Spectroscopic study of impurities and associated defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) meteorites

TL;DR

This study uses spectroscopic techniques to analyze impurities and defects in nanodiamonds from meteorites, revealing similarities to synthetic nanodiamonds and identifying silicon-vacancy defects for the first time.

Contribution

It provides new insights into the defect structures and nitrogen environment in meteoritic nanodiamonds, including the first observation of silicon-vacancy complexes.

Findings

Nitrogen in MND is mainly associated with lattice imperfections.

MND nitrogen concentration is low and similar to synthetic nanodiamonds.

Silicon-vacancy defects are observed in MND for the first time.

Abstract

The results of spectroscopic and structural studies of phase composition and of defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) chondrites indicate that nitrogen atomic environment in meteoritic nanodiamonds (MND) is similar to that observed in synthetic counterparts produced by detonation and by the Chemical Vapour Deposition (CVD)-process. Most of the nitrogen in MND appears to be confined to lattice imperfections, such as crystallite/twin boundaries and other extended defects, while the concentration of nitrogen in the MND lattice is low. It is suggested that the N-rich sub-population of MND grains may have been formed with high growth rates in environments rich in accessible N (i.e., N in atomic form or as weakly bonded compounds). For the first time the silicon-vacancy complex (the "silicon" defect) is observed in MND by photoluminescence spectroscopy.