title: Nano-scale synthesis of the complex silicate minerals forsterite and enstatite.
abstract: Olivine is a relatively common family of silicate minerals in many terrestrial and extraterrestrial environments, and is also useful as a refractory ceramic. A capability to synthesize fine particles of olivine will enable additional studies on surface reactivity under geologically relevant conditions. This paper presents a method for the synthesis of nanocrystalline samples of the magnesium end-member, forsterite (Mg2SiO4) in relatively large batches (15-20g) using a sol-gel/surfactant approach. Magnesium methoxide and tetraethylorthosilicate (TEOS) are refluxed in a toluene/methanol mixture using dodecylamine as a surfactant and tert-butyl amine and water as hydrolysis agents. This material is then cleaned and dried, and fired at 800°C. Post-firing reaction in hydrogen peroxide was used to remove residual organic surfactant. X-ray diffraction showed that a pure material resulted, with a BET surface area of up to 76.6m2/g. The results of a preliminary attempt to use this approach to synthesize nano-scale orthopyroxene (MgSiO3) are also reported.
authors.affiliation: Chemical Sciences Division, MS 6110, P.O. Box 2008, Bldg. 4100, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6110, USA. Electronic address: anovitzlm@ornl.gov.
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Anovitz
authors.affiliation: Center for Nanophase Materials Science Division, MS 6494, P.O. Box 2008, Bldg. 8610, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6494, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Rondinone
authors.affiliation: Chemical and Engineering Materials Division, MS 6454, P.O. Box 2008, Bldg. 8600, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6454, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Sochalski-Kolbus
authors.affiliation: Chemical Sciences Division, MS 6110, P.O. Box 2008, Bldg. 4100, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6110, USA.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Rosenqvist
authors.affiliation: Chemical Sciences Division, MS 6110, P.O. Box 2008, Bldg. 4100, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6110, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Cheshire
keywords: Clinopyroxene; Enstatite; Forsterite; Nanosynthesis; Olivine; Orthopyroxene; Pyroxene