Design and Degradation of UV Emitting Luminescent …€¢ Solar chemistry → Solar radiation +...

Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 1

Design and Degradation of UV Emitting

Luminescent Materials for Xe Excimer

Discharge Lamps

Thomas Jüstel & Mike Broxtermann

RG Tailored Optical Materials

Institute for Optical Technologies

Münster Univ. of Applied Sciences

[email protected]

University Stuttgart

@ January 30th, 2018


Ozone layer

Va

cu

um

UV

UV

-C

UV

-B (

280

–300 n

m)

UV

-A &

UV

-B (

300

–320 n

m)

1.37 kW/m2

Classification and impact ofUV Radiation (100 - 380 nm)

Vacuum UV (100 - 200 nm)• Photolysis of water• Cleavage of N2 and O2

• Ozone formation

UV-C (200 - 280 nm) & UV-B (280 - 300 nm)• Ozone cleavage

UV-B (300 - 320 nm) &UV-A (320 - 380 nm)• Photochemical

degradation of airpollutants

• Disinfection at photo-catalytically active sites


Contents

1. Motivation

2. Chemistry and Physics of Luminescent Materials

3. UV Radiation Sources

4. Xe Excimer Discharge Lamps

5. VUV to UV Converter - Design

6. Phosphor Converted Xe Excimer Lamps - Degradation

7. Spin-off: Nanoscale UV Phosphors

8. Summary & Outlook


1. MotivationOngoing increase ot water consumption and pollution

• UV-C Radiation (265 nm) inactivates micro organisms

due to DNA modification

• VUV Radiation (180 - 200 nm) oxidizes due to

H2O cleavage into radical species

Industrial installations → discharge lamps

Mobile devices → discharge lamps or LEDs

Wat

er

consu

mption / 1

09

m3

0

1000

2000

3000

4000

5000

6000

1900 1950 2000 2050Year

Agriculture

Industry

Household

Total


1. Motivation

Water impurities

• Microorganisms: Bacteria, viruses, spores, …

• Chemical (micro)pollutants: Toxic, bioactive, or non-

biodegradable organic compounds, NO3-

• Micro & nanoplastics “Great Pacific Garbage Patch”

Trend to apply green chemistry for water treatment

• Avoid use of toxic/ hazardous substances (Cl2, ClO2, NaOCl)

• Convert total organic compounds (TOC) to CO2 and H2O

• Introduce energy efficient and sustainable processes

• Biochemistry → Microorganism design, genetics

• Catalysis → Catalytic pigments and coatings

• Photochemistry → Frequency selective radiation sources

• Solar chemistry → Solar radiation + converter

• Fast analytics → Optical spectroscopy using radiation

sources switchable in the ns-range

Ongoing increase ot water consumption and pollution


2. Chemistry and Physics of LMsA luminescent material (phosphor) converts absorbed energy into

electromagnetic radiation beyond thermal equilibrium

Host• Coordination number and geometry• Symmetry of activator sites• Optical band gap• Phonon spectrum

Dopants, impurities, and defects• Concentration• Phase diagram and miscibility gaps

Particle surface• Zeta-potential• Surface area• Coatings Light in- and outcoupling

Particle morphology• Shape• Particle size distribution

Eu2+

Eu2+

Eu2+

Mn2+

VO


Temp. dependent PL of selected

LMs upon 254 nm excitation

2. Chemistry and Physics of LMs

250 300 350 400 450 500 550 600 650 700 750 800

0,0

0,2

0,4

0,6

0,8

1,0 PRO-2009-AB-012 ex307nm

PRO-2009-AB-012 mon656nm

Rela

tive in

tensity [a.u

.]

Wavelength [nm]

656 nm

0 100 200 300 400 500

0,0

0,2

0,4

0,6

0,8

1,0 LiEuMo2O

8

Ideal

YAG:Ce U728

No

rm. em

issio

n in

teg

rals

[a.u

]

Exc. density [W/mm2]

0 2000 4000 6000 8000 100001

10

100

1000

Decay Measurement

Inte

ns

ity

[c

ou

nts

]

time [ns]

T=100.00 K

T=150.00 K

T=200.00 K

T=250.00 K

T=300.00 K

T=350.00 K

T=400.00 K

T=450.00 K

T=500.00 K

Linearity of YAG:Ce

and LiEuMo2O8

Excitation and emission

spectrum of Mg2TiO4:Mn

Decay curves of

SrSi2N2O2:Eu

Relevant physical properties

PL spectra

CIE colour point

Luminous efficacy

Quantum yield (QY)

Colour point consistency

Decay curve

Thermal quenching

Linearity

Stability under operation


Quenching and degradation mechanisms

Reversible quenching

• Thermal quenching at high temperature

• Saturation at high power density

Irreversible degradation

• Dissolution/decomposition in applicat. medium BaSi2O5:Pb2+

• Thermal oxidation or reduction of the activator LaPO4:Ce3+

• Photo oxidation or reduction of the activator BaMgAl10O17:Eu2

• Reactions with the glass wall (Y,Gd)BO3:Tb3+

• Reaction with discharge species, e.g. Hg or Xe Zn2SiO4:Mn2+

• Hydrolysis by moisture YF3:Pr3+

Choose chemically stable and radiation hard host

& activator e.g. Lu3Al5O12:Gd3+ (L80 >> 10000 h!)

Otherwise: Particle coatings or lower activator conc.

