Stabilization of N6 and N8 anionic units and 2D polynitrogen layers in high-pressure scandium polynitrides
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-03-12 |
| Journal | Nature Communications |
| Authors | Andrey Aslandukov, Alena AslandukovĐ°, Dominique Laniel, Saiana Khandarkhaeva, Yuqing Yin |
| Institutions | European Synchrotron Radiation Facility, University of Chicago |
| Citations | 21 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Pressure Scandium Polynitrides
Section titled âTechnical Documentation & Analysis: High-Pressure Scandium PolynitridesâExecutive Summary
Section titled âExecutive SummaryâThis research details the high-pressure, high-temperature synthesis and characterization of four novel scandium polynitrides, demonstrating significant advancements in high-energy-density materials (HEDM) research, a field critically reliant on high-quality diamond components.
- Novel Synthesis: Four new scandium polynitrides (Sc2N6, Sc2N8, ScN5, and Sc4N3) were synthesized by direct reaction of Sc and N2 at extreme conditions (78-125 GPa and 2500 K) using Laser-Heated Diamond Anvil Cells (LH-DACs).
- Unique Structures: The nitrogen-rich phases feature previously unknown catenated anionic units: N66- and N86-, and corrugated 2D-polynitrogen layers consisting of fused N12 rings.
- Electronic Properties: Density Functional Theory (DFT) calculations show Sc2N6 and Sc2N8 exhibit anion-driven metallicity, while ScN5 is an indirect semiconductor (Band Gap: 1.8 eV at 96 GPa).
- HEDM Potential: Sc-polynitrides are confirmed as promising HEDMs, with calculated volumetric energy density, detonation velocity (Vd), and detonation pressure (Pd) significantly higher than those of TNT.
- Diamond Requirement: The success of this study hinges on the mechanical and thermal stability of the diamond anvils under extreme pressure (up to 125 GPa) and temperature (2500 K), requiring the highest grade of MPCVD Single Crystal Diamond (SCD).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the synthesis and characterization of the novel scandium polynitrides, highlighting the extreme conditions required for their formation and their potential as HEDMs.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Synthesis Pressure Range | 78 - 125 | GPa | Direct reaction of Sc and N2 |
| Synthesis Temperature | 2500 (±300) | K | Laser-heated DAC experiments |
| ScN5 Bulk Modulus (K0) | 205 | GPa | DFT-fitted Birch-Murnaghan EOS |
| ScN5 Density (Ï) | 3.71 | g/cmÂł | Calculated density |
| ScN5 Volumetric Energy Density (VED) | 14.0 | kJ/cmÂł | HEDM metric (vs. TNT 7.2 kJ/cmÂł) |
| ScN5 Gravimetric Energy Density (GED) | 3.76 | kJ/g | HEDM metric (vs. TNT 4.3 kJ/g) |
| ScN5 Detonation Velocity (Vd) | 9.8 | km/s | Calculated (vs. TNT 6.9 km/s) |
| ScN5 Detonation Pressure (Pd) | 60 | GPa | Calculated (vs. TNT 19 GPa) |
| ScN5 Band Gap | 1.8 | eV | Indirect semiconductor (at 96 GPa) |
| Novel Anionic Units | N66-, N86- | N/A | Previously unknown catenated nitrogen species |
Key Methodologies
Section titled âKey MethodologiesâThe synthesis and characterization of the high-pressure scandium polynitrides relied on specialized high-pressure techniques utilizing high-quality diamond components.
- High-Pressure Apparatus: BX90-type large X-ray aperture Diamond Anvil Cells (DACs) were used, equipped with Boehler-Almax type diamonds (culet diameters: 250, 120, and 80 ”m).
- Sample Loading: Scandium pieces (sizes ranging from 40x40x8 ”m³ down to 15x15x5 ”m³) were loaded into Rhenium gaskets (pre-indented thickness 15-20 ”m).
- Pressure Medium: Molecular nitrogen (N2, purity grade N5.0) was loaded using a BGI high-pressure gas loading system (1300 bars).
- Laser Heating: A home-made double-sided laser-heating system (YAG lasers, λ = 1064 nm) was used to heat the samples to 2500 (±300) K.
- Pressure Measurement: Pressure was determined using the Raman signal from the diamond anvils and monitored via X-ray diffraction of the Rhenium gasket edge.
