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Ba3Ga(PO4)3:Dy 3+荧光粉阴极射线发光研究

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2024年8月14日发(作者:威元绿)

维普资讯

第31卷第1期 

2008年2.月 

电子器件 

Chinese Joumal Of Electron Devices 

Vo1.31 No.1 

Feb.2008 

Cathodoluminescent Properties of Ba3 Ga(PO4)3:Dy3+Phosphor 

DUAN C ,CHEN Jun 一,DENG S Z ,XUN S ,HAN Bing ,LIANG H B ,SU@ang 

f L s缸 K 上,口6Dm细 。,o 。 加 ^缸 r 如口 丁 加 。g ,口 G眦 g 。 g P加 K 上,口6Dm细 。,D 户 ] 

}Material and Technology,Sun Yat-sen University,Guangzhou 510275,P.R.China; 

l 2.School of Chemistry and Chemical Engineering,Sun Yat-sen University,Guangzhou 510275,P.R.China 

I 

I 

Abstract:Cathodoluminescent properties of Ba3 Gd(PO4)3:Dy3+phosphor were studied.The phosphor was 

synthesized by high-temperature solid-phase reaction.Cathodoluminescence spectra,the Commission In- 

ternational de 1’Eclairage colour coordinates and photoluminescence spectra were determined.The Catho- 

doluminescence measurement shows that the Commission International de l’Eclairage(CIE)chromaticity 

coordinates of Ba3Gd(PO4)3:0.06Dy计phosphor are x=0.454 and y=O.424,and the color temperature is 

2889.3 K.The results show that the phosphor is a 1ow color temperature,warm-white phosphor with high 

saturation currents and can endure high-current-density bombardment. 

Key words:cathodoluminescence;phosphor;Ba3Gd(PO4)3:Dy3十 

E] C:4260 

Ba3 Ga(PO4 3:Dy3+ 荧光粉阴极射线发光研究* 

段春艳 ,陈 军 ,邓少芝 ,许宁生 ,韩 冰 ,梁宏斌 ,苏 锵 

(\.2 萋中山大学化学与化学工程学院, 广州 5蝮1027 5梢 戢糯点她 ), 

摘 要:本文研究了采用高温固相法合成的Ba3Gd(PO4)。:Dy3 荧光粉的阴极射线发光特性。测试并比较了电子轰击前后 

荧光粉的CL谱、色坐标以及PL谱变化。Ba3Gd(PO4)。:0.O6Dy3 荧光粉的色坐标为x=0.454,y一0.424,T =2889.3 K。 

测试结果显示该荧光粉是一种低色温、暖白光荧光粉,并且具有高的饱和电流,有耐大电流密度电子束轰击的能力。 

关键词:阴极射线发光;荧光粉;Ba3Gd(PO4)。:Dy3 

中图分类号:TN873.3 文献标识码:A 文章编号:1005-9490(2008)01-0184-05 

In recent years,significant progresses have been 

made in the area of cathodoluminescent light sources 

employing field emission cathode.which have the ad— 

vantages of high brightness。1ow-power consumption 

and are environmentally friendly[1-43.But as to the 

ray tubes(aR,] )or projection tubes(PR,] ).Cath— 

dolouminescent phosphor for appliatcion in field emis— 

sion 1ight source requires high effiacy cat 1ower excia- t

tion volages(5~10 kV)tthan CR_TS and PRTS,ther- 

l'na1 stability under continuous higher current densities 

phosphors,most of the reported fidd emission light 

ources utislize phosphors optiizemd for color cathode- 

(100~200“A/cm2),and having color coordinates 

(white 1ight)of traditional 1ight sources,Usually,re- 

收稿日期:2007-04-30 

基金项目:See Acknowledgments 

作者简介:段春艳(1976一),女,博士研究生,研究方向为场发射显示器用荧光粉; 

陈军(1967一),男,教授,主要研究方向为纳米光电材料及器件; 

邓少芝(1963一),女,教授,主要研究方向为纳米光电材料及器件; 

许宁生(1957-),男,教授,主要研究方向为纳米光电材料及器件; 

冰(1983一),男,硕士研究生,研究方向为稀土发光材料的光谱性质; 

锵(1931一),男,中国科学院院士,教授,研究方向为稀土化学与物理. 

梁宏斌(1965一),男,副教授,研究方向为稀土化学与物理; 

维普资讯

第1期 段春艳,陈 军等:Ba。Ga(PO4)。:Dy。+荧光粉阴极射线发光研究 185 

searchers rely on mixing three primary color phosphors 

to achieve the warm-white or cold-white light phos— 

phors for cathodoluminescent vacuum light sourcesl_5J. 

In the mixed white light phosphors,the green 

film,organic lacquer which has the function of creating 

a igh rheflective aluminum-mirror wa sprayed onto the 

phosphor layer.Then the aluminum layer was evapo— 

rated onto this lacquered phosphor layer. ter evapo— 

or blue phosphors,especially blue phosphors,of— 

ten are sulfide-based phosphors.It is well known 

that sulfide—-based phosphors have the highest lu—- 

ration of the aluminum film,the samples were baked 

at 390℃for ten minutes in air and the lacquer was re— 

moved.The CI spectrum。the Commission Intema— 

tional de l’Eclairage(CIE)colour coordinates and CL 

intensity were measured in an ultrahigh vacuum cham— 

minous efficiencies and excellent chromaticity in all 

the currently available industrial phosphors[ .But 

sulfide—based phosphors face the problems of 

catho-doluminescent degradation and decomposi— 

tion,and generate harmful gases causing the poi— 

soning of the cold cathode.Moreover,cathodolumi— 

nescent intensity of these phosphors tends to saturate 

at high-current densities.A1l these can cause chroma— 

ticity problem in mixed white light phosphors.There— 

fore,the development of phosphor materials is one of 

the key issues for cathodoluminescent light sources. 

