title: Anomalous Freezing of Nano-Confined Water in Room-Temperature Ionic Liquid 1-Butyl-3-Methylimidazolium Nitrate.
abstract: Non-crystal formation of ice is investigated by simultaneous X-ray diffraction and differential scanning calorimetry measurements upon cooling to -100 °C. At room temperature, size-tunable water confinement (≈20 Å size) in a room-temperature ionic liquid (RTIL, 1-butyl-3-methylimidazolium nitrate, [C4 mim][NO3 ]) exists in a water-rich region (70-90 mol % D2 O). The confined water (water pocket) is characterized by almost monodispersive size distribution. In [C4 mim][NO3 ]-x mol % D2 O (70<x<94), the absence of sharp Bragg reflections and a distinct exothermal peak indicate that crystallization/cold crystallization both of [C4 mim][NO3 ] and D2 O is suppressed, even upon slow cooling and heating.
authors: Department of Materials Science and Engineering, National Defense Academy, Yokosuka, 239-8686, Kanagawa, Japan. ab@nda.ac.jp.
authors: Hiroshi
authors: H
authors: Abe
authors: Department of Applied Chemistry, National Defense Academy, Yokosuka, 39-8686, Kanagawa, Japan.
authors: Takahiro
authors: T
authors: Takekiyo
authors: Department of Applied Chemistry, National Defense Academy, Yokosuka, 39-8686, Kanagawa, Japan.
authors: Yukihiro
authors: Y
authors: Yoshimura
authors: Graduate school of Environmental Engineering for Symbiosis, Soka University, Hachioji, 192-8577, Tokyo, Japan.
authors: Koji
authors: K
authors: Saihara
authors: Graduate school of Environmental Engineering for Symbiosis, Soka University, Hachioji, 192-8577, Tokyo, Japan.
authors: Akio
authors: A
authors: Shimizu
keywords: anomalous freezing; crystal polymorphs; ionic liquids; nano-confined amorphous ice; nano-confinement in liquids