• Journal of Korea Foundry Society
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• v.29 no.6
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• pp.270-276
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• 2009

After casting button-type small ingots of ternary Fe-Mn-S alloys which had three different Mn/S ratios (1, 5 and 70) in a vacuum arc furnace, the effect of the ratio on the sulfide formation was investigated. In case of the Mn/S ratio of 1, if alloy composition was located in an iron-rich corner on a Fe-Mn-S ternary phase diagram, only duplex MnS-FeS sulfide films were observed in the grain boundary. If the alloy composition was located in the miscibility gap area of the phase diagram, primary globular dendritic sulfides and dendritic sulfide slags were generated within the grain and tubular monotectic sulfides were also detected in the grain boundary. When the Mn/S ratio was 5, if the alloy composition was in the iron-rich corner, only bead-like sulfides were generated. On the other hand, if the composition was in the miscibility gap area, globular dendritic sulfides and dendritic sulfide slags were generated in the form of primary sulfide inclusions and rod-like eutectic sulfides were observed in the grain boundary. Especially, if the contents of Mn and S increased more in the miscibility gap area of the phase diagram, primary globular sulfides containing iron intrusions were observed. In case of Mn/S ratio of 70, if the contents of Mn and S was decreased in the Fe corner of the phase diagram, only bead-like sulfides were observed in the grain boundary. Despite the composition was outside the miscibility gap area of the phase diagram, if the contents of Mn and S increased, clusters of fine sulfide particles as well as fine spherical primary monophase sulfides were observed in the grain boundary.

• Korean Journal of Materials Research
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• v.21 no.6
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• pp.295-298
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• 2011

ZnS:Mn, Dy yellow phosphors for White Light Emitting Diode were synthesized by a solid state reaction method using ZnS, $MnSO_4{\cdot}5H_2O$, S and $DyCl_3{\cdot}6H_2O$ powders as starting materials. The mixed powder was sintered at $1000^{\circ}C$ for 4 h in an air atmosphere. The photoluminescence of the ZnS:Mn, Dy phosphors showed spectra extending from 480 to 700 nm, peaking at 580 nm. The photoluminescence of 580 nm in the ZnS:Mn, Dy phosphors was associated with $^4T_1{\rightarrow}^6A_1$ transition of $Mn^{2+}$ ions. The highest photoluminescence intensity of the ZnS:Mn, Dy phosphors under 450 nm excitation was observed at 4 mol% Dy doping. The enhanced photoluminescence intensity of the ZnS:Mn, Dy phosphors was explained by energy transfer from $Dy^{3+}$ to $Mn^{2+}$. The CIE coordinate of the 4 mol% Dy doped ZnS:Mn, Dy was X = 0.5221, Y = 0.4763. The optimum mixing conditions for White Light Emitting Diode was obtained at the ratio of epoxy : yellow phosphor = 1:2 form CIE coordinate.

• Proceedings of the Korean Vacuum Society Conference
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• 1994.02a
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• pp.50-50
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• 1994

Half-metallic Heusler alloys (NiMnSb, ppdMnSb, pptMnSb) have attracted much attention due to their unique electronic and magnetic structures. Sppin-ppolarized band structure calculation ppredicts metallic behavior for the majority sppin states and semiconductor behavior for the minority sppin states. We have studied the electronic structures of these half-metallic Heusler alloys by core-level pphotoemission sppectroscoppy of Mn 2pp and 3s XppS sppectra. We found large intensities of Mn 2pp satellites and 3s exchange spplitting comppared with other metal Mn-alloys. These satellite structure can be understood by applying Anderson imppurity model. This fact supports the calculated sppin pprojected ppartial density of states which suggests that the valence electrons be highly sppin ppolarized near Fermi level and that the electrons involved with charge-transfer be mainly minority sppin ones which have semiconducting band structure. The trend of charge transfer energies Δ from ligands (Sb 5pp) to Mn 3d, obtained from our model fitting, is consistent with that calculated from sppin pprojected ppartial density of state. Also the trend of d-d electron correlation energies U calculated from Mn Auger line L3 VV by Mg $K\alpha$ source is comppatible with that resulted from our model fitting. We fitted the Mn 3s curve in the same way as for insulating Mn comppounds by using the same pparameters calculated from Mn 2pp curve fitting exceppt for the Coulomb interaction energy Q between core hole and d-electrons. The 3s sppectra were analyzed by combing the charge transfer model and a simpple model taking into account the configuration mixing effect due to the intra-shell correlation. We found that the exchange interaction between 3s hole and 3d electrons is mainly respponsible for the satellite of Mn 3s sppectra. This is consistent with the neutron scattering data, which suggests local 3d magnetic moment. We find that the XppS analysis results of Mn 2pp and 3s satellite structures of half-metallic Heusler alloys are very similar to those of insulating transition metal comppounds.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.627-631
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• 2010

ZnS:Mn yellow phosphors doped with Cu for white light emitting diodes were synthesized by solid state reaction method. The optical properties and structures of ZnS:Mn,Cu phosphors were investigated by x-ray diffraction, photoluminescence, and scanning electro microscopy. Photoluminescence excitation spectra originated from $Mn^{2+}$ were ranged from 450 nm to 500 nm. The yellow emission at around 580 nm was associated with $^4T_1{\rightarrow}^6A_1$ transition of $Mn^{2+}$ ions in ZnS:Mn,Cu phosphors. The highest photoluminescence intensity of the phosphors under 405 nm excitation was obtained at Cu concentration of 0.02 mol%. The enhanced photoluminescent intensity in the ZnS:Mn,Cu phosphors was interpreted by energy transfer from Cu to Mn.

