• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.5 no.2
• /
• pp.152-164
• /
• 1995

$xPb(Fe_{1/2}Nb_{1/2})O_3 - (1 - x)Pb(Mg_{1/3}Nb_{2/3})O_3$ powders were synthesized by the molten salt synthesis method using the NaC!- KCI flux with 1 : 1 molar ratio, and their powders and dielectric properties were investigated. The synthesized powders showed less agglomerated shape with the average particle size of less than $2 \mu\textrm{m}$. The composition $x0.3Pb(Fe_{1/2}Nb_{1/2})O_3-0.7Pb(Mg_{1/3}Nb_{2/3})O_3$ could be sintered at $1000{\times}C$ and its dielectric constnat was over 11, 000.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.4
• /
• pp.667-672
• /
• 1998

Pyroelectric properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ ceramics prepared by the columbite precursor method have been investigated as a function of the sintering temperature in the range of $1000^{\circ}C$ to $1250^{\circ}C$. The $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ ceramics show typical relaxor ferroelectric behavior. The optimum condition for obtaining samples with high densities and improved pyroelectric properties occur at a sintering temperature of $1250^{\circ}C$ and sintering times of 2 hours. The $Pb(Mg_{1/3}Nb_{2/3}O_3-PbTiO_3$ ceramics show the possibility for pyroelectric sensors with pyrostat.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2000.10a
• /
• pp.66.2-66
• /
• 2000

• Journal of the Korean Ceramic Society
• /
• v.30 no.9
• /
• pp.723-730
• /
• 1993

The mechanism of formation of perovskite phase and the dielectric properties of PZMN[Pb(Zn, Mg)1/3Nb2/3O3] ceramics were examined using two different types of the columbite precursors, (Mg, Zn)Nb2O6 (MZN) and MgNb2O6＋ZnNb2O6 (MN＋ZN). The formatin of perovskite phase in PbO＋MN＋ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, thepyrochlore/perovskite transformation in the PbO＋MZN system proceeded uniformly with a spatial homogeneity. The degree of diffuseness of the rhombohedral/cubic phase transitionis higher in the PbO＋MN＋ZN system than in the PbO＋MZN specimen, indicating a broadened compositional distributjion of the B-site catons (Nb+5, Zn+2, Mg+2) in the PbO＋MN＋ZN system.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1996.06b
• /
• pp.185-217
• /
• 1996

Pb(Mg1/3Nb2/3)O3은 높은 유전율과 전기저항 및 유전율의 온도변화율이 적은 Pb계 relaxor의 대표적인 재료로서 적층 세라믹 콘덴서 재료에의 응용이 크게 기대되고 있다. 그러나 산화물 분말을 이용하는 일반적인 세라믹스 합성방법으로는 Pb(Mg1/3Nb2/3)O3의 단일상의 합성이 어렵고, 합성과정에서 저유전율상인 pyrochlore상이 합성이 어렵고, 합성과정에서 저유전율상인 pyrochlore상이 공존하여 Pb(Mg1/3Nb2/3)O3의 전기적 특성을 저하시킨다. 본연구에서는 용액을 이용하여 Pb(Mg1/3Nb2/3)O3의 단일상을 합성하고자 하였다. 출발물질로는 값싼 금속염인 Niobium Oxalate, magnesium Nitrate 및 Lead Nitrate를 선정하고 증류수에 용해하여 혼합용액을 제좋고, 합성방법으로는 초음파 분무 열분해법과 에멀젼법을 이용하였다. 초음파 분무 열분해법에서는 75$0^{\circ}C$에서 합성한 분말을 다시 75$0^{\circ}C$에서 하소하여 Pb(Mg1/3Nb2/3)O3 단일상을 합성할 수 있었으며, 에멀젼법에서는 80$0^{\circ}C$에서 Pb(Mg1/3Nb2/3)O3 단일상을 합성할 수 있었다.

