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;
韩
苏
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
一
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
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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;
韩
苏
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
一
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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