powerpoint presentation · 2019. 9. 6. · title: powerpoint presentation created date: 2/16/2004...

New blue and green emitting BAM Phosphors for Fluorescent Lamps and Plasma Displays

T. Jüstel*, W. Busselt, P. Huppertz, W. Mayr, J. Meyer, P.J. Schmidt, D.U. Wiechert

Philips Research Laboratories, D-52066 Aachen, Germany *University of Applied Science Münster, D-48565 Steinfurt, Germany

Prof. Dr. T. Jüstel, March 17th, 2004 2

Outline

• Application of BAM phosphors

• Phases in the BaO-MgO-Al2O3-(EuO) system

• Luminescence of Eu2+ doped BAM-I and BAM-II

• BAM-I and –II doped by transition metal ions

• BAM-I with a blue body color

• Summary


Applications of BAM PhosphorsBlue and green emitter in exc. at [nm]Hg low pressure lamps 185, 254Xe2* excimer lamps 172 Plasma displays 147, 172

Commercial products• BAM-I blue• BAM-I blue-green• BAM-I green

Main concerns • thermal and photostability• colour point (shift)


Phases in the BaO-MgO-Al2O3 System

ß-alumina phasesBAM-I = BaMgAl10O17BAM-II = BaMg3Al14O25“extended spinel blocks”

Impurity phasesBaO excess BaAl2O4MgO/Al2O3 excess MgAl2O4Al2O3 excess Al2O3

2 BaMg2Al16O27 = BaMgAl10O17 + BaMg3Al14O25 + 4 Al2O3 “impurity phase”(M. Goebbels et al., 1998)

MgAl2O4

AlO1,5BaAl2O4

mol-%

1800°C

BaMg3Al14O25

BaMgAl10O17

123

45


Structure of BAM-I and BAM-II

BAM-I „BaO + MgAl10O16“ BAM-II „BaO + Mg3Al14O24“

c-axis

Spinel block

Conduction layer BaO

Spinel block

Conduction layer BaO

Spinel block


Phases in the BaO-MgO-Al2O3-EuO SystemImpurity phases (presence of Eu)BaO excess BaAl2O4:Eu2+

Al2O3 excess EuAl12O19 Eu2+

EuAlO3 Eu3+

Synthesis of BAM-I and BAM-IIrequires strict control of startingcomposition

(M. Dauscher, diploma thesis, 2001)

EuO

BaAl2O4

BaO

AlO1,5

EuAl12O19

(EuAlO3)

MgAl2O4

BAM-II

BAM-I

BaAl12O19

MgO


Luminescence of Eu-doped BAM-I (10% Eu2+)

• Optical band gap Eg = 7.0 eV (~180 nm)• Excitation bands at 170, 250, and 310 nm (4f7 → 4f65d1)• Emission band at 453 nm ⇒ x = 0.150 y = 0.060• QE254nm > 90%

100 200 300 400 500 600 700 8000,0

20,0

40,0

60,0

80,0

100,0Host lattice

Eu2+

4f7 - 4f65d1

R

efle

ctio

n [%

]

Wavelength [nm]

Reflection spectra Emission and excitation spectra

100 200 300 400 500 600 700 8000,0

0,2

0,4

0,6

0,8

1,04f65d1 - 4f7Host lattice

Rel

ativ

e In

tens

ityWavelength [nm]

4f7 - 4f65d1


Luminescence of Eu-doped BAM-II (10% Eu2+)

• Excitation bands at 170, 250, and 310 nm (4f7 → 4f65d1)• Emission band at 450 nm ⇒ x = 0.150 y = 0.050• QE254nm > 90%• Weaker absorption due to lower BaO/MgO-Al2O3 ratio

Reflection and excitation spectra Emission spectra

350 400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0 BaMgAl10O17:Eu10% BaMg3Al14O25:Eu10%

Emis

sion

inte

nsity

[a.u

.]Wavelength [nm]

100 200 300 400 500 600 700 8000,0

0,2

0,4

0,6

0,8

1,0

0

20

40

60

80

100

Host lattice

Reflection (%

)

Eu2+

4f7 - 4f65d1

Excitation spectrum Reflection spectrum

Sample WM137

Rel

ativ

e in

tens

ity

Wavelength [nm]


