1. Irradiation effects in high melting oxides and
synthesis of new luminescent composite materials
Abu Zayed M. Saliqur Rahman, Dr. Sc.
Department of Mechanical Engineering
University of Malaya
Kuala Lumpur, Malaysia
Seminar at Laboratori Nazionali di Legnaro
Time and Date: 11.00 -12:00
28 June, 2016
Place: Rostagni meeting room

2. Outline of the talk
• Self-introduction
• Introduction
• Purpose of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

3. Self-introduction
• Origin: Bangladesh
• Center of research and life: Japan, China and
Malaysia (last 13 years)

4. 2003-2011
2011-2014
2014- till now

5. Japan

6. RIKEN

7. China

8. Malaysia
Electrodeposition Electromigration
Group dinner

9. Nanoindentation

10. Some family photographs

11. Outline of the talk
• Self-introduction
• Introduction
• Purpose of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

12. Introduction
• Irradiation effects in solids have been studied for quiet a long
period of time as it can modify optical, magnetic and structural
properties of the solid materials.
• Many works are still yet to be done within the field of irradiation
effects in solids compare to other fields in solid state due to
limitation of the experimental and irradiation facilities.
• In recent days, many new composite materials have been
discovered. Irradiation effects in these new composite materials
are unknown which also triggered much more investigation in
this interesting field of research.

13. Importance of irradiation effects in solids:
1) To know the behavior of candidate materials in
irradiating environment such as nuclear reactor, high
energy physics establishment, other irradiation
facilities
2) Irradiation-induced synthesis or fabrication of
nanomaterial or colloids
3) Application in aerospace technology
4) Radiation detection and measurement technology
(Scintillators)

14. • Irradiation effects in alkali halides and metals are
well understood comparing to oxides.
Reason:
Complex nature of oxide crystal structure
and lack of high purity crystal.
• In this study, irradiation effects in two oxides namely
α-Al2O3 and MgAl2O4 are investigated by using
various experimental methods.
• Another important part of this research is to synthesis
of new luminescent composite materials for various
application including radiation detector, outdoor
devices etc.

15. Outline of the report
• Acknowledgement
• Introduction
• Purpose of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

16. Purpose of the study
• To investigate the anion vacancies in neutron- and electron-irradiated
MgO.nAl2O3 single crystals by using photoluminescence techniques.
• To investigate the cation vacancies in fast neutron-irradiated MgO.nAl2O3
single crystals by positron annihilation techniques.
• To investigate irradiation-induced formation of aggregate defects in neutron-
irradiated α-Al2O3 by using near-infrared (NIR) photoluminescence,
scanning electron microscopy (SEM) and optical microscopy(OM).
• To synthesize Sm-doped phosphors using pure Na2SO4 and investigate
irradiation-induced conversion of Sm3+ ions into Sm2+ within Na2SO4.
• To synthesize Sm-doped SiO2-Na2SO4 and LDPE-Na2SO4 luminescent
composite and investigate luminescence properties of these composites.

17. Outline of the report
• Acknowledgement
• Introduction
• Purpose of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

18. Experimental
• Samples
single crystals of α-Al2O3 and MgAl2O4
• Origin
1) Kyoto ceramics (Japan)
2) Crystal Tech (German)
3) Furuuchi Chemical Co. Japan
• Production method
1) Edge-Defined Film-Fed Growth
2) Czochralski Method

19. Synthesis of samples:
• Sm-doped Na2SO4
(Melt-mixing at 950˚ C for 30 mins)
• Sm-doped SiO2-Na2SO4 composite
(Melt-mixing at 1050˚ C for 30 mins)
• Sm-doped LDPE-Na2SO4 composite
Two step synthesis:
1st step synthesis of Na2SO4:Sm phosphor by melt-
mixing at 940˚ C for 20 mins.
2nd step melt-mixing at 150˚ C followed by hot press.

20. Synthesis of phosphor samples at 1050˚C
Samples in crucible after synthesis
Red luminescence from phosphors under
365 nm UV light excitation
No luminescence from host matrix under
UV light

21. • Irradiation (Place)
1) Kyoto University Reactor Research Institute
Linear Accelerator (LINAC), Low temperature loop (LTL) ,
Hydro exposure tube (HET), Gamma ray irradiation facility
2) Japan material testing reactor (JMTR), JAEA
3) Institute of High Energy Physics (IHEP)
4) China Institute of Atomic Energy (CIAE)
• Irradiation (type)
1) Neutron
2) Electron
3) Gamma

22. Irradiation Facility
パラフィン遮蔽
水遮蔽
コンクリート遮蔽
鉛遮蔽
床面 リード線
Liq. He
Liq. N2
試料挿入棒
Heガス
ゲートバルブ
キャナ-ル
真空層
照射ダクト
E-4
Al/SUS 継ぎ手
実験孔
炉心
冷却水
炉壁
試料
重コンクリート
遮蔽プラグ
Heガス戻り
ライン
Heガス送り
ラインSUS製戻り
パイプ
照射試料運搬
ジュワ-
試料落し口
Sample holder (LTL)
Sample holder (HET)