Due to the problems in sulfide-based phosphors,rare 

earth doped oxide-based materials have been studied 

and regaMed as possible alternative phosphors due to 

their superior chemical and thermal stability under e— 

lectron beam excitation[ 一引.In this study,eathodolu— 

imnescent properties of Ba3Gd(P04)3:Df+white 

phosphor which was synthesized by high temperature 

solid phase reaction have been studied. 

1 Experimental 

The phosphor was synthesized by high—-tem— 

perature solid—state reaction method.The reactants 

were BaC()3(A.R.),NH4 H2PO4(A.R.),Gd203 

(99.9 ),and Dy203(99.9 ).The stoichiomet— 

ric reactants were first pre-fired at 600℃,and then 

heated at 1250℃in air.By varying the concentra— 

tion of Dy2 03,different Dy doped Ba3 Gd(P04)3 

phosphor can be prepared.In this study,Ba3 Gd 

(P04)3:0.O6DF+and Ba3Gd(PO4)3:0.03Dy。+are 

characterized. 

The phases of Ba3 Gd(P04)3:Dy3+phosphor were 

identified by powder X-ray difraction (Ⅺ 。 

RIGAKU D/max 2200)using Cu Ka( 一1.54178 

A)radiation,and the powder morphologies were stud- 

ied by scanning electron microscopy(SEM。JSM- 

6330F).Phosphor layers were deposited onto indium 

tin oxide(ITO)glass using a sediment method at 6 

er_g ̄crn2 with a solution of potassium silicate and ni— 

trate of baryta ter deposition。the samples were 

baked at 150℃for 30 minutes.For some samples。 

100 nlTl aluminum thin film was evaporated onto the 

phosphor layer.Before evaporation of the aluminum 

ber that has a base pressure of~5×10—0 Pa The ex— 

citation volatge was varide from 0 to 10 kV and the 

anode current density from 0 to 400 uA/cm .The 

CI spectrum and the CIE color coordinates were 

measured at 7 kV,30“A/cm .The CI intensity 

was measured with a I S1 1 0 luminance meter at the 

direction facing the incident electron.The CL 

spectrum and the CIE colour coordinates were 

measured with an OPT-2000 optical spectrometer。 

which has an accuracy of±0.005.An electron gun 

with carbon nanotube(CNT)cold cathode was 

employed in the CL measurement.Photolumines— 

cence(PL)spectra were measured using a HITA— 

CHI F-4500 fluorescence spectrophotometer with a 

150 W Xe lamp.Phosphors both before and after 

high—current—density bombardment were tested. 

Also,X-ray photoelectron spectroscopy(XPS) 

spectra of the phosphor were recorded before and 

after high-current-density bombardment using an 

ESCAI AB 250 XPS system.The X-ray gun for 

the XPS measurements had an Al(Ka)target with 

photon energy 1486.6 eV. 

2 Resul ts and Discussion 

The morphology of the Ba3 Gd(PO4)3:Dy。+ 

phosphors are shown in Figure 1,The average 

grain size is 5~10 um.Figure 2 shows XRD spec— 

tra of the phosphors.Analysis of the XRD data 

shows Ba3 Gd(PO4)3 has a body—centered cubic 

structure with the cell parameter a—1.047 nm 

(JCPDS 29-0163). 

Figure 3 shows CI spectra of Ba3Gd(PO4)3: 

By'+phosphor.Figure 4 gives the CIE coordinates 

of Ba3Gd(P04)3:Dya+in the CIE 1931 diagram. 

The CI spectra of Ba3 Gd(PO4)3:Dy3+phosphor 

consist of three peaks.The maximum emission 

peak of Ba3Gd(PO4)3:0.06Dy计phosphor was lo— 

cated at 584 nm(the yellow band),corresponding 

to the F9/2 Hl3/2 transition of Dy。+;the emis— 

sion peak of 492 nm(the blue band)corresponds 

to the Fg/2 。Hl5/2 transition of Dy3+;the 

维普资讯

186 电 子器件 

≈_ 

第31卷 

B善_d 

,≈_,抽!s_§u1 

Fig.1 Morphology of Ba ̄Gd(PO4)3:D phosphor 

Fig.2 X-ray diffraction pattern of B ̄Gd(PO4)3:D 

Wavaen ̄h/nill 

Fig.3 CL spectra of Ba3 Gd(Po4)3:D phosphor 

emission peak of 676 nm(the red band)corre— 

sponds to the F9/2 H1 1/2 transition of Dye+[ . 

The CIE chromaticity coordinates were x一0.454 

and y一0.424(Figure 4(a)),and the color tem- 

perature was 2889.3 K.The strongest emission 

peak of Ba3 Gd(PO4)3:0.03Dy ̄+phosphor was lo— 

cated at 583 nm。the CIE chromaticity coordinates 

were x=0.465 and y一0.427(Figure 4(b)), 

and the color temperature was 2757.2 K.It can be 

seen that the CIE coordinates have some shifts 

when the concentration of the activator in the 

phosphor is different.From above results,one can 

see that Ba3 Gd(PO4)3:Dy3+phosphor is a low col— 

or temperature,warm-white phosphor. 

