• Bulletin of the Korean Chemical Society
• /
• v.24 no.5
• /
• pp.647-649
• /
• 2003

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.304.2-304.2
• /
• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.

• Korean Journal of Optics and Photonics
• /
• v.14 no.6
• /
• pp.594-599
• /
• 2003

By using the spectroscopic ellipsometry, we have measured and analyzed the optical characteristics of P $r^3$$^{+}$-doped selenide glasses of Ge-Sb-Se system, a strong candidate material for U band fiber amplifiers. The ellipsometric spectra measured in the transparent wavelengths range of the material were all fitted to a model consisting of ambient/roughness/thin fil $m_strate structures to obtain simultaneously the optical properties such as refractive index, in terms of Sellmeier parameters and film structure of P $r^3$$^{+}$-doped selenide glasses. Repeated measurements on different positions in both polished faces rendered to verify positional dependence of measured spectre-ellipsometric data. Hence, the model made possible the analysis of the optical characteristics of the glasses. Even though surface roughness was mainly responsible for the position dependencies, the averaged refractive indexes were as precise as to reflect the minute compositional change tantamount to 1 mol%. The measured refractive indexes are useful for design of core and clad compositions of single-mode selenide optical fibers.

• Nuclear Engineering and Technology
• /
• v.44 no.8
• /
• pp.945-952
• /
• 2012

The sorption of selenium ions onto iron and iron compounds as a disposal container material and its corrosion products, and onto bentonite as a buffer material, was studied to understand the behaviors of selenium in a waste repository. Selenite was sorbed onto commercial magnetite very well in solutions at around pH 9, but silicate hindered their sorption onto both magnetite and ferrite. Unlike commercial magnetite and ferrite, flesh synthesized magnetite, green rust and iron greatly decreased selenium concentration even in a silicate solution. These results might be due to the formation of precipitates, or the sorption of selenide or selenite onto an iron surface at below Eh= -0.2 V. Red-colored Se(cr) was observed on the surface of a reaction bottle containing iron powder added into a selenite solution. Silicate influences on the sorption onto magnetite and iron for selenide are the same as those for selenite. Even though bentonite adsorbed a slight amount of selenite, the sorption cannot be ignored in the waste repository since a very large quantity of bentonite is used.

• Korean Journal of Materials Research
• /
• v.27 no.9
• /
• pp.459-465
• /
• 2017

Nano-sized Zinc selenide (ZnSe) powder was successfully synthesized using Zn and Se precursors in a hydrothermal process. Temperature for the synthesis was varied from $95^{\circ}C$ to $180^{\circ}C$ to evaluate its influence on the microstructural properties of the synthetic particles. ZnSe powder thus fabricated was characterized using various analytical tools such as SEM, XRD, TEM and UV-Vis methods. Two types of ZnSe particles, that is, the precipitated particle and the colloidal particles, were identified in the analysis. The precipitated particles were around 100 nm in average size, whereas the average size of the colloidal particles was around 20 nm. The precipitated particles made at $150^{\circ}C$ and $180^{\circ}C$ were found to be a single phase of ZnSe; however, an inhomogeneous phase was obtained at the lower synthesis temperature of $95^{\circ}C$, suggesting that the temperature for the synthesis should be over $100^{\circ}C$. The precipitated particles were inactive in the UV-Vis absorption investigation, whereas the colloidal particles showed that absorptions occurred at 380 nm in the UV-Vis spectrum.

• ETRI Journal
• /
• v.23 no.3
• /
• pp.97-105
• /
• 2001

$1.6\;{\mu}m$ emission originated from $Pr^{3+}:\;(^3F_3,\;^3F_4)\;{\longrightarrow}\;^3H_4$ transition in $Pr^{3+}-\;and\;Pr^{3+}/Er^{3+}$-doped selenide glasses was investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and fullwidth at half-maximum of the fluorescent emission are ~1650nm and 120nm, respectively. A moderate lifetime of the thermally coupled upper manifolds of ${\sim}212{\pm}10{\mu}s$ together with a high stimulated emission cross-section of ${\sim}(3{\pm}1){\times}10^{-20}\;cm^2$ promises to be useful for $1.6{\mu}m$ band fiber-optic amplifiers that can be pumped with an existing high-power 1480 nm laser diode. Codoping $Er^{3+}$ enhances the emission intensity by way of a nonradiative $Er^{3+}:\;^4I_{13/2}\;{\longrightarrow}\;Pr^{3+}:\;(^3F_3,\;^3F_4)$ energy transfer. The Dexter model based on the spectral overlap between donor emission and acceptor absorption describes well the energy transfer from $Er^{3+}$ to $Pr^{3+}$ in these glasses. Also discussed in this paper are major transmission loss mechanisms of a selenide glass optical fiber.

