AC Impedance Spectroscopy of CaF2‐doped AlN Ceramics. Issue 3 (13th December 2013)

• Record Type: Journal Article
• Authors: Lee, Hyeon‐Keun; Lee, Hyun Min; Kim, Do Kyung; Chan, H.
• Is Part Of: Journal of the American Ceramic Society. Volume 97:Issue 3(2014)
• Page Start: 805
• Page End: 810
• Publication Date: 2013-12-13
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.12685
• Languages: English
• ISSNs: 0002-7820

Abstract

<abstract abstract-type="main" id="jace12685-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The electrical conductivity of CaF₂‐doped aluminum nitride (AlN) ceramics was characterized at high temperatures, up to 500°C, by AC impedance spectroscopy. High thermal conductive CaF₂‐doped AlN ceramics were sintered with a second additive, Al₂O₃, added to control the electrical conductivity. The effects of calcium fluoride (CaF₂) on microstructure and related electrical conductivity of AlN ceramics were examined. Investigation into the microstructure of specimens by TEM analysis showed that AlN ceramics sintered with only CaF₂ additive have no secondary phases at grain boundaries. Addition of Al₂O₃ caused the formation of amorphous phases at grain boundaries. Addition of Al₂O₃ to CaF₂‐doped AlN ceramics at temperatures 200°C–500°C revealed a variation in electrical resistivity that was four orders of magnitude larger than for the specimen without Al₂O_3. The amorphous phase at the grain boundary greatly increases the electrical resistivity of AlN ceramics without causing a significant deterioration of thermal conductivity.</p> </abstract>