• 한국세라믹학회지
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• 제23권4호
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• pp.62-68
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• 1986

$(Pb_{1-x} La_x)(Zr_{0.65} Ti_{0.35})_{1-x/4}O_3$ (PLZT X/65/35) powders were prepared by molten salt synthesis using NaCl-K Cl and conventional calcining of oxides. The effects of molten salt on formation and charactrization of PLZT powder and on dielectric piezolectric and optical properties of PLZT ceramics were studied, The completed PLZT powder formation in the presence of fused salt was attained at 50-10$0^{\circ}C$ lower temperature than that in solid state reaction and the particle size of the powder made by molten salt synthesis was markedly increased with increasing calcining temperature. The substitution of Na and/or K ions in NaCl-KCl for Pb ion in process of molten salt synthesis was increased with increasing La concentration Z. These substituted Na and/or K ions were identified as the origins of decreasing coupl-ing factor and optical transmittance of PLZT ceramics.

• 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.

• 한국세라믹학회지
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• 제22권3호
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• pp.13-18
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• 1985

Semiconductive $Ba_{0.9}Sr_{0.1}TiO_3$ was prepared by both the Calcining of mixed Oxides (C. M. O) and the Molten Salt Synthesis(M.S.S) methods to investigate the PTCR effects. In the Molten Salt Synthesis method the temperature of calcination for Synthesis of $BaTiO_3$ could be lowered from 110$0^{\circ}C$ to 80$0^{\circ}C$. The M.S.S Specimens had smaller grain size and more homogeneous size distribution at the same sintering temperature as compared with the C. M. O specimens. The M. S. S. specimens showed greater PTCR effects and current variations in the time vs. current charac-teristics than those of C. M. O Specimens.

• 한국전기전자재료학회논문지
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• 제11권5호
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• pp.378-383
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• 1998

Microstructure and additive effect of Lead Zirconate-Titanate(PZT) ceramics prepared by molten salt synthesis method with additives $Nb_2O_5, Fe_2O_3$ and MnO were investigated.The grain PZT ceramics ws decreased with the increase $Nb^{5+} or Fe^{3+}$ while increased with the increase $Mn^{2+}$ addition. The relative resistivity of PZT ceramics was increased with the increase $Mn^{5+}$ addition, while decreased with the increase $Mn^{2+}$ addition. And the dielectric and the piezoelectric constant of PZT ceramics showed 2,100 and 342pC/N at $Mn^{5+}$ addition of 0.75 mol%, respectively.

• 한국결정성장학회지
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• 제31권5호
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• pp.197-202
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• 2021

Z형 육방정 페라이트인 Ba₃Co₂Fe₂₄O₄₁(Ba₃Z)와 Ba_1.5La_1.5Co₂Fe₂₄O₄₁(Ba_1.5La_1.5Z) 분말을 1차 하소 후 용융염 합성법을 통해 합성하였다. Ba₃Z의 경우, 1000℃에서 하소한 결과 M형 육방정 페라이트와 Y형 육방정 페라이트가 합성되었으며, 이후 1150℃와 1200℃에서 소결했을 때 Z형 육방정 페라이트를 얻을 수 있었다. 하지만 Ba_1.5La_1.5Z의 경우 1000℃에서 하소하였을 때 M형 육방정 페라이트와 CoFe₂O₄(Spinel 상) 그리고 LaFeO₃으로 합성되었으며, Z형 육방정 페라이트는 용융염 합성 과정에서 합성되지 않았다. 또한 입자 형상의 종횡비는 용융염 합성 시 소결온도가 증가함에 따라 감소하는 경향을 보였다. 따라서 높은 종횡비를 갖는 단상의 Ba_1.5La_1.5Z를 합성하기 위해서는 용융염 합성 전 1차 하소 온도가 Spinel 상이 형성되는 온도보다 낮아야 될 것으로 판단된다.

