What is the Difference Between Boron Nitride and Graphite

Boron nitride and graphite are two crystalline materials with similar layered structures. Both consist of sheets of atoms arranged in a hexagonal lattice. However, they have different electrical properties, which give them different applications.

What is the difference between boron nitride and graphite? Boron nitride is made from boron and nitrogen atoms linked by strong covalent bonds, whereas graphite is made from pure carbon atoms arranged in a hexagonal lattice with strong covalent bonds within each layer.

Key Areas Covered

1. What is Boron Nitride  
      – Definition, Features, Composition 
2. What is Graphite
      – Definition, Features, Composition 
3. Similarities Between Boron Nitride and Graphite
      – Outline of Common Features
4. Difference Between Boron Nitride and Graphite
      – Comparison of Key Differences
5. FAQ: Boron Nitride and Graphite
      – Answers to Frequently Asked Questions

Key Terms

Boron Nitride, Graphite

What is Boron Nitride

Boron nitride is composed of nitrogen and boron atoms bonded together with covalent bonds. It has the chemical formula BN. It is a ceramic compound and is also referred to as white graphene. This is because it is structurally similar to graphene.

Figure 1: Boron Nitride

Boron nitride is an electrical insulator, which means it doesn’t conduct electricity. It exists in different crystalline forms with distinct properties. The most stable form is hexagonal BN (h-BN), which mirrors the structure of graphite. Here, boron and nitrogen atoms form hexagonal rings stacked in layers. Layers of boron nitride can slide over each other, giving lubricating properties to the material even at high temperatures. Another form, cubic BN (c-BN), has a structure similar to diamond. The process of creating c-BN involves applying high pressure and temperature to h-BN.

There are many applications of boron nitride. Due to its lubricating properties, it is used in machinery, cosmetics, and molds. Boron nitride has a higher thermal conductivity. This property is used in electronics and semiconductors. It is also used in coatings, neutron shielding, and nanotechnology.

What is Graphite

Graphite is a naturally occurring crystalline form of carbon. Graphite has a well-defined, ordered structure. Imagine thin sheets of carbon atoms arranged in a hexagonal pattern, like a honeycomb. These sheets are stacked on top of each other.

The carbon atoms within each sheet are linked by strong covalent bonds, making the sheets themselves very stable. However, the forces holding the sheets together are weak van der Waals forces. This allows the sheets to slide easily over each other. Hence, it gives graphite lubricating properties.

Figure 2: Graphite

Electrons can move freely within each sheet, making graphite a good conductor of electricity. The strong covalent bonds within the sheets contribute to graphite’s high melting point.

There are many applications of graphite. They are commonly used in pencils. The friction between the graphite layers allows them to transfer onto paper when rubbed. They are also used in lubrication, as electrodes, composite materials, and as a graphene precursor.

Similarities Between Boron Nitride and Graphite

1. Both BN (hexagonal form) and graphite consist of sheets of atoms arranged in a hexagonal lattice.
2. The forces holding the sheets together in both BN and graphite are weak van der Waals forces.
3. The strong covalent bonds within each layer of both BN and graphite lead to high melting points for these materials.

Difference Between Boron Nitride and Graphite

Definition 

• Boron nitride is composed of boron and nitrogen atoms linked by covalent bonds. Meanwhile, graphite has pure carbon atoms arranged in a hexagonal lattice with covalent bonds within each layer.

Electrical Conductivity

• Boron nitride is an insulator due to the lack of free electrons for conduction, while graphite conducts electricity well within the layers due to delocalized electrons in the carbon rings.

Chemical Reactivity

• Boron nitride is highly inert (chemically inactive) at high temperatures, while graphite can react with oxygen at high temperatures, releasing carbon dioxide.

Color

• While boron nitride is white or grayish-white, graphite is black or grayish-black.

Conclusion

Boron nitride is a crystalline material made of boron and nitrogen atoms linked by covalent bonds, whereas graphite is a crystalline material made of pure carbon atoms arranged in a hexagonal lattice with covalent bonds within each layer. This is the difference between boron nitride and graphite.

FAQ: Boron Nitride and Graphite

1. Why is BN harder than graphite?

The hardness depends on the type of BN. Hexagonal BN, like graphite, is soft due to weak bonds between its slippery layers. But cubic BN, with a diamond-like structure, is super hard – second only to diamond itself.

2. Is boron nitride similar to graphite?

Yes, both boron nitride and graphite are similar as they share a layered structure and are slippery. However, boron nitride is a ceramic and is strong at high temperatures, while graphite conducts electricity well.

3. What is stronger than boron nitride?

Under extreme conditions, scientists created carbon nitride materials that surpass even cubic boron nitride, previously the second strongest after diamond.

4. What are the advantages of boron nitride?

Boron nitride has several advantages. BN is resistant to high heat. In addition, it does not react easily, and conducts heat well.

5. Is boron nitride harder than diamonds?

No. Cubic boron nitride (c-BN) is incredibly hard but falls short of diamonds. However, c-BN boasts better heat resistance, making it ideal for machining tasks where diamonds would degrade.

Reference:

1. “Boron Nitride.” Science Direct. 
2. “Graphite Carbon.” Encyclopedia Britannica. 

Image Courtesy:

1. “Boron-nitride-(hexagonal)-side-3D-balls” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Graphite” By Rob Lavinsky, iRocks.com (CC-BY-SA-3.0) via Commons Wikimedia