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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)

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.

We report on the high-pressure growth, structural characterization, and investigation of the electronic properties of single-crystalline LaFeAsO co-substituted by Sm and P, in both its normal- and superconducting states. Here, the appearance of superconductivity is attributed to the inner chemical pressure induced by the smaller-size isovalent substituents. X-ray structural refinements show that the partial substitution of La by Sm and As by P in the parent LaFeAsO compound leads to a contraction in both the conducting Fe2(As,P)2 layers and the interlayer spacing. The main parameters of the superconducting state, including the critical temperature, the lower- and upper critical fields, as well as the coherence length, the penetration depth, and their anisotropy, were determined from magnetometry measurements on a single-crystalline La0.87Sm0.13FeAs0.91P0.09O sample. The critical current density (jc), as resulting from loops of magnetization hysteresis in the self-generated magnetic field, is 2 × 106 A/cm2 at 2 K. Overall, our findings illustrate a rare and interesting case of how superconductivity can be induced by co-substitution in the 1111 family. Such approach delineates new possibilities in the creation of superconductors by design, thus stimulating the exploration of related systems under multi-chemical pressure conditions., Journal of Alloys and Compounds, 958, ISSN:0925-8388, ISSN:1873-4669

The crystal growth rate of LiGe2(PO4)3 phase from lithium germanium-phosphate glass was studied. The glass have been homogenized using the previously established temperature-time conditions, which make it possible to remove volatile substances from the glass melt. The atomic absorption spectrophotometry (AAS) was used to determine the chemical content of the obtained glass and scanning electron microscope (SEM) were used to reveal the isothermal process of crystal growth. The crystal growth rates were determined experimentally and theoretically.

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.

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.

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.

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.

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.

Synthetic biphasic bioceramics composed of hydroxyapatite (HA) and other calcium phosphates (CPs) can provide promising efficiency in the treatment of bone defects based on the rapid dissolution of the CPs, to allow its replacement by freshly formed bone, along with the slow resorption of the HA, to preserve the volume of the grafted area. For this purpose, the present study was conducted to prepare nanosized biphasic calcium phosphate (n-BCP) using a facile mechanochemical process. The experimental outputs were also compared to the commercial-grade HA in terms of physicochemical features. The Rietveld refinement was utilized to calculate the phase contents and crystal structures of the composites, including crystallite size, lattice parameters, and unit cell volume. Besides, the atomic arrangement of Ca1, Ca2, PO43−, and OH− groups in the hexagonal crystal structure of HA and triclinic structure of anhydrous dicalcium phosphate (DCPA) was determined. The phase fraction, crystallite size, and the powder density of the biphasic structures, which were derived by Rietveld refinement, were found to be affected by ball-milling. In addition to biphasic structures, a monolithic hexagonal HA with an isotropic crystal growth was formed after 7 h of ball-milling under an argon atmosphere. The in vitro test in a simulated body fluid (SBF) confirmed the bioactivity of the biphasic structure through the formation of a bone-like apatite layer after one week.

A novel type of liquid gating technology has been developed to prepare a polyethylene oxide (PEO) single-crystal film, and the crystal growth was observed via atomic force microscopy. The self-seeding method has been widely used in the preparation of polymer single crystals, but the mechanism through which single polymer crystals are formed via the combination of liquid gating technology and the self-seeding method remains unclear. To elucidate the mechanism of this process, a series of experiments were conducted in which a dilute polymer solution was sprayed onto a mica substrate to form a single-crystal film through liquid gating technology to study the effect of the crystallization time on the morphology of a thiol PEO (mPEO-SH) crystal. Based on this research, it was found that liquid gating helps to prevent twinning during crystal growth. The combination of liquid gating and self-seeding technology thus provides a new strategy for polymer single-crystal growth.

