Early Stages Of Crystallization Research Articles

From Ions to Crystals: A Comprehensive View of the Non-Classical Nucleation of Calcium Sulfate.

The early stages of mineralization continue to be in the focus of intensive research due to their inherent importance for natural and engineered environments. While numerous observations have been reported for single steps in the pathways of various crystallizing phases in previous studies, the complexity of the underlying processes and their elusive character have left central questions unanswered in most cases. In the present work, we provide a detailed view on the nucleation of calcium sulfate mineralization-an abundant mineral with broad use in construction industry-in aqueous systems at ambient conditions. As experimental basis, a co-titration procedure with potentiometric, turbidimetric and conductometric detection was developed, allowing solution speciation and the formation of crystallization precursors to be monitored quantitatively as the level of nominal (super)saturation gradually increases. The nature and spatiotemporal evolution of these precursors was further elucidated by time-resolved small-angle X-ray scattering (SAXS) and analytical ultracentrifugation (AUC) experiments, complemented by cryogenic transmission electron microscopy (cryo-TEM) as a direct imaging technique. The results reveal how ions associate into nanometric primary species, which subsequently aggregate and develop anisotropic order by intrinsic structural reorganization. Our observations challenge the common understanding of fundamental notions such as the nucleation barrier or the meaning of supersaturation, with broad implications for mineralization phenomena in general and the formation of calcium sulfate in geochemical settings and industrial applications in particular.

Von Ionen zu Kristallen: Neue Einblicke die nicht‐klassische Keimbildung von Calciumsulfat

AbstractDie frühen Stadien der Mineralisierung stehen aufgrund ihrer inhärenten Bedeutung für Prozesse in natürlicher Umgebung sowie in technischen Anwendungen weiterhin im Fokus intensiver Forschung. Obwohl bereits viele wertvolle Beobachtungen für einzelne Schritte in den verschiedenen Phasen eines Kristallisationsvorgangs berichtet wurden, blieben wesentliche Fragen zumeist unbeantwortet aufgrund der Komplexität der zugrundeliegenden Mechanismen und des transienten Charakters der beteiligten Vor‐ und Zwischenstufen. In der vorliegenden Arbeit geben wir einen detaillierten Überblick zur Keimbildung von Calciumsulfat (einem Mineral mit großer Bedeutung für die Bauindustrie) in wässrigen Systemen bei Umgebungsbedingungen. Als experimentelle Grundlage wurde ein Titrationsverfahren mit gleichzeitiger potentiometrischer, turbidimetrischer und konduktometrischer Detektion entwickelt, um die Assoziation von Ionen in Lösung und die Bildung von Vorläuferstrukturen bei kontinuierlich ansteigender nomineller Übersättigung quantitativ verfolgen zu können. Die Eigenschaften dieser Präkursoren und ihre zeitliche Entwicklung vor und während der Nukleation wurden in situ mittels Kleinwinkel‐Röntgenstreuung (SAXS) und analytischer Ultrazentrifugation (AUC) aufgeklärt. Zusätzlich wurde Transmissionselektronenmikroskopie unter kryogenen Bedingungen (Kryo‐TEM) als bildgebendes Verfahren genutzt. Die Ergebnisse zeigen, wie sich Ionen zu nanometrischen Primärspezies verbinden, die anschließend aggregieren und durch intrinsische strukturelle Reorganisation eine anisotrope Ordnung entwickeln. Unsere Beobachtungen stellen das gängige Bild von grundlegenden Begriffen wie der Keimbildungsbarriere oder der Bedeutung der Übersättigung in Frage. Daraus ergeben sich weitreichende Auswirkungen auf unser Verständnis von Kristallisationsphänomenen im Allgemeinen und der Bildung von Calciumsulfat in geochemischen und angewandten Systemen im Besonderen.

Crystallization-Controlled Structure and Thermal Properties of Biobased Poly(Ethylene2,5-Furandicarboxylate).

