--- title: HEM Sapphire | Freudiger SA description: Discover high-quality HEM Sapphire, produced using the Heat Exchange Method for superior optical clarity and durability in various industrial applications. image: https://freudigersa.com/hubfs/Featured%20Image.jpg --- # HEM Sapphire [Download technical sheet](https://freudigersa.com/hubfs/Schede%20tecniche/HEM%20HEAT%20EXCHANGE%20METHOD%20SAPPHIRE.pdf?hsLang=en) [Require your custom solution](https://freudigersa.com/materials/hem-sapphire#contact-us) ## What is HEM Sapphire The Heat Exchange Method (HEM) is a technique used to grow large, high-quality synthetic Sapphire crystals. This method is particularly known for producing crystals with excellent optical and structural properties, making them suitable for a wide range of industrial and technological applications. ## Technical informations | Growth Process | | | --- | --- | | In Heat Exchange Method (HEM) the Sapphire crystal grows in a specially designed furnace where heat is carefully controlled and distributed. The process is designed maintain a precise temperature gradient | | | Controlled Growth | The slow cooling and precise temperature control result in a crystal with fewer defects and inclusions, leading to high optical clarity and uniformity | | 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 | HEM Sapphires have exceptional clarity due to the controlled growth process, which minimizes inclusions and defects | | Transparency | High transparency, making these Sapphires ideal for high end optical applications | | Birefringence | Low birefringence, which is desirable for applications requiring consistent optical properties | | Transmission range | 0.15 to 5.5 micron (from UV to mid-IR) | | Mechanical Properties | | | High mechanical strength, making HEM Sapphire suitable for demanding applications where durability is critical | | | Excellent wear resistance due to its hardness | | | Thermal Conductivity | High thermal conductivity, which is useful in heat-dissipating components | | Thermal Properties | | | Melting Point | Approximately 2,050°C, similar to other forms of Sapphire | | Thermal Shock Resistance | Excellent, allowing it to withstand rapid temperature changes withoutcracking | | Thermal Conductivity | 25 W/mK at 300K | | Market Value | | | HEM Sapphires are valued primarily for their use in high-tech and industrial applications, where their superior properties are critical. The cost is often related to the size, purity, and intended application of the Sapphire | | ## HEM Sapphire applications ** #### Optical Components HEM Sapphire is commonly used in the production of high-quality optical windows, lenses, and other components that require superior clarity and durability. ** #### Semiconductors  It is widely used as a substrate in LED manufacturing and other semiconductor applications due to its excellent thermal and electrical properties. ** #### Aerospace Employed in aerospace applications for windows and other components that require extreme durability and resistance to harsh environments. ** #### Watch Crystals Used for high-end watch faces due to its scratch resistance and clarity. ** #### Medical Devices Applied in medical lasers and other devices where high-purity, transparent materials are required. [Download technical sheet](https://freudigersa.com/hubfs/Schede%20tecniche/HEM%20HEAT%20EXCHANGE%20METHOD%20SAPPHIRE.pdf?hsLang=en) ## The HEM method: how it works The HEM method begins by melting high-purity alumina in a crucible inside a furnace with carefully controlled thermal gradients. A seed crystal is placed at the bottom, above a water-cooled heat exchanger. As the melt slowly solidifies from the bottom upward, the cooling system helps manage stress and ensures even crystal growth. This bottom-up growth process enables the production of very large sapphire boules, sometimes over 40 cm in diameter, while maintaining exceptional clarity, mechanical strength, and low birefringence. ### FAQ What is HEM Sapphire?** HEM Sapphire (Heat Exchanger Method Sapphire) is a synthetic sapphire grown using a technique designed to minimize thermal stress during crystal formation. Unlike Kyropoulos or EFG, the HEM process uses a special furnace equipped with multiple heating zones and a heat exchanger at the base. The result is the growth of very large sapphire boules with excellent homogeneity, low internal stress, and outstanding optical quality. How is HEM Sapphire produced?