2. Chemistry and Physics of LMs

300 400 500 600 700 8000

20

40

60

80

100

BaSi2O5:Pb from suspension

BaSi2O5:Pb from production

Re

fle

cta

nce

[%

]

Wavelength [nm]


Overview

Solar radiation > 300 nm

Hg discharge lampslow-pressure 185, 254 nmamalgam 185, 254 nmmedium-pressure 200 – 400 nm

Xe discharge lamps 230 – 800 nmD2 discharge lamps 110 – 400 nm

Excimer laser 193 nmSolid state laser Nd3+ 4th harmon. 266 nm

Excimer discharge lampsXe2* 172 nmKrCl* 222 nmXeBr* 282 nmXeCl* 308 nm

(Al,Ga)N LEDs 210 – 365 nm(In,Ga)N LEDs 365 – 400 nm



Solar Radiation

~ 5% UV ~ 60% VIS ~ 35% IR

The solar spectrum depends on daytime & season,

air pressure, clouds, particles (dust) and so on

AM

0A

M1

.0

Earth‘s surface

0,0

0,2

0,4

0,6

0,8

1,0

500 1000 1500 2000 2500 3000 3500 4000

Black Body (T = 5800 K)

0,0

0,2

0,4

0,6

0,8

AM0 (extraterrestric)

No

rmali

sed

em

issio

n in

ten

sit

y [

a.u

.]

500 1000 1500 2000 2500 3000 3500 4000

0,0

0,2

0,4

0,6

0,8 AM1.5 (48.2 ° angle)

Wavelength [nm]

O2

O3

H2O

CO2

CO2

<400 400-500 500-600 600-700 >700

37.8 W/m² 130.4 W/m² 144.6 W/m² 134.0 W/m² 269.2 W/m²

5.3% 18.2% 20.2% 18.7% 37.6%


48.2°


Direct radiation: Diffuse radiation:Filtered solar radiation Scattered solar radiation

CCT = 5500 - 6500 K CCT = 10600 K

50 W/m2 UV total and 0.1 W/m2 UV-B almost no UV radiation

~ 1000 W/m2 ~ 50 W/m2



Present trend: Use solar light & combine with traditional light sources,

e.g. for water, air, and surface disinfection or for indoor illumination



Low Pressure Hg Amalgam Medium Pressure Hg

UV-C wavelength 254 nm 254 nm 200 - 280 nm

Typical lamp power 4 ... 100 W 100 ... 300 W 1 ... 17 kW

Lamp efficiency < 40% 30 ... 35% 10 ... 15%

GAC factor 85% 85% 80%

UV-C power per length 0.2 W / cm 0.7 W / cm 15 W / cm

Wall temperature 40 °C 100 °C 600 - 800 °C

Selection based on application area and life cycle cost

Hg vapour discharge lamps - Overview


Hg lamp

invented

1904 for

Rachitis

therapy


„LED platform“

465 nm LEDs Illumination

410 nm LEDs Full conversion

365 nm LEDs Black light

265 nm LEDs Disinfection

375 400 425 450 475 500 525 375 400 425 450 475 500 525 550

Em

iss

ion

inte

ns

ity

(a

.u.)

Wavelength [nm]

diodesLaser

400nm

425nm

450nm

465nm

480nm

500nm

LEDs

„Laserdiode platform“

940 nm Remote control

785 nm CD

655 nm DVD

405 nm Blue ray DVD

LEDs and laser diodes



Ozone generator

(Wedeco AG)

Flat lamp

for LCD

Backlighting

(Osram AG)

Exhaust treatment

(Siemens AG)UV Radiation sources (Xenon)

Heraeus Noblelight

Triton

Osram Xeradex

Devices using a dielectric barrier excimer discharge (either O2 or Xe)




Lamp sketch and principle of working

p(Xe) = 300 mbar

P = 10 - 100 W

U = 3 - 5 kV

f = 10 - 50 kHz

Micro discharge

channel

Surface

discharge

Surface

discharge

Xe Xe*

Xe* + 2 Xe Xe2* + Xe

Xe2* 2 Xe + hν (172 nm)

hν (190 - 700 nm) = f(luminescent screen)

R(t)

CD

CD

CG

ignition

~


1st Continuum

2nd Continuum

Excimer highest excited state

Monomer

Ground states

Fast dissociation

Excited monomeric Xe species:

Emits 147 nm (8.44 eV)

Xe resonance line

1st Emission continuum:

148 nm (8.38 eV)

Xe2[0+

U(3P1)high n] Xe2[0+

g(1S0)]

152 nm (8.16 eV)

Xe2[1U(3P2)high n] Xe2[0+

g(1S0)]

2nd Emission continuum:

186 nm (7.38 eV)

Xe2[0+

U(3P1)low n] Xe2[0+

g(1S0)]

172 nm (7.21 eV)

Xe2[1U(3P2)low n] Xe2[0+

g(1S0)]


Xe and Xe2* energy levels and discharge emission spectrum


150 nm

172 nm

Lamp spectrum

Converter screen

Wavelength [nm]

147 nm 172 nm

Reso

nan

ce L

ine

Em

issio

n in

ten

sit

y 2n

dC

on

tinu

um

1s

tCo

ntin

uu

m

Lamp glass

150 nm


Xe excimer spectrum and typical lamp parameter

Example: Osram XERADEX L40/120/SB-S46/85

Power consumption = 20 W

Diameter = 4 cm

Length = 12 cm

Wall load ~ 0.15 W/cm2

Output power = 6 W

Power density = 0.04 W/cm2

Wall plug efficiency ~ 30% (including driver)

