• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.436-439
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• 2000

Change of dielectric loss of use in high relative permitivity capacitor BaTiO$_3$ ceramic depends on Mn doping have been investigated. The powders used in this study were commercial BaTiO$_3$, TiO$_2$and, MnCO$_3$. Sample was fabricated by conventional ceramic process. The quantity of Mn was changed gradually from 0.lmol% to 10mo1%. The sintering densities were reduced with increasing amount of MnCO$_3$. This result is because of increase of low density second phase BaMnO$_3$. When the samples were doped by over 0.2mol% of MnCO$_3$, average grain sizes were enlarge to several tens ${\mu}{\textrm}{m}$. The dielectric losses were reduced by Mn doping to lmol% but, increased from lmol% to 10mo1% gradually.

• Electronic Materials Letters
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• v.14 no.6
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• pp.733-738
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• 2018

Undoped and Mn-doped $In_2O_3$ films were prepared by radiofrequency magnetron sputtering technique. The effects of Mn doping on the structural and optical properties of as-prepared films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Mn doping can enhance the intensity of (222) peak in Mn-doped $In_2O_3$ thin film, indicating Mn dopant promotes preferred orientation of crystal growth along (222) plane. XPS analyses revealed that the doped Mn ions exist at + 2 oxidation states, substituting for the $In^{3+}$ sites in the $In_2O_3$ lattice. UV-Vis measurements show that the optical band gap $E_g$ decreases from 3.33 to 2.87 eV with Mn doping in $In_2O_3$, implying an increasing sp-d exchange interaction in the film. Our work demonstrates a practical means to manipulate the band gap energy of $In_2O_3$ thin film via Mn impurity doping, and significantly improves the photoelectrochemical activity.

• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.531-535
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• 1996

ZnGa2O4 and Mn-doped ZnGa2O4 were synthesized using the state reaction method to investigate their photoluminescence characteristics depending on Mn concentration. Under 254nm excitation, ZnGa2O4 exhibited a broad-band emission extending from 330 nm to 610 nm peaking at 450nm. On the other hand Mn-doped ZnGa2O4 showed a new strong narrow-band emission peaking at 504 nm and maximum intensity at the doping concentration of 0.006 mole Mn.

• Journal of Magnetics
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• v.16 no.1
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• pp.19-22
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• 2011

[ $BiFeO_3$ ]is a multiferroic material that attracts attentions of many research groups due to its potential as being ferroelectric and ferromagnetic above room temperature. We have prepared both undoped- and Mn-doped $BiFeO_3$ by sol-gel auto-ignition method. Doping of Mn has resulted in decreasing grain size from 60 to 32 nm. X-ray diffraction data show that the samples are pure and single-phase. Infrared measurements on $BiFeO_3$ and Mn-doped $BiFeO_3$ revealed intrinsic stretching vibrations of tetrahedral sites of $Fe^{3+}$-O and of octahedral $Bi^{3+}$-O as well. On the other hand, as the Mn concentration increases, the magnetic moment of $BiFeO_3$ increases. It gives some suggestions in manipulating structural and magnetic properties of $BiFeO_3$ by doping Mn.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1067-1072
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• 2014

In this study, we report a new approach for $Mn_3O_4$-graphene nanocomposite by ex situ method. This nanocomposite shows two-dimensional aggregation of nanoparticle, and doping effect by decorated manganese oxide ($Mn_3O_4$), as well. The graphene film was made through micromechanical cleavage of graphite on the $SiO_2/Si$ wafer. Manganese oxide ($Mn_3O_4$) nanoparticle with uniform cubic shape and size (about $5.47{\pm}0.61$ nm sized) was synthesized through the thermal decomposition of manganese(II) acetate, in the presence of oleic acid and oleylamine. The nanocomposite was obtained by self-assembly of nanoparticles on graphene film, using hydrophobic interaction. After heat treatment, the decorated nanoparticles have island structure, with one-layer thickness by two-dimensional aggregations of particles, to minimize the surface potential of each particle. The doping effect of $Mn_3O_4$ nanoparticle was investigated with Raman spectra. Given the upshift in positions of G and 2D in raman peaks, we suggest that $Mn_3O_4$ nanoparticles induce p-doping of graphene film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.249-254
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• 2008

Ag doping effect on $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode material was studied. Specially, we focused on rate performance of Ag doped samples. The $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ powder was prepared by simple combustion method and the Ag was doped using $AgNO_3$ during gelation process. Based on X-ray diffraction analysis, there was no structural change by Ag doping, but the 'metallic' form of Ag was included in the doped powder. Both bare and Ag 1 wt.% doped sample showed similar discharge capacity of 242 mAh/g at 0.2C rate. However, as the increase of charge-discharge rate to 3C, Ag 1 wt.% doped sample showed higher discharge capacity (172 mAh/g) and better cyclic performance than those of bare sample. The discharge capacity of Ag 5 wt.% doped sample was relatively low at all rate condition. However it displayed better rate performance than other samples.

