Reference materials play a crucial role for highly accurate isotope and trace element analysis of secondary ion mass spectrometry and they are used to calibrate instrumental fractionation of samples with various compositions. However, it is often a challenge to prepare natural or synthetic reference materials that are homogenous on a micron or even sub-micron scale. Dr. Yangting Lin and his group reported a novel method to synthesize homogeneous reference materials via sintering nano-crystals. Coarse-grained crystals (100-500 μm) of calcite have been grown from a starting material of 20-40 nm calcite powder at 1000°C and 1 GPa for 24 h, which is ~400°C below the liquidus line of calcite under the same pressure. The non-molten sintering process and high temperature of the experiments ensure a homogeneous composition of the synthesized calcite, which was confirmed by in situ analysis of O isotopes and trace elements P and Sr in the synthetic calcite using Cameca NanoSIMS 50L and ims 1280. Another important advantage of this method is that the compositions of the synthetic reference materials can be accurately and conveniently determined from the bulk starting materials using independent analytical techniques.

This paper was published in Journal of Analytical Atomic Spectrometry on July 25, 2014 (Link).