Crystallization-controlled structure and thermal properties of biobased poly(ethylene 2,5-furandicarboxylate) (PEF) were studied. The cold-crystallization temperature controlled the structure and thermal properties of the biobased PEF. The melting was complex and evidenced the presence of a significant fraction of less-stable crystals with a low melting temperature that linearly increased with Tc, which formed already during the early stages of crystallization, together with those melting at a higher temperature. Low Tc resulted in the α'-phase formation, less crystallinity, and greater content of the rigid amorphous phase. At high Tc, the α-phase formed, higher crystallinity developed, the rigid amorphous phase content was lower, and the melting temperature of the less-stable crystals was higher; however, slight polymer degradation could have occurred. The applied thermal treatment altered the thermal behavior of PEF by shifting the melting of the less stable crystals to a significantly higher temperature. SEM examination revealed a spherulitic morphology. A lamellar order was evidenced with an average long period and small average lamella thickness, the latter about 3-3.5 nm, only slightly increasing with Tc.

Measuring Oxygen Solubility in Amorphous and Semicrystalline Polyolefins Using Test Particle Insertion: A Comparative Study of Polyethylene and Isotactic Polypropylene.

The test particle insertion method is used to study the solubility of oxygen in two commonly used polymers: polyethylene (PE) and isotactic polypropylene (iPP). Amorphous samples for both polymers were prepared by means of Monte Carlo and molecular dynamics simulations, and the oxygen solubility was measured across different temperatures. The solubility-temperature dependence for iPP proved to be nonmonotonic due to the interplay between binding and reorganizational enthalpy, while for PE, it appeared to be monotonic based on the available data in the studied temperature range. A broad comparison to experiments and simulations is included. Further oxygen insertions were also performed in semicrystalline PE and iPP samples at ambient temperature, and the obtained values were compared to a linear relationship which correlates the solubility in the purely amorphous phase with the solubility in the crystalline phase. The solubility of PE closely follows the linear relationship, while iPP exhibits some divergence. All the semicrystalline samples were previously annealed at elevated temperatures for long periods (a few μs), and a strong effect of annealing was observed on the structure and the solubility of iPP. A well-developed iPP lamellar structure emerged at longer annealing times, while PE develops that structure already in the early crystallization stages. The solubility of semicrystalline iPP samples with lamellar morphology exhibited better agreement with extrapolated solubility values of the amorphous state─the extrapolation was made using a linear relationship connecting solubility in the purely amorphous phase and solubility in mixed phases (amorphous and crystalline). Results on the correlation of the solubility with the local structural ordering are also present.

Re-evaluating the diffusivity of phosphorus in olivine: Implications of low diffusive mobility for thermochronology

Heterogeneities in the phosphorus (P) content of olivine are relatively resistant to diffusive homogenization when compared with other compositional heterogeneities. Thus, heterogeneities in the spatial distribution of P can preserve petrological information about olivine crystals from the earliest stages of crystallization which have been otherwise eliminated. However, compared to independent determinations of protracted cooling timescales in slowly cooled rocks, P enrichments are so sharp as to suggest a rate of diffusive mobility that is many orders of magnitude slower than previously suggested. Here, we heat single natural olivine crystals with sharply defined P heterogeneities (0.02–0.15 wt% P2O5 over 0.5 μm spatial scale) in a 1-atmosphere gas-mixing furnace for durations of 10–20 days at 1400°C, thus exposing them to conditions that should be sufficient for complete diffusive relaxation according to published P diffusivity values. However, high-precision chemical analysis of the same interior section before and after heating reveals no discernable difference in the sharpness of phosphorus concentration patterns. Therefore, diffusion chronometry applied to skeletal P enrichments in olivine currently provides erroneously short diffusive timescales. We discuss several possible causes for these discrepancies and the implications for diffusion chronometry as applied to phosphorus in olivine.

