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AM80-xSn 마그네슘 합금의 반응고 주조 및 압출에 따른 미세조직 및 기계적 특성
김대환 ( Dae-hwan Kim ),임인택 ( In-taek Im ),( Qinlin Jin ),임수근 ( Su-gun Lim ) 한국주조공학회 2016 한국주조공학회지 Vol.36 No.6
In a recent study, the microstructures and mechanical properties of AM80-xSn magnesium alloys with semi solid casting and hot extrusion process were investigated. With increasing Sn content, the amount of β(Mg2Sn) phase increased, while the α-Mg dendritic size decreased. The hardness was increased by the Mg2Sn as the Sn content increased. With increasing Sn content, permanent mold cast and semi solid cast AM80 Mg alloy showed less reduction of hardness and also of extruded AM80 Mg alloy after annealing. In the case of the mechanical properties, the extruded semi solid casting AM80 Mg alloy showed higher tensile strength and yield strength with increasing Sn content compared to the extruded permanent mold cast AM80 Mg alloy at room temperature.
Qin, Lin,Bi, Shala,Cai, Peiqing,Chen, Cuili,Wang, Jing,Kim, Sun Il,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.755 No.-
<P><B>Abstract</B></P> <P>Series of Mn<SUP>4+</SUP>-activated LiLa<SUB>2</SUB>NbO<SUB>6</SUB> red emitting phosphors were prepared by the solid state method. The structural and luminescence properties are investigated on the basis of X-ray diffraction (XRD), emission and excitation spectra, and luminescence decay curves. The LiLa<SUB>2</SUB>NbO<SUB>6</SUB>:Mn<SUP>4+</SUP> phosphors can be efficiently excited by near-UV to blue light and exhibit bright red emission at around 712 nm, which can be assigned to the <SUP>2</SUP>E<SUB>g</SUB>→<SUP>4</SUP>A<SUB>2g</SUB> transition of the 3 d<SUP>3</SUP> electrons in [MnO<SUB>6</SUB>] octahedra. Temperature dependent emission spectra and decay curves from 10 to 480 K are analyzed to understand the luminescence mechanism of Mn<SUP>4+</SUP> in LiLa<SUB>2</SUB>NbO<SUB>6</SUB> lattice. Notably, such a novel red emitting phosphor shows special anti-thermal quenching behavior.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We provide a comprehensive study of the luminescence mechanism of the Mn<SUP>4+</SUP> ion. </LI> <LI> Sharp emission lines belong to vibrational modes are observed at low temperature. </LI> <LI> The LiLa<SUB>2</SUB>NbO<SUB>6</SUB>:Mn<SUP>4+</SUP> phosphor shows special anti-thermal stability at low temperature. </LI> </UL> </P>
Qin, Lin,Cai, Peiqing,Chen, Cuili,Wang, Jing,Kim, Sun Il,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.738 No.-
<P><B>Abstract</B></P> <P>Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> blue-emitting phosphors were synthesized by the solid state reaction in a reductive atmosphere. The crystal structure of Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphors were characterized by using the X-ray powder diffraction (XRD) measurement. The luminescence properties are investigated systematically based on the crystal structure. Emission and excitation spectra of the Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphor along with the decay curves were characterized. Under the excitation of UV light, the phosphor exhibits a broad band emission around 410 nm ascribed to the allowed 4<I>f</I> <SUP>6</SUP>5<I>d</I>→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition, together with a sharp line at 360 nm corresponding to the forbidden 4<I>f</I> <SUP>7</SUP>(<SUP>6</SUP>P<SUB>7/2</SUB>)→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition of the Eu<SUP>2+</SUP> ions. The temperature dependent emission spectra and decay curves were measured to investigate the origins of the emission and the thermal stabilities of the as-prepared phosphors. The as-prepared Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphors display interesting and stable luminescence properties, which can act as promising blue-emitting phosphor candidates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB> fluoride by a simple solid state method. </LI> <LI> The phosphor exhibits a bright broad band emission. </LI> <LI> 4<I>f</I> <SUP>7</SUP>(<SUP>6</SUP>P<SUB>7/2</SUB>)→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition of the Eu<SUP>2+</SUP> ions can be observed in this system; </LI> <LI> The Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphor shows excellent thermal stability at high temperature. </LI> </UL> </P>
Qin, Lin,Cai, Peiqing,Chen, Cuili,Cheng, Han,Wang, Jing,Kim, Sun Il,Seo, Hyo Jin American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.24
<P>Europium- (Eu-) doped BaNb(2)V(2)O(11)powders with layered mixed -anion structure were prepared through the solid state method successfully. The obtained powders were characterized using X-ray powder diffraction (XRD), structural refinement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV-vis) absorption spectra, and photoluminescence (PL) measurements. The experimental results demonstrate that BaNb2V2O11 powders could absorb the UV-vis light effectively with the band gap energy of 2.219 eV. The introduction of Eu5 in the host contributes to the decrease of the band gap energy (2.137 eV). Moreover, the photocatalytic activities of the obtained powders were evaluated through the photocatalytic degradation of the methylene blue (MB) solutions under visible light irradiation as a function of time. All the results indicate that the BaNb2V2O11 powders can be used as a potential visible -light -driven photo catalyst. Notably, due to the introduction of Eu3+, the photocatalytic degradation rate of MB solutions could be improved dramatically. The influence of the existence of Eu3+ on the photocatalytic properties is further discussed in detail based on the crystal structure characteristic.</P>