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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)

Hexagonal SiGe-2H has been recently shown to have a direct bandgap, and holds the promise to be compatible with silicon technology. Hexagonal Si and Ge have been grown on an epitaxial lattice matched template consisting of wurtzite GaP and GaAs, respectively. Here, we present the growth of hexagonal Si and SiGe nanowire branches grown from a wurtzite stem by the vapor−liquid−solid growth mode, which is substantiated by in situ transmission electron microscopy. We show that the composition can be tuned through the whole range of stoichiometry from Si to Ge, and the possibility to realize Si and SiGe heterostructures in these branches.

The studies on the physico-mechanical properties of commonly used energetic materials (EMs) that were pursued by the group led by Professor John Sherwood are reviewed in this paper. The studies ranged from the growth of high quality single crystals and the characterisation of their defect and dislocation structures, mechanical testing, through to the study of polymorphism of EM crystals and fundamental aspects of crystallization processes generally. The work performed lead to the definition of good growth conditions for all the EMs studied and to the full characterization of the defect structure, slip systems and hardness properties of cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN). Partial characterization of the defect structures and hardness properties of cyclotetramethylene tetranitramine (HMX) and 2-4-6 trinitrotoluene (TNT) were also achieved. Additionally, fundamental crystal growth and polymorph information was defined, allowing a deeper understanding of the crystallization and crystal structure of TNT. In addition to the general review, some thoughts as to possible future routes for further study that could suitably utilize the complementary nature of established and modern techniques. Original funding of the work was though the European Offices of the US Army and US Navy.

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.

Rare-earth fluorine-containing molybdates of the Ln5Mo3O16+δ oxygen–electron conductor family with the LiLa4Mo3O15F composition were synthesized for the first time as single crystals by the flux method. An accurate X-ray diffraction analysis of the obtained crystals was carried out at 20 and −183 °C. The LiLa4Mo3O15F compound is isostructural to the fluorine-free analogue with a cubic structure (space group Pn3¯n). It is shown that lithium atoms replace one of the two positions of lanthanum in the more distorted LaO8 polyhedron. According to X-ray diffraction analysis, fluorine atoms replace the positions of over-stoichiometric oxygen located in the vast cavities of the structure. So, fluorine anions can promote the interstitial conductivity of F-containing LiLa4Mo3O15F molybdates.

In this work, we present results on the growth of centimeter-scale pentacene crystals using the physical vapor transport method in a dual-temperature zone horizontal furnace. It was established that intensive crystal growth processes occurred in transition regions with sudden temperature changes, while crystal growth was practically not observed in regions with slightly varying temperatures. During crystal growth, co-precipitating golden needle-like crystals reaching lengths of more than 10 mm were obtained. Using the method of single-crystal X-ray diffraction at 85 and 293 K for dark-blue lamellar pentacene crystals, the crystal structure was refined in a triclinic system with sp.gr. P1¯. It was established that the golden needle crystals consisted of molecules of the pentacene derivative—5,14-pentacenedione, the crystal structure of which was solved for the first time in a rhombic system with sp.gr. P212121. The absorption and luminescence spectra of pentacene and 5,14-pentacenedione in toluene solutions were obtained and analyzed. The electrical properties of the prepared pentacene thin films and single crystals grown under physical vapor transport conditions were evaluated by fabricating and characterizing field-effect transistors (FETs). It was shown that the presence of impurities in the commercial pentacene material had a significant effect on the morphological quality of thin polycrystalline films and noticeably reduced the hole mobility.

The M-type barium hexaferrite substituted with titanium, BaFe12−xTixO19, was synthesized from sodium carbonate flux and the obtained single crystals with a maximum degree of substitution of up to about x = 0.9 were characterized. XPS measurements were carried out for the identification of side products and in particular in order to assign the valence states of the transition-metal constituents. Due to the aliovalent exchange of iron(III) with titanium(IV), an additional charge balance needs to occur. No titanium(III) was detected, while the amount of iron(II) increased in the same order of magnitude as the amount of titanium(IV); thus, the major charge balancing is attributed to the reduction of iron(III) to iron(II). According to the XPS data, the amount of titanium(IV) typically is slightly higher than that of iron(II). This is in line with a tendency to a minor formation of vacancies on the transition-metal sites becoming more important at higher substitution levels according to PXRD and WDS measurements, completing the picture of the charge-balance mechanism. XRD taken on single crystals indicates the distribution of titanium and vacancies over three of the five transition-metal sites.