** HEM Sapphire is produced by melting high-purity alumina in a crucible and cooling it from the bottom up with a heat exchanger. A seed crystal at the base guides the growth, while the controlled thermal gradient minimizes stress. This process allows large, high-quality sapphire boules to form with excellent clarity and low internal defects. Can you manufacture custom geometries or micro-components?** Yes, we produce both standard and fully customized Sapphire components, including complex shapes and micro-parts with tight tolerances, tailored to your specifications. Do you provide prototypes?** Yes, we support the development of prototypes and pre-series batches, allowing you to test performance and functionality before moving into full-scale production. Is there a minimum order quantity?** No, we handle both single custom parts and large production runs. Our process is designed to meet your volume requirements without compromising on quality or precision. Do you ship internationally?** Yes, we serve clients worldwide and manage international logistics, ensuring smooth delivery regardless of your location. ### Want more information about our HEM 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 HEM Sapphire. *****The technical specifications and material information provided on this website adhere to industry standards and are not determined by our company. While we strive to ensure accuracy, these details are for informational purposes only and may be subject to change. ```json { "@context" : "https://schema.org", "@type" : "Organization", "address" : { "@type" : "PostalAddress", "addressCountry" : "", "addressLocality" : "6934 Bioggio", "addressRegion" : "Switzerland", "postalCode" : "", "streetAddress" : "Via Stazione 3" }, "knowsLanguage" : "en", "logo" : { "@type" : "ImageObject", "url" : "https://143914375.fs1.hubspotusercontent-eu1.net/hubfs/143914375/Freudiger%20Logo.svg" }, "name" : "Freudiger SA", "url" : "https://freudigersa.com/materials/hem-sapphire" } ``` ```json { "@context" : "https://schema.org", "@type" : "Dataset", "creator" : { "@type" : "Organization", "name" : "Freudiger SA", "url" : "https://freudigersa.com" }, "description" : "Technical information sheet for sapphire grown with the Heat Exchange Method (HEM): chemical composition and physical, optical, mechanical and thermal properties.", "keywords" : [ "HEM sapphire", "Al2O3", "technical properties", "sapphire material" ], "license" : "https://freudigersa.com", "name" : "HEM Sapphire — Technical Properties", "variableMeasured" : [ { "@type" : "PropertyValue", "name" : "Growth process", "value" : "In Heat Exchange Method (HEM) the sapphire crystal grows in a specially designed furnace with a precise temperature gradient. Slow cooling and temperature control reduce defects and inclusions." }, { "@type" : "PropertyValue", "name" : "Chemical formula", "value" : "Al₂O₃ (Aluminum oxide)" }, { "@type" : "PropertyValue", "name" : "Hardness", "value" : "9 on the Mohs scale, only second to diamond" }, { "@type" : "PropertyValue", "name" : "Density", "value" : "Approximately 3.98 g/cm³" }, { "@type" : "PropertyValue", "name" : "Clarity", "value" : "Exceptional clarity due to controlled growth that minimizes inclusions and defects." }, { "@type" : "PropertyValue", "name" : "Transparency", "value" : "High transparency; suitable for high-end optical applications." }, { "@type" : "PropertyValue", "name" : "Birefringence", "value" : "Low birefringence; desirable for applications requiring consistent optical properties." }, { "@type" : "PropertyValue", "name" : "Transmission Range", "value" : "0.15 to 5.5 micron (from UV to mid-IR)." }, { "@type" : "PropertyValue", "name" : "Mechanical strength", "value" : "High mechanical strength for demanding applications where durability is critical." }, { "@type" : "PropertyValue", "name" : "Wear resistance", "value" : "Excellent wear resistance due to high hardness." }, { "@type" : "PropertyValue", "name" : "Thermal conductivity", "value" : "25 W/mK at 300K." }, { "@type" : "PropertyValue", "name" : "Thermal shock resistance", "value" : "Excellent; withstands rapid temperature changes without cracking." }, { "@type" : "PropertyValue", "name" : "Melting point", "value" : "≈ 2050 °C" }, { "@type" : "PropertyValue", "name" : "Market value (context)", "value" : "Primarily valued for high-tech and industrial applications; cost depends on size, purity and intended application." } ] } ``` ```json { "@context" : "https://schema.org", "@type" : "FAQPage", "mainEntity" : [ { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "HEM Sapphire (Heat Exchanger Method Sapphire) is a synthetic sapphire grown using a technique designed to minimize thermal stress during crystal formation. 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