Quantum‐Grade Nanodiamonds from a Single‐Step, Industrial‐Scale Pressure and Temperature Process
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2025-10-02 |
| Journal | Advanced Functional Materials |
| Authors | Yahua Bao, Michal Gulka, Parkarsh Kumar, Jakub Čopák, Priyadharshini Balasubramanian |
| Institutions | UNSW Sydney, Center for Integrated Quantum Science and Technology |
| Citations | 1 |
| Analysis | Full AI Review Included |
Quantum-Grade Nanodiamonds via Pressure & Temperature (PTQ) Processing: A 6CCVD Material Analysis
Section titled “Quantum-Grade Nanodiamonds via Pressure & Temperature (PTQ) Processing: A 6CCVD Material Analysis”This technical documentation analyzes the findings of the research paper “Quantum-Grade Nanodiamonds from a Single-Step, Industrial-Scale Pressure and Temperature Process” and connects the material requirements and performance metrics to 6CCVD’s advanced MPCVD diamond capabilities.
Executive Summary
Section titled “Executive Summary”The research demonstrates a breakthrough in scalable quantum material production using a single-step High-Pressure High-Temperature (PTQ) plastic deformation method on nanodiamonds (NDs).
- Industrial Scalability: The PTQ method achieves industrial-scale yields of quantum-grade NDs (~g/min), drastically surpassing traditional multi-step irradiation and annealing methods (~g/week). This process reduces production time by a factor equivalent to 40 years of current methods being condensed into one week.
- Superior Spin Properties: The resulting 50-nm NDs exhibit exceptional NV spin properties, including a bulk-like T₁ relaxation time approaching 1 ms.
- Enhanced Quantum Performance: A striking ≈5-fold enhancement in optical Rabi contrast (15.9% average) was achieved compared to commercial electron-irradiated NDs (3.2%).
- Improved Charge Stability: PTQ NDs show a greatly enhanced negatively charged NV center (NV⁻) stability, evidenced by a single-particle NV⁻/NV⁰ PL ratio of 3.21 (more than two-fold higher than the commercial benchmark).
- High Crystalline Purity: The high-temperature plastic deformation induces lattice healing, resulting in lower internal strain and prolonged 13C T₁ spin relaxation times (55 s).
- Biocompatibility: The PTQ NDs are non-cytotoxic and suitable for dual-color bioimaging applications (NV and H3 centers).
- Methodology: The process involves subjecting HPHT diamond powder (≈120 ppm N) to extreme conditions (≈7 GPa, ≈1700 °C) for 4 minutes in a modified commercial cubic press apparatus.
Technical Specifications
Section titled “Technical Specifications”The following table extracts key performance and process parameters achieved using the PTQ method compared to commercial electron-irradiated nanodiamonds (COMM).
| Parameter | PTQ Value | COMM Value | Unit | Context |
|---|---|---|---|---|
| Process Pressure | ≈7 | N.A. | GPa | Single-step PTQ method |
| Process Temperature | ≈1700 | >600 | °C | Single-step PTQ vs. Annealing |
| Production Yield | ~g/min | ~g/week | - | Industrial scale comparison |
| Nanodiamond Size (Avg) | 52.0 ± 14.5 | 47.5 ± 17.6 | nm | Acid oxidized samples |
| NV⁻/NV⁰ PL Ratio (Single Particle) | 3.21 ± 0.26 | 1.47 ± 0.12 | - | Measure of charge stability |
| Optical Rabi Contrast (Avg) | 15.9 ± 1.8 | 3.2 ± 0.3 | % | ≈5-fold enhancement |
| All-Optical T₁ Relaxation Time | 989 (Approaching 1) | 170 | µs (ms) | Bulk-like value achieved |
| NV Excited State Lifetime (TAVG) | 24.0 | 19.5 | ns | Amplitude-averaged lifetime |
| Zero-Field Splitting (2*E) | 15.2 ± 1.0 | 18.2 ± 0.3 | MHz | Lower internal strain in PTQ |
| P1 Concentration (Substitutional N) | 10.9 ± 2.1 | 8.6 ± 1.7 | ppm | Measured by EPR |
| 13C T₁ Relaxation Time | 55 | 22 | s | Preservation of bulk properties |
| Lattice Structure | Crystalline Cubic Diamond | Crystalline Cubic Diamond | - | Confirmed by XRD |
Key Methodologies
Section titled “Key Methodologies”The PTQ process is a single-step, high-yield alternative to traditional multi-step irradiation and annealing for NV center creation.
- Starting Material Preparation: Commercially available, non-luminescent 50-nm HPHT diamond powder (Grade MA4, containing ≈120 ppm substitutional nitrogen) was used.
