Thermal history of diamond from Arkhangelskaya and Karpinsky-I kimberlite pipes
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-07-26 |
| Journal | Journal of Mining Institute |
| Authors | E. A. Vasilev, G. Yu. Kriulina, Victor Garanin |
| Institutions | Saint Petersburg Mining University, Institute of Mineralogy |
| Citations | 7 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study provides a comprehensive spectroscopic and morphological analysis of 650 natural diamond crystals from the Arkhangelskaya and Karpinsky-I kimberlite pipes to define their thermal history and growth conditions.
- Unique Thermal History: Diamonds from both pipes exhibit evidence of extremely low natural annealing temperatures/durations, a unique feature compared to other deposits. This is supported by the high frequency of low-temperature hydrogen-containing defects (3050-3310 cm-1 bands).
- Nitrogen Characteristics: Both deposits show low nitrogen aggregation (NBs less than 20% for the majority of crystals) and unimodal total nitrogen (Ntot) distributions (800-1400 ppm range).
- N3 Defect as Indicator: The nitrogen-vacancy N3 center (415 nm absorption) is detected in 35% (Karpinsky-I) to 47% (Arkhangelskaya) of crystals. The presence of N3 strongly correlates with octahedral habit and complex thermal histories, indicating growth via the tangential mechanism.
- Morphological Dominance: Dodecahedroids (dissolution forms) dominate the collections (50-60%), while crystals retaining octahedral habit (or transitional forms with striation) account for about 15%.
- Population Identification: Based on morphology, defect concentration, and thermal history indicators (N3, Bâ band, H-defects), three distinct populations of crystals were identified, confirming a multi-stage formation process for these deposits.
- Spectroscopic Diversity: The Bâ band (indicating aggregated nitrogen) is present in 78% of Karpinsky-I and 62% of Arkhangelskaya samples, while the N3 system is active in photoluminescence (PL) spectra, often dominating blue luminescence in octahedra.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Total Sample Size | 650 | crystals | 350 Arkhangelskaya, 300 Karpinsky-I |
| Crystal Size Range | 3 - 5 | mm | Size of crystals studied |
| Ntot (Karpinsky-I Peak Range) | 1050 - 1200 | ppm | Total nitrogen concentration (unimodal distribution) |
| Ntot (Arkhangelskaya Peak Range) | 900 - 1050 | ppm | Total nitrogen concentration (unimodal distribution) |
| Nitrogen Aggregation (NBs) | < 30 | % | Over 90% of Karpinsky-I crystals |
| N3 Absorption Detection | 35 / 47 | % | Karpinsky-I / Arkhangelskaya crystals |
| Bâ Band Detection | 78 / 62 | % | Karpinsky-I / Arkhangelskaya samples |
| Low-Temperature H-Defect Bands | 3050, 3144, 3154, 3188, 3310 | cm-1 | Hydrogen-containing defects (lowest temperature form) |
| N3 Zero-Phonon Line Peak | 415 | nm | Visible absorption spectrum |
| Minimum Detectable N3 Absorption | 0.01 | cm-1 | Absorption coefficient (αN3) |
| IR Spectroscopy Resolution | 2 | cm-1 | VERTEX-70 Fourier spectrometer setting |
| PL Spectroscopy Temperature | 77 | K | Low-temperature measurements |
Key Methodologies
Section titled âKey MethodologiesâThe study employed a comprehensive, non-destructive spectroscopic approach combined with morphological analysis:
- Morphological Classification: Crystals were categorized based on dominant growth mechanism (tangential {111} or normal {100}) and dissolution degree (octahedra, cuboids, dodecahedroids, tetrahexahedroids).
- Infrared (IR) Absorption Spectroscopy:
- Instrument: Bruker VERTEX-70 Fourier spectrometer with Hyperion1000 microscope.
- Analysis: Calculated total nitrogen concentration (Ntot) and the proportion of nitrogen aggregated into B defects (NBs). Determined absorption coefficients for the Bâ band (αBâ) and the N3VH defect band (α3107).
