• Resources Recycling
• /
• v.11 no.1
• /
• pp.3-8
• /
• 2002

In order to make the high purity Mn$_3$O$_4$powder for the raw material of soft ferrite, Mn is extracted from the dust and the extracted solution is refined. The dust is generated in producing a medium-low carbon ferromanganese and contains 90% Mn$_3$O$_4$. Mn$_3$O$_4$in the dust was reduced into MnO by roasting with charcoal. Injection of the 180g/L of the reduced dust into 4N HCI solution increased pH of the leaching solution higher than 5 and then a ferric hydroxide was precipitated. Because the ferric hydroxide co-precipitates with Si ion etc, Fe and Si ion was removed from the solution and the about 10% Mn solution was obtained. The solution was diluted with water to Mn-15000 ppm and $NH_4$F was injected into the diluted solution at $70^{\circ}C$ to the F-3000 ppm. As a result, Ca ion is precipitated as $CaF_2$and the residual concentration of Ca was 14 ppm. Injection of the equivalent (NH$1.5M_4$)$_2$$CO_3$solution as 2 L/min at $25^{\circ}C$ into the above solution precipitated a fine and high purity $MnCO_3$powder. The deposition was filtrated and roasted at $1000^{\circ}C$ for 2 hours. As a result, $MnCO_3$powder is converted into $Mn_3$$O_4$powder and it had $8.2\mu$m of median size. The final production is above 99% $Mn_3$$O_4$powder and it satisfied the requirement of high purity $Mn_3$$O_4$powder for a raw material of soft ferrite.

• Journal of the Korean Magnetics Society
• /
• v.11 no.4
• /
• pp.141-145
• /
• 2001

The Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ exchange bias layers (EBLs), which have a small amounts of Pt, exhibit a high value of H$\_$ex/. The Si/Ni-Fe/Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBL shows the largest H$\_$ex/ of 187 Oe, which is equivalent to a exchange energy (J$\_$ex/) of 0.146 erg/cm$^2$. Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBLS are estimated to have blocking temperature of about 250 $\^{C}$, which is higher than those of Mn-Ir EBLs and Mn-Ir-Pt EBLs with higher Pt contents. This result implies that a little addition of Pt element promotes thermal stability in the Mn-Ir-Pt EBLs. The chemical stability of Mn-Ir-Pt EBLs was characterized by potentiodynamic test, which was performed in 0.001 M NaCl solution. The current density of Mn-Ir-Pt films was gradually reduced with increasing Pt content. The present results indicate that the Mn-Ir-Pt with a small amount of Pt is suitable for an antiferromagnetic material for a reliable spin valve giant magnetoresistance device.

• Journal of the Korean Ceramic Society
• /
• v.44 no.11
• /
• pp.639-644
• /
• 2007

Spinel pigments, developing black color in high temperature glazes at oxidation or reduction atmosphere, without CoO because of its high price were synthesized by solid solution method. Ten mixed compositions consisted of NiO, MnO, $Fe_2O_3 and $Mn_2O_3$ were fired at $1250^{\circ}C$ for 1h. The resulting pigments were characterized by using XRD, FT-IR, SEM and UV-vis spectrometer. Structure of the pigments are spinel and particles' shape are spherical or cubic. Glazed tiles containing 5 wt% pigments were fired at $1260^{\circ}C$ and $1240^{\circ}C$ in reduction atmosphere. Color in glazes were analyzed by UV-vis spectrometer. Colors of NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole% in lime glaze showed black in oxidation, in reduction NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.55{\cdot}Mn_2O_3$ 0.0125 mole% showed black. In case of lime-barium glaze, NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.975 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black color in oxidation and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.725 MnO $0.275{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black one in reduction.

• Journal of the Korean Magnetics Society
• /
• v.8 no.3
• /
• pp.156-160
• /
• 1998