• Toxicological Research
• /
• v.25 no.3
• /
• pp.140-146
• /
• 2009

This study was performed to evaluate the toxicity of cadmium selenide for a period of 28 days in Sprague-Dawley rats. Each of 10 healthy male and females rats per group received daily oral administration for 28-day period at dosage levels 30, 300 and 1,000 mg/kg of body weight. Mortality and clinical signs were checked, and body weight, water intake and food consumption were also recorded weekly. There were no dose-related changes in food consumption or urine volume. All animals survived to the end of study with no clinical signs or differences in body weight gain observed when compared with the control group. At the end of study, all animals including control group, were subjected to necropsy. Blood samples were collected for hematology tests including coagulation time and biochemistry analysis. Blood coagulation time and relative organ weight were unaffected by all received doses. White Blood Cell (WBC) counts significantly increased in the 300 mg/kg administered male animal group when compared to the control. Monocyte (MO) value were also increased significantly in both 300 and 1,000 mg/kg male animal group. However, Mean Corpuscular Volume (MCV) were significantly decreased compared with the control in the 1,000 mg/kg dose groups for male and female animals. Mean Corpuscular Hemoglobin (MCH) decreased significantly for female in the 300 and 1,000 mg/kg group compared to the control. Blood biochemical values of Inorganic phosphorus (IP) were significantly increased in both the 300 and 1,000 mg/kg dose groups in male animals when compared to the control. Creatinine (CRE) levels indicated significant increase in kidney function for the female, 30 mg/kg dose group when compared with control. There was a significant decrease in thymus absolute organ weight in the female, 1,000 mg/kg dose group when compared with control. Histopathological findings revealed no evidence of injury related to cadmium selenide except for one case of focal hepatic inflammation in the high dose (1,000 mg/kg) group. One case of lung inflammation was also seen in the control group. Basis on these result, the No Observable Adverse Effect Level (NOAEL) of cadmium selenide was determined to be more than 1,000 mg/kg/day for male and female rats under conditions in this study.

• Polymer(Korea)
• /
• v.30 no.3
• /
• pp.266-270
• /
• 2006

Poly [(dimethylmethylyinyl) siloxane] phosphineoxide (PMViSPO) was prepared by adding phosphorus oxychloride $(POCl_3)$ to poly (dimethylmethylyinyl) siloxane (PMViS) at $0^{\circ}C$ under nitrogen atmosphere. Cadmium selenide (CdSe) was prepared by reacting cadmium oxide (CdO), tetradecyl-phosphonic acid (TDPA), trioctylphosphine oxide (TOPO) at $300^{\circ}C$, and adding solution of dissolved Se to tributylphosphine (TBP) and trioctylphosphine (TOP) CdSe-poly [(dimethylmethylvinyl) siloxane] phosphine-oxide (CdSe-SPO) adduct was synthesised by adding PMViSPO to CdSe solution. Liquid silicone rubber composite (LSRC-1) was prepared by compounding $\alpha,\omega-vinyl$ poly (dimethylsiloxane) (VPMS), $\alpha,\omega-hydrogen$) poly(dimethylsiloxane) (HPMS), and CdSe under Pt catalyst, and also LSRC-2 was prepared from VPMS, HPMS, and CdSe-SPO using Pt catalyst. It was confirmed that CdSe nanoparticles with photoluminescence characteristics was dispersed uniformly in LSR matrix. The diameter of CdSe was $30\sim50nm$. By measuring the number of CdSe nanoparticles, 202 particles of CdSe in LSRC-2 and 165 particles of CdSe in LSRC-1 were dispersed in the same area of LSR matrix. Thermal stability for LSRC-2 compounded with CdSe-SPO was better than LSRC-1.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.1
• /
• pp.133-143
• /
• 1997

Piezoelastic materials have recently attracted considerable attention because of their potential use in intelligent structural systems. In this paper, we treat a transient piezothermoelastic problem in a hexagonal plate of crystal class 6mm subjected to antisymmetric heating temperature. We analyze this problem by use of the potential function method. Numerical calculations are carried out for a cadmium selenide solid, and the results are presented graphically in comparison with those derived from the similar problem in a cadmium selenide plate subjected to symmetric heating temperature for a symmetry transient problem.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.86-87
• /
• 2008

In this study, we studied the nature of thin films formed by photodoping chalcogenide materials with for use in programmable metallization cell devices, a type of ReRAM. We investigated the resistance of Ag-doped chalcogenide thin films varied in the applied voltage bias direction from about 1 M$\Omega$ to several hundreds of $\Omega$. As a result of these resistance change effects, it was found that these effects agreed with PMC-RAM. The results imply that a Ag-rich phase separates owing to the reaction of Ag with free atoms from the chalcogenide materials.