The role of deformation on the early crystallization and rheology of basaltic liquids

This study highlights the rheological variation of magmatic systems during the early crystallization stage, which undergoes very different shear stress. Etna basaltic glass, made from natural rock powder, was used as a starting material. Nine shear rate-controlled experiments were conducted at 1150 °C (below liquidus temperature and undercooling degree ΔT ∼ 40 °C) with shear rates (γ˙) of 0.1, 1 and 10 s−1 using wide-gap concentric cylinder viscometry. Three additional experiments were conducted without spinning the melts (no shear, γ˙= 0 s−1). Run-products were collected after 3, 6 and 9 h. The experiment with the highest shear rate (γ˙=10s−1) showed a brittle failure when viscosity reached the value of 2.90 log (Pa·s) and after ca. 1150s. The measured viscosity matches the shear stress at 7244 Pa, corresponding to the brittle failure in our partly crystallised system at these conditions. After 9 h, the response of the partly crystallised Etna basalt to different deformation rates results in decreasing viscosity from 4.89 to 3.83 and 2.90 (log Pa s) as the γ˙ increases from 0.1 to 1 and 10 s−1, respectively. The main outcome of this study relates to the nucleation and growth of minerals with shear deformation. The deformation-free (γ˙ = 0 s−1) runs show the presence of only two phases: glass and Fe-oxides (Fe-ox) with only a few vol% (1–3) of oxides crystals after 3, 6 and 9 h. The deformation-bearing (γ˙ = 0.1, 1 and 10 s−1) runs show different scenarios: after 3 h, we observed only Fe-ox for a γ˙ of 0.1 s−1 (similar to deformation-free ones). As the shear rate increases to 1 s−1 and 10 s−1, solid phases after 3 h experiments are Fe-ox, plagioclase and clinopyroxene. Crystal growth rate depends on the applied shear rate: the highest rate is 1.1 × 10−6 cm/s and was measured for plagioclase after a 3 h experiment for γ˙ = 10 s−1. At γ˙ = 0.1 s−1, the plagioclase growth rate decreases to 2.70 and 1.35 × 10−6 cm/s as experimental time increases from 6 to 9 h, respectively. The vast range of shear stress and the systematic data obtained in this study are fundamental to deciphering crystallization dynamics suffered by magmas in volcanic reservoirs, dikes, conduits and lavas.

Growth process of boehmite with large particles in ammonia system

The development of a novel technology for extracting aluminum resources from coal fly ash through direct leaching with an ammonium hydrogen sulfate solution represents a significant advancement. A pivotal stage within this process is the reaction crystallization between NH4Al(SO4)2·12H2O solid and NH3·H2O. Despite its many benefits, the fine particle size of the resultant product has impeded its widespread adoption. To tackle this challenge, this study concentrated on examining the growth mechanism of boehmite with larger particles in the presence of ammonia. Analysis revealed a distinct morphological evolution process for large-particle boehmite, progressing from a flaky morphology to a flower-like nanostructure with flaky features, and then further transitioning into particles displaying flower-like nanostructures and culminating in the formation of large particles with smooth surfaces. Initially, the early stages of crystallization were governed by kinetic factors, followed by a self-assembly phase, ultimately resulting in the final morphology of large particles, dictated by thermodynamic considerations. Density functional theory calculations underscored the significant role of H2O molecule adsorption in boehmite's growth trajectory, leading to the formation of pseudo-boehmite and inducing shifts in the X-ray diffraction peaks. The growth units remained integral throughout the entirety of the crystal growth process.

A study of crystallized behavior, microstructure and magnetic properties of new Co28Fe28Ni19Si13B8Cu1Nb1Mo2 high-entropy metallic glass

The crystallized behavior, microstructure and magnetic properties of Co28Fe28Ni19Si13B8Cu1Nb1Mo2 high-entropy metallic glass are studied by DSC, XRD, TEM and VSM. The results show that two crystallization peaks occur with a difference of approximately 129–149 K, but the activation energy is different. The activation energy of the first peak is 175.3 kJ/mol and the second is that of 460.1 kJ/mol. After annealing, the Co7Fe3 phase first precipitates with a feature of three-dimensional growth. When the annealing temperature is higher than the second crystallization temperature, the phases such as (Fe,Ni,Mo)23B6, Co3Mo2Si, Co4B, Fe3Mo precipitate sequentially, meanwhile Cu accumulates into small clusters to provide heterogeneous nucleation centers for the crystalline phase in the early stage of crystallization. Finally, the Hc increase with temperature, and the Ms first increasing and then decreasing with the maximum value of 93.11 emu/g at 893 K.

