• 한국세라믹학회지
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• 제12권2호
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• pp.10-14
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• 1975

Bodies whose compositions are in the ternary system BaCO3-TiO2-SnO2 containing from 5 to 90 mol % stannic oxide were prepared to improve the thermal characteristics of barium titanate dielectrics. Bodies having dielectric constant (K) of 2100 at 1 KHz, low negative temperature coefficients of 1500ppm up to about 9$0^{\circ}C$, Curie Temperature of 2$0^{\circ}C$, and dissipation factor of 0.2-0.4% were obtained with addition of 15 mole % stannic oxide.

• 약학회지
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• 제13권1호
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• pp.16-21
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• 1969

When ultrasonic wave with barium titanate as an ultrasonic transducer (96.84kc, 1.4kv, 240mA) was applied to a dilute glucose solution, glucose was oxidized to glucuronic acid. It was found that the lower the glucose concentration, the higher the oxidation rate. The aeration and the presence of ferrous sulfate as a catalyst were found to increase the rate. The optimal duration for applying the wave to the solution was found to be six hours.

• 한국세라믹학회지
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• 제23권5호
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• pp.41-46
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• 1986

공침법에 의하여 얻어진 고순도 극미립자인 $BaTiO_3$ 분말의 분산거동을 조사하였다 분산매로는 수용매와 비수용매인 methyl ethyl ketone(MEK)과 ethanol (ETOH)을 이용하였다 Suspension 에서의 입자의 분산상태는 pH 변화와 MEK, ETOH의 몰 비를 조절하여 각각의 suspensions에 polymer(polyvinyl butyral)를 첨가시켜 변화하였으며 그 거동은 유동학적 성질 침강 거동 electrokinetic 성질을 측정함으로써 파악되었다 비 수용매의 몰 비가 3:1 MEK/ETOH-$BaTiO_3$에서 polymer를 0.5~1% 첨가시켰을 때 입자의 분산이 가장 잘 이루어졌다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2004년도 International Symposium on Powder Materials and Processing
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• pp.53-53
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• 2004

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.104-106
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• 1995

A curious resistivity anomaly in high curie point barium-lead-titanate materials with positive temerature coefficient of resistivity (PTCR) has been observed just below the curie point, besides the normal PTCR anomaly. The additional resistivity anomaly was observed in the resistivity-temperature characteristics.

• Journal of Korean Vacuum Science & Technology
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• 제4권4호
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• pp.97-101
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• 2000

In this study, two kinds of barium strontium titanate (BST) samples were prepared. One is a conventional BST film that is sputtered in a mixture of argon and oxygen. The other is a nitrogen-incorporated BST film that is sputtered in a mixture of oxygen and intentionally added nitrogen instead of argon gas. The structural properties of both of the BST films had not changed significantly with the species of sputtering gas. However, the leakage current of BST films sputtered at ($N_2$+O$_2$) atmosphere was lower than those sputtered at (Ar +O$_2$) atmosphere: 1.9$\times$10$^{-8}$ A/cm$^2$ at 2V for the films prepared at (Ar +O$_2$) atmosphere and 8.6$\times$10$^{-9}$ A/cm$^2$ for the films at ($N_2$+O$_2$) atmosphere. From an XPS analysis, it has been found that nitrogen atoms are incorporated in BST films with a concentration of 1.92 at% and form a certain oxynitride phase. It is proposed that nitrogen atoms are able to fill the oxygen vacancies of BST films during sputtering process, and then the leakage current reduces due to a decrease in the vacancies. The BST films sputtered at ($N_2$+O$_2$) atmosphere have superior electrical properties to the films sputtered at (Ar +O$_2$), without any significant structural changes.

