• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.492-496
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• 2004

In this study, (0.96 －x)(PSN-PZT)－xBF－0.04 PNW＋0.3wt%MnO$_2$＋0.6wt%CuO ceramics were fabricated with the variations of the amount of BiFeO$_3$substitution and sintering temperature for the development of modified ceramics which can be sintered in the low temperature($\leq$100$0^{\circ}C$ ), and their microstructural, dielectric and piezoelectric characteristics were investigated. As the amount of BiFeO$_3$ substitution was increased, the density, mechanical quality factor(Q$_{m}$) and electromechanical coupling factor(k$_{p}$) showed the maximum value at each of sintering temperature. At sintering temperature of 98$0^{\circ}C$ and BiFeO$_3$substitution of 2 mol%, the density, dielectric constant and electromechanical coupling factor(k$_{p}$) showed the maximum value of 7.84 g/㎤, 1415 and 0.49, respectively. And at sintering temperature of 95$0^{\circ}C$ and BiFeO$_3$substitution of 3mol%, mechanical quality factor showed the maximum value of 1062. 1062.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.158-164
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• 1995

Solid solutions Sr$_{2}$(Ta$_{1-x}$ Nb$_{x}$)$_{2}$O$_{7}$, (x=0.0-1.0), composed of strontium tantalate(Tc=-107.deg. C) and strontium-niobate(Tc=1342.deg. C) were prepared by the conventional mixed oxide method and the flux method(molten salt synthesis method). Phase relation, sintering temperature, grain-orientation and dielectric properties for sintered ceramic samples were investigated with different compositions. Both Curie temperature and dielectric constant at Curie temperature were increased, and sintering behavior and the degree of grain-orientation were improved with the increase of Nb content. The single phase Sr$_{2}$(Ta/sib 1-x/Nb$_{x}$)$_{2}$O$_{7}$ powder was synthesized by using the flux method at lower temperatures, and sintering temperature was also reduced by using the flux method-derived powder than using the mixed oxide-derived powder. Sintering characteristics and dielectric properties of the specimens prepared by the flux method were better than those derived through the conventional mixed oxide method.thod.hod.

• 한국전기전자재료학회논문지
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• 제14권7호
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• pp.572-577
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• 2001

The electrical properties of Pr$_{6}$ O$_{11}$ -based ZnO varistors consisting of ZnO-Pr$_{6}$ O$_{11}$ -CoO-Cr$_2$O$_3$-Er$_2$O$_3$ ceramics were investigated with sintering temperature in the range of 1325~f1345$^{\circ}C$. As sintering temperature is raised., the nonlinear exponent was increased up to 1335$^{\circ}C$, reaching a maximum 70.53, whereas raising sintering temperature further caused it to decrease, reaching a minimum 50.18 and the leakage current was in the range of 1.92~4.12 $\mu$A. The best electrical properties was obtained from the varistors sintered at 1335$^{\circ}C$, exhibiting a maximum (70.53) in the nonlinear exponent and a minimum (1.92 $\mu$A) in the leakage current, and a minimum (0.035) in the dissipation factor. On the other hand, the donor concentration was in the range of (0.90~1.14)x10$^{18}$ cm$^{-3}$ , the density of interface states was in the range of (2.69~3.60)x10$^{12}$ cm$^{-2}$ , and the barrier height was in the range of 0.77~1.21 eV with sintering temperature. With raising sintering temperature, the variation of C-V characteristic parameters exhibited a mountain type, reaching maximum at 134$0^{\circ}C$. Conclusively, it was found that the V-I, C-V, and dielectric characteristics of Pr$_{6}$ O$_{11}$ -based ZnO varistors are affected greatly by sintering temperature.

• 한국분말재료학회지
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• 제24권2호
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• pp.108-114
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• 2017

We fabricate fine (<$20{\mu}m$) powders of $Bi_{0.5}Sb_{1.5}Te_3$ alloys using a large-scale production method and subsequently consolidate them at temperatures of 573, 623, and 673 K using a spark plasma sintering process. The microstructure, mechanical properties, and thermoelectric properties are investigated for each sintering temperature. The microstructural features of both the powders and bulks are characterized by scanning electron microscopy, and the crystal structures are analyzed by X-ray diffraction analysis. The grain size increases with increasing sintering temperature from 573 to 673 K. In addition, the mechanical properties increase significantly with decreasing sintering temperature owing to an increase in grain boundaries. The results indicate that the electrical conductivity and Seebeck coefficient ($217{\mu}V/K$) of the sample sintered at 673 K increase simultaneously owing to decreased carrier concentration and increased mobility. As a result, a high ZT value of 0.92 at 300 K is achieved. According to the results, a sintering temperature of 673 K is preferable for consolidation of fine (<$20{\mu}m$) powders.

