• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.05a
• /
• pp.101-102
• /
• 2006

BTO ($BaTiO_3$) thin film is one of the high dielectric materials for high-density dynamic random access memories (DRAMs) due to its relatively high dielectric constant, It is generally known that BTO film is difficult to be etched by plasma etching, but high etch rate with good selectivity to pattern mask was required. The problem of sidewall angle also still remained to be solved in plasma etching of BTO thin film. In this study, we first examined the patterning possibility of BTO film by chemical mechanical polishing (CMP) process instead of plasma etching. The sputtered BTO film on TEOS film as a stopper layer was polished by CMP process with the sell-developed $BaTiO_3$- and $TiO_2$-mixed abrasives slurries (MAS). respectively. The removal rate of BTO thin film using the $BaTiO_3$-mixed abrasive slurry ($BaTiO_3$-MAS) was higher than that using the $TiO_2$-mixed abrasive slurry ($TiO_2$-MAS) in the same concentrations. The maximum removal rate of BTO thin film was 848 nm/min with an addition of $BaTiO_3$ abrasive at the concentration of 3 wt%.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1615-1617
• /
• 2004

5 mol% $BaWO_4$를 첨가시켜 합성한 Ba$(Mg_{1/3}Ta_{2/3})O_3$를 이용하여 비방사유전세선로에 삽입되는 세라믹스 공진기를 제자하고 기존의 $MgTiO_3-CaTiO_3$계 세라믹스 공진기와 공진특성을 비교하여 그 특성을 고찰하였다. 그 결과 BMT 세라믹스는 기존의 $MgTiO_3-CaTiO_3$계 세라믹스보다 품질계수가 2배 이상 크게 높게 측정되었고, 측정 사진의 관찰 결과 전파차단성도 우수할 것으로 예상되기 때문에 BMT가 비방사유 전체선로에 삽입되는 유전체 공진기 재료로서 적용될 경우 우수한 공진특성을 발휘할 것으로 판단된다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.30 no.3
• /
• pp.103-109
• /
• 2020

The effect of La₂O₃ addition on the crystalline phase, microstructure, and dielectric properties of BaTiO₃ has been studied as a function of the amounts of La₂O₃. 0.3 mol% TiO₂-excess BaTiO₃ powder was synthesized by solid-state reaction, and then the powder compacts with various amounts of La₂O₃ were sintered at 1250℃ for 2 hours. Room temperature XRD showed changes in the lattice parameters and a decrease of tetragonality (c/a) as the amounts of La₂O₃ increased. It can be explained that the phase transition from tetragonal to cubic phase occurred because La³⁺ replaced Ba²⁺ site, which increased the instability of the tetragonal phase. As La₂O₃ was added over 0.1 mol%, the critical driving force for growth (Δg_c) increased over maximum driving force (Δg_max). As the result, the grain size decreased with La₂O₃ addition. Dielectric constant decreased as the amounts of La₂O₃ increased, which was analyzed with crystal structure and microstructure.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.99.1-99
• /
• 2003

• Korean Chemical Engineering Research
• /
• v.46 no.1
• /
• pp.99-105
• /
• 2008

Core-shell structured $BaTiO_3$ powders were produced via nano-coating of $Cr_2O_3$ and $Mn_2O_3$ to barium titanate powder system for MLCCs. From preliminary experiments, the optimal solution reaction condition employing using $KMnO_4$, $K_2Cr_2O_4$ and sulfur was established. Not only powders of $Cr_2O_3$ and $Mn_2O_3$ were synthesized but also their coating on $BaTiO_3$ powders were peformed under the same reaction condition. The coating was carried out in two ways, one-step and two-step, and its results were characterized for comparison. Conclusively speaking, two oxide additives were coated onto the $BaTiO_3$ powder surface with high quality and excellent reaction yield even under mild condition, which indicates that the contents as well as the properties of additive shell layer can be precisely controlled with rather ease.