The microstructural development during crystallization firing of a commercially-available dental-grade nanostructured lithia-zirconia glass-ceramic (Vita Suprinity® PC) was unraveled using a wide battery of ex-situ and in-situ characterization techniques. It was found that the milling blocks are slightly crystallized glass-ceramics, with a complex chemical composition and consisting of partially de-polymerized glass plus lithium silicate (Li2SiO3) nanocrystals. It was also found that during crystallization firing the glassy matrix first reacts with part of the Li2SiO3 to form lithium disilicate (Li2Si2O5) at ∼810−820 °C, and then lithium orthophosphate (Li3PO4) precipitates from the glass. This results in glass-ceramics with abundant nanocrystals embedded in a sparse zirconosilicate glass matrix (containing many other cations subsumed) that, due to its high viscosity, inhibited crystal growth. Therefore, these dental glass-ceramics are not reinforced with zirconia (ZrO2) crystals unless over-fired above ∼890 °C and at the expense of its singular nanostructure. Finally, this study opens doors for optimizing the clinical performance of these dental glass-ceramics via microstructural tailoring.

The effect of crystallization of y-Y2Si2O7 (Y-c and Y2S-c2)/Y4.67(SiO4)3O (Y2S-c1) single crystal or simultaneously y-Y2Si2O7, Al6Si2O13 and SiO2 crystals (YMS-c) on the hardness and thermal expansion coefficient (TEC) of Y2O3–Al2O3–SiO2 (YAS) glass is studied. Crystallization activation energy is 591, 650 and 282 kJ/mol for Y, Y2S and YMS glasses, crystallization mechanisms of glasses Y and Y2S (Tc1) are surface crystallization and one-dimensional crystal growth, while YMS glass is two- and one-dimensional growth of crystals. The volume fraction of crystalline phases in Y-c (91.45%), Y2S-c1 (83.00%) and -c2 (92.55%) glass ceramics are larger than that of YMS-c (71.11%), precipitated y-Y2Si2O7 single crystal decrease the TEC ( × 10−6 °C−1/30–1000 °C) of Y and Y2S parent glasses to 3.95 (Y-c) and 5.09 (Y2S-c2) while Y4.67(SiO4)3O single crystal increase the TEC of Y2S-c1 to 7.15, YMS-c has the smallest TEC (3.34) among studied glass ceramics, the enhancing effect of Y4.67(SiO4)3O on the hardness of Y2S glass is more than that of y-Y2Si2O7. Y and YMS glasses could be used as coating, sealing and jointing materials for SiC ceramics used in the high temperature fields.

Here, the effect of the organic conjugated small molecule crystal growth process on the evolution of the crystal morphology and consequent charge transport properties are studied. Evaluations are carried out on a donor-acceptor-donor structured organic small molecule, 7,9-di(thiophen-2-yl)-8Hcyclopenta[a]acenaphthylen-8-one) (DTCPA), which crystallizes in a monoclinic structure. Recrystallization of the DTCPA molecule is carried out by employing four growth methods via solvent evaporation through both concentrated and dilute solutions using a polar solvent, N-methyl-2-pyrrolidone. The four growth methods are slow evaporation of solvent from a dilute solution (SED) and a concentrated solution, quenching the hot concentrated solution, and slow cooling of hot concentrated solution. The morphological and optical studies demonstrated recrystallized particle size varying from 0.01 mm to 10 mm. The structural analysis revealed crystallite size from 30 nm to 160 nm. Current-voltage characterization and conductivity measurements indicate that these structural and morphological variations are critical factors in influencing and determining the electronic charge transport properties. The SED method results in relatively larger crystallites size and percent crystallinity, which leads to higher conductivity. Overall, by utilizing various growth methods for DTCPA, change in particle size, crystallite size, percent crystallinity, and optical absorption is assessed, which in turn affects the electrical properties.

The development of new infrared (IR) nonlinear optical (NLO) materials with strong second-harmonic generation (SHG) responses and high laser-induced damage thresholds (LIDTs) is urgent but challenging. Herein, the defective diamond-like chalcogenide Hg3P2S8 (HPS) was rationally designed and fabricated by a flexible and rigid tetrahedral motif combined strategy. HPS exhibits a phase-matching SHG response of similar to 3.6 x AGS (the largest one in the reported ternary sulfides), high LIDT (similar to 3 x AGS), wide IR transparent region (0.43-16.3 mu m), moderate birefringence (0.043 at 1064 nm), and good physicochemical stability and crystal growth habits. Theoretical analyses confirm that the large SHG effect originates from the synergistic effects between distorted HgS4, PS4, and vacancy-induced nonbonding electrons. The results indicate that HPS is a promising NLO candidate for high-power, high-efficiency laser output in the mid-IR region, which provides an insight into the exploration of new IR NLO materials.