• Journal of the Korean Ceramic Society
• /
• v.35 no.2
• /
• pp.123-128
• /
• 1998

Multilayer ceramic capacitors(MLCC) were prepared by laminating the layer of composition with dif-ferent Curie temperature to improve temperature coefficient in the Pb(Mg1/3Nb2/3)O3-PbTiO3 binary system. Green sheet was formed by tape casting using Pb(Mg1/3Nb2/3)O3-PbTiO3 and PbTiO3 synthesized with solid state reaction of PBO. Nb2O5 MgO and TiO2. Green sheet with electrode of 70Ag-30Pd was laminated under 300 kg/cm2 at 70$^{\circ}C$ and sintered at 1100$^{\circ}C$ for 2hr. Curie temperatues for MLCC with 10 layers of pure PMN and 0.9PMN-0.1PT were lowered to -22$^{\circ}C$ and 36$^{\circ}C$ respectively. MLCC with 7 layers of PMN and 3 layers of 0.9PMN-0.1PT showed nearly zero temperature coefficient of capacitance in the range of -20∼30$^{\circ}C$ and sum of dissipation factor of each layer.

• Journal of the Korean Ceramic Society
• /
• v.33 no.1
• /
• pp.17-24
• /
• 1996

Pb(Mg1/3Nb2/3)O3 powder with high purity chemical homogeniety and reactivity was prepared by solvent eva-poration of common solution. The common solution was fabricated using a Pb(NO3)2 Mg(NO)3 and NB solution which was prepared by dissolving NbC in H2O2 acquous solution. In precusor powder prepared by solvent evaporation method the synthetic temperature of Pb(Mg1/3 Nb2/3)O3 phase was lowered. And the formation of homogeneous Pb(Mg1/3Nb2/3)O3 phase was enhanced but the formation of pyrochlore phase was reduced. The dielectric constant of PMN ceramics from the synthesized powder was found to increase with both sintering temperature and excess MgO and subsequent analysis of the microstructures confirmed that this was due to an increase in grain size. The grain size dependence is explained as a consequence of low-permittivity grain boundaries.

• Journal of the Korean Ceramic Society
• /
• v.33 no.11
• /
• pp.1267-1275
• /
• 1996

Green sheet was prepared by tape casting in the composition of (1-x)Pb(Mg1/3Nb2/3)O3-PbTiO3 system using Pb(Mg1/3Nb2/3)O3 and PbTiO3 synthesized with PbO, Nb2O5 MgO and TiO2 The densest green sheet was obtained in the weight ratio 70:30 of powder to binder. Green sheet wasmultilayered in metal mould and formed into lamination at 7$0^{\circ}C$, 300kg/cm2 The lamination was sintered at 110$0^{\circ}C$ 2hr, Dielectric constant and Curie temperature of disc type sintered body was highered with increasing the amount of PbTiO3 and was in the range of 19000-21000, -7~45$^{\circ}C$ respectively. Green and sintered relative density of lamination was 61% and 95% respectively.

• Journal of the Korean Ceramic Society
• /
• v.31 no.12
• /
• pp.1443-1448
• /
• 1994

Pb(Mg1/3Nb2/3)O3-PbTiO3-BaTiO3 solid solution was formed by mixed-oxide method. The phase during formation was analysed by XRD and formation mechanism was investigated. While heat-treating Pb(Mg1/3Nb2/3)O3 composition, the first, Pb2Nb2O7 and Pb3Nb2O8 pyrochlore phases are formed, and finally Pb(Mg1/3Nb2/3)O3 perovskite phase with containing Pb3Nb4O13 pyrochlore phase is obtained at 80$0^{\circ}C$. When Pb(Mg1/3Nb2/3)O3 composition is modified with PbTiO3 which have strong ionic bonding and high tolerance factor, the amount of pyrochlore phase is decreased by increasing of stability in perovskite structure.

• Journal of the Korean Ceramic Society
• /
• v.33 no.10
• /
• pp.1117-1123
• /
• 1996