CL properties of Ba3Gd(PO4)3:0.06Dy3+ 

phosphor were measured after working at 2 kV。3O 

uA/cm for 15 minutes.Figure 5(a)shows the lu— 

minance variation with anode voltage when the cur— 

rent densities were at 63 uA/cm .The luminance 

increased as a function of the anode voltage.The 

luminance reaches over 1996 cd/m at 10 kV,63 

“A/cm for the phosphor screen with a 100 nm a- 

您19 『1ch wnB咄 D Ⅻn 

、 

, G 1 ,5o 

\= 

580 

I a \ 0 

O 

630 

-' ) 驯 

/ 

/ / 

. 

/ 

/ 

Fig.4 The CIE coordinates of Ba3 Gd(PO4)3:D . 

(a)I ̄Gd(FO4)3:0.06Dy ̄ ;(b)t ̄Gd(FO4)3:0.03Dy ̄+ 

luminum film,which is 5.2 times higher than that 

of the phosphor without an aluminum film.The 

luminance for phosphor without Al layer is low 

probably due to the high resistance of phosphor 

materials besides the mirror effect of Al film[103. 

目.8 §

—.- 

wi

口_

th1

Ej

00 nm

 

AI / 

.—

/ 

. 

0 2 4 6 8 10 

V 

(a)Luminance vs.anode voltage 

J,u A・cm-2 

(b)Luminance vs.current density 

Fig.5 CL properties of Ba3Gd(PO4)3:D phosphor 

The luminance as function of current density 

at different anode voltages was tested and the re— 

suhs are shown in Figure 5(b).The excitation 

voltage was varied from 2 to 7 kV.At a fixed volt— 

age,with increasing of the current density,the lu— 

minance increases continuously until current densi- 

ty reaches about 500 ̄A/cm 。which is the maxi- 

mum current density our testing facility could 

reach.Also,after evaporation of the aluminum 

film,the luminance increases.When at voltage of 

7 kV and current density of 402 ̄A/cmz,the lumi- 

nance reaches 5034 cd/m . 

Figure 6 shows plot of the luminance vs.current 

density measured from the commercial phosphor 1S: 

维普资讯

第1期 段春艳,陈 军等:Ba3Ga(PO )3:Dy。+荧光粉阴极射线发光研究 187 

Cu,Au,Al and YAGG:Tb at different beam voltages. 

The sampls were eprepared using the identical method 

nd condaitions,Comparig Fingure 5(b)and Figure 6, 

we can see that when the current densitis reeach 

量.口口 q∞口一量j I.置.8 口 量j 

more deep-colored than the surrounding areas.So 

it is easy to identify and analyze the bombarded at- 

eas of the samples after electron bombardment. 

PL spectra and CL spectra were measured for 

1 20 u |cn-i2,the brightness of the commercial phos— 

phor GG:乃ceases to ncrease. 鼢en the current 

Ba3 Gd(PO4)3:0.06Dya+phosphors before and af— 

ter high—current-density bombardment.PL spectra 

of the phosphors were measured with 380 nm exci— 

tation.PL spectra of Ba3 Gd(PO4)3:0.03Dya+and 

Ba3Gd(PO4)3:0.06Dy什were similar.After high— 

densities reach 90以/CITI2,the brightness of the com- 

mercial phosphor ZnS:Cu,Au, reaches its maxi— 

mum.But for BaaGd(PO4)3:Dd+phosphor,within 

the current range of our testing facility,no saturation 

is observed.Therefore,accoridng to the above com- 

parison,it can be seen that the Ba3Gd(PO4)3:Dy3十 

phosphor has hi.gher saturation current and can endure 

high-current-density bombardment. 

"-W--2 k

5 kV  . ,一\, 。. 

一 、kV 

多 

量口口 u写=一置j 

. 

0 2O 4O 6O 8O 1OO 12O 14O 16O 

J/uA・cm-2 

(a) 

J, A・cm" 

(b) 

Fig.6 Plot of luminance vs.current density of 

(a)YAGG:Tb and(b)ZnS:Cu,Au,A1 phosphors 

testing at various excitation voltages 

To find out the chemical state of the phosphor 

surface after high-current-density bombardment, 

BaaGd(PO4)3:0.06Dd+phosphors without aluminum 

layer were obmbarded at 134“A/C1TI2,7 kV for 3 h. 

The luminance of the BaaGd(PO4)3:Dy3+phosphor 

iwthout aluminum layer decreased after the long time 

high-current-density bombardment.Figure 7 shows 

the plot of luminance vs.anode voltage at eurrent den~ 

sity of 63 pA/cm2 before and after elcetron bombard- 

ment.Comparign the luminance before and after obm- 

bardment,it can be seen that after 3 h bombardment, 

at the same anode voltage,the lumiannce decreased 

obviously. 

The areas of the phosphors being exposed to 

high—current densities bombardment became visibly 

current—densitv bombardment,decreases in the PL 

intensity of Ba3 Gd(PO4)3:Dy3+phosphor were ob— 

served. 

