Boron nitride exhibits exceptional strength, particularly in its atomically thin, monolayer form, which is among the strongest known materials.
The Remarkable Strength of Monolayer Boron Nitride
Monolayer boron nitride (BN) demonstrates extraordinary mechanical properties. Its strength is characterized by two key metrics: Young's modulus, which measures stiffness, and fracture strength, which indicates the maximum stress a material can withstand before breaking.
For atomically thin monolayer boron nitride, studies have determined these properties to be:
| Property | Value | Unit | Description |
|---|---|---|---|
| Young's Modulus | 0.865 ± 0.073 | TPa | Measures stiffness or resistance to elastic deformation. A higher value indicates greater stiffness. |
| Fracture Strength | 70.5 ± 5.5 | GPa | Represents the maximum stress a material can withstand before fracturing. |
To put these numbers into perspective:
- Young's Modulus: The Young's modulus of monolayer BN is comparable to that of graphene (around 1 TPa), another famously strong two-dimensional material. This makes it significantly stiffer than conventional engineering materials like steel, which has a Young's modulus of approximately 200 GPa (0.2 TPa).
- Fracture Strength: With a fracture strength exceeding 70 GPa, monolayer BN is incredibly robust. High-strength steel typically has a fracture strength in the range of 0.5 to 2 GPa, highlighting boron nitride's superior breaking strength at an atomic scale.
Understanding Boron Nitride's Strength
Boron nitride exists in various forms, including hexagonal boron nitride (h-BN), which shares a similar layered structure with graphite, and cubic boron nitride (c-BN), which has a diamond-like structure. The data provided above specifically pertains to the atomically thin, two-dimensional form of h-BN, often referred to as monolayer BN.
The exceptional strength of monolayer BN arises from the strong covalent bonds between boron and nitrogen atoms within its hexagonal lattice structure. This atomic arrangement provides a high degree of stability and resistance to external forces.
Practical Implications and Applications
The extreme strength and stiffness of boron nitride make it a highly promising material for various advanced applications:
- Reinforcing Agent: Its high Young's modulus and fracture strength make it an excellent candidate for strengthening composite materials, leading to lighter and more durable products for aerospace, automotive, and sports equipment industries.
- Protective Coatings: Boron nitride's hardness and chemical inertness, especially in its cubic form, make it suitable for wear-resistant coatings on tools and machinery, enhancing their longevity.
- High-Performance Electronics: In its monolayer form, BN can serve as a robust substrate or insulating layer in advanced electronic devices, particularly those requiring flexible, durable, and atomically thin components. Its thermal conductivity and electrical insulation properties complement its mechanical strength.
- Extreme Environment Materials: Its stability at high temperatures and chemical resistance make it valuable for components operating in harsh conditions.
In summary, monolayer boron nitride is a material of extraordinary strength and stiffness, far surpassing many conventional materials, and holds immense potential for future technological advancements.
