• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.305-312
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• 1995

Thin films of Pb(Mg, Zn)1/3Nb2/3O3 were fabricated by spin coating the Pb-Mg-Zn-Nb-O complex alkoxide sols on(111) Pt-coated MgO (100) planes. It was observed that the content of H2O and the rheological characteristics of sol greatly influenced the orientation of perovskite grains after thin-film formation. A strong preferential orientation of (100)-type planes of the perovskite grains was obtained for the sol aged for 15 days with the molar ratio of H2O to total metal alkoxides=2. As small angle X-ray scattering experiment in the Porod region was performed to correlate the observed preferential orientation with the network structure of precursors at various stage of aging. It was shown that the degree of branching of the Pb-Mg-Zn-Nb-O precursor chain had a direct effect on the preferred oreintation, and weakly branched precursor systems led to highly oriented grains after thin-film formation.

• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.347-352
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• 1991

The effects of Ta2O3 doping on the microstructure, electrical properties and thermal expansion in Pb(Zr0.525Ti0.475)O3 ceramics were studied. Density, average grain size, electromechanical coupling factor kp and thermal expansion coefficient of unpoled and poled samples were measured as a function of Ta2O5 content. Average grain size was decreased and density increased above 0.6 mol% Ta2O5 addition. In case of 0.2 mol% addition, density showed minimum according to grain growth. Dielectric constant and electromechanical coupling factor kp were the lowest in 0.2 mol% addition increased with Ta2O5 addition.

• The Korean Journal of Ceramics
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• v.6 no.4
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• pp.385-389
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• 2000

Residual stresses in epitaxial films were measured by X-ray diffraction method. Lattice strains of the (hkl) planes measured along particular Ψ-angles were converted to the in-plane stress according to the equation of stress-strain tensor conversion. Residual tensile stresses were observed in epitaxial PbTiO$_3$ films deposited on (100) SrTiO$_3$ substrate. Tensile stresses approximately 0.9 GPa were measured in Pb-rich films, while it increased to approximately 2.0 GPa with the decreasing of Pb content in the case of Pb-poor films, which ascribed to the formation of lead and oxygen vacancies (expressed as x in Pb$_1-x$TiO$_3-x$).

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.184-189
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• 2002

This study, compared with data of PbO-base glass system is a part of new glass composition design with Bi-base composition for PDP Rib. As $Bi_2O_3-B_2O_3-ZnO$ glass composition including Bi, which have similar density value and work facility to PbO, properties of softening point, thermal expansion coefficient, chemical durability, dielectric constant, and structural changing by XPS were investigated. $Bi_2O_3-B_2O_3-ZnO$ glass system, added 50∼80 wt% $Bi_2O_3$ widely, were presented 400∼480$^{\circ}C$ softening temperature, $68{\sim}72{\times}10^{-7}/^{\circ}C$ thermal expansion coefficient and 13∼25 dielectric constant. These results were showed similar physical properties with Pb-base glass system of same composition content, application possibility as starting composition of rib material was identified through micro-control of components and physical properties. The bonding energy of $O_{1s}$ as the $Bi_2O_3$ content decreasing was increased and full width at half-maximum (FWHM) was decreased, which is caused by non-bridging oxygen increasing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.288-291
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• 2002

An alkoxide-based sol-gel method was used to fabricate $(Pb_{x},Sr_{1-x})$TiO3 (PST) thin films on a Pt/Ti/SiO2/Si substrate, and the dielectric properties of the PST thin films were investigated as a function of the Pb/Sr composition for use in tunable microwave device applications. The dielectric properties of the PST films were strongly dependent on the Pb/Sr ratio. The dielectric constant and dielectric loss of the PST films increased with increasing Pb content, and the figure of merit (FOM) reached a maximum value of 27.5 at a Pb/Sr ratio of 4:6. The tunability increased with increasing Pb content. The dielectric constant, loss factor, and tunability of PST (50/50) thin films were 404, 0.023, and 51.73%, respectively. From the result, the PST films with good dielectric properties are useful candidates for tunable microwave device.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.256-262
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• 2000