150 nm

Simplified reaction scheme

Xe(1S0) + e- Xe(3P1) + e-

Xe(3P1) Xe(1S0) + h147 nm

Xe(3P1) + 2 Xe Xe2(3u

+) + Xe

Xe2(3u

+) 2 Xe(1S0) + h172 nm


Host lattices

Fluorides Phosphates Borates Silicates Aluminates

Activator ions

Nd3+

Tl+, Pb2+, Pr3+, Bi3+

Gd3+, Bi3+, Pr3+, Ce3+

Tm3+, Pb2+, Ce3+, Eu2+

100 nm 200 nm 280 nm 320 nm 400 nm

UV-B UV-AUV-CVUV

5. VUV to UV Converter Design

UV Emitter - Suitable host lattices and activator ions


Pr3+ energy level scheme - Host impact


3H4

En

erg

y[1

03

cm

-1]

3H5

3H6

1S0

1D2

1G4

3P23P0

3F2

0

10

20

30

50

40

60[Xe]4f2 [Xe]4f15d1 Oh site distorted Oh site

3F3

3F4

3P1, 1I6



Pr3+ energy level scheme - Host impact1S0 –

2S+1LJ line emission

YF3:Pr

NaYF4:Pr

SrAl12O19:Pr

LaMgB5O10:Pr

LaB3O6:Pr

4f15d1 – 4f2 band emission

LiYF4:Pr 218 nm

YPO4:Pr 232 nm

KYF4:Pr 235 nm

YAlO3:Pr 245 nm

YBO3:Pr 263 nm

Lu2Si2O7:Pr 273 nm

Lu3Al5O12:Pr 310 nm

Y3Al5O12:Pr 320 nm

1D2-3HJ line emission

Y2O3:Pr 615 nm

CaTiO3:Pr,Na 615 nm

Blue emission

Red emission

UV band emission

UV line emission

213, 236

252, 271

407 nm

En

erg

y o

f the

low

est

cry

sta

l-field

co

mp

on

en

to

f [Xe]4

f15

d1

1D2


Pr3+ energy level scheme - Host impact

[Xe]4f15d1 – [Xe]4f2 vs. [Xe]4f2 – [Xe]4f2 emission

NaYF4:Pr3+ 213, 236 nm hexagonal CN 9 E([Xe]4f15d1) > E(1S0)

KYF4:Pr3+ 235 nm hexagonal CN 7 E([Xe]4f15d1) < E(1S0)

200 300 400 500 600 700 800

0,0

0,2

0,4

0,6

0,8

1,0KYF4:Pr3+

Inte

nsity [a

.u.]

Wavelength [nm]

Emission bei 160 nm

Anregung bei 232 nm

Reflexion

200 300 400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

NaYF4:Pr3+

Inte

nsity [a.u

.]

Wavelength [nm]

Emission bei 160 nm

Anregung bei 272 nm

Reflexion



100 200 300 400 5000,0

0,2

0,4

0,6

0,8

1,04f

15d

1

Host

lattice

3F

J

3H

6

3H

5

3H

4

Wavelength [nm]

Distorted

dodecahedra

CN = 8

Y-O distances

4 x 2.24 Å

4 x 2.24 Å

CF splitting

~ 12000 cm-1

Centroid shift

~ 9600 cm-1

CFS and centroid shift reduces energy

of lowest crystal-field component of the

[Xe]4f15d1 configuration by ~ 22000 cm-1

E(4f15d1) below E(1S0)

[Xe]4f15d1 - [Xe]4f2 band emission

Situation in YPO4

(Eg = 9.0 eV)


Pr3+ energy level scheme - Impact of the host

Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 2430.01.2018

Converter for differnet Xe excimer radiator applications

1. Water splitting and NOx removal

YPO4:Nd 190 nm

2. Mineralisation of µ-pollutants: Pharmaceuticals, hormones, …

YPO4:Bi 241 nm

YPO4:Pr 235 nm

LaPO4:Pr 225 nm

CaSO4:Pr,Na 218 nm

3. Disinfection: Water, surfaces, air, …

YPO4:Bi 241 nm

CaLi2SiO4:Pr,Na 252 nm

YBO3:Pr 265 nm

Y2Si2O7:Pr 275 nm

4. Photopolymerisation: UV curing

Lu3Al5O12:Gd 311 nm

LaMgAl11O19:Gd 311 nm

Y3Al5O12:Pr 320 nm




150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

3F

J

3H

6

3H

4

Energy /eV

Inte

nsity (

no

rm.)

Wavelength /nm

172

nm

YPO4:PrExc.: 160 nm

Em.: 233 nm

Germicidal efficiancy (DIN 5031-10): 60.6%

4f15d

1

3H

5

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

Re

fle

cta

nce

/ %

Ba

SO

4

150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

1S

0

1P

1/3P

2/3P

1

Energy /eV

Inte

nsity (

norm

.)

Wavelength /nm

17

2 n

m

Germicidal efficiancy (DIN 5031-10): 43.8%

YPO4:BiExc.: 160 nm

Em.: 260 nm

3P

1

MMCT

0

10

20

30

40

50

60

70

80

90

100

Reflecta

nce / %

BaS

O4

150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

2G

7/2

2H

11/2

4F

9/2

Energy /eV

Inte

nsity (

norm

.)