The aim of this work is to present an efficient procedure for growing large metallic single crystals that associates a classical growth technique (namely, the critical strain-annealing—CSA—method) with advanced methods of accurate full-field strain measurements based on digital image correlation (DIC) technique and of sample geometry design using finite element analysis. Measuring the critical plastic strains with an accuracy better than 0.1% resulted in a significantly improved construction of the recrystallization diagram. Applying this “DIC-assisted CSA method” to an A1050 commercially pure aluminum allowed obtaining in less than two days (26 h to 30 h) large multi-crystal samples with a half dozen of large grains. Their length between 35 mm and 100 mm was in full agreement with the obtained recrystallization diagram.

Several effective methods have been developed recently to demonstrate simultaneous high energy and high power density in Lithium - carbon fluoride (Li-CFx) batteries. These methods can achieve as high as a 1000 Wh/kg energy density at a 60–70 kW/kg power density (40–50 C rate) in coin cells and a 750 Wh/kg energy density at a 12.5 kW/kg power density (20 C rate) in pouch cells. This performance is made possible by an ingenious nano-architecture design, controlled porosity, boron doping, and electrolyte additives. In the present study, we show that a similarly great performance, a 931 Wh/kg energy density at a 59 kW/kg power density, can be achieved by using a polyacrylonitrile binder and a LiBF4 electrolyte in Li-graphite fluoride coin cells. We also demonstrate that the observed effect is the result of the right combination of the binder and the electrolyte. We propose that the mechanistic origin of the observed phenomena is an electro-catalytic effect of the polyacrylonitrile binder. While our proposed method has a competitive performance, it also offers a simple implementation and a scalable production of high-energy and high-power primary Li-CFx cells.

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 successful growth of single crystals of a cubic Laves-phase material HoAl2 with the space group Fd-3m is reported in this study. The crystals were grown by a floating-zone method with five laser diodes as a heat source. Al-rich feed rods were prepared as compensation for heavy evaporation during the growth. The nominal ratio for the feed rods was optimized as Ho:Al = 1:2.5. Single crystals of HoAl2 with a length of 50 mm were first grown in this technique. Obtaining the large-sized crystal by the floating-zone method enabled us to systematically explore the physical properties using the same batch crystal. The crystal possessed a second-ordered ferromagnetic transition at 29 K and a first-ordered spin-reorientation transition at 20 K. The bulk physical properties, such as specific heat, magnetic susceptibility, isothermal magnetization, and thermal expansion measurements, were measured. Additionally, a magnetocaloric effect was evaluated by the magnetic entropy change. We demonstrate that anisotropic physical properties along the principal axes ([100], [110], and [111]) emerged below the magnetically ordered states, in contrast to the isotropic behavior in the paramagnetic state.

A detailed analysis of morphology of gallium nitride crystal growth obtained by ammonothermal and halide vapor phase epitaxy methods was carried out. The work was conducted to determine the source of triangular planar defects visible in X-ray topography as areas with locally different lattice parameters. It is shown that the occurrence of these defects is related to growth hillocks. Particular attention was paid to analyzing the manner and consequences of merging hillocks. In the course of the study, the nature of the mentioned defects and the cause of their formation were determined. It was established that the appearance of the defects depends on the angle formed between the steps located on the sides of two adjacent hillocks. A universal growth model is presented to explain the cause of heterogeneity during the merging of growth hillocks.

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.

Magnetic and magnetoelectric (ME) properties of honeycomb lattice antiferromagnets M4Nb2O9 (M = Mn, Co, Mn1-xCox ) were investigated. Mn4Nb2O9 show colinear antiferromagnetic order and ME effect in the temperature range below TN = 109 K. The electric polarization induced by ME effect shows a maximum at 90 K, which reflects the temperature dependence of the magnetic susceptibility along the c axis. Magnetization measurements of Co4Nb2O9 under an applied electric field revealed that the magnitude of magnetization varies in proportion to the applied electric field. Changes in magnetic transition temperature and magnetic anisotropy were investigated for (Mn1-xCox )4Nb2O9 single crystals. It was found that the magnetic transition temperature changes linearly with composition, while the magnetic anisotropy changes by replacing Mn with a small amount of Co.

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.

