• Journal of the Mineralogical Society of Korea
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• v.4 no.1
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• pp.22-31
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• 1991

Three crystal structures of dehydrated $Ag^+$-and $Ca^{2+}$- exchanged zeolite $A(Ag_4Ca_4-A,\;Ag_^Ca_3-A,\;and\;Ag_8Ca_2-A)$ treated at 250${\circ}C$ with 0.1 Torr of Rb vapor have been determined by single-crystal x-ray diffraction techniques in the cubic space group Pm3m at 21(1)${\circ}C$ (a=12,271(1)${\AA}$, 12.255(1)${\AA}$, and 12.339(1)${\AA}$, respectively). Their structures were refined to the final error indices. R(weighted) of 0.072 with 130 reflections, 0.050 with 110 reflections, and 0.083 with 86 reflections, respectively, for which $I>3{\rho}(I)$. In each structure, Rb species are found at three different crystallographic sites:3$Rb^+$+ions per unit cell are located at 8-ring centers, ca. 5.6 to 6.4 $Rb^+$ ions are found opposite 6-rings on threefold axes in the large cavity, and ca. 2.5 to 3.0 $Rb^+$ ions are found on threefold axes in the sodalite unit. Also, Ag species are found at two different crystallographic stites: ca. 0.7 to 2.1 $Ag^+$ lie opposite 4-rings and ca. 2.2 to 4.8 Ag atoms are located near the center of the large cavity. In these structures, the numbers of Ag atoms per unit cell are 2.2, 2.4, and 4.8, respectively, and these may form hexasilver clusters at the centers of the large cavities. The $Rb^+$ ions, by blocking 8-rings, may have prevented silver from migrating out of the structure. Each hexasilver cluster is stabilized by coordination to up to 13 $Rb^+$ions. An excess absorption of about 0.8 Rb atom per unit cell indicates that the presence of a triangular symmetric $(Rb_3)2^{+}$ cation in sodalite cavity. At least one large-cavity six-ring $Rb^+$ ion must necessarily approach this cluster and may be viewed as a member of it to give $(Rb)_4^{3+}$, $(Rb)_5^{4+}$ or $(Rb)_6^{5+}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.197-206
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• 1999

The stochiometric mixture of evaporating materials for the $AgInSe_2$single crystal thin films were prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the $AgInSe_2$polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $C_0$ were 6.092 $\AA$ and 11.688 $\AA$, respectively. To obtain the single crystal thin films of AgInSe$_2$, the mixed crystal was deposited on thoroughly etched semi-insulator GaAs(100) substrate by HWE system. The source and substrate temperature were fixed to $610^{\circ}C$ and $450^{\circ}C$ respectively, and the thickness of the single thin films was obtained to 3.8 $\mu\textrm{m}$. The crystallization of single crystal thin films was investigated by the photoluminescence (PL) and double crystal X-ray dirrfaction (DCXD). The Hall effect was measured by the method of van der Pauw and carrier density and mobility dependence on temperature were studied. The carrier density and mobility of $AgInSe_2$single crystal thin films deduced from Hall data are $9.58{\times}10^{22} electron/m^3,\; 3.42{\times}10^{-2}m^2/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $AgInSe_2$single crystal thin film, the spin orbit coupling $\Delta$So and the crystal field splitting $\Delta$Cr were obtained to 0.29 eV and 0.12 eV at 20 K respectively. From PL peaks measured at 20 K, 881.1 nm (1.4071 eV) and 882.4 nm (1.4051 eV) mean $E_x^U$ the upper polariton and $E_x^L$ the lower polariton of the free exciton $(E_x)$, also 884.1 nm (1.402 eV) express $I_2 peak of donor-bound exciton emission and 885.9 nm (1.3995 Ev) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 887.5 nm (1.3970 eV) was analyzed to be PL peak due to DAP.

• Analytical Science and Technology
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• v.21 no.4
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• pp.272-278
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• 2008

Methods to separate 14 rare earth elements (REEs) and yttrium by the $AG^{(R)}$ 50W-X8 cation exchange resin, and to determine REEs by inductively coupled plasma atomic emission spectrophotometry (ICP-AES) were described. Ion exchange capacities of REEs on the resin were so high that the REEs were quantitatively ion exchanged under the flow rate of 0.3~1.0 mL/min at pH 1~6. The breakthrough capacity curve of the REEs showed that ion exchange capacities of light REEs (Cerium group) were greater than that of the heavy REEs (Yttrium group). When $200{\mu}g$ of each REEs was ion exchanged on 100 mg of resin, most of the heavy REEs were quantitatively desorbed with 10 mL of 2.0 M of $HNO_3$, while most of the light REEs with 30 mL. The method was applied to the monazite sample. The REEs could be separated from matrix, since ion exchange capacities of matrix ions of Ca, Ti, Mg, Mn were much lower than that of the REEs. However the relative standard deviations of the analytical results by the present method were not improved, as high as 1~5%.

• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.20-22
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• 1994

The preparation of $YBa_2Cu_4O_8$ thick film on Ag substrate by electrophoretic deposition was directly studied. Electrophoretic deposition was carried out in solution, which was composed of presintered $YBa_2Cu_4O_8$ powder, sodium, and 2-propanol as a solvent. The deposited thick films were heat-treated in $O_2$ at 815$^{\circ}$C for 12 hours and at 450$^{\circ}$C for 12 hours. We succeeded in obtaining superconducting $YBa_2Cu_4O_8$ films on Ag substrate. Even though the chemical reactions at the $YBa_2Cu_4O_8$/Ag interface occurred in the range of 10 ${\mu}$m, superconductivity was not depressed. The thickness of the films was in the range of 60-80 ${\mu}$ m. The characteristics of the films were examined by electric resistance measurements, X-ray diffraction, and SEM observations.

• Progress in Superconductivity
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• v.8 no.1
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• pp.119-121
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• 2006

We studied the mechanical and magnetic properties of Y-Ba-Cu-O superconductor with and without resin and Ag impregnation. Bulk YBCO superconductor was manufactured with the top-seeded melt-growth method. Typical sample of 40mm X 20mm X 3mm was made and then 8 holes with 0.5mm diameter were drilled arbitrally. Epoxy resin and $AgNO_3$ were systematically added into the holes to compare the mechanical and magnetic properties of YBCO superconductor before and after reinforcement of resin and Ag. Based on the result of 3 point bending, bending strength increased with increasing amounts of resin and carbon nano-tube. However, it was found that the levitation force decreased after making hole, compared with virgin sample without hole.

• Journal of Technologic Dentistry
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• v.14 no.1
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• pp.23-43
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• 1992

Corrosion characteristics of four commerial gold-based dental alloys(C-1; Au75%, Ag13.9%, Pd3%, Cu & etc.,8.1%, C-2 ;Au 52.08, Ag 24%, Pd 5%, Cu & etc.,18.92, C-3 ; Au 53%, Ag 22%, Pd 5%, Pt 3% Cu & etc.,17%, C-4 ; Au 53%, Pd4, Pt1.5%, Ag & Cu & etc.,41.5%) and four experimental ternary Au-Ag-Cu alloys(E-1 ; Au 50%, Ag 30%, Cu 20%, E-2 ; Au 50%, Ag 20%, Cu 30%, E-3 ; Au 50%, Ag 10%, Cu 40%, E-4 ; Au 50%, Ag 40%, Cu 10%) were investigated by potentiodynamic polarization analysis and the structure was examined by optical microscope and SEM. All corrosion testing was conducted in 1% NaCl solution. The main results are as follows : 1. The corrosion resistence of commercial alloys was decreased in the order of C-1, C-3, C-4, C-2. C-2. 2. The E-1 and E-3 ternary alloys exhibits the higher corrosion resistence than E-2 and E-4 alloys. 3. The cast microstructure of alloys reveals dendrite morphology which shows the significant microsegregation caused by the difference in the diffusion rate between liquid and solid. 4. It is found that the surface corrosion products were mainly AgCl by X-ray diffraction results.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.234-238
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• 1989

The crystal structure of partially $Ag^+$-exchanged zeolite A, $Ag_{3.2}Na_{8.8}$-A, vacuum dehydrated at $360^{\circ}C$ and then exposed to 0.1 torr of cesium vapor for 12 hours at $250^{\circ}C$ has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m (a = 12.262(2)${\AA})\;at\;21(1)^{\circ}C$. The structure was refined to the final error indexes $R_1=0.068\;and\;R_2=0.072$ by using 338 reflections for which $I_o\;>\;3{\sigma}(I_o)$ and the composition of unit cell is $Ag_{3.2}Cs_{8.8}-A.\;3\;Cs^+$ ions lie on the centers of the 8-rings at sites of D4h symmetry. Two crystallographycally different 6-ring $Cs^+$ ions were found: 1.5 $Cs^+$ ions at Cs(2) are located inside of sodalite cavity and 4.3 $Cs^+$ ions at Cs(3) are located in the large cavity. The fractional occupancies observed at Cs(2) and Cs(3) indicate that the existence of at least three types of unit cells with regard to the 6-ring $Cs^+$ ions. For example, 50% of unit cells may have two $Cs^+$ ions at Cs(2) and 4 $Cs^+$ ions at Cs(3). 30% of unit cells may have one Cs+ ion at Cs(2) and 5 $Cs^+$ ions at Cs(3). The remaining 20% would have one $Cs^+$ ion at Cs(2) and 4 $Cs^+$ ions at Cs(3). On threefold axes of the unit cell two non-equivalent Ag atom positions are found in the large cavity, each containing 0.64 and 1.92 Ag atoms, respectively. A crystallographic analysis may be interpreted to indicate that 0.64 $(Ag_5)^+$ clusters are present in each large cavity. This cluster may be viewed as a tetrasilver molecule $(Ag_4)^0$(bond length, 2.84${\AA}$) stabilized by the coordination of one $Ag^+$ ion.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.126-133
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• 1992