- Blending: The diamond powder was mechanically blended with diamagnetic sodium chloride (NaCl) at a 75/25 wt.% ratio.
- Encapsulation: The ND/NaCl mixture was loaded into a Ta metal container within a cubic press cell, designed for simultaneous pressurization and resistive heating.
- PTQ Treatment: The cell was subjected to extreme conditions:
- Pressure: Applied pressure of ≈7 GPa.
- Temperature: ≈1700 °C.
- Duration: 4 minutes.
- Mechanism: The high pressure induces plastic deformation in the diamond particles, while the high temperature increases nitrogen mobility, enabling the formation of NV centers (vacancy + substitutional nitrogen) within the diamond-stable region. The molten NaCl acts as a semi-hydraulic fluid, preventing graphitization.
- Post-Processing: The treated NDs were washed to remove NaCl, sonicated to break agglomerates, and then surface-oxidized (either air oxidation at 475-500 °C or acid oxidation).
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The PTQ research highlights the critical need for high-quality diamond material with controlled nitrogen content and minimal lattice defects for advanced quantum applications. While the paper focuses on nanodiamond powder, 6CCVD specializes in high-purity, large-area MPCVD diamond plates and wafers, offering superior platforms for integrated quantum device fabrication and thin-film sensing.
| Research Requirement / Application | 6CCVD Solution & Capability | Engineering Value Proposition |
|---|---|---|
| High-Purity Starting Material | Single Crystal Diamond (SCD) Wafers and High-Purity Polycrystalline Diamond (PCD) plates. | We provide the highest quality MPCVD diamond, offering superior structural purity and lower intrinsic defect density than typical HPHT starting materials, leading to potentially longer T₂ coherence times in bulk or thin-film NV devices. |
| Controlled Nitrogen Doping (P1 Centers) | Custom Nitrogen Doping during MPCVD growth. | 6CCVD offers precise control over substitutional nitrogen (P1) concentration (e.g., 1 ppm to >100 ppm) in SCD and PCD, allowing researchers to optimize NV conversion yield and density for specific quantum sensing or qubit applications. |
| Low Strain & High Crystallinity | Optical Grade SCD with ultra-low surface roughness (Ra < 1 nm) and Inch-size PCD (Ra < 5 nm). | The paper emphasizes that low lattice strain is crucial for high Rabi contrast and long T₁/T₂. Our advanced polishing and growth techniques minimize strain and surface defects, maximizing the performance of near-surface NV centers. |
| Scalable Platform for Integrated Devices | Custom Dimensions: Plates/wafers up to 125 mm (PCD) and substrates up to 10 mm thick. | Transitioning from nanodiamond powder to large-area SCD or PCD wafers enables the fabrication of scalable, integrated quantum sensor arrays and thin-film devices, overcoming the handling limitations of ND powders. |
| Device Integration & Readout | Custom Metalization Services: In-house deposition of Au, Pt, Pd, Ti, W, and Cu. | For replicating or extending the ODMR and Rabi measurements, integrated microwave delivery structures are essential. We provide custom metal contacts directly on the diamond surface, streamlining device prototyping and manufacturing. |
| Bioimaging & Sensing Platforms | Boron-Doped Diamond (BDD) thin films and SCD/PCD substrates. | For applications like bioimaging and electrochemical sensing, our BDD material offers robust, chemically inert, and conductive platforms, complementing the NV/H3 center research presented. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Nanodiamonds with nitrogen vacancy (NV) centers are a promising workhorse for myriad applications, from quantum sensing to bioimaging. However, despite two decades of extensive research, their use remains limited by the lack of scalable methods to produce quantum‐grade material. While traditional NV‐production methods involve multi‐step irradiation and annealing processes, a fundamentally different approach is presented here based on a single‐step high‐temperature plastic deformation. It enables industrial‐scale yield of high‐quality luminescent nanodiamonds while significantly reducing production time and costs. Utilizing a unique cubic press apparatus capable of reaching higher temperatures and pressures, 50‐nm luminescent nanodiamonds with outstanding optical and spin properties are achieved in a single step from non‐luminescent material. Compared to electron‐irradiated nanodiamonds, i.e., common commercially available material, this method yields NV centers with significantly improved charge stability, T 1 relaxation times approaching 1 ms, and a ≈5‐fold enhancement in optical Rabi contrast. What this streamlined process produces in one week would require more than 40 years by current irradiation and annealing methods. Scalable, quantum‐grade nanodiamonds are thus unlocked, providing the missing link for their widespread adoption.