Vibrational spectroscopy of the borate mineral kotoite Mg3(BO3)2

Abstract

Vibrational spectroscopy has been used to assess the structure of kotoite a borate mineral of magnesium which is isostructural with jimboite. The mineral is orthorhombic with point group: 2/m 2/m 2/m. The mineral has the potential as a new memory insulator material.The mineral has been characterised by a combination of Raman and infrared spectroscopy.The Raman spectrum is dominated by a very intense band at 835cm−1, assigned to the symmetric stretching mode of tetrahedral boron. Raman bands at 919, 985 and 1015cm−1 are attributed to the antisymmetric stretching modes of tetrahedral boron.Kotoite is strictly an hydrous borate mineral. An intense Raman band observed at 3559cm−1 is attributed to the stretching vibration of hydroxyl units, more likely to be associated with the borate mineral hydroxyborate. The lack of observation of water bending modes proves the absence of water in the kotoite structure.