BAM-I and –II doped by Transition Metal Ions

λ1

λ2

λUV

• Divalent RE ions Ba2+ sites in the conduction layer Eu2+, Yb2+

• Divalent TM ions tetrahedral gaps in the spinel blocks Mn2+, Co2+

• Trivalent TM ions octahedral gaps in the spinel blocks Cr3+, Ti3+


BAM-I doped by Transition Metal Ions

Luminescence spectra ofBaMgAl10O17:Cr3+

Luminescence spectra ofBaMgAl10O17:Mn2+

100 200 300 400 500 600 700 8000,0

0,2

0,4

0,6

0,8

1,0

0

20

40

60

80

100

Reflection (%

)

Emission spectrum Excitation spectrum Reflection spectrum

Rel

ativ

e in

tens

ity

Wavelength [nm]100 200 300 400 500 600 700 800

0,0

0,2

0,4

0,6

0,8

1,0

0,0

0,2

0,4

0,6

0,8

1,0

Reflection (%

)

Emission spectrum Excitation spectrum Reflectionspectrum

Rel

ativ

e in

tens

itySample WM123

Wavelength [nm]

BAM-I: exc. at λmax at x y transitionCr3+ 190 nm 694 nm 0.596 0.257 3d3-3d3

Mn2+ 180 nm 515 nm 0.146 0.722 3d5-3d5


BAM-I:Eu doped by Mn2+

300 350 400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0 BAM-I:0.05Mn BAM-I:0.10Eulow Mn BAM-I:0.10EumediumMn BAM-I:0.10EuhighMn

Rel

ativ

e in

tens

ity

Wavelength [nm]150 200 250 300 350

0,0

0,2

0,4

0,6

0,8

1,0

BAM-I:0.05Mn BAM-I:0.1EumediumMn BAM-I:0.1EuhighMn

Ligh

t out

put L

O =

QE*

(1-R

)Wavelength [nm]

Emission spectra Light output

• Efficient energy transfer from Eu2+ to Mn2+

• Eu2+ improves VUV efficiency of Mn2+ doped BAM-I• High Mn2+ concentration reduces VUV efficiency of BAM-I:Eu,Mn


CB

VB

4f65d1

3d5

Eu2+ Mn2+

ET

250 nmEg = 7.0 eV(< 180 nm)

Host lattice Eu2+(4f65d1) Mn2+(3d5*)sensitiser for Mn2+ luminescence

Mn2+(3d5)

ET ET

515 nm

Energy Pathways in BAM-I:Eu,Mn

450 nm 515 nm310 nm

3d5*

4f7(8S7/2)

170 nm


BAM-II doped by Mn2+

Phosphor λmax at [nm] x y LE (lm/W)BAM-I:Mn 515 0.148 0.733 438BAM-II:Mn 520 0.185 0.738 515(data for 160 nm excitation)

Emission spectra of BAM-I:Mn and BAM-II:Mn

Excitation and reflection spectraof BAM-I:Mn and BAM-II:Mn

400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0 BaMgAl10O17:Mn BaMg3Al14O25:Mn

Emis

sion

inte

nsity

[a.u

.]Wavelength [nm]

100 200 300 400 500 600 700 8000,0

0,2

0,4

0,6

0,8

1,0

0

20

40

60

80

100

Reflection spectrum

(%)

BaMgAl10O17:MnBaMg3Al14O25:Mn

Rel

ativ

e in

tens

ity

Wavelength [nm]


BAM-II:Eu (10%) doped by Mn2+

Eu2+ 450 nm160 nm Host lattice

Mn2+ 520 nm

254 nm Eu2+ 450 nm

Emission spectra of BAM-II:Eu,MnExcitation and reflection spectra

350 400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0

Mn2+

Emission spectrum 160 nm exc. Emission spectrum 254 nm exc.

Emis

sion

inte

nsity

[a.u

.]Wavelength [nm]

Eu2+

100 200 300 400 500 600 700 8000,0

0,2

0,4

0,6

0,8

1,0

0

20

40

60

80

100

Reflection (%

)

Excitation spectrum Reflection spectrum

Rel

ativ

e in

tens

ity

Wavelength [nm]