Wavelength /nm

17

2 n

m

Germicidal efficiancy (DIN 5031-10): 57,3 %

YPO4:NdExc.: 160 nm

Em.: 200 nm

4f25d

1

4IJ

0

10

20

30

40

50

60

70

80

90

100

Reflecta

nce / %

BaS

O4

λmax(YPO4:Bi) = 241 nm

λmax(YPO4:Pr) = 235 nm

λmax(YPO4:Nd) = 193 nm

Y3+ site: CN = 8

Chosen converter material must be radiation hard

YPO4 as the host material

mineral: Xenotime

structure: Zircon type

crystal system: tetragonal

space group: I41/amd (#141)

unit cell

T. Jüstel, H. Nikol, J. Dirscherl, W. Busselt, US 6398970 B1

T. Jüstel, H. von Busch, G. Heussler, W. Mayr, US 7298077 B2

G.F. Gärtner, G. Greuel, T. Jüstel, W. Schiene, US 7687997 B2

T. Jüstel, J. Meyer, W. Mayr, US 7808170 B2

T. Jüstel, P. Huppertz, D.U. Wiechert, W. Mayr, H. von Busch, US 7855497 B2

G. Greuel, T. Jüstel. J.M. Kuc, US 9334442 B2


Germicidal efficacy of doped ortho-phosphate YPO4

Germicidal Action Curve (GAC):

Efficacy of deactivation of E. Coli (DIN 5031-10)


200 250 300 350 400 450 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

GAC

YPO4:Nd

Em

issio

n inte

nsity (

norm

.)

Spectral germicidal efficacy DIN 5031-10 (E.Coli)

Germ

icid

al effic

acy /a.u

.

Wavelength /nm

GAC-Eff (YPO4:Nd) = 57.3 %

200 250 300 350 400 450 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

GAC

YPO4:Bi

Em

issio

n Inensity (

norm

.)


Germ

icid

al effic

acy /a.u

.

Wavelength /nm

GAC-Eff (YPO4:Bi) = 43.8 %

200 250 300 350 400 450 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

GAC

YPO4:Pr

Em

issio

n Inensity (

norm

.)


Germ

icid

al effic

acy /a.u

.

Wavelength /nm

GAC-Eff (YPO4:Pr) = 60.6 %

𝐸𝑓𝑓𝐺𝐴𝐶(𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟) = (𝐸𝑚𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟× 𝐺𝐴𝐶)

𝐸𝑚𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟

YPO4:Bi

YPO4:Pr

YPO4:Nd

Goal: Log-4 reduction


YPO4:Bi or YPO4:Pr comprising lamps

Goal: Degradation of sulfamethoxazol (antibiotic)

Source: A. Nietzsch, DLR

Source: N. Braun, GVB

Photolytical degradation by the use of a phosphor converted Xe excimer lamp

allows a reduction of the required dose by 95% compared to an amalgam lamp

6. Phosphor Converted Xe Excimer Lamps


H2O filled dive-in test stand for

Xe excimer co-axial lamps

Converter

screen

Operation

period

Relative radiation

intensity loss

YPO4:Bi 792 hours - 50 %

YPO4:Pr 792 hours - 60 %

YPO4:Nd 763 hours ~ -50 %

But: An YPO4:Bi lamp has reached its

rated end of life after just about 240

hours of operation if L70 is applied


Lifetime of Xe excimer lamp comprising YPO4:Bi or YPO4:Ln

Choice was based on

LnPO4 phosphors are stable in discharge lamps

Wide band gap (Eg ~ 8.8 eV) limits re-absorption

50 100 150 200 250 300 350 400 450 500 550 600 650 700

100

120

140

160

180

200

220

240

260

IUV-C

Lamp with YPO4:Bi

Inte

gra

ted U

V-C

In

tensity /

a.u

.

Run-time /h

0

-10

-20

-30

-40

-50

-60

-70

-80

Degradation Lamp with YPO4:Bi

De

gra

da

tion

/ %

L70

L70 @ ≈ 240 h



50 100 150 200 250 300 350 400 450 500 550 600 650 700

100

120

140

160

180

200

220

240

260

IUV-C

Lamp with YPO4:Bi

Inte

gra

ted U

V-C

In

tensity /

a.u

.

Run-time /h

0

-10

-20

-30

-40

-50

-60

-70

-80

Degradation Lamp with YPO4:Bi

De

gra

da

tion

/ %

L70

L70 @ ≈ 240 h 150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

norm

.)

Wavelength /nm

Exc.: 160 nm

Em.: 233 nm

YPO4:Bi

YPO4:Bi aged

0

10

20

30

40

50

60

70

80

90

100

Reflecta

nce / %

BaS

O4

240 260 280 300 320 340 360 380

Lifetime of Xe excimer lamp comprising YPO4:Bi or YPO4:Ln

Lamp degradation due to several processes YPO4:Bi as-made and aged

(PL and reflection spectra)

Discharge related Phosphor related

XeO* formation Reduction of Bi3+ Bi2+, Bi+

Sputtering of central wire Degradation of ortho-phosphate host

(defects or phosphate reduction?)


150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

no

rm.)

Wavelength /nm

Exc.: 160 nm

Em.: 235 nm

YPO4:Pr

YPO4:Pr aged

0

10

20

30

40

50

60

70

80

90

100

Re

fle

cta

nce

/ %

Ba

SO

4

YPO4:Pr3+

new

absorption

due to host

degradation

150 200 250 300 350 400 450 500 550 600 650 700 750 800

8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

no

rm.)

