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We report new experimental data on the composition of magmatic amphiboles synthesised from a variety of granite (sensu lato) bulk compositions at near-solidus temperatures and pressures of 0.8–10 kbar. The total aluminium content (Al tot ) of the synthetic calcic amphiboles varies systematically with pressure ( P ), although the relationship is nonlinear at low pressures (<2.5 kbar). At higher pressures, the relationship resembles that of other experimental studies, which suggests of a general relationship between Al tot and P that is relatively insensitive to bulk composition. We have developed a new Al-in-hornblende geobarometer that is applicable to granitic rocks with the low-variance mineral assemblage: amphibole + plagioclase (An 15–80 ) + biotite + quartz + alkali feldspar + ilmenite/titanite + magnetite + apatite. Amphibole analyses should be taken from the rims of grains, in contact with plagioclase and in apparent textural equilibrium with the rest of the mineral assemblage at temperatures close to the haplogranite solidus (725 ± 75 °C), as determined from amphibole–plagioclase thermometry. Mean amphibole rim compositions that meet these criteria can then be used to calculate P (in kbar) from Al tot (in atoms per formula unit, apfu) according to the expression: P kbar = 0.5 + 0.331 8 × Al tot + 0.995 4 × Al tot 2 This expression recovers equilibration pressures of our calibrant dataset, comprising both new and published experimental and natural data, to within ±16 % relative uncertainty. An uncertainty of 10 % relative for a typical Al tot value of 1.5 apfu translates to an uncertainty in pressure estimate of 0.5 kbar, or 15 % relative. Thus the accuracy of the barometer expression is comparable to the precision with which near-solidus amphibole rim composition can be characterised.

Phase-change random-access memory (PCRAM) is one of the leading candidates for next-generation data-storage devices, but the trade-off between crystallization (writing) speed and amorphous-phase stability (data retention) presents a key challenge. We control the crystallization kinetics of a phase-change material by applying a constant low voltage via prestructural ordering (incubation) effects. A crystallization speed of 500 picoseconds was achieved, as well as high-speed reversible switching using 500-picosecond pulses. Ab initio molecular dynamics simulations reveal the phase-change kinetics in PCRAM devices and the structural origin of the incubation-assisted increase in crystallization speed. This paves the way for achieving a broadly applicable memory device, capable of nonvolatile operations beyond gigahertz data-transfer rates.

Arc magmatism is fundamental to the generation of new continental or island arc crust. However, the mechanisms that add to the chemical complexity of natural calc-alkaline magmas ranging from basaltic to rhyolitic compositions are debated. Differentiation mechanisms currently discussed include magma mixing, assimilation, crustal melting, or (fractional) crystallisation. In this contribution, the differentiation of arc magmas by decompression-driven crystallisation is investigated. We performed a set of equilibrium crystallisation experiments at variable crustal pressures (200–800 MPa) on a hydrous high-Al basalt (3.5 wt.% of H2O in the starting material) with run temperatures varying from near-liquidus conditions (1110 °C) to 900 °C. Oxygen fugacity was buffered at moderately oxidising conditions close to the NNO equilibrium. Combining these novel experiments with previous polybaric fractional crystallisation experiments (Marxer et al., Contrib Mineral Petrol 177:3, 2022) we demonstrate the effects of pressure on the crystallisation behaviour of calc-alkaline magmas with respect to liquid and cumulate lines of descent, mineral chemistry, and phase proportions. Decompression shifts the olivine-clinopyroxene cotectic curve towards melt compositions with higher normative clinopyroxene and enlarges the stability field of plagioclase. This exerts a key control on the alumina saturation index of residual liquids. We argue that near-adiabatic (or near-isothermal) decompression accompanied by dissolution of clinopyroxene entrained during residual melt extraction in the lower crust keeps arc magmas metaluminous during crystallisation-driven differentiation thereby closely reproducing the compositional spread observed for natural arc rocks.

