Probing Local Pressure Environment in Anvil Cells with Nitrogen-Vacancy (N-V−) Centers in Diamond
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2020-02-18 |
| Journal | Physical Review Applied |
| Authors | Kin On Ho, Man Yin Leung, Yaxin Jiang, Kin Pong Ao, Wei Zhang |
| Institutions | Chinese University of Hong Kong, Chinese University of Hong Kong, Shenzhen |
| Citations | 31 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: NV Center Pressure Sensing
Section titled “Technical Documentation & Analysis: NV Center Pressure Sensing”Executive Summary
Section titled “Executive Summary”This research validates the use of Nitrogen Vacancy (NV-) centers in diamond particles as highly sensitive, spatially-resolved quantum sensors for pressure mapping in high-pressure anvil cells. 6CCVD is uniquely positioned to supply the high-quality diamond materials necessary to replicate and advance this critical metrology.
- Quantum Sensing Validation: NV centers in diamond are confirmed as robust, high-precision pressure sensors, operating effectively across wide temperature (6 K to 295 K) and pressure (up to 61.4 kbar) ranges.
- High Spatial Resolution: The methodology achieved unprecedented spatial resolution (~1 µm) for in-situ pressure distribution measurements, crucial for analyzing non-hydrostatic media solidification.
- Precise Calibration: The pressure dependence of the NV- zero-field splitting (ZFS) D was precisely calibrated at dD/dP = 1.49 ± 0.02 MHz/kbar, confirming consistency even across the solidification transition.
- Solidification Dynamics: The technique successfully tracked the pressure-induced solidification transition of Daphne oil 7373 (critical pressure ~28 kbar), identifying pressure inhomogeneity via ODMR linewidth broadening.
- Versatile Integration: The NV center sensor is compatible with existing diamond anvil cell (DAC) designs and can be integrated with other experimental probes (e.g., magnetic susceptibility, NMR).
- 6CCVD Material Relevance: Replication and scaling of this research require high-purity, custom-dimensioned Single Crystal Diamond (SCD) or Polycrystalline Diamond (PCD) wafers for sensor fabrication or use as designer anvils.
Technical Specifications
Section titled “Technical Specifications”The following hard data points were extracted from the experimental results, demonstrating the performance metrics of the NV center diamond sensor system:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Pressure Sensitivity (dD/dP) | 1.49 ± 0.02 | MHz/kbar | Longitudinal ZFS D change used for pressure derivation |
| Maximum Pressure Tested | 61.4 | kbar | Achieved in non-hydrostatic regime (Daphne oil 7373) |
| Temperature Range Tested | 6 to 295 | K | Cryogenic to Room Temperature operation |
| Spatial Resolution (Confocal) | ~1 | µm | Best spatial resolution achieved for local pressure mapping |
| Nanodiamond (ND) Particle Size | 1 | µm | Diameter of the NV center sensor particles |
| Nitrogen Concentration in NDs | 3 | ppm | Nitrogen precursor concentration |
| Critical Solidification Pressure | 26.2 to 29.3 | kbar | Onset of solidification for Daphne oil 7373 |
| Gasket Hole Diameter | 400 | µm | Pressure chamber size in the anvil cell |
| Microcoil Diameter | 200 | µm | Used for Microwave (MW) transmission |
| ZFS D at Ambient Conditions | 2.87 | GHz | Zero-Field Splitting at ambient pressure and room temperature |
Key Methodologies
Section titled “Key Methodologies”The experiment utilized a combination of high-pressure cell design, specialized diamond materials, and advanced optical/microwave spectroscopy:
- Pressure Cell Configuration: Anvil-type pressure cells were employed, utilizing Moissanite anvils and a Beryllium Copper gasket with a 400 µm central hole to confine the pressure medium (Daphne oil 7373).
- Sensor Preparation: Nanodiamonds (NDs) of 1 µm diameter, containing 3 ppm nitrogen concentration (for NV- creation), were drop-casted onto the anvil surface or a dummy sample inside the pressure chamber.
- Microwave (MW) Delivery: A 200 µm diameter microcoil was integrated into the cell to transmit MW radiation for Electron Spin Resonance (ESR) measurements.
- Optical Readout: Optically Detected Magnetic Resonance (ODMR) spectra were measured using 520 nm laser diodes. Both simple fluorescence microscopy (for benchmarking) and high-resolution confocal microscopy (for 1 µm spatial mapping) were used.