Wavelength /nm

Exc.: 160 nm

Em.: 233 nm

YPO4:Bi

YPO4:Bi aged

0

10

20

30

40

50

60

70

80

90

100

Re

fle

cta

nce

/ %

Ba

SO

4240 260 280 300 320 340 360 380

YPO4:Bi3+

new

absorption

by Bi+/ Bi2+

200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

norm

.)

Wavelength /nm

Exc.: 160 nm

Em.: 233 nm

YPO4 aged

0

10

20

30

40

50

60

70

80

90

100

YPO4

Reflecta

nce / %

BaS

O4

undoped YPO4

Degradation of YPO4:Bi, YPO4:Pr, and undoped YPO4



200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

no

rm.)

Wavelength /nm

Exc.: 160 nm

Em.: 233 nm

YPO4 aged

0

10

20

30

40

50

60

70

80

90

100

YPO4

Re

fle

cta

nce

/ %

Ba

SO

4

YPO4

as-made

YPO4

aged

YPO4

aged + 365 nm

200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

77K

100K

123K

150K

175K

200K

225K

250K

Energy /eV

Inte

nsi

ty /a.u

.

Wavelength /nm

275K

300K

325K

350K

375K

400K

Ex.: 350

Em.: 750YPO

4 aged @

425K

450K

475K

500K

0

10

20

30

40

50

60

70

80

90

100

Refle

ctance

/ %

BaS

O4

Temperature dependent spectroscopy on aged YPO4 samples

Aged undoped YPO4

shows intense red

photoluminescence

Nature of luminescence process?



6. Phosphor Converted Xe Excimer LampsBi3+ doping Pr3+ doping

200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

77K

100K

125K

150K

175K

200K

225K

Energy /eV

Inte

nsi

ty (

norm

.)

Wavelength /nm

250K

275K

300K

325K

350K

375K

400K

425K

450K

475K

500KYPO

4:Bi aged

Exc.: 340nm

Em.: 700nm

0

10

20

30

40

50

60

70

80

90

100

Refle

ctance

/ %

BaS

O4

200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

77K

100K

123K

150K

175K

200K

225K

250K

Energy /eV

Inte

nsi

ty /

a.u

.

Wavelength /nm

275K

300K

325K

350K

375K

400K

Ex.: 350

Em.: 750YPO

4 aged @

425K

450K

475K

500K

0

10

20

30

40

50

60

70

80

90

100

Re

flect

ance

/ %

Ba

SO

4

Gd3+ doping

YPO4 host

250 300 350 400 450 500 550 600 650 700 750 800

5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity (

norm

.)

Wavelength /nm

17

2 n

m

Exc.: 348 nm

Em.: 735 nmYPO

4:Pr aged @

80 K

100 K

120 K

140 K

160 K

180 K

200 K

220 K

240 K

260 K

280 K

300 K

320 K

340 K

360 K

380 K

400 K

420 K

440 K

460 K

480 K

500 K

0

10

20

30

40

50

60

70

80

90

100

Reflecta

nce / %

BaS

O4

200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

77K

100K

125K

150K

175K

200K

225K

250K

275K

Energy /eV

Inte

nsi

ty (

no

rm.)

Wavelength /nm

Exc.: 345 nm

Em.: 750 nmYPO

4:Gd

300K

325K

350K

375K

400K

425K

450K

475K

500K

0

10

20

30

40

50

60

70

80

90

100

Re

flect

ance

/ %

Ba

SO

4

Luminescence process:

• Independent of type of

dopant ion

• Similar PL found for

aged LuPO4 and LaPO4

PL related to phosphate

YPO4:Gd YPO4:Gd

aged

YPO4:Gd

aged +

365 nm



Further analytics on degraded LnPO4 (Ln = Y, La, Gd, Lu)

• XRD and 31P-NMR No phase transitions or impurity phase formation

• Photoluminescence spectroscopy Spectral features characteristic for

ns2 ns1np1 luminescence, as already known for As3+, Sb3+, and Bi3+

• Decay curve main component 1/e = 5 ms PL of s2-ion with a small

spin-orbit (S.-O.) coupling, which increases with atomic number!

P+V P+III

[Ne]3s0 [Ne]3s2

Reduction of P5+ by hot e- and Xe+∙

impingement due to intimate contact

to barrier discharge

P+VO43- + Xe+ + e- P+IIIO3

3- + XeO

0 5 10 15 20 25 30 35 4010

0

101

102

103

104

Inte

nsity

/cou

nts

time / ms

YPO4 recovered

Fit (2nd.

exponential)

Exc.: 330 nm

Em.: 770 nm

1 = 1378.24 s ± 56.70 s

2 = 5007.80 s ± 25.91 s

1= 11.31%

2 = 88.63%

= 1.114

+

-

P3+

As3+

Sb3+

Bi3+

+

-

-

+



200 250 300 350 400 450 500 550 600 650 700 750 800

6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5

Energy /eV

Inte

nsity /

arb

. un

its

Wavelength /nm

80 K

100 K

120 K

140 K

160 K

180 K

200 K

220 K

240 K

260 K

280 K

300 K

320 K

340 K

360 K

380 K

400 K

420 K

440 K

460 K

480 K

500 K

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

Reflection @ RT

Re

fle

cta

nce

/ %

Ba

SO

4

C AB A

C AB

1S0

3P0

3P1

3P2

1P1

A

1S0

3P0

3P1

3P2

1P1

Exc. Em.

x

Simplified energy level

diagram of an ns2 ion

Photoluminescence of degraded LnPO4 (Ln = Y, La, Gd, Lu)

Conclusions:

• Formation of LnPO4:P3+

• First known example of P3+ [Ne]3s2 to [Ne]3s13p1 photoluminescenceM. Broxtermann, R. Poettgen, T. Jüstel, et al., J. Luminescence, publication in preparation



Improvement of stability of LnPO4:M (Ln = Y, La, Gd, Lu; M = Pr, Nd, Bi)

Approach: Particle coating with Al2O3 (Eg ~ 7.5 eV) to reduce interaction with

Xe discharge and to absorb radiation from discharge below 160 nm

YPO4:Bi

Al2O3

172 nm

241 nm

0 60 120 180 240 300 360

4

5

6

7

pH

pH

Time /min.

