Sr2CeO4 phosphor was synthesized by mechanical milling and reactive sintering in this work. The solid state reaction of SrCO3 and CeO2 (2∶1) started at about 850 ℃ and completed at 1 000 ℃ for about 4 h. Two types ...Sr2CeO4 phosphor was synthesized by mechanical milling and reactive sintering in this work. The solid state reaction of SrCO3 and CeO2 (2∶1) started at about 850 ℃ and completed at 1 000 ℃ for about 4 h. Two types of formation mechanism of Sr2CeO4 were proposed. When the starting powder mixture was fired above 1 000 ℃, the unstable intermediate phase SrCeO3 was developed, which then reacted with SrCO3 to form the final product Sr2CeO4, however, SrCO3 and CeO2 converted directly to Sr2CeO4 at a lower temperature. The XRD results showed the crystal structure of Sr2CeO4 was orthorhombic. The emission spectra displayed a broad band with maximum at about 465 nm. The mechanical milling of starting power mixture and the sintering temperature had no effect on this emission spectra.展开更多
The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed ...The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed at 420 nm,which consists of two peaks located at 408 and 445 nm,respectively.The two peaks are originated from the transition 5d→ 2F 5/2（4f）and 5d→ 2F 7/2（4f）of Ce 3+ ions.The energy level difference value of the two emission bands is 2 038 cm-1,which is consistent with the theoretic value（2 000 cm-1）between the ground state:2F 5/2 and 2F 7/2 of Ce 3+ ions.The excitation spectra extend from 250 to 400 nm and the peak positions around 365 nm.In addition,the effect of the concentration of Ce 3+ ions and the role of charge compensation of different ions to the emission intense were investigated,the experiment results suggest that when the proportion of Ce 3+ ions to Sr2MgSiO5 were 0.03（molar ratio）,the strongest emission was obtained.Li+,Na+,K+ and Cl-ions can all enhance the intensity of the emissions;especially Cl-ions gave the best improvement.展开更多
文摘Sr2CeO4 phosphor was synthesized by mechanical milling and reactive sintering in this work. The solid state reaction of SrCO3 and CeO2 (2∶1) started at about 850 ℃ and completed at 1 000 ℃ for about 4 h. Two types of formation mechanism of Sr2CeO4 were proposed. When the starting powder mixture was fired above 1 000 ℃, the unstable intermediate phase SrCeO3 was developed, which then reacted with SrCO3 to form the final product Sr2CeO4, however, SrCO3 and CeO2 converted directly to Sr2CeO4 at a lower temperature. The XRD results showed the crystal structure of Sr2CeO4 was orthorhombic. The emission spectra displayed a broad band with maximum at about 465 nm. The mechanical milling of starting power mixture and the sintering temperature had no effect on this emission spectra.
文摘The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed at 420 nm,which consists of two peaks located at 408 and 445 nm,respectively.The two peaks are originated from the transition 5d→ 2F 5/2（4f）and 5d→ 2F 7/2（4f）of Ce 3+ ions.The energy level difference value of the two emission bands is 2 038 cm-1,which is consistent with the theoretic value（2 000 cm-1）between the ground state:2F 5/2 and 2F 7/2 of Ce 3+ ions.The excitation spectra extend from 250 to 400 nm and the peak positions around 365 nm.In addition,the effect of the concentration of Ce 3+ ions and the role of charge compensation of different ions to the emission intense were investigated,the experiment results suggest that when the proportion of Ce 3+ ions to Sr2MgSiO5 were 0.03（molar ratio）,the strongest emission was obtained.Li+,Na+,K+ and Cl-ions can all enhance the intensity of the emissions;especially Cl-ions gave the best improvement.
