title: Pulse laser ablation in water fragmentation of amorphous silica in water with optional NaCI spiking.
abstract: Amorphous SiO2 powders having two kinds of medium range order (MRO) were subjected to pulse laser ablation in water (PLAL) for X-ray diffraction, transmission electron microscopy and spectroscopy characterization. The powders fragmented down to 10-20 nm in size are mainly hydrogenated amorphous phase retaining Si-2nd O but not Si-2nd Si MRO. There are minor co-existing crystallites of beta-cristobalite, H2Si2O5 as well as additional alpha-tridymite and Na2SiO3 when water is spiked with NaCI for PLAL. Na-signature also caused lower vibration frequency of the hydrogenated silica network. The opal-like hydrogenated phase assemblage of amorphous phase, cristobalite and tridymite thus formed have a minimum band gap at ca. 5 eV for potential optoelectronic and catalytic applications in UV range and shed light on natural occurrence in dynamic settings such as meteorite impact and lightening strike on silicate-enrich crustal rocks.
authors.affiliation: Department of Materials and Optoelectronic Science, National Sun Yat-Sen University Kaohsiung, Taiwan 80424, ROC.
authors.forename: Zih-Ling
authors.initials: ZL
authors.lastname: Chen
authors.forename: Chao-Hsien
authors.initials: CH
authors.lastname: Wu
authors.forename: Pouyan
authors.initials: P
authors.lastname: Shen
authors.forename: Shuei-Yuan
authors.initials: SY
authors.lastname: Chen