Ceramics, magnetic

Over the past 60 years ceramic magnets have become firmly established as electrical and electronic engineering materials most contain iron as a major constituent and are known collectively as ferrites . 

During the 1930s the Philips researchers in The Netherlands made important contributions to the science and technology of ferrites, especially the pioneer, J.L. Snoek who, in the West, saw the industrial significance of ferrites as telecommunications was rapidly advancing. The development of the magnetically hard hexagonal ferrite ( Ferroxdure ) is also due to Philips [5]. 

Electroceramics Materials, Properties, Applications. 2nd Edition. Edited by A. J. Moulson and J. M. Herbert. 2003 John Wiley Sons, Ltd ISBN 0 471 49747 9 (hardback) 0 471 49748 7 (paperback) 

---

The main categories of electrical/optical ceramics are as follows phosphors for TV, radar and oscilloscope screens voltage-dependent and thermally sensitive resistors dielectrics, including ferroelectrics piezoelectric materials, again including ferroelectrics pyroelectric ceramics electro-optic ceramics and magnetic ceramics. 

Valenzuela, R. (1994) Magnetic Ceramics (Cambridge University Press, Cambridge). 

Finally, the combination of dendrimers and organometallic entities as fundamental building blocks affords an opportunity to construct an infinite variety of organometallic starburst polymeric superstructures of nanoscopic, microscopic, and even macroscopic dimensions. These may represent a promising class of organometallic materials due to their specific properties, and potential applications as magnetic ceramic precursors, nonlinear optical materials, and liquid crystal devices in nanoscale technology. 

Most of the important magnetic ceramics are of the ferrimagnetic class. However, some ceramics do exhibit other types of magnetic behavior. These ceramic materials will be described first, followed by a more thorough description of an important class of ferrimagnetic ceramics called ferrites. Finally, a topic related to the magnetic properties of ceramic superconductors will be introduced. 

Synthetic ferrites also exhibit ferrimagnetism. Ferrites are magnetic ceramic materials which are made by mixing iron (III) oxide with, for instance, powdered oxides and carbonates and subsequently compressing and sintering them. They are produced in large quantities and in many different shapes. We distinguish soft and hard ferrites. 

---