- UV-Visible Absorption Spectroscopy:
- Instrument: Shimadzu UV-2550 spectrometer.
- Analysis: Measured the absorption coefficient (αN3) at the 415 nm peak to quantify the N3 nitrogen-vacancy defect system.
- Photoluminescence (PL) Spectroscopy (Room Temperature):
- Instrument: Horiba FL-3 spectrometer (Xe lamp excitation at 350 nm and 450 nm).
- Analysis: Identified broad bands (S3, maximum ~550 nm) and the N3 system, correlating luminescence type with crystal habit.
- Photoluminescence (PL) Spectroscopy (Low Temperature):
- Instrument: Renishaw InVia spectrometer (Laser excitation at 488 nm and 787 nm, T=77 K).
- Analysis: Detailed study of specific defect systems (e.g., S2 system at 489 nm, H-related lines) to refine thermal history determination.
Commercial Applications
Section titled âCommercial ApplicationsâThe detailed characterization of nitrogen defects and thermal history in these diamonds has implications for resource management and advanced material science:
- Resource Prospecting and Geology:
- Typomorphic Indicators: The unique defect signatures (low NBs, presence of low-temperature H-defects) serve as essential typomorphic features for identifying and distinguishing primary kimberlite sources in the East European Platform, aiding future exploration efforts.
- Deposit Modeling: The confirmation of multi-stage diamond formation improves regional geological models, crucial for estimating resource potential and mine planning.
- Diamond Grading and Certification:
- Color Origin: The correlation between N3 defects and yellow/yellow-green luminescence is vital for accurately grading Type Ia diamonds, affecting their commercial value.
- Advanced Materials and Quantum Technology:
- Defect Precursors: Diamonds with extremely low natural annealing (low NBs) are excellent starting materials for controlled defect engineering. These crystals contain nitrogen in forms (A and C defects) that can be converted into specific quantum defects (like NV centers) through targeted irradiation and annealing processes.
- Thermal Stability Research: Determining the thermal stability range of defects in these low-annealing diamonds is a necessary step for optimizing HPHT processing recipes used in synthetic diamond manufacturing for high-tech applications.
View Original Abstract
This work studies and compares the main morphological, structural, and mineralogical features of 350 diamond crystals from the Karpinsky-I and 300 crystals of the Arkhangelskaya kimberlite pipes. The share of crystals of octahedral habit together with individual crystals of transitional forms with sheaf-like and splintery striation is higher in the Arkhangelskaya pipe and makes 15 %. The share of cuboids and tetrahexahedroids is higher in the Karpinsky-I pipe and stands at 14 %. The share of dodecahedroids in the Arkhangelskaya and Karpinsky-I pipes are 60 % and 50 %, respectively. The indicator role of the nitrogen-vacancy N3 center active in absorption and luminescence is shown. Crystals with the N3 absorption system have predominantly octahedral habit or dissolution forms derived from the octahedra. Their thermal history is the most complex. Absorption bands of the lowest-temperature hydrogen-containing defects (3050, 3144, 3154, 3188, 3310 cmâ1, 1388, 1407, 1432, 1456, 1465, 1503, 1551, 1563 cmâ1), are typical for crystals without N3 system, where in the absorption spectra nitrogen is in the form of low-temperature A and C defects. The above mentioned bands are registered in the spectra of 16 % and 42 % of crystals from the Arkhangelskaya and Karpinsky-I pipes, respectively. The diamond of the studied deposits is unique in the minimum temperature (duration) of natural annealing. Based on a set of features, three populations of crystals were distinguished, differing in growth conditions, post-growth, and thermal histories. The established regularities prove the multi-stage formation of diamond deposits in the north of the East European Platform and significant differences from the diamonds of the Western Cisurals. The results suggest the possibility of the existence of primary deposits dominated by diamonds from one of the identified populations.