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The atomic structure of perovskite, a complex oxide. The red spheres are oxygen atoms, and the blue and green spheres are atoms of other elements.

A complex oxide is a chemical compound that contains oxygen and at least two other elements (or just one other element in at least two oxidation states).^[1] Complex oxide materials are notable for their wide range of magnetic and electronic properties, such as ferromagnetism, ferroelectricity, and high-temperature superconductivity. These properties often come from their strongly correlated electrons in d or f orbitals.

Natural occurrence

Many minerals found in the ground are complex oxides. Commonly studied mineral crystal families include spinels and perovskites.

Applications

Complex oxide materials are used in a variety of commercial applications.

Magnets

Magnets made of the complex oxide ferrite are commonly used in transformer cores, inductors, and refrigerator magnets.^[2] Ferrites are ideal because they are magnetic, electrically insulating, and inexpensive.

Transducers and actuators

Piezoelectric transducers and actuators are often made of the complex oxide PZT (lead zirconate titanate).^[3] These transducers are used in applications such ultrasound imaging and some microphones. PZT is also sometimes used for piezo ignition in lighters and gas grills.

Capacitors

Complex oxide materials are the dominant dielectric material in ceramic capacitors.^[4] About one trillion ceramic capacitors are produced each year to be used in electronic equipment.

Fuel cells

Solid oxide fuel cells often use complex oxide materials as their electrolytes, anodes, and cathodes.^[5]

Gemstone jewelry

Many precious gemstones, such as emerald and topaz, are complex oxide materials. Some complex oxide materials have also been synthesized as inexpensive diamond simulants, though today they are no longer state-of-the-art (strontium titanate, yttrium aluminum garnet, and gadolinium gallium garnet).

New electronic devices

As of 2015, there is research underway to commercialize complex oxides in new kinds of electronic devices, such as ReRAM, FeRAM, and memristors. Complex oxide materials are also being researched for their use in spintronics.

Another potential application of complex oxide materials is superconducting power lines. A few companies have invested in pilot projects, but the technology is not widespread.

Commonly studied complex oxides

Lead zirconate titanate (a piezoelectric material)
Lanthanum aluminate (a high-dielectric insulator)
Strontium titanate (a high-dielectric semiconductor)
Lanthanum strontium manganite (which exhibits colossal magnetoresistance)
Barium titanate (a multiferroic material)
Bismuth ferrite (a multiferroic material)
Yttrium barium copper oxide (a high-temperature superconductor)
Bismuth strontium calcium copper oxide (a high-temperature superconductor)

References

^ Ishihara, Tatsumi (2009). Perovskite Oxide for Solid Oxide Fuel Cells (1 ed.). Springer US. p. 1. ISBN 978-0-387-77708-5.
^ Goldman, Alex (2006). Modern Ferrite Technology (2nd Edition ed.). Springer US. pp. 217–226. ISBN 978-0-387-28151-3. {{cite book}}: |edition= has extra text (help)
^ "What is "PZT"?". American Piezo. APC International, Ltd. Retrieved 19 June 2015.
^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1109/MEI.2010.5383924, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1109/MEI.2010.5383924 instead.[1]
^ "Lanthanum strontium cobalt oxide cathode powder". Fuel Cell Materials. Retrieved 19 June 2015.

External links

[1] Ishihara, Tatsumi (2009). Perovskite Oxide for Solid Oxide Fuel Cells (1 ed.). Springer US. p. 1. ISBN 978-0-387-77708-5.

[2] Goldman, Alex (2006). Modern Ferrite Technology (2nd Edition ed.). Springer US. pp. 217–226. ISBN 978-0-387-28151-3. {{cite book}}: |edition= has extra text (help)

[3] "What is "PZT"?". American Piezo. APC International, Ltd. Retrieved 19 June 2015.

[capacitor-4] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1109/MEI.2010.5383924, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1109/MEI.2010.5383924 instead.[1]

[5] "Lanthanum strontium cobalt oxide cathode powder". Fuel Cell Materials. Retrieved 19 June 2015.

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@@ Line 43: / Line 43: @@
 == Commonly studied complex oxides ==
-* [[Lead zirconate titanate]] (a piezoelectric material)
+* [[Lead zirconate titanate]] (a [[piezoelectric]] material)
 * [[Lanthanum aluminate]] (a [[high-κ dielectric|high-dielectric]] insulator)
-* [[Strontium titanate]] (a high-dielectric semiconductor)
+* [[Strontium titanate]] (a high-dielectric [[semiconductor]])
-* [[Lanthanum strontium manganite]] (colossal magnetoresistance)
+* [[Lanthanum strontium manganite]] (which exhibits [[colossal magnetoresistance]])
-* [[Barium titanate]] (a multiferroic material)
+* [[Barium titanate]] (a [[multiferroic]] material)
 * [[Bismuth ferrite]] (a multiferroic material)
-* [[Yttrium barium copper oxide]] (a high-temperature superconductor)
+* [[Yttrium barium copper oxide]] (a [[high-temperature superconductor]])
 * [[Bismuth strontium calcium copper oxide]] (a high-temperature superconductor)