A series of (Lu0.99−xEr0.01Ybx)2O3 and (Lu0.99−xEr0.01Ybx)2O2S (x = 0—0.1) phosphor particles are... more A series of (Lu0.99−xEr0.01Ybx)2O3 and (Lu0.99−xEr0.01Ybx)2O2S (x = 0—0.1) phosphor particles are prepared to investigate their upconversion luminescence properties. Under 980 nm pumping laser, the two phosphors both exhibit strong green emission at ≈520—573 nm and weak red emission at ≈648—688 nm arising from 4S3/2/2H11/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively. The optimum concentrations of Yb3+ sensitizers are found to be 1.0 at% in oxide and 0.5 at% in oxysulfide, and their corresponding CIE chromaticity coordinates are (0.29, 0.69) and (0.33, 0.65). The Lu2O2S:Er/Yb phosphor exhibits ≈42 times higher luminescence intensity than the Lu2O3:Er/Yb contrast. More Yb3+ addition further increases the proportion of red emission by the cross‐relaxation between adjacent Yb3+ and Er3+ and the multiphonon relaxation. The luminescence intensities of the two phosphors gradually increase as the laser output power increases and the upconversion mechanisms are both identified ...
Textured PbTiO3 (PT) ceramics were fabricated by slip casting in a high magnetic field of 12 T. T... more Textured PbTiO3 (PT) ceramics were fabricated by slip casting in a high magnetic field of 12 T. The sample obtained from the powder calcined at 1100 °C was (100), (010), and (001)-oriented, and the orientation factor was 90 %. On the other hand, the sample obtained from the powder calcined at 900 °C was not oriented. Aggregability and crystallinity of powder are an important factor when textured ceramics are fabricated by slip casting in a high magnetic field.
Abstract An oriented La2NiO4 cathode was successfully fabricated on a dense Gd2O3-doped CeO2 elec... more Abstract An oriented La2NiO4 cathode was successfully fabricated on a dense Gd2O3-doped CeO2 electrolyte pre-coated with conducting polypyrrole by electrophoretic deposition in a static magnetic field of 12 T for use in low-temperature operating solid oxide fuel cell. The orientation of La2NiO4 was based on an anisotropic magnetic property in its crystal structure. Firm adhesion of the La2NiO4 cathode to an electrolyte was made by the co-deposition of starch added as a pore former. The La2NiO4 cathode with the preferential orientation of the a-b plane perpendicular to the surface of the electrolyte showed a polarization loss lower than that with a random orientation, leading to an enhancement in the cell performance at 500 °C.
Luminescence comparison of [(Gd1−xLux)0.9Tb0.1]AG green phosphors with (Y0.9Tb0.1)AG and (Lu0.9Tb... more Luminescence comparison of [(Gd1−xLux)0.9Tb0.1]AG green phosphors with (Y0.9Tb0.1)AG and (Lu0.9Tb0.1)AG.
A series of (Lu0.99−xEr0.01Ybx)2O3 and (Lu0.99−xEr0.01Ybx)2O2S (x = 0—0.1) phosphor particles are... more A series of (Lu0.99−xEr0.01Ybx)2O3 and (Lu0.99−xEr0.01Ybx)2O2S (x = 0—0.1) phosphor particles are prepared to investigate their upconversion luminescence properties. Under 980 nm pumping laser, the two phosphors both exhibit strong green emission at ≈520—573 nm and weak red emission at ≈648—688 nm arising from 4S3/2/2H11/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively. The optimum concentrations of Yb3+ sensitizers are found to be 1.0 at% in oxide and 0.5 at% in oxysulfide, and their corresponding CIE chromaticity coordinates are (0.29, 0.69) and (0.33, 0.65). The Lu2O2S:Er/Yb phosphor exhibits ≈42 times higher luminescence intensity than the Lu2O3:Er/Yb contrast. More Yb3+ addition further increases the proportion of red emission by the cross‐relaxation between adjacent Yb3+ and Er3+ and the multiphonon relaxation. The luminescence intensities of the two phosphors gradually increase as the laser output power increases and the upconversion mechanisms are both identified ...
Textured PbTiO3 (PT) ceramics were fabricated by slip casting in a high magnetic field of 12 T. T... more Textured PbTiO3 (PT) ceramics were fabricated by slip casting in a high magnetic field of 12 T. The sample obtained from the powder calcined at 1100 °C was (100), (010), and (001)-oriented, and the orientation factor was 90 %. On the other hand, the sample obtained from the powder calcined at 900 °C was not oriented. Aggregability and crystallinity of powder are an important factor when textured ceramics are fabricated by slip casting in a high magnetic field.
Abstract An oriented La2NiO4 cathode was successfully fabricated on a dense Gd2O3-doped CeO2 elec... more Abstract An oriented La2NiO4 cathode was successfully fabricated on a dense Gd2O3-doped CeO2 electrolyte pre-coated with conducting polypyrrole by electrophoretic deposition in a static magnetic field of 12 T for use in low-temperature operating solid oxide fuel cell. The orientation of La2NiO4 was based on an anisotropic magnetic property in its crystal structure. Firm adhesion of the La2NiO4 cathode to an electrolyte was made by the co-deposition of starch added as a pore former. The La2NiO4 cathode with the preferential orientation of the a-b plane perpendicular to the surface of the electrolyte showed a polarization loss lower than that with a random orientation, leading to an enhancement in the cell performance at 500 °C.
Luminescence comparison of [(Gd1−xLux)0.9Tb0.1]AG green phosphors with (Y0.9Tb0.1)AG and (Lu0.9Tb... more Luminescence comparison of [(Gd1−xLux)0.9Tb0.1]AG green phosphors with (Y0.9Tb0.1)AG and (Lu0.9Tb0.1)AG.
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Papers by Yoshio Sakka