, RSF: 21-79-10012 The authors gratefully acknowledge financial support from the Russian Science Foundation (project no. 21-79-10012). Open Access funding enabled and organized by Projekt DEAL.

The growth of α-glycine crystals from aqueous solution is investigated at constant supersaturations by utilizing the constant chemical potential molecular dynamics method. The study considers two faces (010) and (011) that predominantly determine the α-glycine crystal morphology. The general Amber force field (GAFF) with two different charge sets derived from semi-empirical calculations using the complete neglect of differential overlap method (CNDO) and from density functional calculations using the double-numerical plus d- and p-polarization basis set (DNP) is applied to describe α-glycine. The extended simple point charge model is used to simulate water. It is observed that the GAFF/DNP set leads to a much slower integration of glycine molecules into the crystal structure than the GAFF/CNDO set. The GAFF/CNDO set, however, causes the growth even at concentrations well below the experimental solubility. For the GAFF/DNP set, the influence of potassium chloride (KCl) and sodium chloride (NaCl) on the face growth rates is investigated. The parameters recently proposed by Yagasaki et al. [J. Chem. Theory Comput.2020,16, 2460-2473] are used to describe salt ions, as standard GAFF parameters lead to the unexpected formation of salt clusters at a concentration lower than the experimental solubility value. According to our simulation results, both salts suppress the growth of the (011) and (010) faces. The inhibiting effect of NaCl is much stronger than that of KCl for the (011) face, while both salts have a similar inhibiting effect on the (010) face. The results are in line with the experimental observations of the impact of salt ions on the α-glycine growth rates for the (011) face reported in literature.

Crystallization of lysozyme is investigated upon rapid cooling to 4°C of undersaturated solutions equilibrated at temperatures in the range 30°C–44°C, and for incubation times varying from 12 to 36...

Surface-enhanced Raman scattering (SERS) provides a novel method for low concentration molecular detection. The performances were highly dependent on the sizes, geometries and distributions of metal nanostructures. Here, highly sensitive SERS fiber probe based on silver nanocubes (Ag NCs) was fabricated, by assembled nanostructures on planar and tapered fiber tips. Ag NCs were synthesized by polyol method, and controlled by reductant content, reaction temperatures and crystal growth durations. Tapered fibers with different cone angles were prepared by chemical etching. The electromagnetic distribution simulation indicated that nanocubes had stronger electric field between two cubes and vertex corners than nanosphere, under 532 nm laser excitation. The intensity could reach 53.52 V/m, for cubes with 70 nm edge length. The SERS performance of probes was characterized using crystal violet analyte. The detectable lowest concentration could reach 10–9 and 10–10 M for planar and tapered fiber probes, respectively. The corresponding enhancement factor could be 9.02 × 107 and 6.22 × 108. The relationship between SERS peak intensities and analyte concentrations showed well linear, which indicated both fiber probes could be applied for both qualitative and quantitative analysis. Furthermore, optimal cone angle of tapered fiber SERS probe was 8.3°. The tapered fiber SERS probes have highly sensitive activity and great potential in substance detection.