..-

e--Before 3 hbombardment 

Va/kV 

Fig.7 CL properties of Ba3Gd(P04)3:0.06Dy3 phosphor 

before and after long time high current bombardment 

CL spectra before and after bombardment 

were measured at about 820 cd/m .Comparing CL 

spectra before and after bombardment,the wave— 

length peak does not change and the CIE coordi— 

nates of Ba3 Gd(PO4)3:0.06Dy计after high-cur— 

rent—density bombardment were 一0.458 and v==: 

0.421,which has a change of Ax一0.004 and AY 

===一0.003,respectively.The deviations were with— 

in the values of instrumental error.So it can be 

seen that the Ba3Gd(PO4)3:0.06 Dy。+phosphor 

was stable in the CIE coordinates after 3 h high— 

current-densitv bombardment. 

XPS and EDS measurements were carried out 

on the samples of Ba3Gd(PO4)3:Dy。+both before 

and after electron bombardment.EDS results show 

that after electron irradiation.C contents increased 

on the bombarded area,while the contents of O, 

Ba,Gd,P element decreased. 

XPS spectra of C before and after electron born- 

bardment rae shown in Figure 8.The C ls peak before 

obmbardment is at 284.59 eV.Because only inorganic 

ingredients are added when sedimentign phosphors on 

ITO glass,C signal origiantes from contamiannts when 

the phosphors were exposed in air before bombard- 

ment,B舀graphite,hydrocarbon.After bombard— 

ment the peak of C is at 284.59 eV and its intensity in— 

creased.Continuous accretion of graphitic carobn dur— 

ign electron beam exposure at high-current densities is 

维普资讯

188 电 子 器件 第31卷 

an effect well known to microscopistsIn3.Presumably 

this graphitic phase is produoed by e-beam-induced 

cracking of hydrocarbons adsorbed from the vacuum 

ambient.This carbon contamination optically attenu— 

ates emitted cathodolumin ̄ence,prevents many low 

energy elctreons from ever reaching the phosphor 

一 日}^!ls_里ul 

chromaticity coordinates were x=0.454 and y=0. 

424,and the color temperature was 2889.3 K.The 

results show that Ba3 Gd(PO4)3: +phosphor 

was a low color temperature,warm-white phos- 

phor.It has high saturation current and can endure 

high—current-densitv bombardment.The stability 

grains,and exacerbates surface chargig nwhich reduces 

the arrival energy of electrons[ .Therefore,it could 

of the Ba3 Gd(P04)3:Dy3+phosphor at high-cur— 

rent density makes it a potential candidate for ap— 

cause the decline in CL and PL intensity. 

XPS spectra of O,Ba,Gd,P element before 

and after electron bombardment have no visible 

changes.Therefore the observed decreasing rela— 

tive contents of Ba,Gd,P element on the surface 

of the phosphor may be due to the increased con— 

tent ratio of C element. 

Bindingenergy/eV 

F蟮8 XPS spectraofCd ̄aent beforeaI】d after bombardment 

According to XPS analysis。we can conclude 

that after high current density bombardment,be— 

sides the carbon layer,no evidence shows that 

Ba3 Gd(VO4)3:Dy3+phosphor itself undergoes 

chemical reaction. 

To confirm that the carbon layer cansed the 

decrease of the phosphor performance,the sample 

after bombardment was baked at 450℃in air for 30 

minutes,the carbon layer on the phosphor surface 

was removed.and the sample restored the initial 

color.The CL intensity of the sample was meas— 

ured at the vacuum chamber again.The result is 

shown in Figure 7.It can be seen that the CL in- 

tensity increased to the initial value.This further 

proves that the carbon layer caused the decrease of 

the CL intensity. 

The emission peak of Ba3Gd(PO4)3:Dy3+phos— 

phor was located at 584 n/n,492 n/n and 676 n/n,(2or- 

respondign to the‘F9/2— Hi/2(i一13,15,11)transi— 

tion of Df+.For Ba3Gd(PO4)3:0.06of+,the CIE 

plications in cathodoluminescent light sources. 

Acknowledgments 

The authors gratefully acknowledge the finan— 

cial support of this project by the National Natural 

Science FOundation of China (Grant No. 

50021202,50329201,and 60571035),the Science 

and Technology Ministry of China(Grant No. 

2003CB314701),the Education Ministry of China, 

the Science and Technology Department of Guang— 

dong Province,the Education Department of 

Guangdong Province,and the Science and Tech- 

nology Department of Guangzhou City. 

[1 3 Uemura S,Yotani J,Nagasako T,Kurachi H,Yamada H, 

Ezaki T,Maesoba T,Nakao T,Saito Y and Yumura M, 

Journal of the Society for Information Display[J].2003,11 

(1):145-153. 

[23 Bonard J M,Stockli T,Noury O and Chatelain A,App1. 

Phys.Lett.,口].2001,78:2775. 

[3]Chen J,Zhou X,Deng S z and Xu N S,Ultramicroscopy[J]. 

2003,95:153—156. 

[43 Chen J。LiangXH,DengSz andXuNS,J.Vac.ScL Techn- 

o1.BEJ'].2003,21(4):727. 

[53 Chubun N N,Chakhovskoi A G,Hunt C E.Technical Digest 

of the 17th International Vacuum Nanoelectronics Corderence 

[C3//2004:36-37. 