Resolving the early-stage nucleus structure and evolution in atomic systems

Nucleation underpins a vast range of phase-transition phenomena in many disciplines. Critical to revealing nucleation thermodynamics and kinetics is the understanding of the nucleus structure at its early stage. Typically, it is assumed that nucleation is a sudden local structural transition from one phase to another. Here, we are able to access fundamental steps in the nucleation from amorphous phase by a combination of molecular simulations and experimental observation. We discover a surprising pathway of semicrystalline nucleation where one of the materials components crystallizes and another remains amorphous between the crystalline planes in the nuclei. The early-stage crystallization nucleus is robustly evidenced to undergo a gradual ordering and densification, originating from the presence of diffuse interfaces, and renders an ultralow interfacial energy that is orders of magnitude lower than those typically used in various formulations of nucleation. Our study provides critical information and insight for the early stages of nucleation that determine how crystallization is initiated and benefits controllable synthesis of materials.

Syntectonic Shear-induced Emplacement of Crystallizing Granite Magmas Evident from Magmatic Shear Sense, Mafic Schlierens, and Microgranular Enclaves in the Mesoproterozoic A-type Kanigiri Pluton, Nellore Schist Belt, Southeast India

ABSTRACT The observations on field-based mesoscale magmatic structures suggest that the A-type Kanigiri granite (KG) pluton, Nellore Schist Belt (NSB) has undergone a long plutonic history as evidenced by the continuum of deformation from early magmatic to the ductile regime at the waning stage of pluton evolution. The linear alignment of the KG pluton, which lies sub-parallel to the regional Terrane Boundary Shear Zone (TBSZ), and the long-standing deformation regime indicate the genetic link with this shear zone. The formation of mafic schlierens in the KG pluton owes to the mechanical crystal flow-sorting process during the replenishment of KG magma, which is further induced by the injection of crystal-charged microgranular enclave (ME) magmas in the crystallizing felsic magma chamber. The outflown ME magma blobs from the walls of the conduit during the invasion trigger the local turbulence, resulting the swirling of early crystallized mafic crystals of the host KG magma. This kind of swirling in the host KG magma must have been formed at an early stage of crystallization i.e., crystal-poor condition of the KG melts. When the MEs flow out, gravity causes them to interact with the host KG magma and attempt to dissolve into it. This results in schlieren rims formed around the MEs. The magmatic shearing observed in the KG pluton results from an active crystal-mush environment due to accumulated strain caused by the syntectonic movement as evidenced by the magmatic sense of shears. The locally formed slickensides are sub-magmatic origin during the upward pushing of replenishing ME and another pulse of KG magma. The presence, spread and prevalence of magmatic structures like ME magma globules, magma flowage, mafic schlierens, slickensides and shear sense indicators in the KG pluton suggest that the KG pluton underwent dynamic magma emplacement and evolution due to a shear zone, probably the TBSZ, which acted upon KG pluton in a syntectonic environment.

Studying crystallisation processes using electron microscopy: The importance of sample preparation.

We present a comparison of common electron microscopy sample preparation methods for studying crystallisation processes from solution using both scanning and transmission electron microscopy (SEM and TEM). We focus on two widely studied inorganic systems: calcium sulphate, gypsum (CaSO4·2H2O) and calcium carbonate (CaCO3). We find significant differences in crystallisation kinetics and polymorph selection between the different sample preparation methods, which indicate that drying and chemical quenching can induce severe artefacts that are capable of masking the true native state of the crystallising solution. Overall, these results highlight the importance of cryogenic (cryo)-quenching crystallising solutions and the use of full cryo-TEM as the most reliable method for studying the early stages of crystallisation.

