Raman Spectroscopy for Characterization of Peridotite Paragenesis Mineral Inclusions in Diamonds
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-09-08 |
| Journal | LITHOSPHERE (Russia) |
| Authors | A. D. Kalugina, D. A. Zedgenizov, A. M. Logvinova |
| Institutions | Ural State Mining University, V.S. Sobolev Institute of Geology and Mineralogy |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Raman Spectroscopy for Peridotite Mineral Inclusions in Diamonds
Section titled âTechnical Documentation & Analysis: Raman Spectroscopy for Peridotite Mineral Inclusions in DiamondsâExecutive Summary
Section titled âExecutive SummaryâThis research successfully develops a non-destructive methodology using Raman spectroscopy to quantitatively determine the chemical composition of peridotite mineral inclusions (in situ) within natural diamonds. This technique is highly relevant for mantle geochemistry and diamond exploration.
- Core Achievement: Established quantitative linear regression models correlating specific Raman peak shifts (wavenumber displacement) with the major element composition (Mg, Fe, Ca, Al, Na, Cr) of olivine, clinopyroxene, and garnet inclusions.
- Methodology: Utilized 532 nm Nd:YAG laser Raman spectroscopy combined with Electron Probe Micro-Analysis (EPMA) data to calibrate the spectroscopic correlations.
- Isomorphism Mapping: Demonstrated that shifts in key vibrational modes (e.g., olivine DB1/DB2, pyroxene V11/V16, garnet V1/V3/V2) accurately reflect solid-solution isomorphism (e.g., Forsterite-Fayalite, Diopside-Jadeite).
- Precision: The method achieves high precision in chemical assessment, with modal errors for key components in clinopyroxene and garnet ranging from 0.4 wt % (Na2O) to 1.1 wt % (CaO).
- Critical Limitation Identified: The study explicitly notes that residual strain and crystallographic orientation within the host diamond significantly influence Raman peak positions, causing dispersion in correlations (up to 7.2 cm-1 shifts observed in orthopyroxene), thereby limiting the ultimate precision of the in situ analysis.
- Application: The developed methodology is crucial for distinguishing mineral inclusions from different mantle parageneses (e.g., harzburgite vs. lherzolite).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper detailing experimental parameters and key quantitative results.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Raman Excitation Wavelength | 532 | nm | Nd:YAG Laser Source |
| Laser Power Used | 10 | m W | Power applied to the sample |
| Spectral Resolution Precision | Âą0.5 | cm-1 | Achieved via Lorentzian curve fitting |
| Grating Specification | 1800 | lines/mm | Used with 100 Âľm slit width |
| Olivine Mg# Range Studied | 0.900 - 0.935 | N/A | High-Mg# peridotite inclusions |
| Max Residual Strain Shift (Opx V17) | 7.2 | cm-1 | Maximum observed shift before/after inclusion exposure |
| Clinopyroxene V11 vs Na2O Correlation | r = 0.95 | N/A | Strong positive linear correlation |
| Garnet V1 vs Ca Correlation | r = -0.85 | N/A | Strong negative linear correlation (Formula Units) |
| Garnet V2 vs Cr Correlation | r = -0.87 | N/A | Strong negative linear correlation (Formula Units) |
| Garnet V3 vs Mg Correlation | r = 0.87 | N/A | Strong positive linear correlation (Formula Units) |
| Clinopyroxene CaO Modal Error | 1.1 | wt % | Error relative to EPMA data (for CaO < 5 wt %) |
| Clinopyroxene Na2O Modal Error | 0.4 | wt % | Error relative to EPMA data (for Na2O < 2.5 wt %) |
Key Methodologies
Section titled âKey MethodologiesâThe experimental procedure relied on a combination of precise sample preparation, high-resolution chemical mapping, and advanced Raman spectroscopy techniques.
- Sample Preparation: Natural diamond crystals containing peridotite inclusions (olivine, Opx, Cpx, garnet) were polished along the (110) plane to expose the inclusions for both EPMA and Raman analysis.
- Chemical Composition Determination (EPMA): Chemical composition of the exposed inclusions was determined using a JEOL JXA-8100 EPMA equipped with WDS, operating at 20 keV and 100 nA, with a 0.8 Âľm beam diameter.
- Raman Spectroscopy Setup: Spectra were acquired using a Horiba Jobin Yvon LabRAMHR800 spectrometer utilizing a 532 nm Nd:YAG laser and a 50x objective.
- Spectral Acquisition: Accumulation times were 7-10 seconds, repeated for 10-15 cycles. The spectral range was 100-1200 cm-1.
- Orientation Control: For anisotropic minerals (olivine, pyroxenes), the sample was rotated in 15° steps to analyze the effect of crystallographic orientation on mode intensity and position.