Phase equilibria in the Al-Ta-V system have an important role for designing Al-containing refractory multiprincipal element alloys. In order to improve the available data related to this system and contribute to the development of alloys with good microstructural stability and oxidation resistance, the liquidus projection of the Al-Ta-V system is reported for the first time in the present work. The experimental investigations were carried out via microstructural characterization of thirty-one as-cast alloys using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and x-ray diffractometry (XRD). The primary solidification field of BCC is preponderant in relation to those of the other phases. No microstructural signs of phase separation were observed between the isostructural VAl 3 and ( ε )-TaAl 3 phases, which suggest a MeAl 3 solid solution connecting the Al-Ta and Al-V binary edges. Alloys in all of the primary solidification fields up to 85 at.% (BCC, σ , Ta 39 Al 69 , V 5 Al 8 , MeAl 3 ) were experimentally produced. Two class II and one type III ternary invariant reactions are suggested based on experimental data: ( U I ) Liq + σ ↔ BCC + Ta 39 Al 69 , ( U II ) Liq + Ta 39 Al 69 ↔ V 5 Al 8 + MeAl 3 and ( P I ) Liq + BCC + V 5 Al 8 ↔ Ta 39 Al 69 . Ternary invariant reactions near to the Al-rich corner are suggested based on extrapolated thermodynamic data. The reported ternary compound τ -Al 35 - 48 Ta 32 - 42 V 17 - 30 was not observed in the microstructures of the as-cast alloys obtained in the present work, suggesting that its formation occurs from a solid-state reaction.

Recent experimental observations of the onset of calcium carbonate (CaCO3) mineralization suggest the emergence of a population of clusters that are stable rather than unstable as predicted by classical nucleation theory. This study uses molecular dynamics simulations to probe the structure, dynamics, and energetics of hydrated CaCO3 clusters and lattice gas simulations to explore the behavior of cluster populations before nucleation. Our results predict formation of a dense liquid phase through liquid-liquid separation within the concentration range in which clusters are observed. Coalescence and solidification of nanoscale droplets results in formation of a solid phase, the structure of which is consistent with amorphous CaCO3. The presence of a liquid-liquid binodal enables a diverse set of experimental observations to be reconciled within the context of established phase-separation mechanisms.

Phase equilibria were investigated between 200 and 800 °C in the Cu-Zn binary system. Wavelength dispersive spectroscopy (WDS) was performed to determine the equilibrium compositions, and differential scanning calorimetry (DSC) was performed to investigate the solidus and liquidus temperatures and the invariant reaction temperatures of the Zn-rich portion. The β /( α  +  β ) boundary in the Cu-rich portion extended toward the Cu-rich side as the temperature decreased below the A2–B2 order–disorder transformation temperature, and the phase boundaries of the γ , δ and ε phases shifted toward the Cu-rich side. The liquidus temperatures of the ε  + liquid were higher than those of the previous report. From the experimental results, the phase diagram of the Cu-Zn binary system was determined in the whole composition range.

How water forms ice The various anomalous properties of water have puzzled scientists for decades, and many hypotheses have been put forward to explain their origin. One mystery is the question of what determines the lowest temperature to which water can be cooled before it freezes to ice. Rapid crystallization at low temperatures hampers experimental studies, and simulations are usually prohibitively costly in terms of computer time. Using a simple water model that allows demanding calculations, Emily Moore and Valeria Molinero now show that a sharp increase in the fraction of four-coordinated molecules in supercooled liquid water controls the rate and mechanism of ice formation. The structural change also results in a peak in the rate of crystallization at 225 K; below this temperature, ice nuclei form faster than liquid water can equilibrate. This finding explains the observed thermodynamic anomalies, and why homogeneous ice nucleation rates depend on the thermodynamics of water. One of water’s unsolved puzzles is the question of what determines the lowest temperature to which it can be cooled before freezing to ice. The supercooled liquid has been probed experimentally to near the homogeneous nucleation temperature, T H  ≈ 232 K, yet the mechanism of ice crystallization—including the size and structure of critical nuclei—has not yet been resolved. The heat capacity and compressibility of liquid water anomalously increase on moving into the supercooled region, according to power laws that would diverge (that is, approach infinity) at ∼225 K (refs 1 , 2 ), so there may be a link between water’s thermodynamic anomalies and the crystallization rate of ice. But probing this link is challenging because fast crystallization prevents experimental studies of the liquid below T H . And although atomistic studies have captured water crystallization 3 , high computational costs have so far prevented an assessment of the rates and mechanism involved. Here we report coarse-grained molecular simulations with the mW water model 4 in the supercooled regime around T H which reveal that a sharp increase in the fraction of four-coordinated molecules in supercooled liquid water explains its anomalous thermodynamics and also controls the rate and mechanisms of ice formation. The results of the simulations and classical nucleation theory using experimental data suggest that the crystallization rate of water reaches a maximum around 225 K, below which ice nuclei form faster than liquid water can equilibrate. This implies a lower limit of metastability of liquid water just below T H and well above its glass transition temperature, 136 K. By establishing a relationship between the structural transformation in liquid water and its anomalous thermodynamics and crystallization rate, our findings also provide mechanistic insight into the observed 5 dependence of homogeneous ice nucleation rates on the thermodynamics of water.

