Electroceramics
Electroceramics are specialized synthetic materials designed to interact with electrical or magnetic charges, differing from traditional ceramics that are typically nonconductive. These materials are created through a manufacturing process that alters their conductive properties, enabling a variety of applications in insulators, electrodes, sensors, and mechanical devices. The term ‘electroceramics’ combines Greek roots meaning "amber" and "potter's clay," reflecting the long history of ceramics that dates back over 24,000 years. The production of electroceramics involves manipulating the heating process, known as sintering, which fuses materials together and determines the final properties of the ceramic.
Electroceramics can be categorized into several types based on their functions, including dielectrics, ionics, ferroelectrics, and piezoelectrics. Dielectric ceramics are crucial for components in electronic devices, while ionic electroceramics serve in solid oxide fuel cells. Ferromagnetic electroceramics, which include materials like lead zirconate titanate, are used in sensors and actuators. Other variations, such as mixed ionic/electronic conductors and conductive glass ceramics, provide unique capabilities for specific applications. Overall, electroceramics play a vital role in advancing modern technology through their diverse functionalities and adaptability.
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Electroceramics
Electroceramics are synthetic materials that are specially formulated to be able to interact with electrical or magnetic charges. Some ceramics are nonconductive and are used because they are not affected by heat, electricity, or magnets. However, by manipulating the manufacturing process, the conductive properties of the ceramic material can be changed. These electroceramics have many applications in insulators, electrodes, sensors, actuators, and other components of mechanical devices.
Background
Electroceramics is a combination of two Greek words: electron, meaning "golden" or "amber," and keramos, meaning "pottery" or "potter's clay." The Greek keramos was derived from a Sanskrit word meaning "to burn." People have been making ceramic items for centuries. The earliest known ceramics were made more than 24,000 years ago in Europe.
Ceramics are generally made by mixing earth with a liquid or semi-liquid substance to form clay. This clay is then shaped into the desired form and heated in an oven to very high temperatures, reaching 500 degrees to more than 1,000 degrees. This heating changes the soft, porous pottery to a hard, less permeable substance. There are different types of ceramics, depending on the material used and the way they are made, especially how they are fired—or heated to high temperatures—as the final step of the process.
This firing is key to the final function of the object. It is possible to start with the same type of clay and end up with ceramics with different properties and uses, depending on how each is treated during firing. This heating process is also known as sintering. During sintering, the components of the ceramic are fused together.
An artisan potter making something like a bowl does this to meld the clay molecules together and to help paints and glazes melt and fuse to the pottery. This gives ceramic pottery its finish, including the shiny glazed surface often associated with a ceramic object. Industrial manufacturing also uses sintering to fuse ceramic components together, but these can include metal alloys and other substances, depending on its final intended use. Just as the glaze added by an artisan potter helps to make a bowl's surface smooth, shiny, and resistant to liquids, these additional substances help electroceramics fulfill a specific purpose. While traditional ceramics tend to be nonmagnetic and serve to insulate against heat and electricity, electroceramics are specially treated during the final process to yield properties that allow them to conduct heat, electricity, or to react to magnetic currents.
Overview
Electroceramics are broadly defined as any ceramic that is designed to perform a specific electronic function. There are a number of categories of electroceramics, which are differentiated by the task for which they are designed. These include dielectrics, ionics, ferroelectrics, and piezoelectrics and pyroelectrics.
Dielectric ceramics are used as components in printed circuit boards for electronic devices and in components used in cellular and satellite phones. They are also used as insulators in devices such as capacitors where they help to separate the opposite electrical charges in the device. However, unlike their non-electroceramic counterparts, dielectric ceramics can be easily polarized. This is important in devices such as capacitors.
A capacitor stores electric energy; it has pairs of conductors separated by insulators. When that insulator is a dielectric ceramic, the side of it closest to the positive conductor will have a negative charge, and vice versa. This reduces the overall electrical field in the capacitor, so it requires more energy to return to its original charge; in this way, the dielectric ceramic insulator allows the capacitor to store more energy.
Ionic electroceramics are important components in solid oxide fuel cells (SOFCs). SOFCs are an alternative fuel source with a smaller carbon footprint than traditional fuel cells. However, they require components that can resist high heat and be made in many different formations to work with different fuel types. The ability of ceramics to be formed in virtually any shape and the ability of electroceramics to withstand high heat make them a good candidate for these parts.
Ferromagnetic electroceramics are made by fusing another substance, often lead zirconate titanate or barium titanate, into the ceramic as it is sintered. This allows the resulting ceramic piece to be aligned like a magnet when it is exposed to an electrical field. Ferromagnetic electroceramics are used in sensors, accelerometers, transformers, actuators, spark igniters, and some imaging devices such as sonar and ultrasound machines. Piezoelectric and pyroelectric ceramics are types of ferromagnetic electroceramics differentiated by the types of materials blended into the ceramics.
In addition to the main types of electroceramics, there are several other kinds of ceramics that function as electroceramics but have some key differences. These include mixed ionic/electronic conductors, or MIECs, and conductive glass ceramics. Each fulfills a unique purpose that cannot be accomplished or would be harder to accomplish with other materials.
MIECs can conduct both electrons and ions. Their flexibility in handling both ions and electrons makes them useful in a number of electronic components, including fuel cells, selective membranes that only let through certain substances, some types of sensors and electrodes where their special versatility provides an advantage, and smart windows with glass that can turn from clear to frosted through the application of an electrical current.
Conductive glass ceramics are another class of electroceramics that are not sintered or fired. Instead, they are manufactured like glass. The glass-making process generally involves high heat, but the process used creates a product that is impervious to liquids. The process of making a conductive glass ceramic starts with making glass that is then shaped before being cooled and then reheated as many as two times. Additional metals or other elements may be added, depending on the intended final use. This process was discovered accidentally in 1953 when a glass furnace malfunctioned and superheated while a Corning Glass Works researcher named Stanley Donald Stookey was working with glass and silver to make a photograph plate. Stookey dropped the plate after it was removed from the furnace. It did not break; the resulting product was subsequently marketed as Corning cookware.
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