• Journal of Powder Materials
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• v.28 no.1
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• pp.38-43
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• 2021

A high NIR-reflective black pigment is developed by Mn doping of Fe2O3. The pigment powders are prepared by spray pyrolysis, and the effect of the Mn concentration on the blackness and optical properties is investigated. Mn doping into the crystal lattice of α-Fe2O3 is found to effectively change the powder color from red to black, lowering the NIR reflectance compared to that of pure Fe2O3. The pigment doped with 10% Mn, i.e., Fe1.8Mn0.2O3, exhibits a black color with an optical bandgap of 1.3 eV and a Chroma value of 1.14. The NIR reflectance of the prepared Fe1.8Mn0.2O3 black pigment is 2.2 times higher than that of commercially available carbon black, and this material is proven to effectively work as a cool pigment in a temperature rise experiment under near-infrared illumination.

• Journal of the Korean Institute of Navigation
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• v.25 no.4
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• pp.435-442
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• 2001

A new technique to grow a manganese-doped zinc-sulfide(ZnS：Mn) has been proposed using the repeated deposition of the Hot Wall method. The optical characteristics and crystallinity for the ZnS and ZnS：Mn thin films deposited on a quartz glass substrate by the method were investigated. Also, The ZnS：Mn thin film elcetroluminescent devices were fabricated by the method to study luminescence characteristics. All films showed (111)-oriented cubic structure. By the repeated deposition, the deposition rates were decreased, and the optical characteristics and crystalline properties were improved, which clarifies that the method is effective to deposit the thin films with good crystallinity Futhermore, the crystallinity was more improved by the doping of Mn. Only one peak emission at around 585nm originating from Mn luminescent center is observed In the photoluminescent and electroluminescent spectra of ZnS：Mn films and the luminance of the ZnS：Mn-based thin film electroluminescent devices was obtained below 60cd/$m^2$ . The optical and crystalline properties, luminescence characteristics are discussed in terms of the effects of the repeated deposition and Mn-doping.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.28-31
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• 2018

Phase diagrams of electron- and hole-doped $Sr_2VO_3FeAs$ are investigated using Co and Mn substitution at Fe site. Metallic nature survives only for Co (electron) doping, not for Mn (hole) doping. The conductivity of $Sr_2VO_3(Fe,M)As$ (M=Mn,Co) is sensitive to the structural modification of FeAs microstructure rather than carrier doping. This finding implies that the FeAs layer plays a dominant role on the charge conduction, thus the $SrVO_3$ layers should be considered as an insulating block. Also, we found that the superconductivity is rapidly suppressed by both dopants. This result is different from the conventional behavior that superconductivity is induced by doping in the most of Fe pnictides. Our finding strongly supports the uniqueness of $Sr_2VO_3FeAs$ among the Fe pnictide superconductors.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.36-41
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• 1995

Dielectric properties were investigated at Mn doped $(Pb_{1-x}Ca_{x})ZrO_{3}$ with x=0.38 in microwavefrequencies. Both the density and Q values of sintered ceramics increased with increasing calciningtemperature. In the sample sintered at $1300^{\circ}C$ for 2 hrs, the deped Mn ions completely solubled in $(Pb,Ca)ZrO_{3}$ phase until 0.5wt% and the grain size was independent of doping amount. It was observed thathigh dielectric constant of 90 - 100 and high quality factor of 1300 at 4 GHz for O.l5wt% Mn doped$(Pb_{0.62}Ca_{0.38})ZrO_{3}$. The Mn" and Mn" worked as acceptors in $(Pb,Ca)ZrO_{3}$ which created the oxygen vacancies and affected the increment of the Q values. However, the excess Mn doping more than 0.5wt% resulted in decreasing Q values.decreasing Q values.