• The Korean Journal of Ceramics
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• 제5권2호
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• pp.189-194
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• 1999

Crystallization of glasses in the system (Ca, Sr, Ba)$O-Al_2O_3-B_2O_3-SiO_2-TiO_2$ and dielectric properties of crystallized glasses were investigated. As increasing B2O3 content and decreasing SiO2 content in the glass, the major crystalline phase changed from $(Sr, Ba)_2TiSi_2O_8$ to (Ca, Sr, Ba)TiO3, the dielectric constant of crystallized glasses increased and the Temperature Coefficient of Capacitance (TCC) changed to negative. The dielectric constant and TCC was estimated for (Sr, Ba)2TiSi2O8 phase as 18 and -440 $ppm/^{\circ}C$, respectively and for (Ca, Sr, Ba)TiO3 phase as 307 and -1900 $ppm/^{\circ}C$, respectively. The dielectric properties of (Ca, Sr, Ba)TiO3 phase (in this study) were similar to those of (Ca, Ba) TiO_3 solid-solution^12)$, but $(Sr, Ba)_2TiSi_2O_8$ phase (in this study) and $Sr_2TiSi_2O_\;8^4$ showed the different properties.

• 한국재료학회지
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• 제2권4호
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• pp.248-256
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• 1992

본 논문에서는 ATi$O_3$(A=Ca, Sr, Ba) 조성을 갖는 단순 페롭스카이트 구조에서 생성되는 격자결함 구조에 대하여 고찰하였다. 페롭스카이트 구조는 고충전밀도를 갖기 때문에 프렌클 결함은 고려되지 않았다. 쇼트키결함이나, 고유전자결함도 자연적으로 포함된 억셉타 불순물 농도에 비하면 무시할 정도로 적은 양이다. 실제적으로 전기적 특성에 영향을 주는 것은 전하적 결함을 발생하는 aliovalent 불순물이다. 삼성분계이기 때문에 양이온간의 비화학양론이 발생하며 BaTi$O_3$나 SrTi$O_3$에서 수백 ppm이내의 AO나 Ti$O_2$의 용해도가 관찰되나, CaTi$O_3$에서는 상당량의 CaO와 $TiO_2의$ 용해가 가능하다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.180-181
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• 2009

$(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, $(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ array thick films doped with 0.1 mol% $MnCO_3$ and $Yb_2O_3$ (0.1~0.7 mol%) were fabricated by the screen printing method on the alumina substrate. And the structural and electrical properties as a function of $Yb_2O_3$ amount were investigated. The thickness of all (Ba,Sr,Ca)$TiO_3$ thick films was approximately 60mm. The Curie temperature of doped with 0.1 mol% $Yb_2O_3$ specimen was $45^{\circ}C$, and the dielectric constant and at this temperature was 1062.

• 한국세라믹학회지
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• 제28권9호
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• pp.689-695
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• 1991

Dielectric properties of Ba1-$\chi$Sr$\chi$Ti1-yCayO3-y ceramics, where Sr and Ca were doped to Ba-site and Ti-site within the range of 0 x 0.24 and 0 y 0.05, respectively, were investigated. The substitution of Ca for Ti, which maintained the high resistivity of these formulations after sintering in a reducing atmosphere, was confirmed. Ca addition decreased the tetragonality c/a, increased the unit cell volume, and lowered Curie temperature, which were attributed to the occupancy of Ca2+ ions on Ti-sites. The lowering of Curie temperature by Ca addition was affected by the substitution of Sr for Ba-site; within 2 mol% of Ca, Curie temperature was lowered at a rate of 2$0^{\circ}C$ and 16$^{\circ}C$ per mol% of Ca at x=0 and x=0.08, respectively. Whereas the resistivity of the formulations without Ca was reduced to 107 {{{{ OMEGA }}cm, when sintered at low oxygen partial pressure of 10-9 MPa, the resistivity value higher than 1011 {{{{ OMEGA }}cm was maintained for the formulations containing Ca more than 0.5 mol%. Dielectric loss factor, tan$\delta$, was about 1% for most formulations.

• 한국세라믹학회지
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• 제31권6호
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• pp.651-659
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• 1994

BaTiO3 ceramics were sintered on Al2O3, MgAl2O4, MgO and Mg-, Ca-, Y-stabilized zirconia setters. Then the influence of setters on the microstructure of BaTiO3 ceramics and the stability of setters were investigated by SEM, EDAX and XRD analyses. The microstructure of BaTiO3 ceramics sintered on Al2O3, MgAl2O4, MgO and Mg-PSZ showed large grain growth, but little grain growth on Ce-TZP(Tetragonal Zirconia Policrystal). Mg-PSZ(Partially Stabilized Zirconia), Ca-PSZ, Ce-TZP setters showed extensive phase transformation. Y-TZP and fused Y-SZ (Stabilized Zirconia) setters were stable. The liquid sintering aids of BaTiO3 ceramics accelerate mass transport. The reaction of SrTiO3 in BaTiO3 with ZrO2 resulted in the formation of SrZrO3.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1994년도 추계 학술발표 강연 및 논문 개요집
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• pp.137-137
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• 1994

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.42-45
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• 2001

$(Ba_{0.6}Sr_{0.4}Ca_{x})TiO_{3}+yZrO_{2}$ wt% (x=0.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed-oxide method and then the structural and dielectric properties as a function of the composition ratio and $ZrO_2$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and $ZrO_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of $ZrO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.42-45
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• 2001

(Ba$_{0.6-x}$Sr$_{0.4}$Ca$_{x}$)TiO$_3$+yZrO$_2$wt% (x=1.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed and ZrO$_2$ contents were studied. All BSCT specimens contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and ZrO$_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of ZrO$_2$./TEX>.

• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.680-684
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• 2007

In this study, we investigated the effects of structural and electrical properties of $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ thick films with variation $Dy_2O_3$ contents. $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ powders, prepared by the sol-gel method, were mixed organic vehicle. The BSCT thick films doped with 0.1, 0.3, 0.5, 0.7 mol% $Dy_2O_3$ were fabricated by the screen-printing techniques on the alumina substrates and the structural and dielectric properties were investigated with variation of $Dy_2O_3$ doping contents. All BSCT thick films were sintered at $1420^{\circ}C$, for 2hr. In the TG-DTA analysis, the formation of the polycrystalline perovskite phase was observed at around $670 ^{\circ}C$. In the XRD analysis, all BSCT thick films showed the cubic perovskite structure. The average thickness of BSCT thick films was approximately $65{\mu}m$. The Curie temperature decreased with increasing $Dy_2O_3$ amount. The relative dielectric constant and dielectric loss of BSCT thick films doped with $Dy_2O_3$ 0.1 mol% were 6267 and 2.6 %, respectively.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 1998년도 제1회 총회 및 추계학술발표회
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• pp.60-60
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• 1998