[6]Benson K B(Ed),Television Engineering Handbook[M], 

McGraw-Hill,New York,1986:230. 

[7]LeeRY,ZhangFL,Penczek J,Wagner BK,YocomPN, 

Summers C J。J.Vac.Sci.Techno1.BEJ'],1998,16:855. 

[83 Leskela M,Alloy J.CompdEJ'].1998,275—277:702—708. 

[93 Liang H B,Zeng Q,su Q,Lin H H,Tian z F,Zhang G B, 

Fu Y B。Spectroscopy Letters[J3,in press. 

[103 Itoh S.Toki H,Kataoka F,Sato Y and Tamura K,Inf.Disp. 

Suppl[J].2000,1:187. 

[113 Hren J J,in Principles of Scanning Microscopy[M],Edited 

by Joy D C。Romig A L and Goldstein J I(Plenum,New 

York),1986:353. 

[12]Seager C H,Tallant D R and Warren W I ,J.App1.Phys. 

口],1997,82(9):4515—4519. 

2024年8月14日发(作者:威元绿)

维普资讯

第31卷第1期 

2008年2.月 

电子器件 

Chinese Joumal Of Electron Devices 

Vo1.31 No.1 

Feb.2008 

Cathodoluminescent Properties of Ba3 Ga(PO4)3:Dy3+Phosphor 

DUAN C ,CHEN Jun 一,DENG S Z ,XUN S ,HAN Bing ,LIANG H B ,SU@ang 

f L s缸 K 上,口6Dm细 。,o 。 加 ^缸 r 如口 丁 加 。g ,口 G眦 g 。 g P加 K 上,口6Dm细 。,D 户 ] 

}Material and Technology,Sun Yat-sen University,Guangzhou 510275,P.R.China; 

l 2.School of Chemistry and Chemical Engineering,Sun Yat-sen University,Guangzhou 510275,P.R.China 

I 

I 

Abstract:Cathodoluminescent properties of Ba3 Gd(PO4)3:Dy3+phosphor were studied.The phosphor was 

synthesized by high-temperature solid-phase reaction.Cathodoluminescence spectra,the Commission In- 

ternational de 1’Eclairage colour coordinates and photoluminescence spectra were determined.The Catho- 

doluminescence measurement shows that the Commission International de l’Eclairage(CIE)chromaticity 

coordinates of Ba3Gd(PO4)3:0.06Dy计phosphor are x=0.454 and y=O.424,and the color temperature is 

2889.3 K.The results show that the phosphor is a 1ow color temperature,warm-white phosphor with high 

saturation currents and can endure high-current-density bombardment. 

Key words:cathodoluminescence;phosphor;Ba3Gd(PO4)3:Dy3十 

E] C:4260 

Ba3 Ga(PO4 3:Dy3+ 荧光粉阴极射线发光研究* 

段春艳 ,陈 军 ,邓少芝 ,许宁生 ,韩 冰 ,梁宏斌 ,苏 锵 

(\.2 萋中山大学化学与化学工程学院, 广州 5蝮1027 5梢 戢糯点她 ), 

摘 要:本文研究了采用高温固相法合成的Ba3Gd(PO4)。:Dy3 荧光粉的阴极射线发光特性。测试并比较了电子轰击前后 

荧光粉的CL谱、色坐标以及PL谱变化。Ba3Gd(PO4)。:0.O6Dy3 荧光粉的色坐标为x=0.454,y一0.424,T =2889.3 K。 

测试结果显示该荧光粉是一种低色温、暖白光荧光粉,并且具有高的饱和电流,有耐大电流密度电子束轰击的能力。 

关键词:阴极射线发光;荧光粉;Ba3Gd(PO4)。:Dy3 

中图分类号:TN873.3 文献标识码:A 文章编号:1005-9490(2008)01-0184-05 

In recent years,significant progresses have been 

made in the area of cathodoluminescent light sources 

employing field emission cathode.which have the ad— 

vantages of high brightness。1ow-power consumption 

and are environmentally friendly[1-43.But as to the 

ray tubes(aR,] )or projection tubes(PR,] ).Cath— 

dolouminescent phosphor for appliatcion in field emis— 

sion 1ight source requires high effiacy cat 1ower excia- t

tion volages(5~10 kV)tthan CR_TS and PRTS,ther- 

l'na1 stability under continuous higher current densities 

phosphors,most of the reported fidd emission light 

ources utislize phosphors optiizemd for color cathode- 

(100~200“A/cm2),and having color coordinates 

(white 1ight)of traditional 1ight sources,Usually,re- 

收稿日期:2007-04-30 

基金项目:See Acknowledgments 

作者简介:段春艳(1976一),女,博士研究生,研究方向为场发射显示器用荧光粉; 

陈军(1967一),男,教授,主要研究方向为纳米光电材料及器件; 

邓少芝(1963一),女,教授,主要研究方向为纳米光电材料及器件; 

许宁生(1957-),男,教授,主要研究方向为纳米光电材料及器件; 

冰(1983一),男,硕士研究生,研究方向为稀土发光材料的光谱性质; 

锵(1931一),男,中国科学院院士,教授,研究方向为稀土化学与物理. 

梁宏斌(1965一),男,副教授,研究方向为稀土化学与物理; 

维普资讯

第1期 段春艳,陈 军等:Ba。Ga(PO4)。:Dy。+荧光粉阴极射线发光研究 185 

searchers rely on mixing three primary color phosphors 

to achieve the warm-white or cold-white light phos— 

phors for cathodoluminescent vacuum light sourcesl_5J. 

