• 한국세라믹학회지
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• 제47권5호
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• pp.450-456
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• 2010

During the process of synthesizing green celsian pigments, attempts were made to replace a given amount of $BaCO_3$ with $SrCO_3$ to accelerate the hexagonal to monoclinic celsian phase transition, which was assumed to promote color development. Monoclinic celsian have been synthesized from Hongkong-Kaolin, $BaCO_3$, $SrCO_3$, $Al(OH)_3$, $SiO_2$ and $SrCO_3$ with 1 to 1.5 wt% of LiF as a mineralizer from 1100 to $1300^{\circ}C$. It was found that replacing $BaCO_3$ with $SrCO_3$ allowed monoclinic celsian to be formed at a lower temperature. While the pigments containing 1 mole of $BaCO_3$ were difficult to synthesize monoclinic celsian with absence of the mineralizer, the formation of monoclinic celsian was successfully achieved even without mineralizer by using 0.25 mole of $SrCO_3$ at $1250^{\circ}C$ for 1 h. The color development was improved from yellowish green to green with increasing amount of $SrCO_3$ being replaced.

• 한국세라믹학회지
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• 제39권5호
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• pp.438-445
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• 2002

본 연구에서는 $PbO-TiO_2-SiO_2-BaO-ZnO-Al_2O_3-CaO-B_2O_3-Bi_2O_3-MgO$계의 유리를 $1,400{\circ}C$에서 용융시킨 후, 급랭, 분쇄하여 glass frit을 제조하였다. Glass frit 분말을 일축가압성형한 후 $750~1,000{\circ}C$의 온도범위에서 2시간 동안 소성 및 결정화 하였다. Glass frit의 결정화는 $750{\circ}$ 전후의 온도에서 시작되었고, 저온에서의 주된 결정상은 $Al_2O_3$와 hexagonal celsian($BaAl_2Si_2O_8$)이었다. 소성온도가 높아지면서 monoclinic celsian, $ZnAl_2O_4,\;Zn_2SiO_4,\;CaTi(SiO_4)O,\;TiO_24 등이 주된 결정상으로 나타났고, 특히 celsian은 hexagonal에서 monoclinic으로 상전이가 발생하였다. 그리고 15wt%의 PbO를 첨가한 glass frit에만 $PbTiO_3-CaTiO_3$ 고용체가 나타났다. 1MHz 대역에서 유전특성을 살펴본 결과 유전상수는 11~16이었고, 유전손실은 0.020 미만이었다. 그러나 15wt%의 PbO를 첨가한 glass frit의 경우는 $PbTiO_3-CaTiO_3$ 고용체 결정상의 존재로 유전상수가 17~26으로 높았고, 유전손실은 0.010~0.015로서 다른 조성들에 비하여 우수한 특성을 나타내었다.

• 한국세라믹학회지
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• 제31권9호
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• pp.981-988
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• 1994

Crystallizable glasses with precipitation of celsian were prepared for the purpose of insulating dielectric layers for the devices such as integrated circuit substrates. Crystallization behavior of these glasses were studied by DTA, SEM, XRD analysis and by the measurement of dielectric properties. The base composition of the glass-ceramic consists in weight percent of 30% SiO2, 10% Al2O3, 26% BaO, 10% CaO, 10% ZnO, 8%TiO2 and 6% B2O3. 2-6 wt% Y2O3 were selected as the nucleating agent to promote monoclinic celsian formation. As a result, in barium-rich glasses containing 4~6wt% Y2O3 , monoclinic celsian was developed as major crystalline phase in the temperature range of 850~90$0^{\circ}C$. Also, the dielectric constant and quality factor of these glass-ceramics were about 9 and more than 1000, respectively.