Subduction-related mafic-silicic magmatism in the Nubian Shield: Tectono-magmatic implications of ensialic island arc association at Central Eastern Desert, Egypt.

For the Wadi El Mayet, the metagabbro-granodiorite-tonalite intrusive complex (MIC) occupies the eastern sector of famous wadi Mubarak–Dabr complex which considered as the largest intrusion in the Egyptian Eastern Desert. The basement associations in the area include volcano-sedimentary rocks, metavolcanics, and ultramafics. The whole successions were intruded by MIC, and granites. The (MIC) comprises multifarious gabbroic varieties namely: olivine, pyroxene, hornblende, uralitized gabbros and rare amphibolites, while silicic portion includes tonalite and granodiorite. Microprobe analytical chemistry of gabbros and granites refers that: the amphiboles are calcic magnesio hornblende formed at low pressure conditions. Chlorites have corundophillite composition. Plagioclase range between labradorite, andesine and oligoclase. Biotite is mainly siderophylite. Muscovite minerals are mainly cheladonite. Geothermo-barometers calculations reveal crystallization temperatures of 550 °C and 860 °C for granites and metagabbros respectively. The (MIC) cover a wide silica range (44.5–74.5 wt %). It has transitional tholeiitic to calc-alkaline magmas. The gabbroic rocks show distinct fecundity with LILE (e.g. Rb, Ba, U and Th), but show observed shortage in most HFSE (e.g. Zr, Nb, Ta). The REE patterns show enrichment in light REE and posse variably positive Eu. It is suggested that, the gabbroic units were likely generated by fractional crystallization of mafic magmas produced through partial melting of metasomatized mantle within island-arc environments. Tonalite - granodiorite (TG) suite show calc-alkaline magmas of I-type settings. They also exhibit enrichment in Ba, Zr, Hf, Rb, U and Th, while P, Nb, Ta and Sr are depleted. Such reductions are harmonious with fractionation of K-feldspar phases. The (TG) show enrichment of (LREE) compare to (HREE) this proposes either the existence of persistent garnet or LREE fertile magma sources. The (TG) is believed to be formed through dehydration melting processes at lower crust settings. Based on the field, geochemistry and structure elements, the investigated mafic and silicic suites are not linked to a single magma origin. The (MIC) can be comparable with intrusions formed in ensialic island-arcs settings. At subduction zone integration between mantle (basaltic suites) and silicic magmas from lower crust forming the early stages of (MIC) crystallization. The whole association was suffered by insignificant fractionation processes and addition of crustal materials during the final stages of (MIC) emplacement.

Changes in the structure of the amorphous phase under heat treatment and deformation

The influence of heat treatment and deformation on the change in the structure of amorphous alloys Co67Fe7Si12B9Nb5, Al87Ni8Y5, Al88Ni6Y6, Al87Ni8Gd5, Al87Ni8La5, Zr50Cu15Ti16Ni19 obtained by melt quen-ching has been studied. It has been established that both heat treatment and deformation lead to the for-mation of a heterogeneous structure, while structure inhomogeneities can be due to formation the regions both with different concentrations of components (during heat treatment) or/and with different density (free volume concentration). At the early stages of crystallization, the phase composition of the emerging struc-ture depends on the type of impact on the amorphous structure and processing parameters (temperature, type and degree of deformation). The sizes of nanocrystals and the fraction of the nanocrystalline component depend on the prehistory of the sample.

Structure evolution of porous alumina during aging process and its support effect on PtSn/Al2O3 catalyzed propane dehydrogenation

