Ceramics Crystalline Structure

Crystal structure is also responsible for many of the properties of ceramics.

Ceramics crystalline structure.

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. Most ceramics are opaque except glass. In addition we can classify ceramics as traditional or advanced ceramic mainly depending on their applications. For example magnesium oxide crystallizes in the rock salt structure.

The atomic structure of ceramic can be either crystalline non crystalline or partially crystalline. In the latter case the glassy phase usually surrounds small crystals bonding them together. Or a combination of crystalline and glassy. Polycrystalline materials are formed by multiple crystal grains joined together during the production process whereas monocrystalline materials are grown as one three dimensional crystal.

The glaze on a fired pot is generally an amorphous supercooled liquid. 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. As with metals the unit cell is used in describing the atomic structure of ceramics. However most often ceramics have a crystalline atomic structure.

As the glaze is melted and cooled in the kiln glass molecules bond together in random strings. Ceramics are by definition natural or synthetic inorganic non metallic polycrystalline materials. 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.

Fe ni al called cations and non metallic ions e g. The properties of ceramics however also depend on their microstructure. Ceramic crystal structures broader range of chemical composition than metals with more complicated structures usually compounds between metallic ions e g. The microstructure can be entirely glassy glasses only.

In figures 2a through 2d representative crystal structures are shown that illustrate many of the unique features of ceramic materials. Each collection of ions is shown in an overall box that describes the unit cell of that structure. Sometimes even monocrystalline materials such as diamond and sapphire are erroneously included under the term ceramics. The structure of most ceramics varies from relatively simple to very complex.

Ceramic crystalline or partially crystalline material most ceramics usually contain both metallic and nonmetallic elements with ionic or covalent bonds. Common examples are earthenware porcelain and brick. O n cl called anions bonding will usually have some covalent character but is usually mostly ionic.