The pure phase (Zr0.8,Sn0.2)TiO4 nano crystals have been prepared by hydrothermal-molten salt method. The effects of the pH of solvent system, the calcinations temperature and the ratio of composite molten salt on the phase composition and crystalline morphology have been investigated. The results show that the high pure phase (Zr0.8,Sn0.2)TiO4 nano crystals with regular morphology were prepared at 1000 oC in NaCl-KCl salt system. The synthesized temperature of single phase (Zr0.8,Sn0.2)TiO4 is lower and the crystal growth is more complete compared with the hydrothermal-solid state method. The rod-like crystalline grain are evenly distributed with a diameter of about 50–60 nm and can be used as start materials for preparing ZST textured ceramics. The (Zr0.8,Sn0.2)TiO4 nano crystal has a certain photocatalytic effect and good UV shielding performance.

The crystal growth kinetics and morphology in germanium disulfide bulk glass and glass surface is described. The structural relaxation taking place below the glass transition is slow and the corresponding volumetric change is negligible. Therefore, it does not affect substantially the crystal growth process. The crystal growth rate of low temperature β-GeS2 and high temperature α-GeS2 polymorphs in the bulk glass is comparable, being slightly decoupled from the shear viscosity below the glass transition. The crystal growth rate of β-GeS2 in an amorphous thin film of the same composition is several orders of magnitude faster than that at the surface of bulk glass. This fast surface crystal growth is strongly decoupled from viscosity. Such behavior resembles the glass-to-crystal fast growth mode observed by several authors in some organic molecular glasses. Taking into account previously reported viscosity and heat capacity data, the crystal growth kinetics of both polymorphs can be quantitatively described by the 2D surface growth model for low and high supercooling. The nonisothermal differential scanning calorimetry experiments are analyzed, providing evidence of a complex nature of the overall crystallization process with apparent activation energy comparable to that obtained from isothermal microscopy measurement of crystal growth in the same temperature range.

Porous zirconium carbide (ZrC) ceramics with stepped morphology were successfully prepared by evaporating solvent combined with high-temperature sintering. Step morphology with different slopes on the skeleton can be tuned by optimizing the sintering temperature. SEM, TEM and in-situ scanning probe image characterizations confirmed that the stepped ZrC ceramic followed a two-dimensional nucleation growth mechanism. Herein a three-dimensional model based on Burton-Cabrera-Frank theory of crystal growth was established to explain the reasons for stepped growth. After 5 thermal shock cycles between 1500 °C and room temperature, the stepped morphology has a positive role on improving the adhesion strength between pyrocarbon and ZrC skeleton in the form of mechanical interlocking. This work provides a strategy for improving the interfacial bonding strength of ultra-high temperature composites by morphology design.

The highly luminescent dicyanodistyrylbenzene-based charge-transfer (CT) cocrystal based on isometric donor and acceptor molecules with a mixing ratio of 2:1 is characterized in the thin film regime. Physical vapor deposited films prepared at different substrate temperatures are analyzed in terms of their thin film structure and transistor performance. The thin film morphologies and crystallographic properties including microstrain and mosaic spread strongly dependent on the substrate temperature. Enhanced crystal growth with rising temperatures leads to a better transistor performance reaching its maximum at 90 °C with a hole and electron mobility of 1.6 × 10–3 and 2.3 × 10–5 cm2 V–1 s–1, respectively. At higher temperatures performance decreases limited by percolation pathways between the enlarged crystals.

Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm2/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm2/Vs, low resistivity of 5.3 × 10−4 Ωcm, and good transmittance of 83.3 %.