Precise control of porous alumina microstructures is always challenging due to the diversity and complexity of the growth process-related alumina crystalline phase and surface properties. In this work, we established a bottom-up synthesis route with a combination of rapid precipitation at high supersaturation and high-temperature aging in terms of enhancing particle aggregation kinetics. Surprisingly, we discovered that there were two distinct growth stages of alumina precursor (ammonium aluminum carbonate hydroxide) during the aging procedure, that is, oriented attachment at the early stage of crystallization and subsequent Oswald ripening. High-temperature aging can effectively strengthen the aggregation kinetics between the particles and produce large mesoporous (∼16 nm) and a remarkable number of defect sites with the exposure of up to 14 % unsaturated pentacoordinate aluminum ions. Owing to the presence of strong metal-support interactions, the alumina-supported PtSn catalyst exhibited excellent catalytic activity in the propane dehydrogenation reaction with propylene formation with 99 % selectivity and superior stability with a low deactivation rate of 0.007 h−1 over 24 h. These results suggested that it was feasible and instructive to achieve precise control of the structure and surface properties of alumina by manipulating the aggregation process of the initial particles during the aging stage.

Monte Carlo simulation of the crystallization of polyethylene nanocomposites with different shape nanofillers

Monte Carlo simulation of coarse-grained models of polyethylene (PE) nanocomposites was developed to study the effect of nanofiller shapes (nanosphere, nanoplate and nanostick) on the early stage of polymer crystallization under stepwise cooling from the melts. The “polymer forcefield” to describe intra- and intermolecular interaction is composed of the rotational isomeric state (RIS) model of PE and the Lennard-Jones (LJ) potential energetics of ethylene units, respectively. Carbon-based nanofillers were used such that polymer-nanofiller interaction was treated using the same LJ parameters as polymer–polymer interaction. The content of trans conformation and the chain/bond order parameter were determined to quantify the degree of polymer crystallization. Simulation suggests that PE nanocomposites filled with nanostick and nanoplate tend to induce earlier crystalline formation and have more ordered structures, especially nanocomposites with nanoplate filler. In contrast, PE nanocomposites filled with nanosphere exhibit slower crystallization with a lower amount of trans fraction and, as a result, form less ordered structures.

Effects of sodium chloride crystallization on shear characteristics of road base aggregates under unsaturated state

The precipitation and intrusion of sodium chloride into pavement structures is inevitable in coastal regions, which can affect the mechanical properties of the road base courses. To investigate this problem, samples with sodium chloride solution were cured in a thermostatic chamber until they reached the specified states of sodium chloride precipitation within the pores. A critical crystallization degree ( ωc) was discovered by computerized tomography scan, corresponding to the start of the formation of porous salt crust cementing the soil particles. A series of unsaturated large-scale triaxial shear tests were then conducted under various states of salt crystallization. The results showed that in the early stages of crystallization (i.e., ω < ωc), the peak stress and internal friction angle decreased with ω because of the coating and lubricating effects of salt powders, while the apparent cohesion remained constant. When ω > ωc, owing to the increasing adsorption and cementation effects of the salt crust, rapid growth was observed for the peak stress, internal friction angle, and apparent cohesion of the road base aggregates. Considering the influence of salt precipitation, a modified shear strength criterion that can predict the shear strength of the salinized road base aggregates was formulated.

Transition Metal Dichalcogenide WS2 Films Prepared with a Combination of Spin/Dip Coating and CVD

Recently, transition metal dichalcogenides (TMDCs) with 2D structure have attracted interest due to their many unique optical and electrical properties. The primary preparation methods for 2D materials are chemical vapor deposition (CVD), exfoliation, and other vacuum technologies. Large-scale synthesis of WS2 via solution-process is rare due to the higher temperature needed for tungsten-based precursors. Combination of spin coating or dip coating with CVD have been studied recently to make large-area 2D TMDC with good electrical properties. Here, we report a new synthetic route for large WS2 crystal that combined solution coatings and CVD process. A solution of sodium tungstate and hydrazine hydrate with sodium thiosulphate was coated on a silicon wafer via dip and spin coating. The films were then treated with CVD at various positions and temperatures to facilitate crystallization. The double coating conditions and CVD parameters were modified to obtain WS2 crystals. Triangular shaped 44 ± 4 µm WS2 crystals could be obtained with simple annealing above 900oC without gas treatment. The synthesized WS2 was found to be bulk with a triangular shape, as confirmed by Raman and AFM analyses. A PL peak of WS2 at 643 nm was observed at an early crystallization stage.