In the mixed white light phosphors,the green 

film,organic lacquer which has the function of creating 

a igh rheflective aluminum-mirror wa sprayed onto the 

phosphor layer.Then the aluminum layer was evapo— 

rated onto this lacquered phosphor layer. ter evapo— 

or blue phosphors,especially blue phosphors,of— 

ten are sulfide-based phosphors.It is well known 

that sulfide—-based phosphors have the highest lu—- 

ration of the aluminum film,the samples were baked 

at 390℃for ten minutes in air and the lacquer was re— 

moved.The CI spectrum。the Commission Intema— 

tional de l’Eclairage(CIE)colour coordinates and CL 

intensity were measured in an ultrahigh vacuum cham— 

minous efficiencies and excellent chromaticity in all 

the currently available industrial phosphors[ .But 

sulfide—based phosphors face the problems of 

catho-doluminescent degradation and decomposi— 

tion,and generate harmful gases causing the poi— 

soning of the cold cathode.Moreover,cathodolumi— 

nescent intensity of these phosphors tends to saturate 

at high-current densities.A1l these can cause chroma— 

ticity problem in mixed white light phosphors.There— 

fore,the development of phosphor materials is one of 

the key issues for cathodoluminescent light sources. 

Due to the problems in sulfide-based phosphors,rare 

earth doped oxide-based materials have been studied 

and regaMed as possible alternative phosphors due to 

their superior chemical and thermal stability under e— 

lectron beam excitation[ 一引.In this study,eathodolu— 

imnescent properties of Ba3Gd(P04)3:Df+white 

phosphor which was synthesized by high temperature 

solid phase reaction have been studied. 

1 Experimental 

The phosphor was synthesized by high—-tem— 

perature solid—state reaction method.The reactants 

were BaC()3(A.R.),NH4 H2PO4(A.R.),Gd203 

(99.9 ),and Dy203(99.9 ).The stoichiomet— 

ric reactants were first pre-fired at 600℃,and then 

heated at 1250℃in air.By varying the concentra— 

tion of Dy2 03,different Dy doped Ba3 Gd(P04)3 

phosphor can be prepared.In this study,Ba3 Gd 

(P04)3:0.O6DF+and Ba3Gd(PO4)3:0.03Dy。+are 

characterized. 

The phases of Ba3 Gd(P04)3:Dy3+phosphor were 

identified by powder X-ray difraction (Ⅺ 。 

RIGAKU D/max 2200)using Cu Ka( 一1.54178 

A)radiation,and the powder morphologies were stud- 

ied by scanning electron microscopy(SEM。JSM- 

6330F).Phosphor layers were deposited onto indium 

tin oxide(ITO)glass using a sediment method at 6 

er_g ̄crn2 with a solution of potassium silicate and ni— 

trate of baryta ter deposition。the samples were 

baked at 150℃for 30 minutes.For some samples。 

100 nlTl aluminum thin film was evaporated onto the 

phosphor layer.Before evaporation of the aluminum 

ber that has a base pressure of~5×10—0 Pa The ex— 

citation volatge was varide from 0 to 10 kV and the 

anode current density from 0 to 400 uA/cm .The 

CI spectrum and the CIE color coordinates were 

measured at 7 kV,30“A/cm .The CI intensity 

was measured with a I S1 1 0 luminance meter at the 

direction facing the incident electron.The CL 

spectrum and the CIE colour coordinates were 

measured with an OPT-2000 optical spectrometer。 

which has an accuracy of±0.005.An electron gun 

with carbon nanotube(CNT)cold cathode was 

employed in the CL measurement.Photolumines— 

cence(PL)spectra were measured using a HITA— 

CHI F-4500 fluorescence spectrophotometer with a 

150 W Xe lamp.Phosphors both before and after 

high—current—density bombardment were tested. 

Also,X-ray photoelectron spectroscopy(XPS) 

spectra of the phosphor were recorded before and 

after high-current-density bombardment using an 

ESCAI AB 250 XPS system.The X-ray gun for 

the XPS measurements had an Al(Ka)target with 

photon energy 1486.6 eV. 

2 Resul ts and Discussion 

The morphology of the Ba3 Gd(PO4)3:Dy。+ 

phosphors are shown in Figure 1,The average 

grain size is 5~10 um.Figure 2 shows XRD spec— 

tra of the phosphors.Analysis of the XRD data 

shows Ba3 Gd(PO4)3 has a body—centered cubic 

structure with the cell parameter a—1.047 nm 

(JCPDS 29-0163). 

Figure 3 shows CI spectra of Ba3Gd(PO4)3: 

By'+phosphor.Figure 4 gives the CIE coordinates 

of Ba3Gd(P04)3:Dya+in the CIE 1931 diagram. 

