The phase constitution in mixed Gd2O3 and B4C by sintering in graphite tube furnace at the temperature of 100～1489 ℃ in argon atmosphere was studied by means of XRD and TG-DTA. The results show that the impurity C r...The phase constitution in mixed Gd2O3 and B4C by sintering in graphite tube furnace at the temperature of 100～1489 ℃ in argon atmosphere was studied by means of XRD and TG-DTA. The results show that the impurity C reacts with O in the B4C at the temperature of 367～458 ℃. When the temperature is 800 ℃, Gd2O3 reacts with B4C, and the reaction products include GdB6, GdB4, GdBO3, GdBC and B. GdBC changes into GdB4 at 1200 ℃. When the temperature is 1470 ℃, GdB6 is obtained by the reaction of GdB4 with elemental B. The content of GdB6 is increasing with the prolonging time.展开更多
In this study, the effects of oxygen flow rate and annealing temperature on Gd_2 O_3 structures and optical properties were systematically analyzed. Gd_2 O_3 films were deposited on both quartz and ZnS substrates by m...In this study, the effects of oxygen flow rate and annealing temperature on Gd_2 O_3 structures and optical properties were systematically analyzed. Gd_2 O_3 films were deposited on both quartz and ZnS substrates by magnetron sputtering and then annealed under vacuum at 700, 800 and 900℃, Restructure and phase transformation from cubic to monoclinic occur at different temperatures depending on the oxygen flow rate. The optical band gap, which is more sensitive to the annealing temperature than oxygen flow rate changes from 5.32 to 5.65 eV. The refractive index is approximately 1.75 at 550 nm and is adjustable by the oxygen flow rate. The transmittance of the ZnS substrate with Gd_2 O_3 film exceeds 80% and reaches82% at the 7.5-9.5 μm range. When ZnS is coated on both sides, the transmittance is increased to approximately 90%. Our results indicate that Gd_2 O_3 films are promising new candidates for anti-reflective coatings in the infrared region.展开更多
Mixed-oxide nanostructures of the type xGd<sub>2</sub>O<sub>3</sub>-(1-x)α-Fe<sub>2</sub>O<sub>3</sub> (x=0.1, 0.3, 0.5 and 0.7) were synthesized by mechanochemical act...Mixed-oxide nanostructures of the type xGd<sub>2</sub>O<sub>3</sub>-(1-x)α-Fe<sub>2</sub>O<sub>3</sub> (x=0.1, 0.3, 0.5 and 0.7) were synthesized by mechanochemical activation for ball milling times of 0, 2, 4, 8 and 12 hours. The systems were subsequently analyzed by Mӧssbauer spectroscopy, X-ray powder diffraction (XRPD), magnetic measurements and optical diffuse reflectance spectroscopy. The magnetic hyperfine field was studied as function of ball milling time for all sextets involved and found to be consistent with the formation of a limited solid solution in the systems investigated. The end-product was the gadolinium perovskite, represented by a doublet whose abundance was derived as function of the milling time. The XRPD patterns recorded for the equimolar composition were dominated by the diffraction peaks of GdFeO<sub>3</sub> after 12 hours of milling. The hysteresis loops were recorded at 300 and 5 K in an applied magnetic field of 5 T and were interpreted as a superposition of paramagnetic behavior of gadolinium oxide and weak ferromagnetic behavior of hematite and gadolinium perovskite. The Morin transition of hematite was inferred from zero-field-cooling-field-cooling (ZFC-FC) curves measured with a magnetic field of 200 Oe in the 5-300 K temperature range and was found to depend on the ball milling time. Optical diffuse reflectance spectra showed that the compounds were semiconductors with an optical band gap of 2.1 eV.展开更多
文摘The phase constitution in mixed Gd2O3 and B4C by sintering in graphite tube furnace at the temperature of 100～1489 ℃ in argon atmosphere was studied by means of XRD and TG-DTA. The results show that the impurity C reacts with O in the B4C at the temperature of 367～458 ℃. When the temperature is 800 ℃, Gd2O3 reacts with B4C, and the reaction products include GdB6, GdB4, GdBO3, GdBC and B. GdBC changes into GdB4 at 1200 ℃. When the temperature is 1470 ℃, GdB6 is obtained by the reaction of GdB4 with elemental B. The content of GdB6 is increasing with the prolonging time.
基金supported by the National Science Fund for Distinguished Young Scholars(51625201)National Key Research and Development Program of China(2016YFE0201600)+3 种基金National Natural Science Foundation of China(51372053)Innovative Research Group of National Natural Science Foundation of China(11421091)International Science&Technology Cooperation Program of China(2015DFR50300)the Major State Basic Search Program(2014CB46505)
文摘In this study, the effects of oxygen flow rate and annealing temperature on Gd_2 O_3 structures and optical properties were systematically analyzed. Gd_2 O_3 films were deposited on both quartz and ZnS substrates by magnetron sputtering and then annealed under vacuum at 700, 800 and 900℃, Restructure and phase transformation from cubic to monoclinic occur at different temperatures depending on the oxygen flow rate. The optical band gap, which is more sensitive to the annealing temperature than oxygen flow rate changes from 5.32 to 5.65 eV. The refractive index is approximately 1.75 at 550 nm and is adjustable by the oxygen flow rate. The transmittance of the ZnS substrate with Gd_2 O_3 film exceeds 80% and reaches82% at the 7.5-9.5 μm range. When ZnS is coated on both sides, the transmittance is increased to approximately 90%. Our results indicate that Gd_2 O_3 films are promising new candidates for anti-reflective coatings in the infrared region.
文摘Mixed-oxide nanostructures of the type xGd<sub>2</sub>O<sub>3</sub>-(1-x)α-Fe<sub>2</sub>O<sub>3</sub> (x=0.1, 0.3, 0.5 and 0.7) were synthesized by mechanochemical activation for ball milling times of 0, 2, 4, 8 and 12 hours. The systems were subsequently analyzed by Mӧssbauer spectroscopy, X-ray powder diffraction (XRPD), magnetic measurements and optical diffuse reflectance spectroscopy. The magnetic hyperfine field was studied as function of ball milling time for all sextets involved and found to be consistent with the formation of a limited solid solution in the systems investigated. The end-product was the gadolinium perovskite, represented by a doublet whose abundance was derived as function of the milling time. The XRPD patterns recorded for the equimolar composition were dominated by the diffraction peaks of GdFeO<sub>3</sub> after 12 hours of milling. The hysteresis loops were recorded at 300 and 5 K in an applied magnetic field of 5 T and were interpreted as a superposition of paramagnetic behavior of gadolinium oxide and weak ferromagnetic behavior of hematite and gadolinium perovskite. The Morin transition of hematite was inferred from zero-field-cooling-field-cooling (ZFC-FC) curves measured with a magnetic field of 200 Oe in the 5-300 K temperature range and was found to depend on the ball milling time. Optical diffuse reflectance spectra showed that the compounds were semiconductors with an optical band gap of 2.1 eV.