Heat Transport and Convective Velocities in Compositionally Driven Convection in Neutron Star and White Dwarf Interiors

We investigate heat transport associated with compositionally driven convection driven by crystallization at the ocean–crust interface in accreting neutron stars, or growth of the solid core in cooling white dwarfs. We study the effect of thermal diffusion and rapid rotation on the convective heat transport, using both mixing length theory and numerical simulations of Boussinesq convection. We determine the heat flux, composition gradient, and Péclet number, Pe (the ratio of thermal diffusion time to convective turnover time) as a function of the composition flux. We find two regimes of convection with a rapid transition between them as the composition flux increases. At small Pe, the ratio between the heat flux and composition flux is independent of Pe, because the loss of heat from convecting fluid elements due to thermal diffusion is offset by the smaller composition gradient needed to overcome the reduced thermal buoyancy. At large Pe, the temperature gradient approaches the adiabatic gradient, saturating the heat flux. We discuss the implications for cooling of neutron stars and white dwarfs. Convection in neutron stars spans both regimes. We find rapid mixing of neutron star oceans, with a convective turnover time of the order of weeks to minutes depending on rotation. Except during the early stages of core crystallization, white dwarf convection is in the thermal-diffusion-dominated fingering regime. We find convective velocities much smaller than recent estimates for crystallization-driven dynamos. The small fraction of energy carried as kinetic energy calls into question the effectiveness of crystallization-driven dynamos as an explanation for observed magnetic fields in white dwarfs.

Solvent and A-Site Cation Control Preferred Crystallographic Orientation in Bromine-Based Perovskite Thin Films.

Preferred crystallographic orientation in polycrystalline films is desirable for efficient charge carrier transport in metal halide perovskites and semiconductors. However, the mechanisms that determine the preferred orientation of halide perovskites are still not well understood. In this work, we investigate crystallographic orientation in lead bromide perovskites. We show that the solvent of the precursor solution and organic A-site cation strongly affect the preferred orientation of the deposited perovskite thin films. Specifically, we show that the solvent, dimethylsulfoxide, influences the early stages of crystallization and induces preferred orientation in the deposited films by preventing colloidal particle interactions. Additionally, the methylammonium A-site cation induces a higher degree of preferred orientation than the formamidinium counterpart. We use density functional theory to show that the lower surface energy of the (100) plane facets in methylammonium-based perovskites, compared to the (110) planes, is the reason for the higher degree of preferred orientation. In contrast, the surface energy of the (100) and (110) facets is similar for formamidinium-based perovskites, leading to lower degree of preferred orientation. Furthermore, we show that different A-site cations do not significantly affect ion diffusion in bromine-based perovskite solar cells but impact ion density and accumulation, leading to increased hysteresis. Our work highlights the interplay between the solvent and organic A-site cation which determine crystallographic orientation and plays a critical role in the electronic properties and ionic migration of solar cells.

Formation of High-Silica Leucocratic Granitoids on the Late Devonian Peraluminous Series of the Russian Altai: Mineralogical, Geochemical, and Isotope Reconstructions

This paper presents data on the geological position, geochemical features, main mineral composition (micas, feldspars), and melt and fluid inclusions in quartz from Aba high-silica leucocratic granitoids in the western part of the Talitsa batholith, Russian Altai. According to these new geochemical data, the granitoids are classified as S-type, meaning they are formed via the partial melting of metasedimentary source rocks. Geological data and oxygen isotope composition analysis indicate that major-phase granitoid magma evolution took place at the level of intrusion formation, whereas the parent melt of late-phase leucogranite evolved in a deeper chamber. The geochemical features (HFSE and REE, and REE spectra) of the granitoids indicate significantly higher differentiation in the late leucocratic phase. The presence of coexisting syngenetic melt and fluid inclusions shows that leucogranite magma was already saturated with volatiles in the early crystallization stages. Based on the new data presented in this work, the Aba rock formation is associated with the volatile saturation of magmatic melts, the exsolution of a fluid phase, and magma degassing.