Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Sintering and Dielectric Characteristics of LaAlO3 Ceramics by Mechanochemical Treatment from La2O3-A12O3 and La2O3-Al(OH)3

La2O3-Al2O3와 La2O3-Al(OH)3를 메카노케미칼로 처리한 LaAlO3세라믹스의 소결 및 유전특성

  • 최상수 (부경대학교 전자공학과) ;
  • 조정호 (부경대학교 전자공학과) ;
  • 김강언 (부경대학교 전자공학과) ;
  • 정수태 (부경대학교 전자공학과) ;
  • 조상희 (경북대학교 무기재료공학과)
  • Published : 2002.01.01
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Abstract

The dielectric properties and synthesis of $LaAlO_3$ ceramics from mixtures of $La_2O_3-Al_2O_3$ (LAO) and $La_2O_3-Al(OH)_3$(LAH) via grinding process were investigated. The single phase $LaA1O_3$of LAO and LAH powders were formed at $1300^{\circ}C$ and $1000^{\circ}C$, respectively. A non-reacted $La_2O_3$ existing in calcined powder was changed to La(OH)$_3$by moisture in the air, and their samples were worse than those of the samples made from a $LaA1O_3$single phase powder. The densities of LAO samples sintered at 150$0^{\circ}C$ for 4 h and LAH samples sintered at $1400^{\circ}C$ for 4 h were 97.3% and 98.3% of theory density, respectively. Grains of LAH sample showed uniformity and their sizes were 0.75 ${\mu}{\textrm}{m}$, and LAO samples showed non-uniformity and their sizes were 4-5 ${\mu}{\textrm}{m}$. Dielectric constant of LAO and LAH samples were the same value (≒22), however dielectric loss of LAH sample (0.0003) were lower than that of LAO sample(0.001)due to grain size.

$La_2O_3-Al_2O_3$(LAO)와 $La_2O_3-Al(OH)_3$(LAH)의 물질을 메카노케미칼 방법으로 분쇄하여 $LaAlO_3$세라믹스의 합성과 유전특성에 대하여 비교.조사하였다. $LaAlO_3$단일상을 얻기 위한 열처리온도는 LAO분말에서 $1300^{\circ}C$, LAH 분말은 $1000^{\circ}C$였다. 하소분말 중에 미 반응한 $La_2O_3$가 존재하면, 공기 중의 습기로 인하여 $La_2O_3$에서 $La(OH)_3$로 변하고,소결체의 밀도는 나빠진다. $1500^{\circ}C$에서 4시간 소결한 LAO 시료는 이론밀도의 97.3%이고, $1400^{\circ}C$에서 4시간 소결한 LAH시료는 98.3%였다. LAO시료는 입자의 크기가 불 균일하고 평균 입경은 4-5${mu}m$이며, LAH시료는 입자가 균일하고 크기가 $0.75{\mu}m$ 정도로 아주 작았다. 비유전율은 LAO와 LAH시료가 비슷하였고, 그 값은 약 22를 나타내었다. 그러나 LAH시료(0.0003)의 유전손실은 LAO시료 (0.001)보다 작았는데 이는 입자의 크기에 기인된다.

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