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Additive Sintering, Postannealing, and Dielectric Properties of SrTaO 2 N
Author(s) -
Sun ShiKuan,
Zhang YaRu,
Masubuchi Yuji,
Motohashi Teruki,
Kikkawa Shinichi
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12806
Subject(s) - sintering , annealing (glass) , materials science , ceramic , dielectric , thermal stability , impurity , analytical chemistry (journal) , dielectric loss , nitrogen , mineralogy , chemical engineering , composite material , chemistry , chromatography , optoelectronics , organic chemistry , engineering
The maintaining of the chemical composition and electrical insulativity of SrTaO 2 N ceramics was investigated during sintering and annealing, using powders prepared by the nitridation of Sr 2 Ta 2 O 7 . Due to the low thermal stability of SrTaO 2 N , the partial loss of SrO and nitrogen induced the formation of a TaO 0.9 impurity after heat‐treating at above 1100°C. The sintering additive SrCO 3 and postannealing in NH 3 were employed to compensate for the loss of SrO and nitrogen to obtain ceramics with the original chemical composition. The as‐sintered SrTaO 2 N ceramics with various relative density ( RD ) were annealed in NH 3 to observe the recovery of color and electrical insulativity. It was found that the inner part of the well‐sintered samples with RD = 95.1% could not be recovered by annealing, and continued to exhibit semiconducting behavior and a black color. On the other hand, for the as‐sintered SrTaO 2 N ceramics with RD < 84%, both the nitrogen content and electrically insulating behavior were completely recovered after annealing. The postannealed SrTaO 2 N ceramics ( RD = 83.3%) possessed a relatively large dielectric constant of 450 with a low dielectric loss of less than 0.1 at 100 Hz, almost independent of frequency and temperature.