Al(OH)3 precipitation by h induced NaN

3 cleavage

8

10

12

14

16

18

20

V(Reaktor) = 0.85 L

m(YPO4:Bi) = 0 g

conc.(NaN3) = 7,65 g/L (6,5g)

c(Al2(SO4)

3x16H

2O) = 2 g/L (1,7 g)

Temperature

Te

mp

era

ture

/°C

147 nm

M. Broxtermann, T. Jüstel, Mat. Res. Bull. 80 (2016) 249



Improvement of stability of LnPO4 (Ln = Y, La, Gd, Lu)

Al2O3 reduces efficacy upon 160 nm,

but hardly upon 172 nm excitation

non coated 1 wt-% Al2O3

2 wt-% Al2O3 4 wt-% Al2O3

150 200 250 300 350 400 450 500 550 600

YPO4:Bi

4 wt% Al2O

3

2 wt% Al2O

3

1 wt% Al2O

3

0 wt% Al2O

3

Inte

nsity (

no

rm.)

Wavelength /nm

Em.: 260 nm // Exc.: 160 nm

0

10

20

30

40

50

60

70

80

90

100R

efle

cta

nce

/ %

Ba

SO

4

220 230 240 250 260 2700,0

0,2

0,4

0,6

0,8

1,0

Wavelength /nm

Inte

nsity (

no

rm.)

2 3 4 5 6 7 8 9 10-200

-150

-100

-50

0

50

100

150

200

2 3 4 5 6 7 8 9 10

neat YPO4

1 wt.% coated

2 wt.% coated

4 wt.% coated

Al2O

3

Ze

ta P

ote

ntial /m

V

pH

2,7 4,5 5,0 6,4 8.1



Lifetime of Xe excimer lamp comprising Al2O3 coated YPO4:Bi particles

50 100 150 200 250 300 350 400 450 500 550 600 650 700

100

120

140

160

180

200

220

240

260

UV-C intensity with YPO4:Bi, neat

UV-C intensity with YPO4:Bi, Al2O

3 coated (4m%, UV-R, 1400°C)

Inte

gra

ted U

V-C

inte

nsity (

norm

by IR

)

Operation time /h

0

-10

-20

-30

-40

-50

-60

-70

-80

Degradation withYPO4:Bi, neat

Degradation with YPO4:Bi, Al2O

3 coated (4m%, UV-R, 1400°C)

Degra

dation / %

Coating type Lamp code Operation time / h 72 216 336 480 700

none 837 loss / % 14.17 29 37.99 55.76 52.21

Al2O3 2 wt-%, urea 838 loss / % 20.29 41.92 48.58 50.06 43.43

Al2O3 4 wt-%, urea 827 loss / % n. a. 22.47 24.04 30.37 32.58

Al2O3 2 wt-%, UV-R 828 loss / % 12.40 24.91 33.81 32.35 40.23

Al2O3 4 wt-%, UV-R 829 loss / % 12.61 26.95 24.94 32.72 42.01

Al2O3 4 wt-%, UV-R, 1400 °C 830 loss / % 5.25 16.28 19.86 24.64 28.44

Optimal particle coating process

• Al2(SO4)3 in water + NaN3

• UV reactor (Hg high-pressure lamp)

• 4 wt-% Al2O3

• 1400 °C post annealing

Results so far

• Factor 2 - 3 less degradation

• Almost no loss of initial efficiency


YPO4:Pr and LuPO4:Pr as 235 nm UV-C emitting nanoparticle scintillators

YPO4:Pr (30 nm)

LuPO4:Pr (5 nm)

100 200 300 400 500 600 700 800 0.0

0.2

0.4

0.6

0.8

1.0

YPO4:Pr3+

(1%)

Emissionsspektrum Anregungsspektrum

Probe EDTA 2

Re

lative

In

tensitä

t

Wellenlänge [nm]

4 f2 5 d

14 f

1

5 d14 f

1

3H4

7. Spin-off: Nanoscale UV Scintillators

°2Theta

10 20 30 40 50 60

Counts

0

25

100

LuPO4:Pr(1%)

EDTA 16

Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 39Friday Afternoon

Idea: Conversion of x-rays to UV-C radiation by nanoscale particles to

improve radiation therapy of cancer

Radiation therapy is a well established

cancer treatment and applied all over

the world, even though it has tremendous

side effects, such as hair loss, diarrhea, …

“UV Nanophors” would result in

• lower radiation dose

• fewer or none side effects

• lower treatment price

• shorter treatment periods


T. Jüstel, C. Feldmann, Philips Patent EP03104756, WO2005058360

Image by

S. Espinoza


Challenge: Provide UV-C scintillator

which meet the following requirements

• High density

• Large GAC overlap

• Diameter: 50 - 150 nm

• Narrow PSD

• Homogeneous morphology

• Redispersibility

• Mainly UV-C emission

• Efficient CL and RL

• Suitable PZC

• Biocompatible host

• Low toxicity

• Stability in water to enable

core-shell structure with linker


Core material

Density

[g/cm3]

