Life Cycle Assessment of Synthetic Nanodiamond and Diamond Film Production

At a Glance

Metadata	Details
Publication Date	2023-12-20
Journal	ACS Sustainable Chemistry & Engineering
Authors	Anna Furberg, Rickard Arvidsson
Institutions	Norwegian Institute for Sustainability Research, KTH Royal Institute of Technology
Citations	2
Analysis	Full AI Review Included

Technical Documentation & Analysis: Life Cycle Assessment of Synthetic Diamond Production

6CCVD (6ccvd.com) specializes in high-purity, custom MPCVD diamond materials for advanced engineering and scientific applications. This analysis leverages the findings of the recent Life Cycle Assessment (LCA) study on Nanodiamond (DND) and MWCVD Diamond Film production to highlight critical material selection and process optimization opportunities, directly aligning 6CCVD’s capabilities with sustainable research goals.

Executive Summary

This LCA provides crucial data on the environmental hotspots associated with synthetic diamond production, particularly via Microwave Chemical Vapor Deposition (MWCVD).

LCA Hotspots Identified: For MWCVD diamond film production, the environmental impact is overwhelmingly dominated by electricity consumption (74% of global warming impact) and the Silicon (Si) substrate (26%).
Functional Units: The study focused on 1 g of Detonation Nanodiamond (DND) (4-5 nm primary particles) and 1 cm² of diamond film (10 µm thickness).
Sustainability Opportunity: Switching the electricity source for MWCVD from global average to wind/solar power significantly reduces global warming, freshwater eutrophication, and terrestrial acidification impacts by 62-71%.
Material Comparison: DND is shown to be environmentally preferable to conventional synthetic diamond grit (HPHT), exhibiting a global warming impact approximately 5 times lower.
Process Sensitivity: Key parameters influencing MWCVD impact include apparatus power, growth rate, and substrate diameter, emphasizing the need for highly optimized CVD recipes.
6CCVD Value Proposition: 6CCVD provides custom MPCVD substrates (SCD and PCD) and engineering consultation to optimize growth parameters (thickness, rate, substrate type) to minimize the identified LCA hotspots, supporting sustainable diamond material development.

Technical Specifications

The following hard data points were extracted from the baseline scenario for Microwave Chemical Vapor Deposition (MWCVD) diamond film production analyzed in the study.

Parameter	Value	Unit	Context
Functional Unit (Film)	1	cm²	10 µm thick diamond film
Film Thickness (Baseline)	10	µm	Common order-of-magnitude
CVD Diamond Density	2800 - 3510	kg/m³	Typical range for CVD-grown diamond
Substrate Material (Baseline)	Silicon (Si)	N/A	Used for polycrystalline film deposition
Substrate Diameter (Baseline)	15	cm	Large-scale commercialized production
Substrate Thickness (Baseline)	775	µm	Based on Chinese Si wafer manufacturer data
MWCVD Power (Baseline)	45	kW	915 MHz operating frequency apparatus
Baseline Growth Rate	6.5	µm/h	Used to calculate required electricity input time
Seeding Density (Films <50 µm)	10¹¹	DNDs/cm²	Required for thin film nucleation
Global Warming Impact (MWCVD)	380	g CO₂ eq/cm²	10 µm film, baseline scenario
Electricity Contribution (GW)	74	%	Dominant MWCVD impact source
Substrate Contribution (GW)	26	%	Second largest MWCVD impact source

Key Methodologies

The life cycle assessment focused on industrial-scale production routes. The MWCVD synthesis parameters used in the baseline scenario are critical for replicating or improving the environmental profile of diamond film production.

Synthesis Technology: Microwave Chemical Vapor Deposition (MWCVD) was selected as the most widely applied CVD technology for industrial production.
Substrate Preparation: Silicon (Si) wafers were used as the substrate for polycrystalline diamond (PCD) film deposition.
Seeding Technique: Electrostatic seeding was applied, utilizing Detonation Nanodiamond (DND) particles (4-5 nm primary size) suspended in DMSO solvent.
Gas Precursors: Methane (CH₄) and Hydrogen (H₂) were used, typically at a 1:99 volume ratio (CH₄:H₂).
Reactor Specifications: A 915 MHz operating frequency apparatus was modeled, accommodating large substrates (up to 15 cm diameter).
Growth Parameters: Typical deposition conditions involved pressures between 0.67-13 kPa and temperatures between 800-1000 °C.
Functional Output: The process yielded a 10 µm thick diamond film on the Si substrate, achieved at a baseline growth rate of 6.5 µm/h.