• Transactions on Electrical and Electronic Materials
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• 제16권4호
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• pp.221-225
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• 2015

The sintering effect on the microstructure, electrical properties, and dielectric characteristics of ZnO-V₂O₅-MnO₂-Nb₂O₅-Dy₂O₃-based ceramics was investigated. With the increase of sintering temperature from 875 to 950℃, the density of the sintered pellets decreased from 5.57 to 5.45 g/cm³ and the average grain size increased from 4.3 to 10.9 μm. The breakdown field decreased noticeably from 6,095 to 996 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900℃ exhibited the best nonlinear properties: 39.2 in the nonlinear coefficient and 0.24 mA/cm² in the leakage current density. The dielectric constant increased sharply from 658.6 to 2,928.8 with the increase of sintering temperature. On the whole, the dissipation factor exhibited a fluctuation with the increase of the sintering temperature, and a minimum value of 0.284 at 900℃.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.425-430
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• 2004

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramics were manufactured with the variations of sintering times, and their microstructural, piezoelectric and dielectric properties were investigated. To manufacture multilayer piezoelectric transformer, the low temperature sintering composition is need, hence, $Li_2CO_3$ and $Bi_2O_3$ were used as sintering aids and the specimens were sintered during 30, 60, 90, 120, 150 and 180 minutes, respectively. At the specimen sintered during 90 minute, mechanical quality factor(Qm), electromechanical coupling factor(kp) and dielectric constant were showed the optimum values of 2356, 0.504 and 1266, respectively. All the specimens showed tetragonality phase, and pyrochlore phase was not shown.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3952-3958
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• 2011

The effect of sintering temperature on the electrochemical property of $LiMn_2O_4$ was investigated. Results showed that the particle size was increased at higher sintering temperatures while the initial capacity was decreased after high temperature sintering. Capacity fading, on the other hand, was suppressed at lower sintering temperatures since the sintering at higher temperatures (${\geq}800^{\circ}C$) increased the Mn ions with a lower oxidation state ($Mn^{+3}$), which induced structural instability during cycling due to dissolution of Mn ions into the electrolyte. In particular, $LiMn_2O_4$ sintered above $830^{\circ}C$ showed severe capacity fading (capacity loss was 38% of initial capacity) by lower coulombic efficiency due to the abnormally increased particle size.

• 한국전기전자재료학회논문지
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• 제18권3호
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• pp.237-242
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• 2005

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramics were manufactured with the variations of sintering times, and their microstructural, piezoelectric and dielectric properties were investigated. Li$_2$CO$_3$ and Bi$_2$O$_3$ were used as sintering aids and the specimens were sintered during 30, 60, 90, 120, 150, and 180 minutes, respectively. At the specimen sintered during 90 minute, mechanical quality factor(Qm), electro-mechanical coupling factor(kp) and dielectric constant were showed the optimum values of 2,356, 0.504 and 1,266, respectively.

• 한국세라믹학회지
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• 제31권7호
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• pp.739-744
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• 1994

The B4C-C system was investigated to gain an understanding of the sintering behaviors of B4C. In order to get sintered density of 97% TD, sintering temperature of 225$0^{\circ}C$ was necessary. Since such a high temperature operation is actually difficult on a commercial basis, our objective was to examine the possibility of decreasing the sintering temperature by adding SiC. The addition of SiC in B4C increases the sintering rate about at 210$0^{\circ}C$ and results in a fine microstructure with more than 98% relative density on 55 wt% B4C-40wt% SiC-5 wt% C composition. The probability of liquid phase sintering was investigated, but the evidences of liquid phase formation were not observed with XRD and TEM observation. It was proposed that the addition of SiC and carbon to B4C reduce interface energy during sintering, which results in enhanced grain-boundary diffusion. Thus, the enhanced grain-boundary diffusion and retarded grain growth by SiC improve densification.

• 한국세라믹학회지
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• 제37권4호
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• pp.302-307
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• 2000

The objective of this study was to investigate the sintering behavior, crystallization characteristic of glass-ceramic and optimal sintering condition on the glass/ceramic composite for fabricating substrate of LTCC. Glass/ceramic composite was made from alumina powder and glass frit, which was composed of SiO2-TiO2-RO-PbO/(R: Ba, Sr, Ca), and was sintered for 0, 30, 60minutes in the temperature range from 700$^{\circ}C$ to 1000$^{\circ}C$. Properties of frit and glass/ceramic compsoite were analyzed by DTA, XRD, SEM and Network Analyzer and so on. Main sintering mechanism was densification occurred above 730$^{\circ}C$ by viscous flow and crystallization starting about 780$^{\circ}C$ affected sintering also. So viscous flow was affected by sintering temperature, duration time, and creation of crystallization phase etc. From this study, it was possible to fabricate glass/ceramic composite by changing sintering temperature and duration time.