• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.321-328
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• 1988

The sintering phenomena, electrical resistivity, dielectric and piezoelectric properties of lead titanate ceramics modified by the partial substitution of La for Pb and Mn for Ti, (Pb1-1.5xLax)(Ti1-yMny)O3 ceramics, have been investigated. In (Pb1-1.5xLax)(Ti1-yMny)O3 system, with increasing lanthanum content, the realtive bulk density increased, but the Curie point and tetragonality (c/a) decreased. The tetragonal-to-cubic phase transition boundary existed in the range of 0.20

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.63-67
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• 2003

Synthesis of $PbLaTiO_{3}$ : Mn powders containing La and Mn was carried out using $PbO,\;TiO_{2},\;La_{2}O_{3}\;and\;MnO_{2}$ as starting materials by hydrothermal method. In the synthesis of single phase $PbLaTiO_{3}$ : Mn powder containing La and Mn, the optimal x value corresponding to La substitution was 0.01 which corresponds to $0.99(Pb_{1-x}La_{2x/3}TiO_{3})+0.01MnO_{2}$. The optimal conditions for the preparation of the powder synthesis were 8 M-KOH solvent of hydrothermal solvent, $270^{\circ}C$ of reaction temperature and 24 hrs of run time. It was found that the synthesized powders had spherical morphology with average particle size of 70 nm and specific surface area of $5.5\;m^{2}/g$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.5-8
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• 1995

The crystal structure and dielectric propoerties of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$ Ceramics were investigated. Sn substitution reduced the volitility of PbO due to the decrease of the unit cell. The crystal structure of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$ Ceramics was refined based on Orthorhombic Cmmm space group, More than two types of phase transition were observed, These phase transitons make the posicitve and negative temperature coefficient of dielectric constant of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1240-1246
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• 1994

While sintering the Pb(Mg1/3Nb2/3)O3-PbTiO3-BaTiO3 system through solid-reaction route, pyrochlore(Pb3Nb4O13) phase while reduces the dielectric constant is inevitably formed. Substitution of Pb(Mg1/3Nb2/3)O3 with PbTiO3 and BaTiO3 can retard the occurrence of pyrochlore phase. The perovskite solid-solution without containing pyrochlore phase can be obtained when we consolidated the materials consisting of PbTiO3 and BaTiO3 at 1200℃ for 2 hours. The sintered body composed of 0.8Pb(Mg1/3Nb2/3)O3-0.1PbTiO3-0.1BaTiO3 composition showed the diffused phase transition(DPT) phenomena and the maximum value of dielectric constant at 0℃ (Tc') with the value of 1.3×104.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.405-409
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• 2003

The effect of substitution of Gd ions for Ca ions in the B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$(C $a_{1-x}$ G $d_{x}$)$_{2.03}$ C $u_{3.06}$ $O_{ 10+{\delta}}$/ (x=0.0~0.06) was investigated by measuring x-ray diffraction patterns, lattice constants, do resistivity and Hall effect. We found the solubility limit of Gd in the 110 K phase to be x < 0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature $T_{c}$ gradually decreased with an increasing the Gd concentration x, corresponding to a small change of the carrier concentration.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.469-484
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• 2022