6CCVD Solutions & Capabilities

The LCA study clearly identifies the substrate material and energy consumption (growth time/rate) as the primary environmental burdens in MWCVD diamond film production. 6CCVD offers specialized materials and customization services that directly address these hotspots, enabling researchers and manufacturers to achieve lower-impact, high-performance diamond solutions.

Applicable Materials for Sustainable MWCVD

The study notes that diamond itself constitutes a possible substrate, which is environmentally advantageous as it eliminates the high impact associated with Si wafer production and disposal.

6CCVD Material Recommendation	Application & LCA Benefit	6CCVD Capability
Optical Grade Single Crystal Diamond (SCD)	Required for high-purity electronics, quantum photonics, and thin-film devices mentioned in the paper.	SCD plates up to 500 µm thickness. Ra < 1 nm polishing for superior surface quality required in advanced applications.
High-Purity Polycrystalline Diamond (PCD)	Ideal for large-area coatings and high-wear resistance applications (e.g., cutting tools).	Custom dimensions up to 125 mm diameter (exceeding the 15 cm baseline Si wafer). Thicknesses up to 500 µm.
Boron-Doped Diamond (BDD)	Relevant for electrochemical applications (wastewater treatment) assessed in related LCA studies.	Custom BDD films and substrates with tailored doping levels for specific conductivity requirements.

Customization Potential to Mitigate LCA Hotspots

6CCVD’s advanced manufacturing capabilities allow for precise control over the parameters identified as sensitive in the LCA (power, growth rate, thickness, substrate size).

Substrate Optimization: The study highlights that the Si substrate contributes 26% of the global warming impact. 6CCVD offers free-standing SCD and PCD wafers (up to 500 µm thickness), eliminating the need for Si disposal and reducing the overall material burden in the final product.
Custom Dimensions and Thickness: We provide custom plates and wafers up to 125 mm (PCD) and offer precise thickness control from 0.1 µm to 500 µm (SCD/PCD). This allows engineers to minimize material usage while meeting functional requirements, directly reducing the mass-based environmental impact.
Surface Engineering: The study utilized DND seeding (10¹¹ DNDs/cm²) for thin film nucleation. 6CCVD provides ultra-smooth polishing (Ra < 1 nm for SCD, < 5 nm for PCD), which is critical for achieving uniform seeding and optimal film growth, potentially allowing for lower seeding densities or faster growth rates, thereby reducing energy consumption.
Metalization Services: For thin-film electronics and semiconductor applications, 6CCVD offers in-house custom metalization (Au, Pt, Pd, Ti, W, Cu) to integrate diamond films directly into devices, streamlining the supply chain and reducing downstream processing impacts.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing MPCVD growth recipes. We can assist researchers and manufacturers in selecting materials and process parameters (e.g., CH₄:H₂ ratio, pressure, power density) to maximize growth rate and material quality, thereby minimizing the electricity input (the 74% global warming hotspot) required for similar Quantum Photonics, Semiconductor, or Hard Coating projects.

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

View Original Abstract

Diamond possesses extraordinary properties, including extreme hardness, thermal conductivity, and mechanical strength. Global industrial diamond production is dominated by synthetic diamond, with important commercial applications in hard coatings and semiconductors. However, the life cycle impacts of synthetic diamond materials are largely unknown. The main aim of this study is to conduct the first detailed life cycle assessments of the typical production routes for nanodiamond and diamond film, which are detonation synthesis and microwave chemical vapor deposition, respectively. The functional units were set to 1 g nanodiamond and 1 cm2 diamond film. A limited number of inputs dominate the assessed impacts: explosives and cooling water for nanodiamond production, and electricity and substrate for diamond film production. Diamond film manufacturers can reduce their global warming, freshwater eutrophication, and terrestrial acidification impacts by 62-71% by sourcing wind or solar instead of global average electricity. However, this comes at the expense of increased mineral resource scarcity impacts at 57-73%. A comparison between nanodiamond and synthetic diamond grit shows that the grit’s global warming impact is about 5 times higher, suggesting that nanodiamond is environmentally preferable. The ready-to-use unit-process data from this study can be applied in future studies of products containing these materials.

Tech Support

Original Source

DOI: https://doi.org/10.1021/acssuschemeng.3c05854

References

2015 - Handbook of Crystal Growth [Crossref]
2017 - Nanodiamonds - Advanced Material Analysis, Properties and Applications
2014 - Nanodiamond [Crossref]