• 분석과학
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• 제15권1호
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• pp.15-19
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• 2002

텅스텐이 첨가된 $BaTiO_x$계 세라믹재료 중 Ba, Ti 및 W의 회수율을 증가시키기 위하여 가압 산 분해법을 이용하여 전처리하였다. $BaTiO_x$계 세라믹재료 시료를 가압 산 부내장치 내에서 HF : HCI ( 1 : 2 ) 혼합산을 가하여 $220^{\circ}C$에서 3시간동안 분해시킨 후 ICP-AES를 이용하여 Ba, Ti 및 W을 정량하였다. 그 결과 Ba는 99.6% Ti는 99.8% W는 99.2%의 회수율과 Ba는 1.02% Ti는 0.73% W는 1.79%의 C.V.값을 각각 얻었다. 이 전처리 방법을 실제시료에 적용하여 25.9% Ba38.8% Ti과 3.31% W 함량을 각각 구할수 있었다.

• 한국세라믹학회지
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• 제24권6호
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• pp.579-585
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• 1987

The effects of flux KCl and dopant Nb2O5 on the PTCR characteristics of BaTiO3 prepared by molten salt synthesis method have been investigated. As the amount of dopant Nb2O5 is over the solubility limit in BaTiO3, the room-temperature resistivity increases, and the PTCR effect and the grain size decrease. The variation of the amount of flux KCl slightly influences on the room-temperature resistivity, PTCR effect and grain size in Nb2O5 doped BaTiO3, but BaTiO3 ceramics prepared by the method of molten salt synthesis show larger PTCR effect than those of conventional calcining of mixed oxides.

• 대한전기학회논문지
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• 제44권8호
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• pp.1068-1074
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• 1995

Effect of (Zn$_{1}$3/Nb$_{2}$3/) $O_{2}$ addition on the phase changes and microwave dielectric properties of BaTi $O_{3}$-3Ti $O_{2}$ ceramics were investigated. Addition of (Zn$_{1}$3/Nb$_{2}$3/) $O_{2}$ to BaTi $O_{3}$-3Ti $O_{2}$ resulted in the formation of Ba $Ti_{4}$$O_{9}$, $Ba_{2}$ $Ti_{9}$ $O_{20}$, Ba(Zn$_{1}$3/Nb$_{2}$3/) $O_{3}$, and Ti $O_{2}$ phases. Ba $Ti_{4}$$O_{9}$ phase was gradually transformed to $Ba_{2}$ $Ti_{9}$ $O_{20}$. This was identified by XRD and microstructure. As the Ba $Ti_{4}$$O_{9}$ phase transformed to $Ba_{2}$ $Ti_{9}$ $O_{20}$ phase, the dielectric constant increased to 37.5. Q*f$_{o}$ value was 40000 at x=0.04, and the temperature coefficient of resonant frequency was +10ppm/.deg. C.C.. C.C.

• 한국세라믹학회지
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• 제42권5호
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• pp.308-313
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• 2005

In this study the electrical conductivity of excess BaO in $BaTiO_3$ was measured to investigate the relationship between defects and solubility in the temperature range of $900^{\circ}C$ to $1300^{\circ}C$ under various oxygen partial pressure. First of all, quenched $BaTiO_3$ powders of various Ba/Ti ratios were analysed by X-ray diffraction to confirm whether second phase is formed or not. As the results, we observed the solubility of BaO in the temperature range of $1200^{\circ}C$ to $1400^{\circ}C$, and it was also found that the conductivity minima move to lower $PO_2$ with increasing excess BaO within solubility limit.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 13th KACG Technical Meeting `97 Industrial Crystallization Symposium(ICS)-Doosan Resort, Chunchon, October 30-31, 1997
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• pp.87-89
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• 1997

The BaTiO$_3$ fine powder was prepared by hydrthermal method using titanium tetrahydoxide (Ti(OH)$_4$) and barium dihydroxide (Ba(OH)$_2$.8$H_2O$) as raw materials. The fine powder was obtained at temperatures as low as 160 to 185$^{\circ}C$. The properties of the BaTiO$_3$ powder were studied as a function of various parameters (reaction temperature, reaction time, Ba/Ti=ratio, etc). The average particle size of the BaTiO$_3$ increased with increasing reaction temperature. After hydrothermal treatment at 17$0^{\circ}C$ for 8 h, the average particle size of the BaTiO$_3$ powder was about 30 nm and the particle size distribution was narrow.

• 한국전기전자재료학회논문지
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• 제30권4호
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• pp.223-228
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• 2017

In this study, in order to develop composition ceramics for refrigeration device application at a temperature of less than $90^{\circ}C$, a $Ba(Ti_{1-x}Zr_x)O_3$ composition was fabricated using a conventional solid-state method. Electrocaloric properties of these ceramics were investigated using the characteristics of P-E hysteresis loops in a wide temperature range from room temperature to $150^{\circ}C$. The Curie temperature of $Ba(Ti_{1-x}Zr_x)O_3$ ceramics decreased with the increase of x. The maximum value of ${\Delta}T=0.07^{\circ}C$ in an ambient temperature of $85^{\circ}C$ under 30 kV/cm appeared when x = 0.125. It was concluded that the composition (x = 0.125) ceramics can be used for refrigeration device applications.

• 한국재료학회지
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• 제9권1호
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• pp.51-56
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• 1999

The $BaTiO_3$ powders were synthesized by GNP (Glycine-Nitrate process). The powders were prepared using carbonate and alkoxide as starting materials and nitric acid was used as a solvent for starting materials as well as an oxidant for combustion. the effects of aggregates in $BaTiO_3$ powders on green densities, sintering and dielectric characteristics were investigated. When the glycine/cation molar ratio was 1.2, reactivity of self-combustion was most intensive and the degree of aggregates after calcination was low. On sintering at $1400^{\circ}C$, maximum theoretical relative density(94.99%%0 was obtained in case of 1.2 molar ratio of glycine/cation. The dielectric constant of this sintered $BaTiO_3$ was 1919.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1274-1276
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• 1994

A study on $BaTiO_3$ ceramics have been shown that dielectric properties of $BaTiO_3$ ceramics strongly depend on the size and ferroelectric domain density of the constituting grain. According to rising substrate temperature from $25[^{\circ}C]$ to $600[^{\circ}C]$, the peak intensity and crystal plane in XRD are increased. In this study, $BaTiO_3$ thin film prepared by RF sputtering from room temperature to $600[^{\circ}C]$ of substrate temperature. Therefore, we tried to investigate the relation between the characteristics of ceramics structure and dielectric factor.

• 한국세라믹학회지
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• 제36권4호
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• pp.354-359
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• 1999

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1436-1437
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• 2011

(1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ lead free piezoelectric ceramics were synthesized to enhance the piezoelectric properties of (Na,K)$NbO_3$. The synthesis and sintering method were the conventional solid state reaction method and general sintering method in air atmosphere. We report the improved piezoelectric properties in the perovskite structure composed of the NKN and BZT ceramics. We investigated the effects of NKN, BZT on the structural and electrical properties of the NKN-BZT ceramics. The NKN-BZT ceramics show good performance with piezoelectric constant $d_{33}$=155pC/N. The results reveal that (1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ ceramics are promising candidate materials for lead-free piezoelectric application.