多面体共替代对Sr_2(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7:Eu~(2+)晶体结构和发光颜色的影响
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摘要
采用高温固相法合成Sr_(1.98)(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7: 2%Eu~(2+)荧光粉完全固溶体,利用X射线衍射、光致发光光谱和光学显微镜进行晶体结构和发光性能的研究. Sr_2Al_2SiO_7和Sr_2MgSi_2O_7同构化合物中包含[MgO_4]、[SiO_4]和[AlO_4]四面体,较大体积的[MgO_4]和较小体积的[SiO_4],共同替代体积相似的[AlO_4],导致[(Si/Al)O_4]收缩和[(Mg/Al)O_4]膨胀,晶胞参数c减少, a和V增大,使Eu~(2+)周围的环境发生改变,晶体场劈裂程度减小,发射峰位从503 nm蓝移至467 nm,实现发光光谱从绿色(0.2384, 0.3919)到蓝色(0.1342,0.1673)的转变.当x为0时,发射峰的半高宽为120 nm, x从0.25增加到1时,半高宽由89 nm逐渐减小至50 nm,多面体的替代会改变荧光粉的发光性能.
A series of Sr_(1.98)(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7: 2%Eu~(2+) phosphors is prepared by the high-temperature solid-state reaction method, the crystal structures and luminescent properties of the prepared phosphors are investigated by measuring the X-ray diffraction, luminescent spectra and optical microscope. The isomorphic compounds of Sr_2 Al_2 SiO_7 and Sr_2 MgSi_2 O_7 contain tetrahedra including [MgO_4], [SiO_4] and [AlO_4]. Although the valences of the[MgO_4]~(6–), [SiO_4]~(4–) and [AlO_4]~(5–) groups are different, the charge imbalance occurs when the [MgO_4]~(6–) and [SiO_4]~(4–) substitutes of [AlO_4]~(5–) and [AlO_4]~(5–), respectively. While the groups are co-substituted, the charge imbalance disappears. And the larger volume of [MgO_4] and the smaller volume of [SiO_4] together replaces the similar volume of [AlO_4], resulting in the decrease of [(Si/Al)O_4] and increase of [(Mg/Al)O_4]. Moreover, the decrease of unit cell parameters c and the increase of a and V due to the increased replacement of Mg~(2+)(0.57 ? for CN =4) by Al~(3+)(0.39 ? for CN = 4) and Si~(4+)(0.26 ? for CN = 4) by Al~(3+)(0.39 ? for CN = 4) cause the ambient temperature to change, the crystal field splitting of the Eu~(2+) cation to be weakened, and the emission spectra to be blue-shifted from 503 nm to 467 nm, which are closely related to the local coordination environment of the Eu~(2+), in addition, this reveals that the emission color of this series of phosphors can be tuned from green with color coordinate(0.2384, 0.3919) to blue(0.1342, 0.1673) by adjusting the chemical compositions via the[MgO_4]~(6–) and [SiO_4]~(4–) groups' co-substitution for [AlO_4]~(5–). The full width at half maximumof emission band is120 nm when x = 0, the photoluminescence emission width decreases monotonically from 89 to 50 nm as x is increased from 0.25 to 1. In other words, the full width at half maximum of emission band exhibits a decreasing trend. The internal quantum efficiency is enhanced with increasing x in Sr_(1.98)(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7: 2%Eu~(2+) phosphors. These results verify that the groups' substitutions are enhanced with polyhedron changing in the solid solutions and contribute largely to the luminescence properties of the phosphor.