Most studies related to the synthesis of TiO2–SiO2 composites for photocatalytic applications did not systematically evaluate the textural and photocatalytic properties obtained from different integration levels between these two phases. Thus, this work investigates the influence of the heat treatment step on the structural properties and photodegradation activity of TiO2–SiO2 composites synthesized by different sol–gel and hydrothermal routes. The as-prepared samples showed significant textural and photocatalytic differences, whereas the heat-treated samples showed similar structures and properties. However, some critical differences could be observed, such as different resistances to crystal growth due to the distinct location of the silica phase. Moreover, it was possible to identify a great photocatalytic enhancement by comparing the heat-treated and as-synthesized samples, which was mainly attributed to the segregation of SiO2 toward surface sites. Here, it was observed that the crystallization of titania after the heat-treatment step had a minor effect on the composites photoactivity since even the as-prepared samples were crystalline. The heat treatment was shown to be fundamental for a controlled segregation of the two phases, promoting a synchronous effect between the adsorption of MB molecules on the silica-rich portion and photocatalysis in the vicinity of such sites, where the titania phase is present. Such behavior was more pronounced in samples prepared with an early addition of TEOS during the synthesis.

l-methionine, boric acid and potassium carbonate were used to prepare l-methionine inserted potassium pentaborate (LMKB5) solution using deionized water as a solvent. A semi-organic crystal was grown by solvent vaporization at lab temperature. Structural analysis was performed on the LMKB5 crystal to affirm cell dimensions. Morphology of the grown crystal was confirmed by scanning electron microscopy (SEM). Energy dispersive x-ray (EDAX) study was used to obtain the elemental composition. The vibrational analysis was performed on the as-grown crystal, which confirms the presence of LMKB5. The optical analysis was performed using a UV–VIS–NIR spectrophotometer to calculate the energy gap of the title material. Thermogravimetry (TG) and differential scanning calorimetry (DSC) analysis are performed on a grown crystal to evaluate the thermal stability of LMKB5 crystal. Differential thermal analysis (DTA) curve affirms that the title material has crystalline nature due to a sharp endothermic peak at 193.49°C. Mechanical strength of the material was estimated using Vicker's microhardness. Laser damage threshold (LDT) studies were carried out to analyze surface damage tolerance stability in crystal. Grown material is essential for a second harmonic generation (SHG).

This work provides an effective method for realizing both resource utilization and high-value utilization of bulk industrial solid waste. The influence of non-equilibrium cooling rates on the internal energy and amorphous structure of the precursor glass is studied to clarify the nucleation process of various crystals. A new method is proposed to control the glass formation and crystal growth process by using the cooling rate of the high-temperature melt. Research results show that the crystallization enthalpy (ΔHc) of the precursor glass decreases with decreasing cooling rates, and the NBO/T gradually decreases. When the non-equilibrium cooling rate is (k) > 10 °C/min, ΔHc is ≥ 157.05 kJ/mol and NBO/T increases to 1.09. Additionally, the glass network structure is unstable and mainly consists of Q4 structural units, which promote canasite-A crystal nucleation. The Cxonotlite:Ccanasite-A ratio increases from 1:1 to 1:5, and the crystallinity increases by 25.49%. The flexural strength of the silicon slag glass-ceramics also increases by 59.19%.

Conventional direct joining technologies are difficult to use with silicon carbide (SiC) materials, especially for fiber composite forms of SiC, because of the harsh conditions required. To reduce the temperature and/or process time required for the direct joining process, an electric current–assisted joining (ECAJ) method was studied. Joining of low–resistivity grade, nitrogen doped β-SiC was demonstrated at a relatively low nominal temperature of 1750 °C with a 10 min hold by enhancing the passage of current through the material. The joining mechanism is discussed in terms of localized overheating and accelerated self-diffusion at the interface. In the case of joining at 2160 °C for 1 min, rapid crystal growth of textured SiC was found at the interface. This study indicates that rapid ECAJ-based direct joining is a practical and appropriate method for joining SiC-based materials.

Here, we present an automated and rapid method for nondestructive mapping of crystal grains in a rod-shaped sample. The approach was designed for application to in situ float-zone crystal growth ex...