Colour Points and Decay Times of BAM-I and BAM-II Phosphors

Composition Decay time 1/e* Color pointsBAM-I:10%Eu 1.5 µs

BAM-I:10%Eu, Mn 1.5 µs, 5.7 ms

BAM-I:10%Eu, Mn 4.8 ms

BAM-I:Mn 5.8 ms

BAM-II:10%Eu 1.4 µs

BAM-II:10%Eu, Mn 5.5 ms

*for 160 nm excitation and a monoexponential decay fit

BAM-I:Cr

BAM-I:Mn

BAM-II:Mn

BAM-I:Eu,Mn

BAM-I:EuBAM-I:Eu,Co


BAM-I:Eu with a Blue Body ColourThe blue pigment CoAl2O4 isisomorphous to MgAl2O4 spinel

• Standard blue pigment for blue CRT phosphor ZnS:Ag

• Co2+: 3d7 (high-spin) occupies tetrahedral sites in Co-spinel⇒ small crystal field splitting⇒ small energy distance

between t2 and e orbitals

• Co2+ (0.72 Å) is likely also located on tetrahedral sites in the spinel blocks of BAM-I and BAM-II as Mg2+ (0.66 Å)

10 20 30 40 50 60 70 80 900

5000

10000

15000

20000

25000

BAM blue Reference BAM V1370

Inte

nsity

two theta [°]

XRD of BAM-I:Eu,Co (Cu kα radiation)


BAM-I:Eu with a Blue Body Colour

Reflection spectrumEmission spectrum

300 400 500 600 700 8000,0

20,0

40,0

60,0

80,0

100,0

BAM-I:Eu BAM-I:Eu, Co1% BAM-I:Eu. Co4% ZnS:Ag (no pigment) ZnS:Ag + 2 wt-% CoAl2O4

R

efle

ctio

n [%

]Wavelength [nm]

350 400 450 500 550 600 650 700 750 8000,0

0,2

0,4

0,6

0,8

1,0 BAM-I:Eu BAM-I:Eu, Co1% BAM-I:Eu, Co4%

Emis

sion

inte

nsity

[a.u

.]

Wavelength [nm]

Co2+ doping results in absorption band equal to that of CoAl2O4

Body colour intensity increases by enhancing Co2+ concentration


BAM-I:Eu with a Blue Body ColourBaMgAl10O17:10%Eu,x%Co

Co2+ conc. x y• x = 0.0 0.150 0.060

• x = 1.0 0.150 0.049

• x = 4.0 0.150 0.047

Colour filter effect!

Light output

Efficiency of BAM-I:Eu,Coat 254 nm = BAM-I:Euat 172 nm = BAM-I:Eu (+ afterglow)at 147 nm < BAM-I:Eu (+ afterglow)

150 200 250 300 3500,0

0,2

0,4

0,6

0,8

1,0

BaMgAl10O17:Eu BaMgAl10O17:Eu,Co

170 nm

Ligh

t out

put =

QE*

(1-R

)

Wavelength [nm]



Decay after 160 nm excitation

0,0001

0,001

0,01

0,1

1

0 50 100 150 200 250

BAM:10%Eu

BAM:10%Eu,1%Co

Nor

mal

ised

Inte

nsity

Time (s)

Eu2+ decay

BAM-I:Eu,Co afterglow can be fitted by a bi-expontential decay function



0,001

0,01

0,1

1

10 100

121 nm140 nm160 nm 170 nm180 nm185 nm190 nm

Nor

mal

ised

inte

nsity

Time (s)

I = a1 exp(-t/ t1) + a2 exp(-t/ t2)

Decay curves as function of excitation wavelength

Results of a bi-exponential fit

0

0,1

0,2

0,3

0,4

0

0,02

0,04

0,06

0,08

0,1

120 140 160 180 200 220

a1(t = 9 s)a2(t = 100 s)

a 1(t

= 9

s) a2 (t = 100 s)

Excitation wavelength (nm)

Most intense afterglow under band edge excitation!

Excitation at band edge can result in hole trapping on Co2+ → Co3+

Band edge


Summary• BAM-I and BAM-II are stable phases in the BaO-MgO-

Al2O3 system

• Impurity phases are easily formed by small deviations from ideal stoichiometry

• BAM-II:Eu is as BAM-I:Eu an efficient blue-emitting phosphor

• Eu2+ facilitates ET from the host lattice to Mn2+ in BAM

• BAM-II:Mn is more saturated green than BAM-I:Mn

• Co-doping of BAM:Eu with Co yields a blue-emitting phosphor with a blue body colour (and afterglow)

powerpoint presentation · 2019. 9. 6. · title: powerpoint presentation created date: 2/16/2004...

Documents