A series of Sr_(1.98)(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7: 2%Eu~(2+) phosphors is prepared by the high-temperature solid-state reaction method, the crystal structures and luminescent properties of the prepared phosphors are investigated by measuring the X-ray diffraction, luminescent spectra and optical microscope. The isomorphic compounds of Sr_2 Al_2 SiO_7 and Sr_2 MgSi_2 O_7 contain tetrahedra including [MgO_4], [SiO_4] and [AlO_4]. Although the valences of the[MgO_4]~(6–), [SiO_4]~(4–) and [AlO_4]~(5–) groups are different, the charge imbalance occurs when the [MgO_4]~(6–) and [SiO_4]~(4–) substitutes of [AlO_4]~(5–) and [AlO_4]~(5–), respectively. While the groups are co-substituted, the charge imbalance disappears. And the larger volume of [MgO_4] and the smaller volume of [SiO_4] together replaces the similar volume of [AlO_4], resulting in the decrease of [(Si/Al)O_4] and increase of [(Mg/Al)O_4]. Moreover, the decrease of unit cell parameters c and the increase of a and V due to the increased replacement of Mg~(2+)(0.57 ? for CN =4) by Al~(3+)(0.39 ? for CN = 4) and Si~(4+)(0.26 ? for CN = 4) by Al~(3+)(0.39 ? for CN = 4) cause the ambient temperature to change, the crystal field splitting of the Eu~(2+) cation to be weakened, and the emission spectra to be blue-shifted from 503 nm to 467 nm, which are closely related to the local coordination environment of the Eu~(2+), in addition, this reveals that the emission color of this series of phosphors can be tuned from green with color coordinate(0.2384, 0.3919) to blue(0.1342, 0.1673) by adjusting the chemical compositions via the[MgO_4]~(6–) and [SiO_4]~(4–) groups' co-substitution for [AlO_4]~(5–). The full width at half maximumof emission band is120 nm when x = 0, the photoluminescence emission width decreases monotonically from 89 to 50 nm as x is increased from 0.25 to 1. In other words, the full width at half maximum of emission band exhibits a decreasing trend. The internal quantum efficiency is enhanced with increasing x in Sr_(1.98)(Al_(1–x) Mg_x)(Al_(1–x) Si_(1+x))O_7: 2%Eu~(2+) phosphors. These results verify that the groups' substitutions are enhanced with polyhedron changing in the solid solutions and contribute largely to the luminescence properties of the phosphor.
引文
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[20]Guo Y,Park S H,Choi B C,Jeong J H,Kim J H 2018 J.Alloy.Compd.742 159
[2]Li S X,Wang L,Zhu Q Q,Tang D M,Liu X J,Cheng G F,Lu L,Taked T,Hirosaki N,Huang Z R,Xie R J 2016 J.Mater.Chem.C 4 11219
[3]Li S X,Wang L,Tang M M,Cho Y J,Liu X J,Zhou X T,Lu L,Zhang L,Taked T,Hirosaki N,Xie R J 2018 Chem.Mater.30 494
[4]Xia Z G,Liu G K,Wen J G,Mei Z G,Balasubramanian M,Molokeev M S,Peng L C,Gu L,Miller D J,Liu Q L,Poeppelmeier K R 2016 J.Am.Chem.Soc.138 1158
[5]Xia Z G,Poeppelmeier K R 2017 Accounts Chem.Res.501222
[6]Ji H P,Huang Z H,Xia Z G,Molokeev M S,Atuchin V V,Fang M H,Liu Y G 2015 J.Phys.Chem.119 2038
[7]Xia Z G,Liu Q 2016 Prog.Mater.Sci.84 59
[8]Ye S,Xiao F,Pan Y X,Ma Y Y,Zhang Q Y 2011 Mat.Sci.Eng.R.71 1
[9]Shang M M,Liang S S,Qu N R,Lian H Z,Lin J 2017 Chem.Mater.29 1813
[10]Dubey S,Deshmukh P,Satapathy S,Singh M K,Gupta P K 2016 Luminesence 32 839
[11]Zhao Y W,Su Q S,Zhang C,An S L 2016 Chinese Rare Earths 37 85(in Chinese)[赵永旺,苏全帅,张超,安胜利2016稀土37 85]
[12]Zhao Y W,Zhang C,Zhao G W,An S L 2017 Chinese Rare Earths 38 87(in Chinese)[赵永旺,张超,赵文广,安胜利2017稀土38 87]
[13]Shuang Y M,Zhu F L,Wang J D 2008 J.Func.Mater.39 1078
[14]Xia Z G,Ma C G,Molokeev M S,Liu Q L,Rickert K, Poeppelmeier K R 2015 J.Am.Chem.Soc.137 12494
[15]Lu F C,Bai L J,Dang W,Yang Z P,Lin P 2015 ECS J.Solid State Sc.4 27
[16]Tam T T H,Hung N Y,Lien N D K,Kien N D T,Huy P T 2016 Sci.Adv.Mater.1 204
[17]Liang J K 2003 Determination of Crystal Structure by Powder Diffraction(Vol.1)(Beijing:Science Press)p78(in Chinese)[梁敬魁2011粉末衍射法测定晶体结构(上册)(北京:科学出版社)第78页]
[18]Denault K A,George N C,Paden S R,Brinkley S,Mikhailovsky A A,Neuefeind J,DenBaars S P,Seshadri R J2012 Mater.Chem.22 18204
[19]Denault K A,Brgoch J,Gaultois M W,Mikhailovsky A,Petry R,Winkler H,DenBaars S P,Seshadri R 2014 Chem.Mater.26 2275
[20]Guo Y,Park S H,Choi B C,Jeong J H,Kim J H 2018 J.Alloy.Compd.742 159