The CI spectra of Ba3 Gd(PO4)3:Dy3+phosphor 

consist of three peaks.The maximum emission 

peak of Ba3Gd(PO4)3:0.06Dy计phosphor was lo— 

cated at 584 nm(the yellow band),corresponding 

to the F9/2 Hl3/2 transition of Dy。+;the emis— 

sion peak of 492 nm(the blue band)corresponds 

to the Fg/2 。Hl5/2 transition of Dy3+;the 

维普资讯

186 电 子器件 

≈_ 

第31卷 

B善_d 

,≈_,抽!s_§u1 

Fig.1 Morphology of Ba ̄Gd(PO4)3:D phosphor 

Fig.2 X-ray diffraction pattern of B ̄Gd(PO4)3:D 

Wavaen ̄h/nill 

Fig.3 CL spectra of Ba3 Gd(Po4)3:D phosphor 

emission peak of 676 nm(the red band)corre— 

sponds to the F9/2 H1 1/2 transition of Dye+[ . 

The CIE chromaticity coordinates were x一0.454 

and y一0.424(Figure 4(a)),and the color tem- 

perature was 2889.3 K.The strongest emission 

peak of Ba3 Gd(PO4)3:0.03Dy ̄+phosphor was lo— 

cated at 583 nm。the CIE chromaticity coordinates 

were x=0.465 and y一0.427(Figure 4(b)), 

and the color temperature was 2757.2 K.It can be 

seen that the CIE coordinates have some shifts 

when the concentration of the activator in the 

phosphor is different.From above results,one can 

see that Ba3 Gd(PO4)3:Dy3+phosphor is a low col— 

or temperature,warm-white phosphor. 

CL properties of Ba3Gd(PO4)3:0.06Dy3+ 

phosphor were measured after working at 2 kV。3O 

uA/cm for 15 minutes.Figure 5(a)shows the lu— 

minance variation with anode voltage when the cur— 

rent densities were at 63 uA/cm .The luminance 

increased as a function of the anode voltage.The 

luminance reaches over 1996 cd/m at 10 kV,63 

“A/cm for the phosphor screen with a 100 nm a- 

您19 『1ch wnB咄 D Ⅻn 

、 

, G 1 ,5o 

\= 

580 

I a \ 0 

O 

630 

-' ) 驯 

/ 

/ / 

. 

/ 

/ 

Fig.4 The CIE coordinates of Ba3 Gd(PO4)3:D . 

(a)I ̄Gd(FO4)3:0.06Dy ̄ ;(b)t ̄Gd(FO4)3:0.03Dy ̄+ 

luminum film,which is 5.2 times higher than that 

of the phosphor without an aluminum film.The 

luminance for phosphor without Al layer is low 

probably due to the high resistance of phosphor 

materials besides the mirror effect of Al film[103. 

目.8 §

—.- 

wi

口_

th1

Ej

00 nm

 

AI / 

.—

/ 

. 

0 2 4 6 8 10 

V 

(a)Luminance vs.anode voltage 

J,u A・cm-2 

(b)Luminance vs.current density 

Fig.5 CL properties of Ba3Gd(PO4)3:D phosphor 

The luminance as function of current density 

at different anode voltages was tested and the re— 

suhs are shown in Figure 5(b).The excitation 

voltage was varied from 2 to 7 kV.At a fixed volt— 

age,with increasing of the current density,the lu— 

minance increases continuously until current densi- 

ty reaches about 500 ̄A/cm 。which is the maxi- 

mum current density our testing facility could 

reach.Also,after evaporation of the aluminum 

film,the luminance increases.When at voltage of 

7 kV and current density of 402 ̄A/cmz,the lumi- 

nance reaches 5034 cd/m . 

Figure 6 shows plot of the luminance vs.current 

density measured from the commercial phosphor 1S: 

维普资讯

第1期 段春艳,陈 军等:Ba3Ga(PO )3:Dy。+荧光粉阴极射线发光研究 187 

Cu,Au,Al and YAGG:Tb at different beam voltages. 

The sampls were eprepared using the identical method 

nd condaitions,Comparig Fingure 5(b)and Figure 6, 

we can see that when the current densitis reeach 

量.口口 q∞口一量j I.置.8 口 量j 

more deep-colored than the surrounding areas.So 

it is easy to identify and analyze the bombarded at- 

eas of the samples after electron bombardment. 

PL spectra and CL spectra were measured for 

1 20 u |cn-i2,the brightness of the commercial phos— 

phor GG:乃ceases to ncrease. 鼢en the current 

Ba3 Gd(PO4)3:0.06Dya+phosphors before and af— 

ter high—current-density bombardment.PL spectra 

of the phosphors were measured with 380 nm exci— 

tation.PL spectra of Ba3 Gd(PO4)3:0.03Dya+and 

Ba3Gd(PO4)3:0.06Dy什were similar.After high— 

densities reach 90以/CITI2,the brightness of the com- 

mercial phosphor ZnS:Cu,Au, reaches its maxi— 

mum.But for BaaGd(PO4)3:Dd+phosphor,within 

the current range of our testing facility,no saturation 

is observed.Therefore,accoridng to the above com- 

parison,it can be seen that the Ba3Gd(PO4)3:Dy3十 

phosphor has hi.gher saturation current and can endure 

high-current-density bombardment. 

"-W--2 k

5 kV  . ,一\, 。. 

一 、kV 

多 

量口口 u写=一置j 

. 

0 2O 4O 6O 8O 1OO 12O 14O 16O 

J/uA・cm-2 

(a) 

J, A・cm" 

(b) 

Fig.6 Plot of luminance vs.current density of 

(a)YAGG:Tb and(b)ZnS:Cu,Au,A1 phosphors 

testing at various excitation voltages 

To find out the chemical state of the phosphor 

surface after high-current-density bombardment, 

BaaGd(PO4)3:0.06Dd+phosphors without aluminum 

layer were obmbarded at 134“A/C1TI2,7 kV for 3 h. 

