Editing Dielectric (section)

==Tunability==
''Tunable dielectrics'' are insulators whose ability to store electrical charge changes when a voltage is applied.<ref name=k>{{cite journal|last1=Lee|first1=Che-Hui|last2=Orloff|first2=Nathan D.|last3=Birol|first3=Turan|last4=Zhu|first4=Ye|last5=Goian|first5=Veronica|last6=Rocas|first6=Eduard|last7=Haislmaier|first7=Ryan|last8=Vlahos|first8=Eftihia|last9=Mundy|first9=Julia A.|last10=Kourkoutis|first10=Lena F.|last11=Nie|first11=Yuefeng|last12=Biegalski|first12=Michael D.|last13=Zhang|first13=Jingshu|last14=Bernhagen|first14=Margitta|last15=Benedek|first15=Nicole A.|last16=Kim|first16=Yongsam|last17=Brock|first17=Joel D.|last18=Uecker|first18=Reinhard|last19=Xi|first19=X. X.|last20=Gopalan|first20=Venkatraman|last21=Nuzhnyy|first21=Dmitry|last22=Kamba|first22=Stanislav|last23=Muller|first23=David A.|last24=Takeuchi|first24=Ichiro|last25=Booth|first25=James C.|last26=Fennie|first26=Craig J.|last27=Schlom|first27=Darrell G.|title=Exploiting dimensionality and defect mitigation to create tunable microwave dielectrics|journal=Nature|year=2013|volume=502|issue=7472|pages=532–536|doi=10.1038/nature12582|pmid=24132232|bibcode=2013Natur.502..532L|hdl=2117/21213|s2cid=4457286}}</ref>

Generally, [[strontium titanate]] ({{chem|Sr|Ti|O|3}}) is used for devices operating at low temperatures, while [[barium strontium titanate]] ({{chem|Ba|1−x|Sr|x|Ti|O|3}}) substitutes for room temperature devices. Other potential materials include microwave dielectrics and carbon nanotube (CNT) composites.<ref name=k/><ref>{{cite journal|last1=Kong|first1=L. B.|last2=Li|first2=S.|last3=Zhang |first3=T. S.|last4=Zhai|first4=J. W.|last5=Boey|first5=F. Y. C.|last6=Ma|first6=J.|title=Electrically tunable dielectric materials and strategies to improve their performances|journal=Progress in Materials Science|date=2010-11-30|volume=55|issue=8|pages=840–893|doi=10.1016/j.pmatsci.2010.04.004|hdl=10356/93905|hdl-access=free}}</ref><ref>{{cite book|last1=Giere|first1=A.|last2=Zheng|first2=Y.|last3=Maune|first3=H.|last4=Sazegar|first4=M.|last5=Paul|first5=F.|last6=Zhou|first6=X.|last7=Binder|first7=J. R.|last8=Muller|first8=S.|last9=Jakoby|first9=R.|chapter=Tunable dielectrics for microwave applications|title=2008 17th IEEE International Symposium on the Applications of Ferroelectrics|year=2008|pages=1|doi=10.1109/ISAF.2008.4693753|s2cid=15835472|isbn=978-1-4244-2744-4}}</ref>

In 2013, multi-sheet layers of strontium titanate interleaved with single layers of [[strontium oxide]] produced a dielectric capable of operating at up to 125&nbsp;GHz. The material was created via [[molecular beam epitaxy]]. The two have mismatched crystal spacing that produces strain within the strontium titanate layer that makes it less stable and tunable.<ref name=k/>

Systems such as {{chem|Ba|1−x|Sr|x|Ti|O|3}} have a paraelectric–ferroelectric transition just below ambient temperature, providing high tunability. Films suffer significant losses arising from defects.