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Miniaturization of semiconductor devices has made structures more fragile, leading to potential collapses due to capillary forces during drying after wet cleaning. This has hampered the integration of transistors according to Moore's law. We have developed a method for preparing nanopillars in a liquid cell and have successfully observed their collapse by means of a crosssectional view in transmission electron microscopy. The dynamics of collapse as a result of capillary interactions involve two steps. First, the nanopillars collapse due to an imbalance in capillary forces caused by a difference in liquid levels at the gas-liquid interface. Second, a liquid pool formed between nanopillars maintains the collapsed state of the nanopillars through surface tension. The nanopillars recover on reimmersion in the liquid after the collapse. This method is effective, and is expected to contribute to the continued development of miniaturization and three-dimensionality of semiconductors.

Experimental confirmation of liquid polymorphs of water, high-density liquid (HDL) and low-density liquid (LDL), is desired for understanding not only the liquid state of matter but also the origin of the mysterious properties of water. However, this remains challenging because the liquid-liquid critical point of water lies in experimentally inaccessible supercooling conditions known as "no man's land". Here, we show by

The mode-coupling theory of glass transition predicts the relaxation time divergence of glass-forming materials at the crossover temperature, which is approximately 1.2 times the calorimetric glass transition temperature. However, this divergence has not been experimentally observed. This is known as the most serious drawback of the mode-coupling theory. The use of viscosity-sensitive single molecule fluorescence probes enables the detection of the poly(vinyl acetate) and poly(ethyl methacrylate) relaxation time enhancement around the crossover temperature, thereby supporting the prediction by the mode-coupling theory.

Multistep pathways in nucleation are now known to be ubiquitous and thus crucial to understand crystal formation processes. In a supersaturated mother phase, many types of source molecules are coagulated to form an amorphous or liquid-like intermediate, which subsequently transforms to a crystal. Such an intermediate possibly has a chemical formula that is inconsistent with that of the bulk crystal. Even in relatively simple vapor-phase homogeneous nucleation, the roles of the multicomponent mixtures at the nanoscale remain unknown. Here, by combining an experimental approach using in situ infrared (IR) measurements of homogeneous nucleation in the vapor phase and automatic quantum-chemical explorations of reaction routes, we show that a liquid-like nature of nucleating nanoparticles in the Al–O binary system induces immiscible phase separation. In an oxygen-deficient atmosphere, aluminum oxide nanoparticles form from supersaturated vapor with a unique shape composed of an Al metal head and an anisotropic...

Multiple pathways in crystal nucleation are now known to be more common than previously predicted; it is, therefore, crucial to understand the early stages of crystallization. Even in relatively simple vapor-phase homogeneous nucleation, the process has significant potential diversity. Here, we experimentally show crystalline Al2O3 nanoparticles forming via precisely two steps in the nucleation process from supersaturated vapor with a moderate cooling rate. In situ FT-IR measurement of nucleation allowed us to observe the formation of Al2O3 nanoparticles. Liquid-like particles first nucleated from the vapor before crystallizing. The crystalline phase was preserved by quenching without further transformation into the most stable α-Al2O3 polymorph. The precipitated phase changed from δ-Al2O3 for pure Al2O3 to γ-Al2O3 or θ-Al2O3 by adding Sb or Cr, respectively. We demonstrate that a two-step process occurs in homogeneous nucleation of refractory materials from supersaturated vapor, which may facilitate poly...

Chiral symmetry breaking in NaClO3 crystallization from an aqueous solution with perturbations has been of great interest. To understand the mechanism, several models focusing on the early stage of the crystallization have been proposed. However, they are ambiguous because the early stage has been barely explored directly. Here, we investigate the early stages of the crystallization process driven by droplet evaporation using a combination of direct in situ microscopic observations and cryogenic single-crystal XRD experiments. We demonstrate that an achiral crystal having P21/a symmetry, which is newly discovered for a solution growth, first appears in the droplet and then transforms into the chiral crystals. Additionally, determination of the lattice constants by XRD experiments (a = 8.42 A, b = 5.26 A, c = 6.70 A, β = 109.71°) revealed that the achiral phase should be identical to Phase III (a = 8.78 A, b = 5.17 A, c = 6.83 A, β = 110°), which is a high-temperature phase from a melt growth of NaClO3. We...