Understanding crystallization and its correlations with liquid dynamics is relevant for developing robust amorphous pharmaceutical solids. Herein, nimesulide, a classical anti-inflammatory agent, was used as a model system for studying the correlations between crystallization kinetics and molecular dynamics. Kinetic parts of crystal growth (ukin) of nimesulide exhibited a power law dependence upon the liquid viscosity (η) as ukin~η−0.61. Bulk molecular diffusivities (DBulk) of nimesulide were predicted by a force-level statistical–mechanical model from the α-relaxation times, which revealed the relationship as ukin~Dbulk0.65. Bulk crystal growth kinetics of nimesulide in deeply supercooled liquid exhibited a fragility-dependent decoupling from τα. The correlations between growth kinetics and α-relaxation times predicted by the Adam–Gibbs–Vogel equation in a glassy state were also explored, for both the freshly made and fully equilibrated glass. These findings are relevant for the in-depth understanding and prediction of the physical stability of amorphous pharmaceutical solids.

With the ammonothermal method, one of the most promising technologies for scalable, cost-effective production of bulk single crystals of the wide bandgap semiconductor GaN is investigated. Specifically, etch-back and growth conditions, as well as the transition from the former to the latter, are studied using a 2D axis symmetrical numerical model. In addition, experimental crystal growth results are analyzed in terms of etch-back and crystal growth rates as a function of vertical seed position. The numerical results of internal process conditions are discussed. Variations along the vertical axis of the autoclave are analyzed using both numerical and experimental data. During the transition from quasi-stable conditions of the dissolution stage (etch-back process) to quasi-stable conditions of the growth stage, significant temperature differences of 20 K to 70 K (depending on vertical position) occur temporarily between the crystals and the surrounding fluid. These lead to maximum rates of seed temperature change of 2.5 K/min to 1.2 K/min depending on vertical position. Based on temperature differences between seeds, fluid, and autoclave wall upon the end of the set temperature inversion process, deposition of GaN is expected to be favored on the bottom seed. The temporarily observed differences between the mean temperature of each crystal and its fluid surrounding diminish about 2 h after reaching constant set temperatures imposed at the outer autoclave wall, whereas approximately quasi-stable conditions are reached about 3 h after reaching constant set temperatures. Short-term fluctuations in temperature are mostly due to fluctuations in velocity magnitude, usually with only minor variations in the flow direction.

Crystallization plays a critical role in determining crystal size, purity and morphology. Therefore, uncovering the growth dynamics of nanoparticles (NPs) atomically is important for the controllable fabrication of nanocrystals with desired geometry and properties. Herein, we conducted in situ atomic-scale observations on the growth of Au nanorods (NRs) by particle attachment within an aberration-corrected transmission electron microscope (AC-TEM). The results show that the attachment of spherical colloidal Au NPs with a size of about 10 nm involves the formation and growth of neck-like (NL) structures, followed by five-fold twin intermediate states and total atomic rearrangement. The statistical analyses show that the length and diameter of Au NRs can be well regulated by the number of tip-to-tip Au NPs and the size of colloidal Au NPs, respectively. The results highlight five-fold twin-involved particle attachment in spherical Au NPs with a size of 3–14 nm, and provide insights into the fabrication of Au NRs using irradiation chemistry.

We consider the process of formation and growth of clusters of a new phase in segregation processes in solid or liquid solutions in an open system when segregating particles are added continuously to it with a given rate of input fluxes, Φ. As shown here, the value of the input flux significantly affects the number of supercritical clusters formed, their growth kinetics, and, in particular, the coarsening behavior in the late stages of the process. The detailed specification of the respective dependencies is the aim of the present analysis, which combines numerical computations with an analytical treatment of the obtained results. In particular, a treatment of the coarsening kinetics is developed, allowing a description of the development of the number of clusters and their average sizes in the late stages of the segregation processes in open systems, which goes beyond the scope of the classical Lifshitz, Slezov and Wagner theory. As is also shown, in its basic ingredients, this approach supplies us with a general tool for the theoretical description of Ostwald ripening in open systems, or systems where the boundary conditions, like temperature or pressure, vary with time. Having this method at one’s disposal supplies us with the possibility that conditions can be theoretically tested, leading to cluster size distributions that are most appropriate for desired applications.

International audience; Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper.