- Pressure Calibration: In-situ pressure was calibrated using the traditional Ruby (Cr:Al2O3) fluorescence spectroscopy (R₁ peak shift) at room temperature.
- Pressure Derivation: Local pressure was derived from the shift in the longitudinal Zero-Field Splitting (ZFS) D, extracted from the center frequency of the ODMR resonances, using the calibrated slope of 1.49 MHz/kbar.
- Solidification Analysis: The onset of solidification was tracked by monitoring the broadening of the ODMR spectrum linewidth and the standard deviation (SD) of local pressure measurements across the cell.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”This research highlights the critical role of high-quality diamond materials in advancing quantum metrology under extreme conditions. 6CCVD provides the specialized MPCVD diamond required to replicate, scale, and extend this work, offering superior material control and customization.
Applicable Materials for NV Center Metrology
Section titled “Applicable Materials for NV Center Metrology”To replicate or extend the high-pressure NV center sensing demonstrated, researchers require diamond with precise control over purity and nitrogen content.
| 6CCVD Material | Relevance to Research | Customization Potential |
|---|---|---|
| High-Purity SCD | Ideal precursor material for creating high-density, high-coherence NV centers via controlled nitrogen implantation or in-situ doping. Essential for low-strain environments (Ra < 1nm polishing available). | Custom N concentration (ppm level) for optimized NV density and coherence time. |
| Optical Grade SCD | Required for use as high-pressure anvils (designer anvils, as referenced in the paper) where high optical transparency (for 520 nm excitation and red fluorescence readout) is mandatory. | Custom thickness (0.1 µm to 500 µm) and orientation for specific DAC designs. |
| Polycrystalline Diamond (PCD) | Suitable for large-area pressure sensor arrays (up to 125mm diameter) or as robust substrates for sensor integration where single-crystal coherence is not the primary constraint. | Custom dimensions up to 125mm diameter, polished to Ra < 5nm for inch-size wafers. |
| Boron-Doped Diamond (BDD) | While not used in this study, BDD is critical for integrated electrochemical sensing or creating conductive layers within the high-pressure cell, compatible with the NV center metrology platform. | Custom doping levels for specific conductivity requirements. |
Customization Potential for Integrated Sensors
Section titled “Customization Potential for Integrated Sensors”The experimental setup utilized a 200 µm microcoil for MW delivery. 6CCVD offers integrated solutions to streamline high-pressure metrology:
- Custom Metalization: We offer internal capability for depositing thin film metal contacts (Au, Pt, Pd, Ti, W, Cu) directly onto diamond substrates. This allows for the fabrication of integrated on-chip MW antennas or microcoils directly on the diamond anvil surface, eliminating the need for external wire coils and improving MW throughput and spatial control.
- Precision Machining: 6CCVD can provide custom laser cutting and shaping services to match specific DAC geometries, ensuring optimal fit and alignment for both anvils and sensor substrates.
- Surface Engineering: Our ultra-smooth polishing (SCD Ra < 1nm) minimizes surface defects and strain, which is crucial for maintaining the coherence and stability of NV centers, particularly when used as stress tensor sensors (sensitive to the ZFS E term).
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team specializes in MPCVD growth and material science for quantum applications. We can assist researchers in:
- Material Selection: Consulting on the optimal diamond grade (SCD vs. PCD) and nitrogen concentration required for specific NV creation protocols (e.g., in-situ doping vs. post-growth implantation).
- High-Pressure Integration: Providing expertise on material preparation and surface finishing necessary for robust performance within high-pressure environments, including thermal management and strain minimization.
- Global Logistics: Ensuring reliable global shipping (DDU default, DDP available) of sensitive diamond materials to high-pressure research facilities worldwide.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Important discoveries have frequently been made through the studies of matter\nunder high pressure. The conditions of the pressure environment are important\nfor the interpretation of the experimental results. Due to various restrictions\ninside the pressure cell, detailed information relevant to the pressure\nenvironment, such as the pressure distribution, can be hard to obtain\nexperimentally. Here we present the study of pressure distributions inside the\npressure medium under different experimental conditions with NV centers in\ndiamond particles as the sensor. These studies not only show a good spatial\nresolution, wide temperature and pressure working ranges, compatibility of the\nexisting pressure cell design with the new method, but also demonstrate the\nusefulness to measure with these sensors as the pressure distribution is\nsensitive to various factors. The method and the results will benefit many\ndisciplines such as material research and phase transitions in fluid dynamics.\n