- Structural Analysis: Synchrotron single-crystal X-ray diffraction (XRD) was performed at ESRF (ID11, ID15b) and APS (13IDD) using highly focused X-ray beams (down to 0.75 x 0.75 ”mÂČ).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful execution of high-pressure research, particularly involving laser heating to 2500 K and pressures up to 125 GPa, demands diamond materials with exceptional purity, thermal stability, and mechanical integrity. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond components for replicating and advancing this research.
Applicable Materials for HPHT Research
Section titled âApplicable Materials for HPHT Researchâ| 6CCVD Material | Specification | Application Relevance |
|---|---|---|
| Optical Grade SCD | High purity, low birefringence, SCD (0.1 ”m - 500 ”m) thickness. | Essential for DAC anvils and windows, providing maximum optical transparency for laser heating and minimizing X-ray background noise during synchrotron measurements. |
| SCD Substrates | Thickness up to 10 mm, polished to Ra < 1 nm. | Used for manufacturing robust, high-precision DAC components that withstand extreme mechanical stress and thermal gradients. |
| Polycrystalline Diamond (PCD) | Plates up to 125 mm diameter, polished to Ra < 5 nm. | Suitable for large-area optical windows, heat spreaders, or specialized support structures in high-pressure apparatus requiring large dimensions. |
Customization Potential for Advanced Experiments
Section titled âCustomization Potential for Advanced ExperimentsâThe complexity of synthesizing novel polynitrides requires highly customized diamond components, which 6CCVD provides through its advanced fabrication capabilities:
- Custom Dimensions and Geometry: We supply SCD and PCD plates/wafers in custom dimensions, crucial for specialized DAC designs (e.g., BX90 type) and specific culet sizes (e.g., 80 ”m, 120 ”m) used in this study.
- Precision Polishing: Achieving high-quality X-ray diffraction data requires flawless optical surfaces. 6CCVD guarantees ultra-smooth polishing (Ra < 1 nm for SCD) necessary for high-resolution synchrotron studies.
- Integrated Metalization: The use of laser heating often requires integrated thermal management or electrical contacts. 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu) for depositing thin films directly onto the diamond surface, enabling advanced in-situ measurements (e.g., resistive heating or electrical transport studies of metallic Sc2N6).
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team can assist researchers and engineers with material selection for similar High-Energy-Density Material (HEDM) Synthesis projects. We provide consultation on optimizing diamond propertiesâsuch as nitrogen content and crystal orientationâto maximize the lifespan and performance of DAC anvils operating under pressures exceeding 100 GPa and temperatures above 2000 K.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Nitrogen catenation under high pressure leads to the formation of polynitrogen compounds with potentially unique properties. The exploration of the entire spectrum of poly- and oligo-nitrogen moieties is still in its earliest stages. Here, we report on four novel scandium nitrides, Sc 2 N 6 , Sc 2 N 8 , ScN 5, and Sc 4 N 3 , synthesized by direct reaction between yttrium and nitrogen at 78-125 GPa and 2500 K in laser-heated diamond anvil cells. High-pressure synchrotron single-crystal X-ray diffraction reveals that in the crystal structures of the nitrogen-rich Sc 2 N 6 , Sc 2 N 8, and ScN 5 phases nitrogen is catenated forming previously unknown N 6 6 â and N 8 6 â units and $${!,}{\infty }{!,}^{2}({{{{{\rm{N}}}}}}{5}^{3-})$$ <mml:math xmlns:mml=âhttp://www.w3.org/1998/Math/MathMLâ> <mml:msub> <mml:mrow> <mml:mspace/> </mml:mrow> <mml:mrow> <mml:mi>â</mml:mi> </mml:mrow> </mml:msub> <mml:msup> <mml:mrow> <mml:mspace/> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mrow> <mml:mo>(</mml:mo> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> <mml:mo>â</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> anionic corrugated 2D-polynitrogen layers consisting of fused N 12 rings. Density functional theory calculations, confirming the dynamical stability of the synthesized compounds, show that Sc 2 N 6 and Sc 2 N 8 possess an anion-driven metallicity, while ScN 5 is an indirect semiconductor. Sc 2 N 6 , Sc 2 N 8 , and ScN 5 solids are promising high-energy-density materials with calculated volumetric energy density, detonation velocity, and detonation pressure higher than those of TNT.