Most theoretical descriptions of stresses induced by freezing are rooted in the (generalized) Clapeyron equation, which predicts the pressure that a solid can exert as it cools below its melting temperature. This equation is central for topics ranging beyond glaciology to geomorphology, civil engineering, food storage and cryopreservation. However, it has inherent limitations, requiring isotropic solid stresses and conditions near bulk equilibrium. Here, we examine when the Clapeyron equation is applicable by providing a rigorous derivation that details all assumptions. We demonstrate the natural extension for anisotropic stress states, and we show how the temperature and pressure ranges for validity depend on well-defined material properties. Finally, we demonstrate how the range of applicability of the (linear) Clapeyron equation can be extended by adding higher-order terms, yielding results that are in good agreement with experimental data for the pressure melting of ice., Journal of Glaciology, ISSN:0022-1430, ISSN:1727-5652

Supersaturating drug delivery systems such as solid dispersions of a drug in a polymer are frequently used in pharmaceutical development to enable oral delivery of poorly soluble drugs. In this study, the influence of the concentration and molecular weight of polyvinylpyrrolidone (PVP) on the precipitation inhibition of the poorly soluble drugs albendazole, ketoconazole and tadalafil is investigated to expand the understanding of the mechanism of PVP as a polymeric precipitation inhibitor. A three-level full-factorial design was used to delineate the influence of polymer concentration and viscosity of the dissolution medium on precipitation inhibition. Solutions of PVP K15, K30, K60 or K120 at concentrations of 0.1, 0.5 and 1% (w/v), as well as isoviscous solutions of PVP of increasing molecular weight, were prepared. Supersaturation of the three model drugs was induced by the use of a solvent-shift method. Precipitation of the three model drugs from supersaturated solutions in the absence and presence of polymer was investigated by the use of a solvent-shift method. Time–concentration profiles of the respective drugs in the absence and presence of polymer pre-dissolved in the dissolution medium were obtained by the use of a μDISS Profiler™ to determine the onset of nucleation and the precipitation rate. Multiple linear regression was used to evaluate the hypothesis that precipitation inhibition is influenced by the PVP concentration (i.e., the number of repeat units of the polymer) and the medium viscosity of the polymer for the three model drugs. This study showed that an increased concentration of PVP (i.e., an increased concentration of the PVP repeat units, independent of the molecular weight of the polymer) in solution increased the onset of nucleation and decreased the precipitation rate of the respective drugs during supersaturation, which can be explained by an increase in molecular interactions between the drug and polymer with increasing concentrations of polymer. In contrast, the medium viscosity had no significant influence on the onset of the nucleation and precipitation rate of the drugs, which can be explained by solution viscosity having a negligible effect on the rate of drug diffusion from bulk solution to the crystal nuclei. In conclusion, the precipitation inhibition of the respective drugs is influenced by the concentration of PVP, i.e., by molecular interactions between the drug and polymer. In contrast, the molecular mobility of the drug in solution, i.e., the medium viscosity, has no influence on the precipitation inhibition of the drugs.

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

With the future of electronics focusing on reduced packing size and efficient high-power applications, ultrawide bandgap semiconductors such as β-Ga2O3 are at the forefront of modern research. The energy gap of an ultrawide bandgap semiconductor is 2 – 4 eV larger than historically common semiconducting materials. This allows for a variety of unintentionally and intentionally introduced defects and dopants to alter the behavior of the matrix material, which must be understood if any device structure is to be constructed. Once understood, engineering of the material can alter fundamental properties. Therefore, this work seeks to further the understanding of bulk single crystal growth of gallium oxide and its resultant optical, electrical, and structural properties while doped or alloyed with a variety of transition metals and metals. Electrical behavior was modulated through doping from n¬-type conduction (e.g., Zr, Hf) and semiconducting (e.g., unintentionally doped, Cr) to heavily insulating (e.g., Zn, Cu, Ni). A novel optical behavior for semiconductors, photodarkening, was also achieved with Cu- and Ni-doped β-Ga2O3. β-Ga2O3 was also studied with respect to alloying (e.g., Al, Sc), specifically to alter the size of the optical bandgap. Of course, through doping, alloying, growth, and post-growth annealing, defects are generated at the surface or in the bulk of the sample which impact electrical and optical behavior, and these were subsequently studied via Fourier transformed infrared spectroscopy as well as positron annihilation spectroscopy. These studies are contributions to the fast-paced and rapidly developing field of gallium oxide, where future work may build upon and functionalize doped or alloyed β-Ga2O3 single crystals, described within this body of work into devices which are fit for the future age of power electronics and opto-electronics.

