The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that cr...The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that crystal structure of CaS has formed at 700 ℃. Spectrum analysis results show that the samples which were stimulated by 980 nm laser after excited by ultraviolet lamp emit red luminescence peaking at 649 nm.展开更多
A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb ...A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb and Sm/Yb ratios found in mainly volcanic rocks in continental China. The ratios change with the depth of origin consistent with the correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios found in oceanic basalt. These ratios increase exponentially with the depth of origin, the lithospheric thickness, of a wide variety of Cenozoic volcanic basalt and Paleozoic kimberlite in the North China Craton, northeastern China continent and vicinity. This functional relationship with depth is shown in a plot of the ratios that forms a concordia curve, which is closely expressed by formulas using 8–degree polynomials. These provide a more accurate gage in measuring the lithospheric thickness than the traditional geophysical methods. When applied to volcanic rock of different ages it also reveals how the thickness has changed over time and thus, greatly aids the understanding of the tectonic history. Relations between the COcontent, mineral reactions and pressure in the upper asthenosphere beneath the base of the lithosphere appears to affect the proportions of REE in partial melts and brings about a close correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios in mantle–derived magmatic rock. This thickness gauge, for both continental and oceanic lithosphere, provides a new approach in analyzing the lithospheric thickness in different tectonic settings and geologic times.展开更多
A systematic study of the phase formation, structure and magnetic properties of the R3Fe29-xTxcompounds (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) has been performed uponhydrogenation. The lattice constants and the...A systematic study of the phase formation, structure and magnetic properties of the R3Fe29-xTxcompounds (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) has been performed uponhydrogenation. The lattice constants and the unit cell volume of R3Fe29-xTxHy decrease withincreasing R atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction.Regular anisotropic expansions mainly along the a- and b-axis rather than along the c-axis areobserved for all of the compounds upon hydrogenation. Hydrogenation leads to an increase inthe Curie temperature and a corresponding increase in the saturation magnetization at roomtemperature for each compound. First order magnetization processes (FOMP) occur in theexternal magnetic fields for Nd3Fe24.5Cr4.5H5.0, Tb3Fe27.0Cr2.0H2.8, and Gd3Fe28.0Cr1.0H4.2compounds展开更多
The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic mi...The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results indicated that the addition of 1.5 wt.% Sm with or without 0.8 Si/Ca led to a decrease in the volume fraction of the β-Mg17Al12 phase and the formation of the intermetallic compounds of Al-Sm, Mg2Si, MgAlCa and Al2Ca. The microstructure of AZ91 alloy was significantly refined and distribution became discrete with additions of Sm and Ca;the average grain size of the α-Mg matrix was reduced from 239.7 ± 16.9 μm to 66.34 ± 5.10 μm. The AZ91-Sm-Ca alloy exhibited a good combination of yield strength at 135 MPa, ultimate tensile strength at 199 MPa and elongation at 4.32%, which was ascribed to grain refinement strengthening. Furthermore, the T6 treated AZ91-Sm-Ca alloy possessed yield strength of 154 MPa and elongation of 7.1%, which was due to grain refinement strengthening and reduction in discontinuous precipitates.展开更多
文摘The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that crystal structure of CaS has formed at 700 ℃. Spectrum analysis results show that the samples which were stimulated by 980 nm laser after excited by ultraviolet lamp emit red luminescence peaking at 649 nm.
基金supported by the Ministry of Land and Resources of China under grant No.201211095
文摘A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb and Sm/Yb ratios found in mainly volcanic rocks in continental China. The ratios change with the depth of origin consistent with the correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios found in oceanic basalt. These ratios increase exponentially with the depth of origin, the lithospheric thickness, of a wide variety of Cenozoic volcanic basalt and Paleozoic kimberlite in the North China Craton, northeastern China continent and vicinity. This functional relationship with depth is shown in a plot of the ratios that forms a concordia curve, which is closely expressed by formulas using 8–degree polynomials. These provide a more accurate gage in measuring the lithospheric thickness than the traditional geophysical methods. When applied to volcanic rock of different ages it also reveals how the thickness has changed over time and thus, greatly aids the understanding of the tectonic history. Relations between the COcontent, mineral reactions and pressure in the upper asthenosphere beneath the base of the lithosphere appears to affect the proportions of REE in partial melts and brings about a close correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios in mantle–derived magmatic rock. This thickness gauge, for both continental and oceanic lithosphere, provides a new approach in analyzing the lithospheric thickness in different tectonic settings and geologic times.
文摘A systematic study of the phase formation, structure and magnetic properties of the R3Fe29-xTxcompounds (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) has been performed uponhydrogenation. The lattice constants and the unit cell volume of R3Fe29-xTxHy decrease withincreasing R atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction.Regular anisotropic expansions mainly along the a- and b-axis rather than along the c-axis areobserved for all of the compounds upon hydrogenation. Hydrogenation leads to an increase inthe Curie temperature and a corresponding increase in the saturation magnetization at roomtemperature for each compound. First order magnetization processes (FOMP) occur in theexternal magnetic fields for Nd3Fe24.5Cr4.5H5.0, Tb3Fe27.0Cr2.0H2.8, and Gd3Fe28.0Cr1.0H4.2compounds
基金financially supported by the National Key Research and Development Program of China(2016YFB0701204)
文摘The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results indicated that the addition of 1.5 wt.% Sm with or without 0.8 Si/Ca led to a decrease in the volume fraction of the β-Mg17Al12 phase and the formation of the intermetallic compounds of Al-Sm, Mg2Si, MgAlCa and Al2Ca. The microstructure of AZ91 alloy was significantly refined and distribution became discrete with additions of Sm and Ca;the average grain size of the α-Mg matrix was reduced from 239.7 ± 16.9 μm to 66.34 ± 5.10 μm. The AZ91-Sm-Ca alloy exhibited a good combination of yield strength at 135 MPa, ultimate tensile strength at 199 MPa and elongation at 4.32%, which was ascribed to grain refinement strengthening. Furthermore, the T6 treated AZ91-Sm-Ca alloy possessed yield strength of 154 MPa and elongation of 7.1%, which was due to grain refinement strengthening and reduction in discontinuous precipitates.
基金supported by the Project of the National Nature Science Foundation of China(GrantNo.51072190)Program for the Nature Science Foundation of Zhejiang Province(Grant No.Z4100030 and Y4100571)~~
