Abstract
Zonal and sectorial heterogeneities in natural diamonds provide information on the growth conditions and post-growth changes. Cathodoluminescence (CL) microscopy revealed these heterogeneities in a very detailed manner with high spatial resolution. In this study, factors affecting the CL images of two natural diamonds were analyzed and the results of cathodoluminescence studies in steady-state (SS-CL) and scanning modes were compared. SS-CL was observed using an optical microscope, and scanning mode was evaluated via SEM (SEM-CL). It was demonstrated that the relative brightness of the <111> and <100> growth sectors in diamond crystals depends on the nature of defects in them and on the method of image detection (steady-state/scanning versus color/panchromatic). The differences between SS-CL and SEM-CL images can be attributed to the kinetics of luminescence and spectral sensitivity of the detectors. It was established that the nature of lattice defects around small inclusions can be changed (e.g., the intensity of blue luminescence from nitrogen-vacancy defects (N3V) decreases due to their transformation into nitrogen–hydrogen defects (N3VH). The hydrogen disproportion between the sectors is caused by different growth mechanisms. Hydrogen atoms in the diamond matrix can affect the kinetics of transformation of the defects by transforming a part of N3V to N3VH.
Highlights
Diamond is a crucial mineral for studying the subcontinental lithospheric mantle and sublithospheric horizons [1,2,3]
The difference between the steady-state CL (SS-CL) and SEM-CL images is attributed to the set of point defects, difference in the kinetics and spectra of their luminescence as well as the spectral sensitivity of the detectors
Peculiarities of the luminescence distribution between the and growth sectors are associated with different hydrogen concentrations, dislocation density, and concentration of inclusions
Summary
Diamond is a crucial mineral for studying the subcontinental lithospheric mantle and sublithospheric horizons [1,2,3]. Diamond crystals record information about their growth conditions and later processes such as deformation by retaining chemical (from uncompromised inclusions) and time–temperature (nitrogen aggregation state) [4,5,6,7,8]. Internal features reveal the complexity of the growth processes of diamonds. CL microscopy provides the most sensitive method for visualizing inhomogeneities in crystals with high resolution and contrast [9,10]. CL reveals zonal and sectorial growth heterogeneities [11,12,13], plastic deformation, and mechanical twinning layers [14,15] as well as irradiation-induced features [16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