The search for new materials and the discovery; investigation and synthesis optimization of novel compounds is a central aspect of materials science and inorganic chemistry. In this work, solid-state synthetic techniques were combined with mechanochemical and flux growth methods to optimize the synthesis in three different systems: The family of RE3Fe3Sb7 (RE = La-Nd, Sm, Gd and Tb) compounds, the bismuth telluride bromides BinTeBr (n = 2, 3) and the bismuth bromide Bi5Br4. The former raise ineterst due to their magnetic and thermoelectric properties, respectiveley. The latter represents a new phase in the binary Bi-Br phae diagram.

Crystallization kinetics of lactose at sub-zero temperatures are modelled in this paper using a population balance model. There are two competing effects on the crystallization kinetics at low temperatures. On the one hand, mass transport and the rate of both mutarotation and nucleation are reduced, reducing the crystallization rate.On the other hand, supersaturation is increased, which increases nucleation and crystal growth and thereby increases the crystallization rate. To explore this phenomenon, the crystal growth of α-lactose monohydrate at sub-zero conditions was modelled, including the effects of mutarotation and nucleation. The model is compared with experiments. It was found that stirring did not have a significant influence, indicating that the process was not limited by mass transfer. Mutarotation had a significant effect; the model showed fast depletion of α-lactose; at high lactose concentrations, the mutarotation of β-lactose could not keep up with this depletion.

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.

Crystallisation fouling is a challenge in numerous applications. To mitigate fouling we need to determine the basic mechanisms involved in the process. While ex situ techniques have been widely used in previous studies, they cannot capture complex dynamic effects. We conducted an in situ investigation of the dynamic effects of crystallisation fouling in a steel pipe (length 3 cm, diameter 3 mm) using X-ray micro-computed tomography (µCT) over more than six days. We employed a custom-developed image reconstruction algorithm, which ensured high spatiotemporal resolution from a laboratory instrument. We quantified the evolving fouling using advanced segmentation techniques of 4D images. To understand how the pipe interface structure impacts reactive transport, the experimental geometries of the flow system were used to perform computational fluid dynamic simulations. These new data allowed us to identify three growth phases: initiation, expansion, and densification

In this study, we report the successful growth of single crystals of a magnetic Weyl semimetal candidate NdAlGe with the space group I41md. The crystals were grown using a floating-zone technique, which used five laser diodes, with a total power of 2 kW, as the heat source. To ensure that the molten zone was stably formed during the growth, we employed a bell-shaped distribution profile of the vertical irradiation intensity. After the nominal powder, crushed from an arc-melted ingot, was shaped under hydrostatic pressure, we sintered the feed and seed rods in an Ar atmosphere under ultra-low oxygen partial pressure (

The maximum undercooling that has been achieved for Ni-Cu alloy, by using molten glass purification and cyclic super-heating technology, is 270 K. With the help of high-speed photography, the solidification front images of Ni-Cu alloy at various typical undercooling were obtained. Two grain refinements occurred in the range of 60 K< ΔT < 100 K and ΔT > 170 K, the solidification front became smoother, and the solidification position appeared randomly. With the increase of undercooling, the transition from solute diffusion to thermal diffusion leads to the transition from coarse dendrite to directional fine dendrite. At large undercooling, considerable stress is accumulated and some dislocations exist in the microstructure. However, the proportion of high-angle grain boundaries is as high as 89%, with twin boundaries of 13.6% and most strain-free structures, and the microhardness decreases sharply. This indicates that the accumulated stress at large undercooling causes the plastic strains in the microstructure, and in the later stage of recalescence, part of the plastic strains is dissipated by the system and acts as the driving force to promote the recrystallization of the microstructure.

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.

Cubic crystals of tripotassium aluminium (or gallium) nitridotriphosphate, K3 M III(PO3)3N (M III = Al, Ga), were grown by application of the self-flux method. In their isostructural crystal structures, all metal cations and the N atom occupy special positions with site symmetry 3, while the P and O atoms are situated in general positions. The three-dimensional framework of these oxidonitridophosphates is built up from [M IIIO6] octahedra linked together via (PO3)3N groups. The latter are formed from three PO3N tetrahedra sharing a common N atom. The coordination environments of the three potassium cations are represented by two types of polyhedra, viz. KO9 for one and KO9N for the other two cations. An unusual tetradentate type of coordination for the latter potassium cations by the (PO3)3N6– anion is observed. These K3 M III(PO3)3N (M III = Al, Ga) compounds are isostructural with the Na3 M III(PO3)3N (M III = Al, V, Ti) compounds.

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.