• Title/Summary/Keyword: barium titanate

Search Result 182, Processing Time 0.025 seconds

A Study of Abnormal Expansion to be Synthesized Barium Titanate in Solid-solid Reaction (Barium Titanate를 고상반응으로 합성할때 일어나는 이상팽창에 관한 연구)

  • 이은상;임대영
    • Journal of the Korean Ceramic Society
    • /
    • v.22 no.6
    • /
    • pp.9-14
    • /
    • 1985
  • When the barium titanate is Synthesized in Solid-solid reaction the abnormal expansion occurs at about 110$0^{\circ}C$. The mixture was made of corresponding to the theoretical composition of barium titanate. The mixture was fired at various temperature from 90$0^{\circ}C$ to 130$0^{\circ}C$, After that the specimen was tested closely with XDR dilatometer and SEM. The results indicate that 1, The activation energy of barium titanate formation was 42 Kcal/mole. 2, Thermal expansion up to to 90$0^{\circ}C$ was mainly caused by $CO_2$ whereas it was mainly caused by the formation of the secondary phase above 100$0^{\circ}C$. 3. Thermal expansion was not influenced by the forming pressure up to 1000kg/$cm^2$ but it was largely influenced bythe forming pressure above 200kg/$cm^2$.

  • PDF

Microwave Characteristics of Barium Titanate for Frequency Sensor and Temperature Sensor (고주파특성 측정을 통한 barium titanate의 주파수센서 및 온도센서 연구)

  • Kim, J.O.;Han, M.H.
    • Journal of Sensor Science and Technology
    • /
    • v.5 no.1
    • /
    • pp.9-14
    • /
    • 1996
  • The effect on the microwave properties was investigated for the barium titanate doped with impurity of $WO_{3}$ 0.230 mole% produced by conventional solid state reaction method. Microwave resistance, reactance and impedance of the barium titanate were measured with 2-port s-parameter method by using network analyzer, in the range of room temperature to $160^{\circ}C$ and of frequency 300 kHz to 300 MHz. And possibility of frequency sensor and temperature sensor was estimated with barium titanate doped with $WO_{3}$.

  • PDF

Effect of the Sintering Temperature on Electrical Properties of Porous Barium-strontium Titanate Ceramics

  • Kim, Jun-Gyu;Sim, Jae-Hwang;Cho, Won-Seung
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.1
    • /
    • pp.5-10
    • /
    • 2003
  • Porous barium-strontium titanate ceramics were fabricated by adding corn- or potato-starch (are referred to as starch). The effect of sintering temperature on the microstructure and electrical properties of the porous ceramics was investigated. The room-temperature electrical resistivity of the barium-strontium titanate ceramics decreased with sintering temperature. The porosity and pore size were decreased and the grain size was increased with increasing the sintering temperature. The porosity and grain size of the barium-strontium titanate ceramics with corn-starch sintered at 1300 and 1450$^{\circ}C$ were 28.5, 22.6% and 3.2, 6.2 $\mu\textrm{m}$, respectively. The average pore sizes of the barium-strontium titanate ceramics with corn-starch sintered at 1300, 1400 and 1450$^{\circ}C$ were 0.5, 0.3 and 0.2 $\mu\textrm{m}$, respectively. The decrease in the room-temperature resistivity with increasing sintering temperature is attributed mainly due to the increase of grain size and the decrease of the electrical barrier height of grain boundaries as well as the partial decrease of porosity.

Synthesis of Monodispersed Barium Titanate Nanopowders by Alkoxide-Hydroxide Sol-Precipitation Method

  • Yoon, Song-Hak;Kim, Min-Gyu;Shin, Nam-Soo;Kim, In-Sung;Baik, Sung-Gi
    • Journal of the Korean Ceramic Society
    • /
    • v.43 no.11 s.294
    • /
    • pp.710-714
    • /
    • 2006
  • Barium titanate nanoparticles were synthesized under N$_2$ atmosphere by the hydrolysis and condensation of barium hydroxide octahydrate and titanium (IV) isopropoxide. The synthesized particles were aggregates of nanosized primary particles. The primary particles of about 20-50 nm in diameter became building blocks of larger secondary particles, which are in most cases spherical in shape. The size and morphological evolution of secondary particles are strongly related to the precursor concentration. The observations suggest that formation and control of secondary particles is an essential step in the alkoxidehydroxide sol-precipitation process to obtain monodispersed barium titanate nanopowders.

[100]-Texturing of Barium Titanate Ceramics Using Sodium Bismuth Titanate Templates: Challenges and Insights

  • Nu-Ri Ko;Temesgen Tadeyos Zate;Wook Jo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.37 no.3
    • /
    • pp.328-331
    • /
    • 2024
  • This research explores the development of [100]-textured barium titanate (BaTiO3, BT) ceramics using sodium bismuth titanate (Na0.5Bi4.5Ti4O15, NBiT) templates, aimed at leveraging the inherent high dielectric property of BT. However, the attempted texturing was unsuccessful, primarily due to bismuth diffusion from the NBiT templates into the BT matrix below the sintering temperature, at 1,000℃. Systematical exploration about the cause of the failure is involved and alternative approaches are proposed in detail to overcome the challenge. These findings contribute to the understanding of techniques and conditions for textured ceramic fabrication and highlight the need for further research in this area.

