Luminescence and defect properties of novel phosphor β-Zn 3(PO 4) 2:Zr 4+ were systematically investigated. Corresponding to its lowest optical absorption transition at 240 nm, phosphor emits a bluish-green light...Luminescence and defect properties of novel phosphor β-Zn 3(PO 4) 2:Zr 4+ were systematically investigated. Corresponding to its lowest optical absorption transition at 240 nm, phosphor emits a bluish-green light at 485 nm, which yields the Stokes shift about 20000 cm -1. The unusual optical properties of Zr 4+ ion are ascribed to its uncommon coordination environment. In addition it shows intensive bluish-green long lasting phosphorescence (LLP) due to the existence of electron trap, which is generated by aliovalent substitution of Zr 4+ ion for the cation site in the matrix as shown in thermoluminescence (TL) spectrum.展开更多
KF Zn 3(PO 4) 2 catalyst was found to be effective for isobutane oxidative dehydrogenation into isobutene. The effects of O 2 concentration in feed gas on isobutene yield and selectivity were discussed. The modi...KF Zn 3(PO 4) 2 catalyst was found to be effective for isobutane oxidative dehydrogenation into isobutene. The effects of O 2 concentration in feed gas on isobutene yield and selectivity were discussed. The modification of zinc phosphate by potassium fluoride leads to the formation of a new compound KF Zn 3(PO 4) 2 and surface basic sites, the catalytic performance of which is thus improved.展开更多
TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3（PO4）2·4H2O nanoparticle and its thermal decomposition kinetics. The resul...TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3（PO4）2·4H2O nanoparticle and its thermal decomposition kinetics. The results show that there are three stages of dehydration between 300 and 800 K during the thermal decomposition of α-Zn3（PO4）2·4H2O nanoparticle. The first stage is controlled by chemical reaction with an activation energy of 69.48 kJ·mol^-1 and a pre-exponential factor of 1.77×10^6 s^-1. The second is controlled by nucleation and growth with an activation energy of 78.74 kJ·mol^-1 and a pre-exponential factor of 5.86×10^9 s^-1. The third is controlled by nucleation and growth with an activation energy of 141.5 kJ·mol^-1 and a pre-exponential factor of 1.01×10^12 s^-1. The kinetic compensative effects not only exist in Arrhenius equation but also in Harcourt-Esson equation. Activation energy E is dependent on both the decomposition fraction α and temperature T.展开更多
The red long-lasting phosphorescent （LLP） of β-Zn3（POa）2：Mn2＋,pr3＋ material was prepared through combustion and conventional solid-state sintering methods. The influence of Pr3＋ ions on luminescence and LLP o...The red long-lasting phosphorescent （LLP） of β-Zn3（POa）2：Mn2＋,pr3＋ material was prepared through combustion and conventional solid-state sintering methods. The influence of Pr3＋ ions on luminescence and LLP of Mn2＋ in 13-Zn3（POa）2：Mn2＋,pr3＋ phosphor was systematically investigated. The phosphor presented a strong photoluminescence peak at 620 nm attributed to the 4T1g→ 6A1 g transition of Mn2＋ ions in octahedral coordination. Red LLP was observed in β-Zn3（PO4）2：Mn2＋,Pr3＋ phosphors with persistence time for more than 2 h. It was found that the long persistent phosphorescent performance of Mn2＋ such as brightness and duration was improved by the energy transfer from Pr3＋ to Mn2＋ when Pr3＋ ions as sensitizers were doped into matrix. The fact that the TL peak at low temperature was largely enhanced in Mn2＋, Pr3＋ codoped ^-Zn3（PO4）2 phosphor showed the significant increase of defect concentration with suitable depth. There existed two factors working together to be responsible for the enhancement of LLP performance in β-Zn3（PO4）2：Mn2＋,Pr3＋.展开更多
文摘Luminescence and defect properties of novel phosphor β-Zn 3(PO 4) 2:Zr 4+ were systematically investigated. Corresponding to its lowest optical absorption transition at 240 nm, phosphor emits a bluish-green light at 485 nm, which yields the Stokes shift about 20000 cm -1. The unusual optical properties of Zr 4+ ion are ascribed to its uncommon coordination environment. In addition it shows intensive bluish-green long lasting phosphorescence (LLP) due to the existence of electron trap, which is generated by aliovalent substitution of Zr 4+ ion for the cation site in the matrix as shown in thermoluminescence (TL) spectrum.
文摘KF Zn 3(PO 4) 2 catalyst was found to be effective for isobutane oxidative dehydrogenation into isobutene. The effects of O 2 concentration in feed gas on isobutene yield and selectivity were discussed. The modification of zinc phosphate by potassium fluoride leads to the formation of a new compound KF Zn 3(PO 4) 2 and surface basic sites, the catalytic performance of which is thus improved.
基金Project supported by the National Natural Science Foundation of China （No. 20566003）, and Youth Science Foundation （No. 0339012） of Guangxi, China.
文摘TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3（PO4）2·4H2O nanoparticle and its thermal decomposition kinetics. The results show that there are three stages of dehydration between 300 and 800 K during the thermal decomposition of α-Zn3（PO4）2·4H2O nanoparticle. The first stage is controlled by chemical reaction with an activation energy of 69.48 kJ·mol^-1 and a pre-exponential factor of 1.77×10^6 s^-1. The second is controlled by nucleation and growth with an activation energy of 78.74 kJ·mol^-1 and a pre-exponential factor of 5.86×10^9 s^-1. The third is controlled by nucleation and growth with an activation energy of 141.5 kJ·mol^-1 and a pre-exponential factor of 1.01×10^12 s^-1. The kinetic compensative effects not only exist in Arrhenius equation but also in Harcourt-Esson equation. Activation energy E is dependent on both the decomposition fraction α and temperature T.
基金Project supported by the National Natural Science Foundation of China(91222110)Key Project of Industry-University-Research of Science and Technology Department of Fujian Province(2010H6029,2012H6026)+1 种基金Key Project of Advanced Industry of Science and Technology Department of Fujian Province(2013H0053)the Training Program of Fujian Excellent Talents in University
文摘The red long-lasting phosphorescent （LLP） of β-Zn3（POa）2：Mn2＋,pr3＋ material was prepared through combustion and conventional solid-state sintering methods. The influence of Pr3＋ ions on luminescence and LLP of Mn2＋ in 13-Zn3（POa）2：Mn2＋,pr3＋ phosphor was systematically investigated. The phosphor presented a strong photoluminescence peak at 620 nm attributed to the 4T1g→ 6A1 g transition of Mn2＋ ions in octahedral coordination. Red LLP was observed in β-Zn3（PO4）2：Mn2＋,Pr3＋ phosphors with persistence time for more than 2 h. It was found that the long persistent phosphorescent performance of Mn2＋ such as brightness and duration was improved by the energy transfer from Pr3＋ to Mn2＋ when Pr3＋ ions as sensitizers were doped into matrix. The fact that the TL peak at low temperature was largely enhanced in Mn2＋, Pr3＋ codoped ^-Zn3（PO4）2 phosphor showed the significant increase of defect concentration with suitable depth. There existed two factors working together to be responsible for the enhancement of LLP performance in β-Zn3（PO4）2：Mn2＋,Pr3＋.