• 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.

• Elastomers and Composites
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• v.53 no.2
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• pp.75-79
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• 2018

ZnS:Mn-glycine (ZnS:Mn-Gly) nanocomposites were synthesized by capping ZnS:Mn nanocomposites with glycine. Zinc sulfate heptahydrate ($ZnSO_4{\cdot}7H_2O$), glycine ($C_2H_5NO_2$), manganese sulfate monohydrate ($MnSO_4{\cdot}H_2O$), and sodium sulfide ($Na_2S$) were used as the source reagents. $ZnS:Mn-Gly-C_{60}$ nanocomposites were obtained by heating the ZnS:Mn-Gly nanocomposites and fullerene ($C_{60}$) at a 2:1 mass ratio in an electric furnace at $700^{\circ}C$ for 2 h. X-ray diffraction (XRD) was used to characterize the crystal structure of the synthesized nanocomposites. The photocatalytic activity of the $ZnS:Mn-Gly-C_{60}$ nanocomposites was evaluated, via the degradation of brilliant green (BG) dye under 254 nm irradiation, with a UV-vis spectrophotometer.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.539-544
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• 2013

A simple synthetic process is demonstrated for the preparation of MnS/carbon nanotube (CNT) composites for Li ion battery electrodes. CNTs were initially treated using a strong acid solution to generate carboxylate ions ($-COO^-$) on their surfaces. The MnS/CNT composites were synthesized by a polyvinyl-pyrrolidone-assisted hydrothermal method in the presence of as-functionalized CNTs. The phase and morphology of the MnS/CNT composites and pure MnS microspheres were characterized using X-ray diffraction and high-resolution transmission electron microscopy. Furthermore, the Li electroactivity levels of the MnS/CNT composites and MnS microspheres were investigated using cyclic voltammetry and galvanostatic cycling. The MnS/CNT composite electrodes showed higher specific capacities exceeding 365 $mA\;h\;g^{-1}$ at a C/10 current rate and enhanced cyclic performance compared to pure MnS microspheres.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.53-58
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• 2011

Cysteine and histidine-capped water-dispersible ZnS:Mn nanocrystals (ZnS:Mn-Cys and ZnS:Mn-His) were synthesized and their effects on E. coli and human cells were investigated. Particle sizes of these nanocrystals were found from HR-TEM images to be 3.5 nm and 4.0 nm, respectively. Their solution photoluminescence spectra showed identical broad emission peaks at 580 nm. ZnS:Mn-His significantly suppressed the growth of E. coli at $100{\mu}g/mL$ and 1 mg/mL concentrations, something not observed with ZnS:Mn-Cys. Consistent with this, greater inhibition of cell proliferation and viability were observed in HEK293 and IMR90 cells in ZnS:Mn-His at $100{\mu}g/mL$ and 1 mg/mL concentrations.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.475-479
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• 2007

Pulsed laser deposition was utilized to grow MnS thin films on c-sapphire substrate using a KrF excimer laser at growth temperatures that ranged from room temperature to $700^{\circ}C$. The results of X-ray diffraction (XRD) and UV-visible spectroscopy were employed to investigate the structural and optical properties of the MnS films. While the growth rate decreased as $T_s$ increased, the overall quality of the film improved. The highest quality MnS film was obtained at $700^{\circ}C$. Variations in the $T_s$ resulted in the MnS films exhibiting different growth mechanisms. The oriented (200) rocksalt MnS film was grown at room temperature. In the case of higher $T_s,\;200{\sim}500^{\circ}C$, the films consisted of mixed phases of rocksalt and wurtzite. The main structure of the films was altered to (111) rocksalt when the temperature was increased to in excess of $600^{\circ}C$. This behavior may very well be the result of elements such as surface energy and atomic arrangement during the growth process. The optical band gap of the obtained ${\alpha}-MnS$ film was estimated to be 3.32 eV.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.137-141
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• 2007

A series of $Ca_{1-x}Sr_{x}S:Mn$ phosphors were synthesized by solid-state reactions. The emission peaks of $Ca_{1-x}Sr_{x}S:Mn$ is blue shifted front 605 to 570 nm with increasing Sr content. Since $Ca_{1-x}Sr_{x}S:Mn$. Mn phosphors exhibit strong absorption in region of 254 nm, the emission wavelength of a fluorescent lamp, these phosphors can be used as wavelength tunable emitting phosphors from reddish orange to yellow. We investigated the optical and structural properties of $Ca_{1-x}Sr_{x}S:Mn$ phosphors.