Phase equilibria in the Mn-Zn binary system were experimentally determined by chemical composition examination, crystal structure determination, and thermal analysis. Major changes were detected for the β , ε , and δ phases. The β -B2 single-phase region could not be confirmed in the studied system because a disordered body-centered cubic structure, which is identical to the δ Mn phase, was confirmed in a quenched sample from the previously proposed region of β phase. The ε phase has been controversial whether the phase is separated into ε , ε 1 , and ε 2 phases or not. By studying a diffusion couple and several alloy compositions, it was established that the ε , ε 1 , and ε 2 phases are not separate and comprise a single ε phase. Furthermore, the δ phase is not present in the Zn-rich region of the system because the corresponding invariant reactions were not detected via thermal analysis.

A sample of micaceous schist of the Cushamen Metamorphic Complex in the Cushamen area (northwestern North Patagonia, Argentina) preserves a complex mineral assemblage, including staurolite, andalusite, garnet, sillimanite, biotite, quartz, and plagioclase. This unit proves an opportunity to analyse a complex mineral association often related to disequilibrium stages or polymetamorphic contexts. Through detailed petrological analysis combining mineral chemistry, X-ray compositional maps, conventional thermobarometry, and phase equilibria analysis, we reconstructed the pressure–temperature ( P–T ) path of this schist. The schist unit preserves a polymetamorphic history characterized by M 1 , M 2 , and M 3 events. The M 1 event is represented by biotite, muscovite, quartz, and plagioclase. The M 2 event, associated with local mid-Carboniferous pluton intrusion, is characterized by andalusite and garnet assemblages, with peak conditions at ~ 3.3 kbar and ~ 563 °C. The main M 3 event, at the time of the Carboniferous–Permian boundary, is defined by garnet, staurolite, sillimanite, biotite, muscovite, plagioclase, and quartz. This event records a progressive P–T evolution from ~ 3.5 kbar and ~ 553 °C to ~ 4.9–5.6 kbar and ~ 620–635 °C, nearing peak conditions. This work highlights the importance of comprehensive approaches in P–T trajectory reconstructions and the critical role of selecting the reactive bulk composition, particularly in rocks with complex mineral assemblages. In addition, this study significantly contributes to understanding the metamorphic evolution of the Cushamen Complex, a unit for which there is limited knowledge regarding its structural and metamorphic evolution. This complex is part of the igneous-metamorphic basement of North Patagonia region (Argentina), which records the Paleozoic evolution of the southwestern margin of Gondwana. Graphical abstract Summary of the main metamorphic events with the calculated P–T conditions

Textured superhydrophobic surfaces—well known for their water-repelling properties—can be used to control the boiling state of a liquid in contact with a hot surface, suppressing the unwanted nucleation of bubbles. Boiling without the bubbles Textured superhydrophobic surfaces are well known and suitably named for their water-repelling properties. Ivan Vakarelski et al . show here that such surfaces can be used to control a very different property — the boiling state of a liquid in contact with a hot surface. They find that the hot surface can be engineered such that the system remains in the 'Leidenfrost' regime, whereby boiling takes place only in a continuous vapour film at the hot surface, rather than going through the familiar 'nucleate boiling' bubbling phase. The complete suppression of nucleate boiling could be advantageous in industrial situations in which vapour explosions are best avoided — in nuclear power plants, for instance. Textured, water-repelling surfaces might also be used to control or prevent other phase transitions, such as ice or frost formation. In 1756, Leidenfrost 1 observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling 2 . In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants 3 . The presence of these vapour films can also reduce liquid–solid drag 4 , 5 , 6 . Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling—by heat transfer—the liquid–gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation 7 , 8 , 9 , and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating 10 .