Recent inclusion models are mainly focused on the compositional evolution of inclusion, steel and slag. Due to the importance of inclusion size distribution to steel properties, the evolution of inclusion size distributions should also be accounted for. As the first step to establish a model to predict the evolution of inclusion size distribution, the nucleation, growth and removal of alumina inclusions in molten steel were modeled by combining Kampmann and Wagner numerical model for nucleation, growth and coarsening with particle size grouping method. The model could simulate the time evolution of the size distribution of alumina inclusions after aluminum de-oxidation. The model was validated by using the experimental size distribution data of alumina inclusions available in the literature. The model calculation results were also compared with previous simulation results. The influences of interfacial tension between steel and inclusion and diffusion coefficient on the calculated inclusion size distribution were investigated. As interfacial tension between steel and alumina increases, the maximum number density decreases and the peak value of radius increases. As diffusion coefficient increases, the maximum number density decreases and the peak-value radius increases. The calculated size distribution curves showed a change from log normal to fractal, which is due to the change of dominating mechanisms for crystal growth and agglomeration.

Recently, there are significant progresses in the growth of organic-inorganic lead halide perovskite single crystals, however, due to their susceptible nucleation and growth mechanisms and solvent requirements, the efficient and generalized growth for these single crystals is still challenging. Here we report the work towards this target with a polymer-controlled nucleation process for the highly efficient growth of large-size high-quality simple ternary, mixed-cations and mixed-halide perovskite single crystals. Among them, the carrier lifetime of FAPbBr3 single crystals is largely improved to 10199 ns. Mixed MA/FAPbBr3 single crystals are synthesized. The crucial point in this process is suggested to be an appropriate coordinative interaction between polymer oxygen groups and Pb2+, greatly decreasing the nuclei concentrations by as much as 4 orders of magnitudes. This polymer-controlled route would help optimizing the solution-based OIHPs crystal growth and promoting applications of perovskite single crystals., Research into single crystal organic-inorganic halide perovskites have gained momentum due to the potential applications, yet the growth is still a challenge. Here, the authors demonstrate a universal method based on polymer controlled nucleation process to achieve large-size and high-quality perovskite single crystals.

The glass-forming ability, crystallization behavior and physical properties of GeS2-Sb2S3-CsX (X = Cl, Br, I) glasses and glass-ceramics (GCs) are systematically studied by various characterization techniques. With the introduction of cesium halides, transparent chalcogenide GCs containing the single nanocrystals of CsX can be obtained in a controlled fashion. The crystallization behavior was investigated in the line of (100-x) (0.5GeS2-0.5Sb2S3)-xCsX glasses. IR-transmitting chalcogenide GCs embedded with CsCl and CsBr nanocrystals of a large crystallinity have been fabricated successfully after thermal treatments, whereas surface crystallization of CsI is dominated in GeS2-Sb2S3–CsI glassy samples. Such distinct crystallization behaviors of CsX crystal phases are compared and discussed with microstructural results. We propose that the ionic diffusion ability of halogen in the GeS2-Sb2S3-CsX glassy network determines the nucleation and crystal growth of CsX. This finding is of guidance meaning for future design of chalcogenide GCs with novel optical functions and microstructures.

We studied the influence of the surface charge of the substrate on the heat stability of electrostatic interactional colloidal silica crystals grown through heterogeneous nucleation from the substrate by relative reflection spectroscopy and optical microscopy. During the crystal growth stage on a negatively charged substrate, a large blue shift of the reflection peak was observed in the reflection spectrum. On the other hand, during crystallisation on a positively charged substrate, the blue shift occurring on the negatively charged substrate was completely suppressed. This blue shift indicates a reduction in the lattice spacing when the crystals push each other during crystal growth. The melting behaviour of the crystal was also investigated in the case of heating from the substrate side. The melting point of the crystal on the positively charged surface was higher than that on the negatively charged surface. The blue shift in the spectrum of the crystals on the positively charged substrate was suppressed in the stage before melting; however, the blue shift increased when the crystal started to melt from the substrate surface. Colloidal crystals formed from heterogeneous nuclei on a positively charged substrate were stabilised by the interaction between the negatively charged colloidal particles in the substrate’s vicinity and the positively charged substrate surface.