• 한국결정성장학회지
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• 제15권6호
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• pp.244-251
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• 2005

수열합성법에 의해 제조된 티탄산바륨 (BT01, BT02, BT03, BT04, BT05)의 입자크기와 분체특성과의 상관관계를 비표면적, 제타전위, XPS, XRD 및 SEM에 의해 조사하였다. 레이져광산법에 의해 측정된 입자의 크기는 비표면적과 XRD를 통해 결정된 격자이방성과 밀접한 관계가 있음을 보였다. 분말의 비표면적은 입자의 크기가 증가함에 따라 감소하였으며, BT03 시료는 동일한 입자크기의 BT04에 비하여 큰 비표면적을 보였으며, 이는 입자들의 응집에 기인하는 것으로 SEM사진 및 XRD 분석을 통하여 밝혀졌다. 입자의 크기가 증가함에 따라 제타전위는 증가하는 경향을 보였으며, BT02와 BT03 분말은 다른 분말에 비하여 제타전위가 큰 음의 값을 나타내었다. XPS 분석결과 분쇄시 티탄산바륨과 물 사이의 반응에 의한 $Ba^{2+}$ 이온의 용출과 관련이 있는 것으로 분석되었다.

• 한국세라믹학회지
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• 제48권4호
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• pp.323-327
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• 2011

The effects of $Dy_2O_3$ and $Er_2O_3$ co-doping on electrical properties and temperature stability of barium titanate ($BaTiO_3$) ceramics were investigated in terms of microstructure and structural analysis. The dielectric constant and the insulation resistance (IR) of 0.7 mol% $Dy_2O_3$ and 0.3 mol% $Er_2O_3$ co-doped dielectrics had about 60% and 20% higher than the values of undoped one, respectively, and the temperature coefficient of capacitance (TCC) met the X7R specification. The addition of $Dy_2O_3$ contributed to electrical properties caused by increase of tetragonality; however, preferential diffusion of $Dy^{3+}$ ions toward A site in $BaTiO_3$ grain exhibited an adverse effect on temperature stability by grain growth. On the other hand, The $Er_2O_3$ addition in $BaTiO_3$ could affect the TCC behavior and the IR with suppression of grain growth caused by reinforcement of grain boundary and electrical compensation. Therefore, the enhanced electrical properties and temperature stability through the co-doping could be deduced from the increase of tetragonality and the suppression of grain growth.

• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.386-392
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• 2021

Multiferroics exhibiting the coexistence and a possible coupling of ferromagnetic and ferroelectric order are attracting widespread interest in terms of academic interests and possible applications. However, room-temperature single-phase multiferroics with soft ferromagnetic and displacive ferroelectric properties are still rare owing to the contradiction in the origin of ferromagnetism and ferroelectricity. In this study, we demonstrated that sizable ferromagnetic properties are induced in the ferroelectric bismuth ferrite-barium titanate system simply by introducing Co ions into the A-site. It is noted that all modified compositions exhibit well-saturated magnetic hysteresis loops at room temperature. Especially, 70Bi_0.95Co_0.05FeO₃-30Ba_0.95Co_0.05TiO₃ manifests noticeable ferroelectric and ferromagnetic properties; the spontaneous polarization and the saturation magnetization are 42 µC/cm² and 3.6 emu/g, respectively. We expect that our methodology will be widely used in the development of perovskite-structured multiferroic oxides.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.310-313
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• 1989

The semiconducting bodies were prepared by doping the bariume titanate with $Sb_2O_3,Nb_2O_5$and by subsequent sintering in air. The sintered bodies were annealed between $1100^{\circ}C$ and $1250^{\circ}C$ for 30 minutes to 2 hours in air. The resistivity was measured as a function of temperature from $20^{\circ}C$ to $240^{\circ}C$. The anomalous effect in resistivity occurred all of the $Nb_2O_5$ and $Sb_2O_3$doped barium titanate specimens, which were sintered in air atmosphere, and the most effective PTC effect occurred through 1 hour of sintering time at $1350^{\circ}C$ and 30 minute of annealing time at $1200^{\circ}C$. The resistivity - temperature characteristics seem to be intimately related to oxygen adsorption at grain boundaries and also to the thickness of insulating layers formed at grain boundaries during heat treatment.