Many crystallization processes of great importance, including frost heave, biomineralization, the synthesis of nanomaterials, and scale formation, occur in small volumes rather than bulk solution. Here, the influence of confinement on crystallization processes is described, drawing together information from fields as diverse as bioinspired mineralization, templating, pharmaceuticals, colloidal crystallization, and geochemistry. Experiments are principally conducted within confining systems that offer well‐defined environments, varying from droplets in microfluidic devices, to cylindrical pores in filtration membranes, to nanoporous glasses and carbon nanotubes. Dramatic effects are observed, including a stabilization of metastable polymorphs, a depression of freezing points, and the formation of crystals with preferred orientations, modified morphologies, and even structures not seen in bulk. Confinement is also shown to influence crystallization processes over length scales ranging from the atomic to hundreds of micrometers, and to originate from a wide range of mechanisms. The development of an enhanced understanding of the influence of confinement on crystal nucleation and growth will not only provide superior insight into crystallization processes in many real‐world environments, but will also enable this phenomenon to be used to control crystallization in applications including nanomaterial synthesis, heavy metal remediation, and the prevention of weathering.

understanding the influence of bubble foams on magma permeability and strength is critical to investigations of volcanic eruption mechanisms. Increasing foam porosity decreases strength, enhancing the probability of an eruption. However, higher porosities lead to larger permeabilities, which can lessen the eruption hazard. Here we measure bubble size and wall thickness distributions, as well as connectivity, and calculate permeabilities and tensile strengths of basaltic foams imaged by synchrotron X-ray tomographic microscopy during bubble growth in hydrated basaltic melts. Rapid vesiculation produces porous foams whose fragmentation thresholds are only 9-10 mPa and whose permeabilities increase from approximately 1×10 − 10 to 1×10 − 9 m 2 between 10 and 14 s despite decreasing connectivity between bubbles. These results indicate that basaltic magmas are most susceptible to failure immediately upon vesiculation and at later times, perhaps only 10's of seconds later, permeability increases may lessen the hazard of explosive, basaltic, Plinian eruptions.

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The Raman spectra of alkali silicate glasses containing 5 to 30 mol % M 2 O (M = Li, Na, K, Rb, and Cs) have been fit successfully with pseudo-Voigt lineshapes of dominantly Lorentzian character in order to quantify the Q n species distributions. This differs from the more popular Gaussian lineshapes which have been used for the past four decades. There is an increase in asymmetry in the Q 3 band, with increasing M 2 O content which appears to result from the weakened Si-O force constants of some Q 3 bands due to charge transfer via M-BO bonds. With charge transfer to the tetrahedra, the negative charge accumulates preferentially on Si atoms thus decreasing Si-O Coulombic interactions, weakening Si-O force constants, and shifting the Q n A 1 symmetric stretch vibrational frequencies to lower values (eg, from ∼1100 cm −1 to ∼1050 cm −1 ). The fraction of affected Q 3 species increases with alkali content, as does the Q 3 peak asymmetry. We propose that this extends through to all the Q n species and postulate that there are multiple vibrational modes for each Q n species which are dictated by their proximity to network modifier cations.

The first comprehensive Li K-edge XANES study of a varied suite of Li-bearing minerals is presented. Drastic changes in the bonding environment for lithium are demonstrated and this can be monitored using the position and intensity of the main Li K-absorption edge. The complex silicates confirm the assignment of the absorption edge to be a convolution of triply degenerate p-like states as previously proposed for simple lithium compounds. The Li K-edge position depends on the electronegativity of the element to which it is bound. The intensity of the first peak varies depending on the existence of a 2p electron and can be used to evaluate the degree of ionicity of the bond. The presence of a 2p electron results in a weak first-peak intensity. The maximum intensity of the absorption edge shifts to lower energy with increasing SiO content for the lithium aluminosilicate minerals. The bond length distortion of the lithium aluminosilicates decreases with increasing SiO content, thus increased distortion leads to an increase in edge energy which measures lithium's electron affinity.