Lu2O3 9.4

LuLaO3 8.2

Lu2O2S 8.9

Lu2SiO5 7.4

LuPO4 6.53

Lu2Si2O7 6.2

Lu3Al5O12 6.7

LuAlO3 8.4

LuBO3 6.9

Image by

S. Espinoza


Material λmax.(Em.) /nm GAC-Efficacy /%

(Y,Lu)PO4:Nd 193 57.3*

CaSO4:Pr,Li 218 68,2

LaPO4:Pr 225 68.9

(Y,Lu)PO4:Pr 235 60.6

(Y,Lu)PO4:Bi 241 43.8 – 50.7

YAlO3:Pr 245 40.6

La2Si2O7:Pr 247 33.4

CaLi2SiO4:Pr 253 44.0

CaMgSi2O6:Pr,Li 260 n. a.

YBO3:Pr 265 45.9

Lu2Si2O7:Pr 266 48.1

Y2SiO5:Pr 270 22.3

BaZrSi3O9 275 47.9

Lu2SiO5 277 15.9

Lu3Al5O12:Pr 310 2.3

Lu3Al5O12:Gd 311 ~ 0

Y3Al5O12:Gd 311 ~ 0

LaMgAl11O19:Gd 311 ~ 0

Y3Al5O12:Pr 320 ~ 0

Material λmax.(Em.) /nm GAC-Efficacy /%

LaPO4:Ce 320 ~ 0

Lu3Al5O12:Tm 345 ~ 0

Y3Al5O12:Tm 345 ~ 0

YPO4:Ce 335, 355 ~ 0

BaSi2O5:Pb 350 ~ 0


Emission peaks and GAC overlap of selected UV-C scintillators



GAC overlap and density of selected UV-C scintillators

LaPO4 LuPO4

Chosen materials


LuPO4

Sedimentation Nucleation (Modified)

Suspension

• A solution of NaH2PO4 (pH 12) is added dropwise to the

second solution of LuCl3 and Pr(NO3)3 dissolved in H2O.

• The precipitate is separated by a centrifuge and washed

with distilled H2O several times to neutral pH value.

• Afterwards, the precipitate is annealed for 2 h at 1000

°C in a reducing atmosphere (CO).

• Lu2O3 and Pr6O11 are suspended in H2O.

• H3PO4 is added to the suspension and mixed for 24 h.

• The precipitate is filtered and washed with distilled H2O

several times to neutral pH value.

• Afterwards, the precipitate is annealed for 4 h at 1000 °C

under CO atmosphere and using

2 wt-% LiF.

Average d50 = 0.1 µm Average d50 = 5.7 µm


From micro to nanoscale particles (bottom-up approach)

Image by

Sara Espinoza



Reproducible synthesis of pure and highly crystalline LuPO4:Pr3+ 100 nm particle activated by 0.1 to 3% Pr3+

PSD of nanoscale LuPO4:Pr(0.0 - 3.0 atom-%) particles

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]

Particle Diameter [m]

0

10

20

30

40

50

60

70

80

90

100

LuPO4

HMS-2017-PM-AU-025

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.07 µm

D50= 0.1 µm

D90= 0.6 µm

= 1.7 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(0.1%)

HMS-2017-PM-AU-024

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.1 µm

D50= 0.1 µm

D90= 0.4 µm

= 0.5 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(0.25%)

HMS-2017-PM-AU-026

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.07 µm

D50= 0.1 µm

D90= 0.7 µm

= 0.8 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(0.5%)

HMS-2017-PM-AU-027

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.08 µm

D50= 0.1 µm

D90= 0.3 µm

= 0.2 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(1%)

HMS-2017-PM-AU-028

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.07 µm

D50= 0.1 µm

D90= 0.3 µm

= 0.5 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(2%)

HMS-2017-PM-AU-031

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.08 µm

D50= 0.1 µm

D90= 0.6 µm

= 0.5 µm

0,01 0,1 1 10 100

0

2

4

6

8

10

12

14

q [

%]


0

10

20

30

40

50

60

70

80

90

100

LuPO4:Pr3+

(3%)

HMS-2017-PM-AU-032

Cu

mu

lativ

e fr

actio

n u

nd

er s

ize [v

ol-%

]

D10= 0.08 µm

D50= 0.1 µm

D90= 0.4 µm

= 0.4 µm

Results from S. Espinoza, H. Jenneboer, H. Kaetker, and A. Uckelmann



Density [g/cm3] 6.5 4.2

Main peak [nm] 235 225

Luminescence 4f-5d and 4f-4f mainly 4f-5d

GAC overlap [%] 61 69

200 250 300 350 400 450 500 550 600 650 700 750 8000,00

2,50x10-2

5,00x10-2

7,50x10-2

1,00x10-1

Tb3+

Tb3+

Tb3+

Pr3+

: [Xe]4f2- [Xe]4f

2

Pr3+

: [Xe]4f15d

1- [Xe]4f

2

Tb3+

LuPO4

LuPO4:Pr

3+ 0.1%

LuPO4:Pr

3+ 0.25%

LuPO4:Pr

3+ 0.5%

LuPO4:Pr

3+ 1%

LuPO4:Pr

3+ 2%

LuPO4:Pr

3+ 3%

Inte

nsi

ty (

a.u

.)