The dielectric properties of complex perovskite ($Pb_{1-x}Ca_{x}$)($Fe_{0.5}Ta_{0.5}$)$O_{3}$ with >($0.5{\le}x{\ge}0.65$ were investigated at microwave frequencies. Dilectric constant decreased with increasing Ca content, and was directly proportional to the cube of average ionic ra야 of A-site. For the specimen of x=0.6 sintered at $1250^{\circ}C$ for 3 h in air, dielectric constant (k) of 63, QF of 11000 GHz, and the temperature coefficient of resonant frequency(TCF) of -14ppm/$^{\circ}C$ were obtained. As Ca content increased, TCF of the specimen negatively increased due to the reduction of the tolerance factor(t). Changes in intrinsic loss with varying Ca content was investigated by the infrared reflectivity spectra ranging 50 to 4000 $cm^{-1}$, which were calculated by the Kramers-Kronig analysis and classical oscillator model. The relative tendency of microwave dielectric properties of the ($Pb_{1-x}Ca_{x}$)($Fe_{0.5}Ta_{0.5}$)$O_{3}$ specimens calculated from the reflectivity data were in good agreement with the results by the post resonant method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.589-598
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• 1997

The effects of PT/PZ ratio variations in a modified PZT system on crystal structure and electrical properties were studied. $0.05Pb(Sn_{0.5}Sb_{0.5})O_3＋xPbTiO_3＋yPbZrO_3$＋0.4Wt% $MnO_2$(＝0.55PSS＋0.11PT＋0.84PZ＋0.4wt%$MnO_2$ ; x＋y=0.95) systems with variations of PT/PZ from 0.50/0.45 to 0.l1/0.84 were sintered at $1250^{\circ}C$ for 2 hr, and then sintering density, crystal structure, dielctric, piezoelectric, pyroelectic and voltage responsity to infrared were investigated. Sintering density was increased from 7.52g/$\textrm {cm}^3$ to 7.82g/$\textrm {cm}^3$ with increasing PZ content. Dielectric constants at 1 KHz were decreased from 1147 to 193 with variation of PT/PZ from 0.50/0.45 to 0.l1/0.84 after poling of $4 KV_{DC}$/mm at $140^{\circ}C$ for 20 minutes. All Dielectric losses at 1 KHz were less than 1 % in all specimens. $K_{p}$ was increased near to 1 of PT/PZ, and maximun value of 48.2 % was .at 0.45/0.50. Pyroelectric coefficient of PT/PZ with 0.l1/0.84 was maximun value, 0.0541 C/$\m^2$K, and voltage responsity to infrared was 1.5 V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.755-759
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• 2008

For the development of a new white dielectric layer in plasma display panel, different $TiO_2$ types as a filler was add to the $Bi_2O_3$-BaO-ZnO glass matrix. The reflectance and dielectric constant of dielectric have been investigated as a function of the mixing content (rutile and anatase), and sintering temperature. The reflectance of dielectric sintered at the 520$^{\circ}C$ appeared most highly and suitable in terms of the adhesion and reflectance of the soda-lime glasses. Also, the thermal expansion coefficient of dielectric was found to be $85.6\times10^{-7}/K$, which was similar to that of the soda-lime glasses. Especially, the dielectric constants were not increased with increasing of $TiO_2$ filler contents.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.12
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• pp.1027-1032
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• 2002

(Pb$\_$0.4/Ca$\_$0.6/)(Fe$\_$1/2/Nb$\_$1/2/)O$_3$ system was modified by 10 mol% Pb(Zn$\_$1/2/W$\_$1/2/)O$_3$ addition and their sinterability and microwave properties were investigated as a function of the amount of flux (0.975PbO-0.025SnO$_2$). With increasing flux content, single perovskite phase was maintained up to 3 wt% flux addition and further addition led to the presence of Pb-rich second phase which was confirmed by EDS analysis. The apparent densities of PCFN-PZW specimen increased and showed maximum values at 2.5 wt% flux addition for the Ts=1000$^{\circ}C$ and 2.0wt% flux addition for the Ts=1050$^{\circ}C$, respectively. The dielectric constant and Q$.$f values strongly depended on the variation of density and microstructure, where the optimum values of $\varepsilon$$\_$r/ = 91.95, Q$.$f = 5938GHz, TCF = +8.15ppm/$^{\circ}C$ were obtained for the 2.5wt% flux added PCFN-PZW specimen sintered at 1000$^{\circ}C$ for 4h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.14-16
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• 1993

In this Paper. Pb($Zn_{x}Nb_{1-x}$)$O_3$ ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1,000($^{\circ}C$). 1(hr). respectively. According to the contents of $ZnO_2$, the depression of pyrochlore phase and its effects were studied. As the results of the XRD patterns and SEM. the pyrochlore and second phase were increased with increasing the $ZnO_2$. As the $ZnO_2$ content was increased. density was decreased.