• 한국결정성장학회지
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• 제15권3호
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• pp.99-103
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• 2005

NaCl-KCl을 flux로 사용한 용융염 합성법을 이용하여 $Pb(Sc_{1/2}Ta_{1/2})O_3$, 분말을 제조하였다. $700^{\circ}C$에서 $800^{\circ}C$의 온도범위에서 상형성 및 분말 상태의 변화를 조사하였다. 용융염 합성법으로 $750^{\circ}C$ 2시간 하소하였을 때, 순수한 페로브스카이트 구조를 가진 $Pb(Sc_{1/2}Ta_{1/2})O_3$ 상이 형성되었으며, 평균 입자 크기는 $0.5\{mu}m$ 이하이고 입방체와 유사한 형상을 갖는 분말이 제조되었다. DIA, X-선 회절 분석, 미세구조 변화를 통해 합성된 분말의 특성을 고찰하였다.

• 한국결정성장학회지
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• 제6권4호
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• pp.501-508
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• 1996

NaCl-KCl 용융염을 사용하여 strontium barium niobate 분말을 합성하였으며 반응온도, 시간 및 용융염의 첨가량 변화에 따른 반응과정 및 입자 형상 변화를 조사하였다. 반응 온도 및 반응 시간이 증가함에 따라 반응율은 증가하였으며, 분말의 형상은 덩어리 형태에서 침상형태로 변화하였다. 용융염의 첨가량 증가에 따라 반응율은 크게 증가하였으나, 분말의 형상은 침상형태에서 구상형태로 변화하였다. NaCl-KCl 용융염을 사용한 합성법에 의해 융제비가 1인 경우 $1000^{\circ}C$에서, 융제비가 4인 경우 $650^{\circ}C$에서 반응율 90 % 이상의 strontium barium niobate 분말 합성이 가능하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.721-723
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• 1992

The electrical resistivity and piezoelectric properties have been studied for Lead Zirconate-Titanate(PZT) with $Nb_2O_5$ dopant, fabricated from conventional mixed-oxide powders and molten salt synthesis. The resistivity and electromechanical coupling factor(Kp) were increased with increasing Nb contents. The reason for increasing of the electrical resistivity below the Curie Temperature(Tc), It is believed that the p-type electrical conduction in PZT is caused by the lead vacancies. The electromechanical coupling factor(Kr) and piezoelectric constant $d_{33}$ were improved by Nb additives. This behavior can be explained as a compensation effect and $Nb^{5+}$ can serve as a donar and contribute electrons to the conduction process. As a result, the optimized $Nb_2O_5$ dopants on the PZT specimens were 0.75 wt%.

• 한국세라믹학회지
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• 제28권1호
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• pp.79-85
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• 1991

The effects of MnO2 on the microstructure and dielectric properties of Pb(Fe1/2Nb1/2)O3 ceramics prepared by KCl-NaCl molten salt synthesis(MSS) method have been investigated. As the amount of MnO2 increased up to 0.25wt%, the density increased and the grain size decreased, while above 0.25wt%, the density decreased with the grain growth. Dielectric constant increased with increasing the amount of MnO2, and dielectric loss decreased up to 0.25wt% and then increased. This is due to the compensation effect by the substitution of Mn4+ to Fe3+ and the appearance of the second phase.

• 한국세라믹학회지
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• 제42권10호
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• pp.672-677
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• 2005

In this study we prepared the Sr-ferrite powders and magnet by a molten salt method using the (NaCl+KCl) salt mixture. Starting materials of $Fe_{2}$$O_{3}$ and Sr$Co_{3}$ were mixed as the molar ratio of 5.70:1, and 0.08 mol$ \% $ $Al_{2}$$O_{3}$, 0.10 mo1$ \% $ Si$O_{2}$ and 0.12 mo1$ \% $ CaO were added as additives. Sr-ferrite powders synthesized at the reaction temperatures of 800$\∼$1200$ ^{\circ}C $ showed the typical M-type hexagonal ferrite phase, and hexagonal plate-like morphology with uniform distribution of 1$\∼$3 $\mu$m particle size. The bulk density of the sintered Sr-ferrite magnet prepared with powders by the molten salt method showed the maximum density of 4.82 g/$cm^{3}$ at the sintering temperature of 1200$^{\circ}C $. The maxima of remanent flux density (Br, 45 emu/g) and coercive force (iHc, 3.75 kOe) occurred at the sintering temperatures of 1150$ ^{\circ}C$ and 1200$^{\circ}C $.