The luminance of the BaaGd(PO4)3:Dy3+phosphor 

iwthout aluminum layer decreased after the long time 

high-current-density bombardment.Figure 7 shows 

the plot of luminance vs.anode voltage at eurrent den~ 

sity of 63 pA/cm2 before and after elcetron bombard- 

ment.Comparign the luminance before and after obm- 

bardment,it can be seen that after 3 h bombardment, 

at the same anode voltage,the lumiannce decreased 

obviously. 

The areas of the phosphors being exposed to 

high—current densities bombardment became visibly 

current—densitv bombardment,decreases in the PL 

intensity of Ba3 Gd(PO4)3:Dy3+phosphor were ob— 

served. 

..-

e--Before 3 hbombardment 

Va/kV 

Fig.7 CL properties of Ba3Gd(P04)3:0.06Dy3 phosphor 

before and after long time high current bombardment 

CL spectra before and after bombardment 

were measured at about 820 cd/m .Comparing CL 

spectra before and after bombardment,the wave— 

length peak does not change and the CIE coordi— 

nates of Ba3 Gd(PO4)3:0.06Dy计after high-cur— 

rent—density bombardment were 一0.458 and v==: 

0.421,which has a change of Ax一0.004 and AY 

===一0.003,respectively.The deviations were with— 

in the values of instrumental error.So it can be 

seen that the Ba3Gd(PO4)3:0.06 Dy。+phosphor 

was stable in the CIE coordinates after 3 h high— 

current-densitv bombardment. 

XPS and EDS measurements were carried out 

on the samples of Ba3Gd(PO4)3:Dy。+both before 

and after electron bombardment.EDS results show 

that after electron irradiation.C contents increased 

on the bombarded area,while the contents of O, 

Ba,Gd,P element decreased. 

XPS spectra of C before and after electron born- 

bardment rae shown in Figure 8.The C ls peak before 

obmbardment is at 284.59 eV.Because only inorganic 

ingredients are added when sedimentign phosphors on 

ITO glass,C signal origiantes from contamiannts when 

the phosphors were exposed in air before bombard- 

ment,B舀graphite,hydrocarbon.After bombard— 

ment the peak of C is at 284.59 eV and its intensity in— 

creased.Continuous accretion of graphitic carobn dur— 

ign electron beam exposure at high-current densities is 

维普资讯

188 电 子 器件 第31卷 

an effect well known to microscopistsIn3.Presumably 

this graphitic phase is produoed by e-beam-induced 

cracking of hydrocarbons adsorbed from the vacuum 

ambient.This carbon contamination optically attenu— 

ates emitted cathodolumin ̄ence,prevents many low 

energy elctreons from ever reaching the phosphor 

一 日}^!ls_里ul 

chromaticity coordinates were x=0.454 and y=0. 

424,and the color temperature was 2889.3 K.The 

results show that Ba3 Gd(PO4)3: +phosphor 

was a low color temperature,warm-white phos- 

phor.It has high saturation current and can endure 

high—current-densitv bombardment.The stability 

grains,and exacerbates surface chargig nwhich reduces 

the arrival energy of electrons[ .Therefore,it could 

of the Ba3 Gd(P04)3:Dy3+phosphor at high-cur— 

rent density makes it a potential candidate for ap— 

cause the decline in CL and PL intensity. 

XPS spectra of O,Ba,Gd,P element before 

and after electron bombardment have no visible 

changes.Therefore the observed decreasing rela— 

tive contents of Ba,Gd,P element on the surface 

of the phosphor may be due to the increased con— 

tent ratio of C element. 

Bindingenergy/eV 

F蟮8 XPS spectraofCd ̄aent beforeaI】d after bombardment 

According to XPS analysis。we can conclude 

that after high current density bombardment,be— 

sides the carbon layer,no evidence shows that 

Ba3 Gd(VO4)3:Dy3+phosphor itself undergoes 

chemical reaction. 

To confirm that the carbon layer cansed the 

decrease of the phosphor performance,the sample 

after bombardment was baked at 450℃in air for 30 

minutes,the carbon layer on the phosphor surface 

was removed.and the sample restored the initial 

color.The CL intensity of the sample was meas— 

ured at the vacuum chamber again.The result is 

shown in Figure 7.It can be seen that the CL in- 

tensity increased to the initial value.This further 

proves that the carbon layer caused the decrease of 

the CL intensity. 

The emission peak of Ba3Gd(PO4)3:Dy3+phos— 

phor was located at 584 n/n,492 n/n and 676 n/n,(2or- 

respondign to the‘F9/2— Hi/2(i一13,15,11)transi— 

tion of Df+.For Ba3Gd(PO4)3:0.06of+,the CIE 

plications in cathodoluminescent light sources. 

Acknowledgments 

The authors gratefully acknowledge the finan— 

cial support of this project by the National Natural 

Science FOundation of China (Grant No. 

50021202,50329201,and 60571035),the Science 

and Technology Ministry of China(Grant No. 

2003CB314701),the Education Ministry of China, 

the Science and Technology Department of Guang— 

dong Province,the Education Department of 

Guangdong Province,and the Science and Tech- 

nology Department of Guangzhou City. 

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