Single crystals of (E)-N′-(4-isopropylbenzylidene)isonicotinohydrazide monohydrate (IBIHM) were grown from ethanol by the slow evaporation from solution growth technique at room temperature. The structure was elucidated by single-crystal X-ray diffraction analysis and crystallized in the orthorhombic system with noncentrosymmetric space group P212121. Optical studies reveal that the absorption was minimum in the visible region and the band-gap energy was estimated using the Kubelka–Munk algorithm. The functional groups were identified by Fourier transform infrared spectral analysis. A scanning electron microscopy study revealed the surface morphology of the grown crystal. Investigation of the intermolecular interactions, crystal packing using Hirshfeld surface analysis and single-crystal X-ray diffraction confirm that the close contacts were associated with molecular interactions. Fingerprint plots of Hirshfeld surfaces are used to locate and analyze the percentage of hydrogen-bonding interactions. The second-harmonic generation efficiency of the grown specimen was superior to that of the reference material, potassium dihydrogen phosphate. The grown crystals were further characterized by mass spectrometry and elemental analysis. Theoretical studies using density functional theory (DFT) greatly substantiated the experimental observations. Large first-order molecular hyperpolarizability (β) of about ∼70× was observed for IBIHM. The efficiency of IBIHM in terms of nonlinear optical response was verified and the molecule displayed greater chemical stability and reactivity.

With the increasing attention of 4H-silicon carbide (4H-SiC) crystals in the applications of high-power electronics, it has become necessary to further improve the development of the 4H-SiC crystal growth process, especially the initial stage of physical vapor transport (PVT) growth, which is a critical step to obtain high quality SiC crystals with polytype stability and low dislocation density. This paper describes a study on dislocation behavior of large diameter 4H-SiC crystals at the early stages of PVT growth. Synchrotron x-ray topography is applied to 6-inch PVT-grown crystals with a thickness of several hundred microns on 4H-SiC seeds. Grazing-incidence topographs in $$g = 11\overline{2}8$$ and $$g = 1\overline{1}09$$ recorded from both the seed crystal and newly grown layer show the presence of screw-type basal plane dislocations (BPDs) with $$b = 1/3\left[ {11\overline{2}0} \right]$$ at the inner region of the wafers, which is further confirmed by comparing with ray tracing simulated images of these dislocations. Their origins are likely from deflection of threading edge dislocations (TEDs) onto the basal plane by the overgrowth of macro-steps. Pairs of threading screw/mixed dislocations (TSDs/TMDs) are found to be newly generated at the initial growth stage and some are deflected onto the basal plane. A high density of newly generated TEDs is observed in the early-grown crystals, which are either nucleated in pairs at the seed/crystal interface or converted from BPDs in the seed crystal. Furthermore, dislocations with unique shapes are observed and found to be associated with deflection of TMDs and TEDs, which become the major source for BPD generation during the early PVT growth stage. Possible models to explain their formation mechanism are developed.

In this work, pure, large Br-doped SnSe2 single crystals were successfully synthesized using the temperature gradient technique. Br acts as a donor, resulting in electron concentrations up to ∼6.83...

In recent years, the preparation of CMAS nanocrystalline glass-ceramics has shown potential as an application of secondary resourcing technology in utilizing Bayan Obo iron ore tailings containing rare earth elements. The crystallization mechanism for nanodiopside-type glass-ceramics was studied via an investigation of the nonisothermal crystallization kinetics of the glass system, combined with the in situ observation of softening and crystallization of the basic glass using a high-temperature laser confocal microscope. The results show that the activation energy of nucleation in the glass system is higher than that of crystal growth by using the Ozawa model. The crystallization mechanism changes as the crystallization fraction increases, that is, from the three-dimensional growth in which the nucleation rate increases with time in an interface-controlled manner (a > 1, b = 1, m = 3) at the initial stage of crystallization to a decreased nucleation rate in a diffusion-controlled growth (a = 0.5, b = 0.5, m = 3) at the middle and later stages. This process involves both surface crystallization and volume crystallization. The crystallization was observed in situ, and it was further confirmed that there exists a critical nucleation temperature between Tg and Tx, which is related to the interface free energy and critical Gibbs free energy difference. When the temperature exceeds the critical value of Tg + 55 K, the system begins to exhibit visible crystallization. With an increase in temperature, the basic glass softened considerably, while the crystal grew significantly. In addition, the surface roughness can be used to characterize the crystallization process, providing a new research method for crystal growth.