• Journal of the Microelectronics and Packaging Society
• /
• v.1 no.2
• /
• pp.105-112
• /
• 1994

BaTiO3 의 B-site에 0-0.03 몰 범위의 NiO를 첨가한 Ba1-xSrxTi1-y-wNiyZrwO3-y 유전 체에서 NiO 첨가가 유전특성 및 절연저항의 내환원성에 미치는 영향을 조사하였다. B-site Ni 치환에 의해 a 축의 격자상수는 증가하고 c 축의 격자상수는 감소하여 정방성 c/a가 감 소하였으며 단위격자의 부피는 증가하였다. NiO 첨가에 따라 큐리온도는 저온으로 이동하 였으며 큐리온도의 변화율은 소결분위기에 영향을 받았다. NiO가 첨가되지 않은 조성에서 는 산소분압 109 MPa의 환원분위기 소성에 의해 비정항이 107$\Omega$.cm로 저하되었으나 0.01 몰이상의 NiO를 첨가한 조성에서는 공기중 소결시 얻을수 있었던 1011$\Omega$.cm로 저하되었으 나 0.01 몰 이상의 NiO를 첨가한 조성에서는 공기중 소결시 얻을 수 있었던 1011$\Omega$.cm 이 상의 비저항을 유지하였다.

• Journal of the Korean Ceramic Society
• /
• v.34 no.7
• /
• pp.703-712
• /
• 1997

The PTCR devices of BaTiO3 doped with Sb2O3, SiO2 were prepared by Liquid Addition Method(LPAM) where doping sources were used in the forms of Liquid. The amounts of doping in LPMA is smaller than that in solid state mixing method. Also the doping process in LPMA is very suitable for BaTiO3-based PTCR devices because it is easy to obtain homogeneous mixing and reproductivity. By optimizing the doping condition in BaTiO3 system, (0.09 mol% Sb2O3, 0.25 wt% SiO2 and 0.02 wt% MnO2) it was possible to fabricate BaTiO3-based PTCR devices whee the room-temperature resistivity and specific resistivity were 15{{{{ OMEGA }}cm and 2$\times$106 respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.2
• /
• pp.253-258
• /
• 1997

The characteristics of crystal structure and phase transition with dopants ($Nb_2O_5$= 0.1~0.4 mol% and $Y_2O_3$ : 0.2~0.4 mol%) on the PTCR $BaTiO_3$ system were investigated. In the case of $Nb_2O_5$ additive, the lattice parameter of PTCR $BaTiO_3$ was changed linearly with the increasement of $Nb_2O_5$ which substituted B-site of BaTiO$_3$ and the lattice parameter of c-axis decreased abruptly at 0.3 mol%. These phenonmena were assumed to originate from the distortion of octahedron and we could confirm that the change of lattice parameter accorded with the characteristics of the phase transition temperature. $Y^{3+}$ ions substituted both of A- and B-site until the 0.3 mol% addition, but $Y^{3+}$ substitution preferred A- to B-site above 0.3 mol%. This was affirmed by the variation ,of lattice parameter and the characteristics of phase transition. It also was found that $Y^{3+}$ions in the A-site substituted both of $Ba^{2＋}$ and $Ca^{2＋}$ ions with equal ratio by Rietveld method.

• Journal of Aerospace System Engineering
• /
• v.13 no.2
• /
• pp.43-50
• /
• 2019

Satellite and aircraft components are greatly affected by the possibility for missions and safety due to temperature effects. In the field of fuel cells, research is actively carried out for UAV. For the efficiency and stability of the fuel cells, the temperature for operations must be confirmed. In this paper, a smart paint was fabricated with $BaTiO_3$ and $SrTiO_3$ ceramics in order to take advantage of the rapid characteristics of the PTC thermistor, which is the resistance changes abruptly above the Curie point. A coating agent was prepared to prevent the paint from peeling off the samples and the coated models were checked for resistance changes. Moreover, the resistance change of the $BaTiO_3$ and $SrTiO_3$ with temperature conditions was measured before and after coating.

• Korean Journal of Materials Research
• /
• v.4 no.7
• /
• pp.798-807
• /
• 1994

The increase in the resistance of $BaTio_{3}$ with addition of Ca is attributed to the formation ofthe acceptor impurity by $CaCa^{2+}$" which substitutes Ti4+. However, some authors suggested that $Ca^{2+}$ can not substitute $Ti^{4+}$ because of its larger ionic radius. In this work, the existence of acceptor by Ca hasbeen studied through the high temperature equilibrium electrical conductivity of $BaTiO_{3}$ codoped with Caand Nb, where Ba/(Ti+Ca+Nb) was kept equal to unity. It was measured at $1000^{\circ}C$, and the oxygenpartial pressure was controlled between $10^{-15}$ ~ 1 atm. Changing the amount of added Ca and Nbresulted in the compensation effect between donor and acceptor, i.e., Nb was compensated by the acceptor.And through the defect chemical interpretation of the measured data, it was concluded that Ti canbe substitued with Ca. The existence of such acceptor was reaffirmated by ICTS(Isotherma1 CapacitanceTransient Spectroscopy) measurements.oscopy) measurements.