• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.378-384
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• 1995

Effects of $La_2O_3$, $MnO_2$ on the dielectric and piezoelectric properties of $0.02Pb(Y_{2/3}W_{1/3}O_3-0.98Pb(Zr_{0.52}Ti_{0.48})O_3$ system were investigated. The addition of La2O3 to the system enhanced electromechanical coupling factor (kp), piezoelectric constant (d33), but hardly changed mechanical quality factor (Qm). On the other hand, the addition of $MnO_2$ increased Qm significantly, but did not degrade kp and d33 so much. The piezoelectric properties of $0.02Pb(Y_{2/3}W_{1/3}O_3-0.98Pb(Zr_{0.52}Ti_{0.48})O_3$ containing 0.1wt% $La_2O_3$, 0.4wt% $MnO_2$ were very good and kp, d33, Qm were 55%, 350$\times$10-12C/N, 780, respectively. The size of the grains was proportional to the change of c/a (tetragonality) ratio caused by the addition of $La_2O_3$ and $MnO_2$, and dielectric, piezoelectric properties were sensitive to the amountof pyrochrole phase.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.6
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• pp.246-251
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• 2001

The $[(Pb_{1-x}$La_{2x/3})TiO_3$, X=0.2] powder was synthesized by the hydrothermal method, and their sintering and dielectric properties according to Mn additive were examined. The relative density of sintered PLT specimen at $1150^{\circ}C$ for 5 hrs with Mn 0.02 mol% additive was 96.7%. The dielectric properties of sintered PLT specimen were changed by content of Mn and increacement of sintering temperature. Dissipation factor was improved by increasing of measuring temperature. Curie temperature of sintered PLT specimens was decreased with increasing of Mn additive.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.960-966
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• 2004

On the bases of the results from "Additive Coating of BaTiO$_3$ Powder using Sol Coating Method I", experimental condition was defined. Representative additives for BaTiO$_3$, that is to say, Mg, Ca and Mn were experimented. The sources of the metal ion were used by organometal complex. As added it, the stability of BaTiO$_3$ sol was evaluated. Mg and Ca were stable, however, The solubility limit of Mn-ATH was 0.05 mol ratio in Mn-ATH/sol. The solubility limit of Mg ion in BaTiO$_3$ was lower than 2 mol%. From the x Ray diffraction patterns, lattice parameters were different with temperature and additives, because the solubility of metal ion was varied in BaTiO$_3$. The dielectric constant of BaTiO$_3$ powders which coated with the 1.5 mol% Mg and calcined at 1200$^{\circ}C$ was increased with 20%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.115-120
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• 2016

$CeO_2$ is used as a co-catalyst with $TiO_2$ to improve the catalytic activity of $MnO_x$ and characterization of nano-sized powder is identified with de-NOx efficiency. A comparison between $MnO_x-CeO_2/TiO_2$ and single $CeO_2$ was conducted in terms of microstructural analysis to observe the behavior of $CeO_2$ in the ternary catalyst. The $MnO_x-CeO_2/TiO_2$ catalyst was synthesized by sol-gel method and the average particle size of the single $CeO_2$ is about $285{\mu}m$ due to the low thermal stability, whereas the particle size $MnO_x-CeO_2/TiO_2$ is about 130 nm. The strong interaction between Ce and Ti was identified through the EDS mapping by transmission electron microscopy (TEM). The improvement about 20 % of $de-NO_x$ efficiency is observed in the low-temperature ($150^{\circ}C{\sim}250^{\circ}C$) and vigorous oxygen exchange by well-dispersed $CeO_2$ is the reason of catalytic activity improvement.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.362-366
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• 2000

$Li_{0.44}MnO_2$cathode material has high reversibility during lithium insertion processes and is not easily damaged through over-charging or over-discharging. $Mn_2O_3$is often present as an impurity phase, and reduce the electrochemical capacity of electrode because this phase is electrochemically inert. Adding of excess NaOH reduced the $Mn_2O_3$to the content under undetectable by X-ray diffraction. Because the capacity can be increased in the cathode materials with larger unit cell, some of the manganese was replaced with titanium having larger ion size, and powders with the formula $Li_{0.44}T_{iy}Mn_{1-y}O_2$(where y = 0.11, 0.22, 0.33, 0.44, and 0.55) was synthesized and characterized. A maximum reversible capacity of 150 mAh/g was obtained for $Li/P(EO)_8$LiTFSI/$Li_{0.44}Ti_{0.22}Mn_{0.78}O_2$cells in electrochemical potential spectroscopy (ECPS) experiments. Cells with the titanium-doped manganese oxides exhibited a fade rate of 0.12 % or less per cycle.

• Journal of the Korean Ceramic Society
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• v.19 no.4
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• pp.293-299
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• 1982

The effects of $MnO_2$ and $Cr_2O_3$ on the Piezoelectrictric properties of Pb(Mg1/2W1/2)0.3 Ti0.4 Zr0.3O3 Ceramics. Electromechanical properties in the system in connection with the sintering temperature and the effects of $MnO_2$ and $Cr_2O_3$ addition. The dielectric constant of the ceramics decreased with the additions of $MnO_2$ while the additions of $Cr_2O_3$ increased the value. The Planar coupling factor (Kp) of the ceramics with 0.2wt% $MnO_2$ and with 0.2wt% $Cr_2O_3$ gave the highest value of 0.52 and 0.513 as sintered at 106$0^{\circ}C$, 108$0^{\circ}C$, respectively. The value of mechanical Q-factor were in parallel with the fired density of the ceramics. The optical micrography of the sintered bodies showed that the additions of $MnO_2$ promoted the grain growth, while the additions of $Cr_2O_3$ retarded the grain growth.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.114-114
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• 1993

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.537-542
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• 1987

The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.399-402
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• 2000

For improvement of B constant in $CaMnO_3$-$CaTiO_3$ perovskite type thermistors, effect of $Cr_2$$O_3$ addition ranged from 0.0wt% to 5.0wt% on electrical properties were investigated with contents and sintering temperatures in the view of crystal and microstructures. The solubility limit of Cr$_2$O$_3$was up to 0.5wt% judging from the result of lattice parameter. The grain size was decreased and the resistance at room temperature and B constant were increased with the addition of $Cr_2$$O_3$.On particular, B constant of$CaMnO_{3-x}$$Cr_2$$O_3$ system was increased greatly from 1574k to 2598k at 0.5wt% $Cr_2$$O_3$addition. Further addition of $Cr_2$$O_3$, however, resulted in the decrease of the resistance and B constant due to the $Cr_2$$O_3$ precipitation on the grain boundary. As the$CaTiO_3$contents increased in the $CaMnO_3$-$CaTiO_3$ system, the resistance at room temperature and B constant were highly changed.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.139-144
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• 2014

Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparation of MnS-$ACF/TiO_2$ composites with titanium (IV) n-butoxide (TNB). The properties of MnS-$ACF/TiO_2$ composites were characterized by XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elements Mn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. The results demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently, the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by $TiO_2$. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.