A Study on Atomosphere Sintering to affect the Abnormal Expansion in Solid-Solid Reaction of $BaTiO_3$ (Barium Titanate를 고상반응으로 합성할 때 팽창에 영향을 주는 분위기조성에 관한 연구)

  • 이은상;임대영
    • Journal of the Korean Ceramic Society
    • /
    • v.23 no.4
    • /
    • pp.41-46
    • /
    • 1986
  • When barium titanate was synthesized in solid-solid reaction the abnormal expansion occurred from 90$0^{\circ}C$ to 110$0^{\circ}C$. The equi molecular mixture of $BaCo_3$ and $TiO_2$ was sintered from 90$0^{\circ}C$ to 130$0^{\circ}C$ on the condition of air vacuum and $CO_2$ atomosphere. After that the specimens were tested closely with XDR Dilatometer and SEM The result indicated that: 1, Volume expansion to be synthesized barium titanate in solid-solid reaction was affected by atomosphere sintering. 2. The solid reaction ot fiorm barium titanate in vacuum atomosphere occurred faster than that in air atomosphere. In vacuum atomosphere the maxium volume expansion was about 30% at 90$0^{\circ}C$ for 2hrs, 3. The solid reaction to form barium titanate in 4CO_2$ atomosphere occurred slower than that in air atomosphere. In $CO_2$ atomosphere the maximum volume expansion was 13% at 100$0^{\circ}C$ for 2 hrs. 4. According to the result of x-ray the expanison was caused by the reaction to form $BaTiO_3$ and change $Ba_2TiO_4$ into 4BaTiO_3$.

  • PDF

Effect of pore size and porosity on electrical breakdown behaviors of $BaTiO_3$ ceramics ($BaTiO_3$ 세라믹의 절연파괴거동에 미치는 기공의 크기와 기공율의 영향)

  • 조경호;우동찬;남효덕;이희영
    • Electrical & Electronic Materials
    • /
    • v.10 no.3
    • /
    • pp.255-261
    • /
    • 1997
  • In this study, pore-containing barium titanate ceramics were prepared with different porosities and pore sizes, in order to better understand how porosity and pore size affect electrical breakdown of barium titanate ceramics. A granulated barium titanate powder was mixed with three grades of commercial polymer microspheres up to 11wt%. The electrical breakdown test was performed at two different temperatures of 30.deg. C(below Tc) and 150.deg. C(above Tc) for samples immersed in a silicon oil bath using a 60kV de power supply. Electrical breakdown strength of pore containing barium titanate ceramics with porosity lower than 10% decreased as pore size and porosity increased. However, above the 10% porosity region, electrical breakdown strength decreased as the pore connectivity increased. From the experimental results, an optimum electrical breakdown model is proposed in an attempt to explain the effect of pores.

  • PDF

Preparation of Ultrafine Barium Titanate Powder by Slurry Spray Pyrolysis (슬러리 분무열분해에 의한 초미립 티탄산 바륨 분말 제조)

  • Lee, Jong-Ho;Hur, Kang-Heon;Lee, Jung-Soo
    • Journal of the Korean Ceramic Society
    • /
    • v.46 no.2
    • /
    • pp.137-145
    • /
    • 2009
  • A remarkable improvement of the productivity in barium titanate by slurry spray pyrolysis process was realized by supplying solid source slurry into the rector. The produced barium titanate powders showed uniform powder properties, and reproducibility with higher tetragonality in the range of 80$\sim$200 nm, case by case. The secondary calcination experiments of the as-prepared powders by spray pyrolysis revealed that the powders as-prepared over 700$^{\circ}C$ showed perfectly different behavior with the lower temperature's ones and the solid state reaction’s case. The result was discussed in terms of the reaction mechanism based on the activation energy analysis.

EFFECT of PREPARATION METHODS and CONDITIONS of PRECURSORS on the PROPERTIES of $BATIO_3$ ALKOXIDE FILMS

  • N., Korobova;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2003.07b
    • /
    • pp.714-718
    • /
    • 2003
  • Usually for the commercial preparation of barium titanate films or ceramics the reaction atmosphere must be preferably in air. However, normally air is not used because it contains carbon dioxide, which can easily react with barium to form the undesired product barium carbonate, leading to unwanted second-phase formation in the (mal stages of the process. In the present work a series of perovskite barium titanate films was prepared by the sol-gel method, using a metal alkoxide solutions in the electrophoretic deposition (EPD). The influence of several process parameters, like sintering temperature of sol preparation before EPD and heat-treatment temperature and non-oxidized atmosphere, on the film properties is described.

  • PDF

A Study on the Characterization of Barium Titanate by a Radiometric Method (I). Synthesis of Barium Titanate by an Oxalate Method (방사능 계측법에 의한 티탄산 바륨의 특성화 연구 (I). 옥살산염법에 의한 티탄산 바륨의 합성)

  • Chul Lee;Yong Kyun Shin;Koo Soon Chung
    • Journal of the Korean Chemical Society
    • /
    • v.33 no.1
    • /
    • pp.65-69
    • /
    • 1989
  • Barium titanyl oxalate was synthesized by adding ethanol solution of oxalic acid to the mixed aqueous solution which contained barium or lanthanum radiotracers in addition to Ba(NO$_3)_2$ and TiO(NO$_3)_2$. The oxalate was finally converted to BaTiO$_3$ by calcination at 1000$^{\circ}$C in air. The chemical formula of the oxalate was confirmed to be BaTiO(CTEX>$_2O_4)_2{\cdot}4H_2O$ by the thermal analysis of the barium titanyl oxalate. When the mixture's molar ratio(Ba/Ti) was within a range of 0.950-1.05, the formation of stoichiometric Barium titanate was confirmed with the help of barium tracers. The homogeneity of lanthanum deposite in the final product was also confirmed through the behavior of lanthanum tracers. The results as well as those obtained by XRD and SEM have been explained on the basis of the fact that the reaction occurs on the molecular level in solution and the barium titanate is formed in crystals of single phase.

  • PDF