Wavelength (nm)

6 5 4 3 2 1,54

Energy (eV)

ex= X-ray

50 kV; 2 mA

Tungsten Target

5 Repeats

Radioluminescence of LuPO4:Pr and LaPO4:Pr 100 nm particles

LuPO4:Pr LaPO4:Pr

200 250 300 350 400 450 500 550 600 650 700 750 8000,00

3,50x106

7,00x106

1,05x107

1,40x107

Pr3+

:[Xe]4f2- [Xe]4f

2

Pr3+

: [Xe]4f15d

1- [Xe]4f

2 YPO

4:Bi

3+ UV-C 13/03 (4.2 m)

HMS-2017-AU-SS-103: LaPO4:Pr

3+ (0.1%)


3+ (0.25%)

HMS-2017-AU-SS-105: LuPO4:Pr

3+ (0.5%)


3+ (1%)

Inte

nsi

ty (

a.u.)

Wavelength (nm)

6 5,5 5 4,5 4 3 2,5 2 1,54

Energy (eV)

ex= X-ray

50 kV; 2 mA

Tungsten Target

5 Repeats



First results on cancer cell lines (source: HMS Boston, Dr. M. Purschke)

Combined treatment causes an increased cell inactivation of 65 to 95%.

Combined treatment of cells with LuPO4:Pr3+ and 2 Gy is equivalent to 4 Gy alone

C o n tro lN P s

4 Gy X

-ra y

4 Gy X

-ra y + N

P s

1 0 0 J m

-2 UV C

0

1

2

3

4

5

6

7

1 0

2 0

Ab

so

rb

an

ce

, a

rb

.un

it

a b s = 4 5 0 n m

Cyclobutane pyrimidine dimer

assay as a proof of concept

0 .0 0 .5 1 .0 2 .5 5 .0 7 .5 0 .0 0 .5 1 .0 2 .5 5 .0 7 .51

1 0

1 0 0

C o n c e n tra tio n o f N P s , m g m l-1

Su

rv

ivin

g f

ra

cti

on

, %

0 G y 2 G y

* *

*

*

**

*

Colony formation assay

14 days after irradiation


8. Summary

180 200 220 240 260 280 3000,0

1,5x103

3,0x103

4,5x103

6,0x103

Nd3+

: [Xe]4f25d

1- [Xe]4f

3

Pr3+

: [Xe]4f15d

1- [Xe]4f

2

YPO4:Nd

3+ TL0138

LuPO4:Pr

3+ (3%) d

50 = 100 nm

LuPO4:Pr

3+ (3%) d

50 = 13 m

Inte

nsi

ty (

a.u.)

Wavelength (nm)

7 6 5 4,13

Energy (eV)

ex=160 nm

3 Repeats

UV emitting (nanoscale) materials

Fluorescent Xe Excimer discharge lamps

• Tailored emission spectra possible by VUV UV converter:

(Y,Lu)PO4:Nd, LaPO4:Pr, (Y,Lu)PO4:Pr, YBO3:Pr, BaZrSi3O9, …

• Lamp lifetime limited to ~1000 h yet

• Degradation mechanism clarified

• Improvement of stability of converter by photochemically

deposited Al2O3 particle coatings

• Many application areas, such as disinfection, purification,

photochemistry, NO3- removal, food processing, …

Nanoscale UV emitting phosphors

• Excitation by x- or cathode-rays

• Local emission of harmful UV-C or VUV radiation

• Use for surface disinfection or therapeutic purposes

• Development of quantitative VUV/x-ray to UV-C spectroscopy


UV emitting (Al,Ga)N LEDs and laser diodes

• Spectral range: 220 – 360 nm

• DUV-LED → DUV laser diodes: Challenging!

• Problems: Spectral consistency, efficiency,

radiation out-coupling, mass production,

encapsulation, …..

Fluorescent Xe excimer discharge lamps

• Spectral range: 190 – 700 nm

• Discharge – converter interaction determines yield

& lifetime

• Advantages: Hg-free, fast switchable, high form

factor, temperature independent

• Problems: Driver eff., lifetime, market access, but

UNEP proposed Hg ban rom 2020 onwards …..

8. Outlook


UV emitting nanoscale core-shell particles for biomedical applications

8. Outlook

Diagnostics

Imaging

Therapy

Delivery

Combination of

these applications,

e.g. for magneto-

optical therapy

GdPO4 (core) +

LuPO4:Pr (shell)

Her, S., Jaffray, D.A. and Allen, C., Gold nanoparticles for applications in cancer radiotherapy,

Mechanisms and recent advancements, Advanced drug delivery reviews, 109 (2017) 84


Acknowledgement

• Research Group “Tailored Optical Materials“ Mike Broxtermann, Jan-Niklas Keil, and Sara Espinoza for their dedicated research work

• HMS Boston, MA, USADr. M. Purschke for fruitful discussions

• University of Tübingen, GermanyProf. H.-J. Meyer for fruitful discussions

• Vilnius University, LithuaniaProf. A. Kareiva for exchange of students

• Universiteit Utrecht, The NetherlandsProf. A. Meijerink for fruitful discussions

• BMBF, BMWI, Merck KGaA Darmstadt, Philips Lighting Eindhoven, Berger GmbH, GVB Solutions in Quartz, and Xylem Herford for generous financial support

Design and Degradation of UV Emitting Luminescent …€¢ Solar chemistry → Solar radiation +...

Documents

Transcript of Design and Degradation of UV Emitting Luminescent …€¢ Solar chemistry → Solar radiation +...