THE MAGNETIC PROPERTIES OF DIAMOND COMPOSITES WITH THE ADDITION OF GRAPHENE

At a Glance

Metadata	Details
Publication Date	2023-04-30
Journal	Sworld-Ger conference proceedings
Authors	А. Н. Соколов, Vladyslav Harhin, Nataliia Rusinova
Institutions	V. Bakul Institute for Superhard Materials
Analysis	Full AI Review Included

Technical Documentation & Analysis: Ferromagnetic Diamond Composites

Executive Summary

This research successfully demonstrates the creation of diamond polycrystalline composites exhibiting ferromagnetic properties through the high-pressure, high-temperature (HPHT) sintering of diamond powders with n-layer graphene (Gn(4)) additives. This breakthrough expands the functional scope of diamond materials beyond traditional mechanical and thermal applications.

Core Achievement: Production of diamond composites displaying clear hysteresis loops, confirming ferromagnetic behavior.
Material Engineering: Graphene (0.3% to 1.0% by weight) was used as an activating additive, influencing the electromagnetic characteristics of the resulting polycrystal.
Performance Metrics: Samples exhibited high coercive forces (H_c up to 303.22 E), classifying them as magnetically solid materials suitable for permanent magnet applications.
Process Parameters: Sintering was performed under extreme conditions (7.0-7.5 GPa and 1250-1350 °C).
Future Applications: The engineered composites show promise for creating permanent magnets and unique biocompatible magnetic materials for medicine and biology.
6CCVD Relevance: While the paper uses HPHT sintering of powders, 6CCVD specializes in producing the high-purity, large-area Polycrystalline Diamond (PCD) and Single Crystal Diamond (SCD) substrates necessary for scaling these advanced functional materials into commercial devices.

Technical Specifications

The following hard data points were extracted from the research paper detailing the synthesis and magnetic characterization of the diamond-graphene composites.

Parameter	Value	Unit	Context
Sintering Pressure	7.0 - 7.5	GPa	HPHT Process
Sintering Temperature	1250 - 1350	°C	HPHT Process
Sintering Duration	~200	s	Time at peak conditions
Press Force (Max)	Up to 20	MN	DO-043 Press Unit capability
HPD Recess Diameter	30	mm	High-Pressure Device (HPD) geometry
Graphene Additive Range	0.3 - 1.0	% (by weight)	Gn(4) n-layer graphene
Diamond Grain Size (Synthetic)	40/28	µm	DSM grade powder
Diamond Grain Size (Natural)	14/10	µm	DM grade powder
Magnetic Saturation Field (H_ms)	5000	E	Field strength required for saturation
VSM Sensitivity	10^-7	emo	Vibrating Magnetometer 7404
Coercive Force (H_c) Max	303.22	E	Achieved with DM 10/14 + 0.3% Gn(4)
Magnetic Saturation Moment (m_s) Max	75.435 x 10^-3	emo/g	Achieved with DSM 40/28 + 1.0% Gn(4)

Key Methodologies

The diamond composites were synthesized using a specialized HPHT sintering process, followed by magnetic characterization.

Material Preparation:
- Used micro-powders of synthetic diamond (DSM 40/28) and natural diamond (DM 14/10).
- Graphene additive was Gn(4) nanoplates (< 4 layers, total thickness < 3 nm) added at concentrations ranging from 0.3% to 1.0% by weight.
High-Pressure Sintering:
- Sintering was performed on a DO-043 press unit (20 MN force) utilizing a “toroid” type high-pressure device (HPD) with a 30 mm central recess.
- The charge was subjected to a pressure of 7.0-7.5 GPa and a temperature of 1250-1350 °C.
- The sintering duration was approximately 200 seconds.
Post-Processing:
- The resulting composite samples (4 mm diameter, 4.5 mm height) were chemically treated to remove residual graphite from the surface.
Magnetic Characterization:
- Magnetic properties were measured using a Vibrating Magnetometer (VSM 7404) in magnetic fields up to 13 kE.
- The presence of a hysteresis loop confirmed ferromagnetic properties, and key metrics (H_c, m_s, loop area) were quantified.

6CCVD Solutions & Capabilities

6CCVD provides the foundational MPCVD diamond materials and advanced processing required to replicate, scale, and integrate the functional diamond composites described in this research into commercial devices, particularly those requiring large-area substrates or specific electrical contacts.

Applicable Materials

While the research utilized HPHT sintering of diamond powders, 6CCVD specializes in high-quality MPCVD growth, offering superior control over purity, grain size, and substrate dimensions, which is critical for scaling functional materials.

6CCVD Material	Relevance to Research	Customization Potential
Polycrystalline Diamond (PCD)	Provides large-area substrates (up to 125 mm diameter) for subsequent surface modification or integration of magnetic layers.	Custom grain sizes and thicknesses (0.1 µm - 500 µm) available, enabling optimization of mechanical and electromagnetic coupling.
Boron-Doped Diamond (BDD)	The paper notes that diamond composites with high electrical conductivity were previously achieved using graphene. BDD offers intrinsic, stable conductivity, potentially replacing or complementing graphene for specific electromagnetic applications.	Available in both SCD and PCD formats, with doping levels tailored for specific conductivity requirements (e.g., heavy doping for electrode applications).
Optical Grade SCD	For applications requiring high purity and low defect density, 6CCVD SCD provides an ideal platform for studying intrinsic magnetism in carbon structures, minimizing interference from metallic impurities noted in the paper.	Thickness control from 0.1 µm up to 500 µm, with Ra < 1 nm polishing for demanding optical or quantum applications.

Customization Potential for Device Integration

The small, sintered samples (4 mm diameter) in the paper are proof-of-concept. 6CCVD enables the transition to functional devices through advanced fabrication services:

Large-Area Substrates: We offer PCD plates up to 125 mm in diameter, far exceeding the dimensions used in the research, crucial for scaling permanent magnet or sensor arrays.
Precision Polishing: Our capability to achieve surface roughness Ra < 5 nm on inch-size PCD ensures optimal interface quality for subsequent thin-film deposition (e.g., magnetic layers or protective coatings).
Custom Metalization: For integrating these magnetic composites into electronic or biological devices, reliable contacts are essential. 6CCVD offers in-house deposition of standard and custom metal stacks, including:
- Au, Pt, Pd (Ideal for biocompatible and sensing applications).
- Ti, W, Cu (Suitable for robust electrical contacts and heat dissipation).

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of diamond and can assist researchers and engineers in selecting the optimal diamond platform (SCD, PCD, or BDD) for similar Permanent Magnet and Biocompatible Magnetic projects. We provide consultation on:

Optimizing substrate purity and defect density to isolate intrinsic magnetic effects.
Designing custom metalization schemes for robust device packaging.
Selecting appropriate polishing grades for surface-sensitive applications (e.g., biological interfaces).
Facilitating global logistics, offering DDU default shipping with DDP available upon request.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The paper presents the results of studying the magnetic properties by magnetometry using a vibrating magnetometer “Vibrating Magnetometer 7404 VSM” of diamond polycrystals obtained by sintering diamond powders with the addition of n-layer graphene at high

Tech Support

Original Source

DOI: https://doi.org/10.30890/2709-1783.2023-26-01-010