The Janggun Pb-Zn deposit has been known one of the four largest deposits (Yeonhwa, Shinyemi, Uljin) in South Korea. The geology of this deposit consists of Precambrian Weonnam formation, Yulri group, Paleozoic Jangsan formation, Dueumri formation, Janggum limestone formation, Dongsugok formation, Jaesan formation and Mesozoic Dongwhachi formation and Chungyang granite. This Pb-Zn deposit is hydrothermal replacement deposit in Paleozoic Janggum limestone formation. The wallrock alteration that is remarkably recognized with Pb-Zn mineralization at this deposit consists of mainly rhodochrositization and dolomitization with minor of pyritization, sericitization and chloritization. Wallrock alteration is divided into the five zones (Pb-Zn orebody -> rhodochrosite zone -> dolomite zone -> dolomitic limestone zone -> limestone or dolomitic marble) from orebody to wallrock. The white mica from wallrock alteration occurs as fine or medium aggregate associated with Ca-dolomite, Ferroan ankerite, sideroplesite, rutile, apatite, arsenopyrite, pyrite, sphalerite, galena, quartz, chlorite and calcite. The structural formular of white mica from wallrock alteration is (K_0.77-0.62Na_0.03-0.00Ca_0.03-0.00Ba_0.00Sr_0.01)_0.82-0.64(Al_1.72-1.48Mg_0.48-0.20Fe_0.04-0.01Mn_0.03-0.00Ti_0.01-0.00Cr_{0.00As0.01-0.00}Co_0.03-0.00Zn_0.03-0.00Pb_0.05-0.00Ni_0.01-0.00)_2.07-1.92 (Si_3.43-3.33Al_0.67-0.57)_4.00O₁₀(OH_1.94-1.80F_0.20-0.06)_2.00. It indicated that white mica from wallrock alteration has less K, Na and Ca, and more Si than theoretical dioctahedral micas. The white micas from wallrock alteration of Janggun Pb-Zn deposit, Yeonhwa 1 Pb-Zn deposit and Baekjeon Au-Ag deposit, and limestone of Gumoonso area correspond to muscovite and phengite and white mica from wallrock alteration of Dunjeon Au-Ag deposit corresponds to muscovite. Compositional variations in white mica from wallrock alteration of these deposits and limeston of Gumoonso area are caused by mainly phengitic or Tschermark substitution mechanism (Janggun Pb-Zn deposit), mainly phengitic or Tschermark substitution and partly illitic substitution mechanism (Yeonhwa 1 Pb-Zn deposit, Dunjeon Au-Ag deposit and Baekjeon Au-Ag deposit), and mainly phengitic or Tschermark substitution and partly illitic substitution or Na⁺ <-> K⁺ substitution mechanism (Gumoonso area).

• Progress in Superconductivity and Cryogenics
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• v.20 no.3
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• pp.1-4
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• 2018

The effect of sulfate substitution on the formation of (Pb,S)-1201 type phase was investigated. Polycrystalline samples with nominal compositions of $(Pb_{0.5}B_{0.5-x}S_x)(Sr_{2-y}La_y)CuO_z$, (x = 0 - 0.5, y = 0.7 - 1.0) and $(Pb_{0.5}S_{0.5})(Sr_{2-y}La_y)CuO_z$ (y = 0.5 - 1.0) were prepared by using a solid-state reaction method. The samples were characterized by powder X-ray diffraction (XRD) and resistivity measurements. XRD data revealed that almost-single (Pb,S)-1201 phase samples could be obtained for x = 0.5 and y = 0.9-1.0, judging from the similar results of the XRD patterns between the (Pb,S)-1201 and (Pb,B)-1201 phases. Each of the samples has a crystal structure with tetragonal symmetry. The sample with x = 0.5 and y = 0.9 is found to show an onset of resistivity dropping at over 23 K and zero resistivity at 12 K.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.548-555
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• 2023

SAPO-34 catalysts were modified with polyethylene glycol (PEG) and Pb to improve their catalytic lifetime and selectivity for light olefins in the conversion of dimethyl ether to olefins (DTO). Hierarchical SAPO-34 catalysts and PbAPSO-34 catalysts were synthesized according to changes in the molecular weight of PEG (M.W. = 1000, 2000, 4000) and the molar ratio of Pb/Al (Pb/Al = 0.0015, 0.0025, 0.0035), respectively. By introducing PEG into the SAPO-34 catalyst crystals, an enhanced volume of mesopores and reduced acidity were observed, resulting in improved catalytic performance. Pb was successfully substituted into the SAPO-34 catalyst frameworks, and an increased BET surface area and concentration of acid sites in the PbAPSO-34 catalysts were observed. In particular, the concentrations of the weak acid sites, which induce a mild reaction, were increased compared with the concentrations of strong acid sites. Then, the P2000-Pb(25)APSO-34 catalyst was prepared by simultaneously utilizing the synthesis conditions for the P2000 SAPO-34 and Pb(25)APSO-34 catalysts. The P2000-Pb(25)APSO-34 catalyst showed the best catalytic lifetime (183 min based on DME conversion > 90%), with an approximately 62% improvement compared to that of the unmodified catalyst (113 min).

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.114.4-114
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• 1998

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.178-180
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• 2005

In this study, in order to develop multilayer low temperature sintering piezoelectric transformer, $Pb_{0.97}Sr_{0.03}[(Mn_{1/3}Nb_{2/3})x(Zr_{0.48}Ti_{0.52})_{1-x}O_3]+$ 0.25wt% $CeO_2$+0.3 wt% $Nb_2O_5$ system ceramics were fabricated using $Li_2CO_3-CaCO_3$ and CuO as sintering aids and their piezoelectric and dielectric characteristics were investigated with the amount of PMN substitution. With increasing PMN substitution, electromechanical coupling factor kp and dielectric constant were increased.