In this work, the effects of reaction conditions on the conventional hydrothermal synthesis and crystal growth kinetics of zeolites Y in aqueous sodium alkaline solutions without the use of organic templates were studied. For this purpose, a series of Y-type zeolites were synthesized at different reaction conditions such as various aging temperatures, crystallization temperatures, Na2O contents of the initial gel and crystallization times using hydrothermal process. The prepared samples were well characterized by the X-ray diffraction (XRD) and N2 adsorption–desorption techniques. The results prove that the Na2O contents of the initial gel and synthesis temperature increase the rate of the Y and P zeolite crystallization. The effect of Na2O and temperature on the synthesis of two different zeolite types (Y and P) with a constant initial synthetic composition under the organic template-free synthesis of zeolite Y was studied. In inappropriate conditions, the P-type zeolite was the major impurity obtained along with the Y-type zeolite. Also from the experimental results, the kinetic parameters for both zeolite Y and zeolite P were calculated. The kinetic study show that the activation energy for crystallization of both zeolites was enhanced by increasing the Na2O content of the initial gel due to the structure-directing role of Na+ cation in the induction period and crystal growth step.

Ni- and Co-incorporated CH3NH3PbI3 perovskite solar cells were fabricated and characterized to optimize the photovoltaic and optical properties related to surface morphology, crystal growth and orientation, and electronic structures. Partially replacing Pb with Ni or Co in the perovskite crystals improved the photovoltaic performance and carrier mobility based on the effective mass in the band structure. In particular, the addition of both Ni and Rb compounds to perovskite improved the long-term stability of the photovoltaic cells, which depended on surface modification and coverage, crystal growth, and the high (100) orientation in the perovskite layer. The short-circuit current density of the cells was increased by promoting the generation and mobility of photoinduced carriers, which were inversely proportional to the effective mass ratio. Electron correlation was associated with the promotion of charge transfer owing to the hybridization between the 3d orbitals of Ni and the 5p orbitals of the I atoms near the valence band state.

Development of robust electrode materials that can work for both Li- and Na-ion batteries received enormous interest in recent times. Especially, exploratory crystal growth offers much reward in re...

As an ideal material platform for deep investigations on superconductivity, high purity YBa2Cu3O7-δ (Y123) single crystals have been highly concerned and requested recently. However, it is very difficult to grow such crystals by the conventional travelling-solvent floating-zone (TSFZ) process due to the intrinsic instability of floating zone caused by the liquid loss. To overcome this obstacle, the feed rod with modified precursor powder (MPP) of 0.5Y2O3+ Ba2Cu3O5 was adopted, instead of the conventional one (Y123). Our experimental results proved that less Ba3Cu7Oy solvent penetrated to the MPP-rod due to its low wettability. Furthermore, it was also observed that less melt dropped down from the floating zone owning to its low fluidity, caused by low dimension of bubbles and Y211 particles generated from the MPP-rod. Consequently, the molten zone was remarkably stabilized and the Y123 single crystal was successful grown. The effective size of the grown boule was about 5 mm (O) × 30 mm. This new conception of altering precursor components for continuous TSFZ growth is universally worth of producing other functional materials.

