Ceramics Crystalline Structure

The atomic structure of ceramic can be either crystalline non crystalline or partially crystalline.

Ceramics crystalline structure. The glaze on a fired pot is generally an amorphous supercooled liquid. In addition we can classify ceramics as traditional or advanced ceramic mainly depending on their applications. In figures 2a through 2d representative crystal structures are shown that illustrate many of the unique features of ceramic materials. Most often fired ceramics are either vitrified or semi vitrified as is the case with earthenware stoneware and porcelain.

Each collection of ions is shown in an overall box that describes the unit cell of that structure. A ceramic is any of the various hard brittle heat resistant and corrosion resistant materials made by shaping and then firing a nonmetallic mineral such as clay at a high temperature. Ceramic crystalline or partially crystalline material most ceramics usually contain both metallic and nonmetallic elements with ionic or covalent bonds. As the glaze is melted and cooled in the kiln glass molecules bond together in random strings.

The properties of ceramics however also depend on their microstructure. Most ceramics have a highly crystalline structure in which a three dimensional unit called a unit cell is repeated throughout the material. By repeatedly translating the unit cell one box in any direction and by repeatedly depositing the pattern of ions within that cell at each new position any size. O n cl called anions bonding will usually have some covalent character but is usually mostly ionic.

Ceramics are by definition natural or synthetic inorganic non metallic polycrystalline materials. Fe ni al called cations and non metallic ions e g. Sometimes even monocrystalline materials such as diamond and sapphire are erroneously included under the term ceramics. Crystal structure is also responsible for many of the properties of ceramics.

In the latter case the glassy phase usually surrounds small crystals bonding them together. Polycrystalline materials are formed by multiple crystal grains joined together during the production process whereas monocrystalline materials are grown as one three dimensional crystal. Most ceramics are opaque except glass. The macro crystalline glazes or more commonly known simply as crystalline glazes have crystals that grow large enough to see.

The crystallinity of ceramic materials ranges from highly oriented to semi crystalline vitrified and often completely amorphous. The microstructure can be entirely glassy glasses only. Common examples are earthenware porcelain and brick. Ceramic crystal structures broader range of chemical composition than metals with more complicated structures usually compounds between metallic ions e g.

As with metals the unit cell is used in describing the atomic structure of ceramics. Therefore the structure the metallic atoms the structure of the nonmetallic atoms and the balance of charges produced by the valence electrons must be considered. The structure of most ceramics varies from relatively simple to very complex.