EFG Sapphire
What is EFG Sapphire
Edge-fed growth Sapphire refers to synthetic Sapphire crystals produced using the Edge-Defined Film-Fed Growth (EFG) method, developed in the 1960s.
This method is commonly used to grow large, high-quality Sapphire crystals that are often used in industrial applications requiring durability, transparency, and thermal stability
Technical informations
| Growth Process | |
|---|---|
| EFG Method | The Edge-Defined Film Fed Growth method involves pulling a crystal from molten Sapphire through a die that defines the shape of the crystal. The Sapphire crystal is grown along the desired axis as it solidifies |
| Shape and Size | EFG allows for the production of Sapphire crystals in specific shapes and sizes, such as rods, tubes, or ribbons. This is useful for various industrial applications where specific dimensions are required |
| Efficiency | The process is efficient and can produce large quantities of Sapphire, making it cost-effective for industrial purposes |
| Chemical Composition | |
| Formula | Al₂O₃ (Aluminum oxide) |
| EFG Sapphire is chemically identical to natural Sapphire, consisting of pure aluminum oxide with minimal impurities | |
| Physical Properties | |
| Hardness | 9 on the Mohs scale, only second to diamond |
| Density | Approximately 3.98 g/cm³ |
| Optical Properties | |
| Clarity | High clarity with few inclusions, making it suitable for optical applications |
| Refractive Index | 1.762 – 1.770 |
| Transparency | EFG Sapphire is highly transparent, which is essential for its use in optics and electronics |
| Birefringence | Low birefringence, which is desirable in applications requiring consistent optical properties |
| Transmission range | 0.15 to 5.5 micron (from UV to mid-IR) |
| Mechanical Properties | |
| Strength | High mechanical strength, making it suitable for use in environments where it might be subjected to high loads |
| Wear Resistance | Exceptional wear resistance due to its hardness |
| Thermal Properties | |
| Melting Point | Around 2,050°C, similar to other forms of Sapphire |
| Thermal Shock Resistance | Excellent, allowing it to withstand rapid temperature changes without damage |
| Thermal Conductivity | 25 W/mK at 300K |
| Market Value | |
| The process is efficient and can produce large quantities of Sapphire | |
| Cost effective production of shaped crystals | |
EFG Sapphire applications
Semiconductors
EFG Spphire is used as a substrate for LED manufacturing and other semiconductor applications due to its excellent thermal and electrical properties.
Watch Crystals
EFG Sapphire is used for watch faces and other precision instruments due to its scratch resistance and clarity.
The EFG method: how it works
The EFG process begins with molten alumina, which is fed upward through a shaped die (or “mold”) by capillary action. A seed crystal is placed on top of the die, and as the temperature is carefully reduced, the sapphire begins to grow directly into the desired form—mirroring the cross-section of the die.
This technique allows for continuous growth of sapphire elements with defined geometries, making it ideal for manufacturing substrates for LEDs, optical windows, and other specialized components where custom shapes and high precision are required.
FAQ
EFG Sapphire (Edge-defined Film-fed Growth Sapphire) is a synthetic sapphire produced through the EFG method, developed in the 1960s. Unlike Kyropoulos or Czochralski crystals, which grow as large cylindrical boules, the EFG process allows the direct growth of sapphire in specific shapes—such as rods, tubes, ribbons, or plates.
This makes EFG Sapphire particularly cost-effective and versatile, since it reduces the need for extensive cutting and polishing while providing the same optical, thermal, and mechanical advantages as other types of synthetic sapphire.
Want more information about our EFG Sapphire? We can also design a custom solution tailored to your application.
We are proud of our products and different material properties. We will be happy to answer your technical and detailed questions about our EFG Sapphire.