- Quantitative Analysis: Raman peak positions were determined via least-squares minimization using Lorentzian functions (OPUS 8.2). Deming regression was applied to correlate peak shifts (cm-1) with EPMA-derived chemical concentrations (wt % or formula units).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research highlights the critical need for high-quality, low-strain diamond material for precise spectroscopic measurements, particularly noting that residual strain in natural diamonds causes significant peak shifts (up to 7.2 cm-1) that introduce dispersion and limit the accuracy of quantitative chemical mapping.
6CCVDâs MPCVD diamond offers the ideal solution to mitigate these experimental limitations and advance high-pressure/spectroscopic research:
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this high-precision spectroscopic research, 6CCVD recommends materials optimized for optical transparency and minimal internal stress:
- Optical Grade Single Crystal Diamond (SCD): SCD is grown with extremely low nitrogen content and minimal lattice defects, resulting in negligible internal strain and background fluorescence compared to natural diamond. This material is essential for minimizing the 0.7-7.2 cm-1 peak shifts caused by residual strain observed in the paper, thereby improving the accuracy of the quantitative regression models.
- High Purity SCD Substrates: Ideal for use as Diamond Anvil Cell (DAC) windows or high-pressure optical components. 6CCVD can supply SCD substrates up to 500 Âľm thick, providing robust, low-absorption windows for controlled high-pressure Raman studies of synthetic or natural mineral phases.
- Custom Polycrystalline Diamond (PCD): For applications requiring large-area optical windows or substrates (up to 125 mm diameter), 6CCVD PCD offers high thermal conductivity and broad spectral transparency, suitable for less strain-sensitive spectroscopic setups.
Customization Potential
Section titled âCustomization Potentialâ6CCVD provides comprehensive engineering services to meet the precise requirements of advanced spectroscopic and high-pressure research:
- Precision Polishing: We offer ultra-smooth polishing (Ra < 1 nm for SCD) and precise crystallographic orientation (e.g., (110) or (100)) necessary for high-magnification microscopy and minimizing surface scattering effects.
- Custom Dimensions and Thickness: 6CCVD manufactures custom plates and wafers up to 125 mm (PCD) and substrates up to 10 mm thick, supporting large-scale high-pressure apparatus or complex optical setups.
- Integrated Metalization: For researchers developing high-pressure cells or integrated sensor arrays related to this geochemical work, 6CCVD offers internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for creating precise electrical contacts or gaskets on the diamond surface.
Engineering Support
Section titled âEngineering SupportâThe quantitative Raman analysis of mineral solid-solutions is highly sensitive to material quality. 6CCVDâs in-house PhD team specializes in diamond material science and can assist researchers in:
- Material Selection: Choosing the optimal SCD grade (e.g., low-strain, specific orientation) to ensure the highest signal-to-noise ratio and minimal peak distortion for quantitative Raman analysis in similar Mantle Geochemistry and High-Pressure Mineralogy projects.
- Strain Mitigation: Consulting on mounting and preparation techniques to minimize induced stress, ensuring that spectroscopic results reflect intrinsic chemical composition rather than extrinsic strain effects.
Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Research subject . Spectroscopic features (Raman spectra) of mineral inclusions of peridotite paragenesis (olivine, orthopyroxene, clinopyroxene, garnet) in natural diamonds of the Yakutian diamondiferous province. Materials and methods . A series of diamonds was studied both with single mineral inclusions and with associations of inclusions of peridotite paragenesis. The chemical composition of mineral inclusions in diamonds was determined using an electron probe micro-analyzer (EPMA). The Raman spectra of inclusions were obtained on a spectrometer equipped with a Nd:YAG laser with a wavelength of 532 nm. Results . The revealed spectroscopic characteristics of mineral inclusions in natural diamonds reflect specific features of their chemical composition. Thus, the shift in the positions of the Raman peaks DB1 and DB2 in the olivine spectra reflects the forsterite - fayalite (Mg-Fe) isomorphism; changes in the positions of valence vibrational modes in the Raman spectra of clinopyroxene Si-O nbr (ν 16 ) and Si-O br (ν 11 ) and orthopyroxene (ν 17 ) reflect the isomorphism of diopside - jadeite (CaMg-NaAl) and enstatite - ferrosilite (Mg-Fe), position shifts of deformation (ν 2 ) and valence (ν 1 , ν 3 ) modes of vibrational energies of the Si-O bond in garnets reflect the Al-Cr and Ca-Mg isomorphism, respectively. Conclusions . For the identified correlations, regression lines were calculated, which can be used to determine the quantitative contents of the main chemical components of mineral inclusions (clinopyroxene and garnet) of peridotite paragenesis in situ in diamonds. The developed method for evaluating the chemical composition of garnet and clinopyroxene inclusions can be used to distinguish clinopyroxene and garnet inclusions from different mantle parageneses.