Crystal structures and magneto-optical properties of $(Mn_{0.5-Z}Sb_{0.5+Z})_{100-y}Pt_y$ (0$(Mn_{0.5-Z}Sb_{0.5+Z})_{100-y}Ag_y$ (0$^{\circ}C$ are C1b-type with fcc and NiAs-type with hcp, respectively. The MnSbAg films have a texture which the c-axis orientation is perpendicular to the film plane by annealing at 300 $^{\circ}C$ for less than 3 hours. The perpendicular anisotropy constants of the $Mn_{47.4}Sb_{47.5}Ag_{5.1}$ film annealed at 300 $^{\circ}C$ for 3 hours are $K_1=6.6{\times}10^5 \; erg/cm^3\;and\;K_2=1.9{\times}10^5\; erg/cm^3$. The Kerr rotation angle of MnSbPt films increases but that of MnSbAg film decreases by decreasing incident wavelength within the range of 700$\leq$ λ$\leq$1000 nm. High polar Kerr angles of 1.7$^{\circ}$ (λ =700 nm) and 0.6$^{\circ}$ (λ =1000 nm), 0.2$^{\circ}$ (λ =700 nm) and 0.97$^{\circ}$ (λ =1000 nm) have been obtained from $Mn_{41.1}Sb_{44,9}Pt_{14.0}$ and $Mn_{47.4}Sb_{47.5}Ag_{5.1}$ alloy films, respectively.

• Analytical Science and Technology
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2004

The synergistic solvent extraction of Mn(II) by N-nitroso-N-phenylhydroxylamineammonium salt (cupferron) and tetrabutylammonium ion ($TBA^+$) has been studied. In the presence of $TBA^+$, over 95% Mn(II) was extracted from an aqueous solution into chloroform by the cupferron in the pH range of 4 to 10. But a part of Mn(II) was extracted with only cupferron. The ternary complex of Mn(II) was more efficiently extracted into $CH_2Cl_2$ and $CHCl_3$ than other nonpolar solvents. The extracted Mn(II) was determined in the back-extracted $HNO_3$ solution by GF-AAS. This fixed procedure was applied to the determination of trace Mn(II) in tap water samples of pH 5.0. The detection limit equivalent to 3 times standard deviation of the background absorption was 0.37 ng/mL and Mn(II) was determined with the range of 0.4 to 1.01 ng/mL in our laboratory's tap water. And the recovery was 94 to 107% in samples in which 2.0 ng/mL Mn(II) was spiked. The interferences of common concomitant elements such as Cu(II), Ca(II), Fe(III) and so on were not shown up to $10{\sim}20{\mu}g/mL$. From these results, this procedure could be concluded to be applied for the determination of trace Mn(II) in other environmental water samples.

• Applied Chemistry for Engineering
• /
• v.9 no.5
• /
• pp.774-780
• /
• 1998

For the stabilization of the spinel structured $LiMn_2O_4$, a fraction of manganese was substituted with various metals such as Mg, Fe, V, W, Cr, Mo with Mn that had a similar ionic radii ($LiM_xMn_{2-x}O_4(0.05{\leq}x{\leq}0.02)$). The $LiM_xMn_{2-x}O_4$ showed a substantial improvement as lower capacity loss than that of the spinel structured $LiMn_2O_4$ when it was used as a cathode material. And with the partial substitution, the chemical diffusion coefficient for $LiMg_{0.05}Mn_{1.9}O_4$ and $LiCr_{0.1}Mn_{1.9}O_4$ was increased by and order of magnitude compared to that of the $LiMn_2O_4$ with spinel structure. The results showed that significant improvement can be made on the electrochemical characteristics as the structure of the $LiMn_2O_4$ electrode material was stabilized by the partial substitution.

• Journal of the Korean Magnetics Society
• /
• v.12 no.1
• /
• pp.24-29
• /
• 2002

It was observed that exchange bias field was increased with smooth surface and better ${\gamma}$-FeMn formation. Sputtering conditions were varied for the control of the surface roughness and ${\gamma}$-FeMn formation. From the results of Cu deposition as underlayer, it was found that ${\gamma}$-FeMn formation was closely related with the thickness of underlayer. After heat treatment, exchange bias field was increased over three times. This improvement was likely that the crystallites of ${\gamma}$-FeMn were well formed. In Co/Cu/Co/FeMn spin valve structure, magnetoresistance was increased over 1.4 times through the heat treatment. This was due to the disappearance of Co/Cu intermixed dead layer and removal of defect, and this was examined by AES analysis.

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

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

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.832-837
• /
• 1999

Stability of a cathode material was determined by Tafel plot in 1 M LiOH solution. The stabilized $LiM_xMn_{2-x}O_4$ (x=0.05~0.1) electrode resulted in overpotential of 0.13~0.15 mV at 100 mA. This overpotential was 0.05 mV lower than that of the spinel structured $LiMn_2O_4$ electrode. Conductivity test at various potentials showed that the conductivity of $LiM_xMn_{2-x}O_4$ was higher than that of the spinel structured $LiMn_2O_4$ and the bulk resistance of $LiM_xMn_{2-x}O_4$ due to the dissolution of $Mn^{2+}$ was lowered.