Homogeneously Eu3+ doped LaOCl single crystals are firstly synthesized in a molten KCl-LiCl flux, and the well-shaped LaOCl:Eu3+ polyhedral micro-plates exhibit noticeable luminescent properties. The bulk LaOCl:Eu3+ micro-plate with a width of 1.03 μm and 1.37 μm in length shows a single crystal characteristic with the crystal face orientation of [00 1 ‾ ]. Both XRD patterns and EDS mapping indicate that the Eu3+ ions have been homogeneously doped into LaOCl lattice. LaOCl:Eu3+ nucleuses generated in molten KCl-LiCl flux at even 350 °C benefited to the decomposition of La(OH)3:Eu3+ precursor, and polyhedral LaOCl micro-plate is easily formed in molten KCl-LiCl salt due to the solid-ionic reaction and crystal growth. The luminescent properties of LaOCl:Eu3+ are firstly enhanced and then weakened with the increasing concentration of the doped Eu3+, 6% Eu3+ doped LaOCl:Eu3+ exhibits the best luminescent properties which can be used as a potential LED material.

Cordierite-based glass-ceramics with non-stoichiometric compositions were prepared by powder sintering method. The effects of MgO/SiO2 ratio and Al2O3 content on the crystallization behavior, microstructure and thermal expansion coefficient of the glass-ceramics were studied. Results indicated that the decreasing Al2O3 content showed a greater effect on decreasing the melting temperature and liquid viscosity than the increasing MgO/SiO2. DTA results showed that, at low temperatures, the MgO/SiO2 ratio dominated crystallization of cordierite due to the lack of liquid. At a high sintering temperature of 1340 °C, the Al2O3 content dominated the crystal growth of cordierite due to its great effect on decreasing the liquid viscosity. The chemical composition close to the stoichiometric cordierite and the absence of quartz were two essential factors for obtaining low thermal expansion coefficients. The decreasing MgO/SiO2 ratio and Al2O3 content caused phase separation with an interconnected structure, which followed the crystallization of cordierite in the Al2O3-rich phase.

Transparent and translucent glass-ceramics (GCs) are found in an increasing number of domestic and high-technology applications. In this paper, we evaluated and optimized the effects of two-stage heat treatments on the resulting crystalline phases and microstructure of a glass of the SiO2–Li2O–P2O5–TiO2–CaO–ZnO–Al2O3 system. The objective was to develop a transparent nanostructured glass-ceramic (GC). After numerous heat treatment trials, we found that a long nucleation period of 72 h at 455 °C followed by a crystal growth treatment at 660 °C for 2 h resulted in a highly translucent GC having homogenously distributed nanocrystals. The relatively high amount of P2O5 (2.5 mol%) induced the formation of lithium disilicate as the main crystal phase. We thus developed a GC having crystals under 50 nm, with a high crystallized fraction (52%vol. Li2Si2O5 and 26% vol Li2SiO3), transmittance of approximately 80% in the visible spectrum for 1.2 mm thick specimens, nano hardness of 8.7 ± 0.1 GPa (load of 400 mN), a high elastic modulus of 138 ± 3 GPa as measured by nanoindentation, and good flexural strength (350 ± 40 MPa) as measured by ball-on-3 balls tests. Due to its high content of Li+, this GC has the potential to be chemically strengthened and can be further developed to be used in a number of applications, such as on displays of electronic devices.

Antisolvent method is one of the most common and efficient techniques used to prepare high-quality lead-halide perovskite film for perovskite solar cells (PSCs). Antisolvent method is crucial for i...

The behavior of oxide precipitates during solar cell fabrication processes and the resulting effect on device performance have been investigated by transmission electron microscopy (TEM) observation. Samples were prepared with different carbon concentration and under different crystal growth conditions, namely using the conventional and an advanced process. The density of oxide precipitates increased monotonically with the carbon concentration, while the cell efficiency improved with decreasing oxygen precipitate density. When the carbon concentration was reduced to below 1016 cm−3, the oxide precipitates grew largely and dislocations were introduced. TEM observations confirmed that the morphology of the oxide precipitates clearly differed depending on the crystal growth conditions. Precipitates grown in platelet form introduced high density dislocations in their surroundings, while the dislocation density was relatively lower around polyhedral-type precipitates. These results thus reveal that oxygen precipitation can be controlled by varying the crystal growth conditions, possibly contributing to the production of high-efficiency solar cells.