This study deals with the crystal growth and the optical characteristics of CdS thin films activatedby silver. CdS:Ag thin films were deposited by using an electron beam evaporation(EBE) technique in vacuumof 1.5X 10-'torr, voltage of 4 kV, current of 2.5 mA and substrate temperature of 250$^{\circ}$C CdS:Ag photoconductivefilms prepared by EBE method show high photoconductivity after annealing at about 550"c for 0.5 h in air andAr gas.The grain size of CdS:Ag thin films annealed in Ar atmosphere (1 atm) was grown over 1 ym and the thicknessof the films is 4-5 pm. The analysis of X-ray diffraction patterns shows that the crystal structures are hexagonal.The diffraction line by (00.2) plane can only be observed, indicating that c-axis of hexagonal grows preferentiallyperpendicular to the substrate. The profiles of photoluminescence spectra of CdS:Ag films show Gaussian typecurves at room temperature, the maximum peak spectral sensitivity of CdS:Ag is located at the wavelength of520 nm.We annealed CdS:Ag thin films in air and Ar vapor in order to make the CdS photoconductors having theintensive photocurrent, the broad distribution of the photocurrent spectrum and the large value of the ratioof the photocurrent (pc) to the dark current(dc). We found that CdS:Ag thin films annealed in air atmospherewas the best one.air atmosphere was the best one.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1011-1019
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• 1998

This work designed Sn-5%Pb-1.5%Ag-x%In solder alloy to develop the solder alloy with low Pb content. This solder alloy doesn't cause environmental pollution. and this study reviewed the probability of replacement of Sn-37%Pb solder as evaluation of melting range, wettability. microstructure, microhardne'ss, tensile strength, drossability of this new solder alloys. The level of international regulation in dissolution amount of Pb ion was 3ppm. But dissolution amount of Pb ion in Sn-5%Pb solder alloy confirmed not to threat the global environmental is 0.46ppm. The melting range of this solder alloy was $183-192^{\circ}C$. Also the range of solidification was very narrow within $5^{\circ}C$. The wettability was similar to Sn-37%Pb solder, and the effect of amount of In addition of wettability couldn't be founded. The probability of replacement in the melting range and wettability is very high. And microhardness of this solder alloy was 1.5 times of conventional type solder. Tensile strength of new solder alloys was a little high than that of conventional type solder. With increasing amount of In% addition, tensile strength was increased, but elongation was decreased. The solder alloy of l%In addition revealed AgSn and Pb on dendrite microstructure boundary, and $Ag_3Sn$, $Ag_3In$ and Pb were revealed on it at the solder alloy of 3% In addition. The drossability was superior to Sn-37%Pb solder alloy and the solder alloys of 2% In addition was not generated for 3hrs.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3209-3212
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• 2014

This paper describes a selective synthetic method of fabricating Ag nanowires by using a modified polyol process. To synthesize the Ag nanowire, an ethylene glycolic solution of silver nitrate and an ethylene glycolic solution of polyvinylpyrrolidone solution containing a small amount of organic oxidant, 1,4-benzoquinone, were slowly added to a hot ethylene glycol medium at $160^{\circ}C$ for 8 min using a syringe pump. The reaction mixtures were heated for an additional 45 min and cooled to room temperature. Finally, the silver nanomaterials were isolated from the mixture by centrifugation. The crystal structure of the nanomaterials was investigated by powder X-ray diffraction analyses, and their morphology was investigated by scanning electron microscopy. A small amount of organic oxidant, 1,4-benzoquinone, played a significant role in controlling the morphology during crystal growth. Consequently, Ag nanowires rather than Ag nanoparticles were selectively obtained.