23. Cryostat (13 K- 120 K)
Monochromator
Sample
holder
4B8 beamline facility VUV-UV
Inside sample chamber
Sample chamber

24. Irradiation conditions:
Neutron irradiation:
Irradiation
Facilities
Neutron Flux
(Φf)(n/cm2 s)
Fluence
(n/cm2)
Displacement
per atom
(dpa)
Atmosphere/
irradiation
temperature
(K)
Japan Materials
Testing Reactor
(JMTR)
6.3×1013 1.2×1020 6.4×10-2 He/470
Hydraulic Exposure
Tube
3.9×1013 7.0×1017~
2.8×1018
3.7×10-4
~1.5×10-3
He/360
Low Temperature
Loop (LTL)
4.8×1011 1.3×1017 6.9×10-5 He/20
Electron Irradiation :
Flux: 1.6×1014 e/cm2·sec Fluence: 5.8×1018 e/cm2 Energy: 30 MeV LNT KURRI-LINAC
Flux: 7.8×1011 e/cm2·sec Fluence: 6.7×1014 e/cm2 Energy: 1.9 GeV RT IHEP
60Co γ-ray Irradiation:
Dose: 0-50 kGy ambient temperature KURRI & CIAE

25. Samples (before and after neutron-irradiation):
MgAl2O4
α-Al2O3
Non-irrad LTL HET JMTR
JMTR
HET LTL Unirrad

26. Measurement Techniques:
• Vacuum ultraviolet (VUV) Spectroscopy
4B8 Beamline of Beijing synchrotron radiation facility (BSRF)
( Photoexcitation, Photoemission spectra, measuring temperature 13 K~ 120 K,
290 K)
• UV-Vis luminescence spectroscopy
• Near-infrared (NIR) photoluminescence spectroscopy
Measuring temperature (13 K- 290 K)
• UV-Vis spectroscopy
• Positron lifetime spectroscopy
•
• Coincidence Doppler broadening (CDB)
• X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX),
Scanning Electron Microscopy (SEM) & Optical Microscopy (OM)

27. Optical Measurement System
1 Power Supply
2 Light Source
3 Shutter
4 Slit
5 Concave mirror
6 Flat mirror
7 Monochromator
8 Lens (Quartz)
9 Filter
10 Lens (Short focus)
11 Sample
12 Photomultiplier
13 DC voltage Power
14 Grating
Light source
Sample
Emission
monochromator
itation
nochromator
PL measurement system

28. Excitation Spectra
Light source
Ｓａｍｐｌｅ
Selecting the
best wavelength
Changing the
wavelength
Wavelength (nm)
P
L
I
N
T.

29. Emission Spectra
Light Source
Sample
Excite with some
selected
wavelength
Reception of light signal by PMT in computer
Detecting wide
rang of visible
light from the
sample
Wavelength (nm)
P
L
I
N
T.

31. Outline of the report
• Acknowledgement
• Introduction
• Purpose of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

32. Some experimental results and
discussion

33. MgAl2O4 (VUV-UV spectroscopy)
Fig.1 VUV-UV photoexcitation (left) and photoluminescence
(right) spectra of irradiated and unirradiated MgO.nAl2O3 (n =
2). Electron- (a), neutron-irradiated (b) and unirradiated (c)
samples. Observation wavelength: 476 nm. Excitation
wavelength: 219 nm.
Fig. 2 Photoexcitation spectra of neutron-irradiated and unirradiated
spinel samples at room temperature. Observation wavelength: 476 nm.
Fig. 3 Vibronic photoexcitation (left) and emission spectra of electron-
(a), neutron-irradiated (b) and (c) unirradiated spinel samples at 13 K.
Observation wavelength : 380 nm. Excitation wavelength: 240 nm.
Fig. 4 Vibronic photoexcitation spectra of neutron-irradiated spinel at
13 K, monitored at (a) 380 (b) 400 (c) 430 and (d) 465 nm.

34. Fig. 5 Vibronic photoexcitation spectra of neutron-irradiated
sample at temperatures 13 to 120 K. Observation wavelength:
380 nm.
Band
(Excitation)
Line
no.
Wavelength
(nm)
Wavenumber
(cm-1)
Energy
separation
(cm-1)
Huang-
Rhys
factor
Debye
Temp.
(K)
230 nm
0
1
2
3
271.3
264.8
260.5
254.0
36,860
37,764
38,388
39,370
0
904
624
982
2.78 518
Table 1: Sharp lines associated with 230 nm photoexcitation band, estimated Huang–Rhys factor
and Debye temperature.

35. Fig. 6 Estimation of Debye temperature and Huang
Rhys factor S from temperature dependence of the
230 nm vibronic photoexcitation band by curve
fitting method.
Fig. 7 Schematic diagram of F-center transition in
irradiated MgO.nAl2O3 (n= 2)
Is/Ib=exp[-S{1+2π2/3×(T/ΘD)2}]

36. MgAl2O4 (Positron annihilation spectroscopy)
Fig. 8 Positron lifetimes and intensities of long lifetimes in
fast neutron-irradiated MgO .nAl2O3(n = 2)
Fig. 9 CDB ratio curves of fast neutron-irradiated and unirradiated
spinel to pure Al. Peak was found approximately at 11×10-3 m0c.
Fig. 10 Schematic diagram of positron trapped in vacancy
and vacancy-oxygen complex in spinel crystal structure.

37. MgAl2O4 (NIR novel PL band)

38. Fig. 11 AFM (a,b) and SPM (c,d) 3-D images of
surface for unirradiated (a,c) and neutron-
irradiated (b,d) spinel single crystal. Scaling of
AFM and SPM images are 5×5 and 4 ×4 µm
respectively
Fig. 12 NIR photoluminescence spectra of
neutron-irradiated (JMTR) spinel single crystal
at temperatures ranging from 13.6 to 300 K.
The excitation wavelength was 532 nm.

39. Fig. 14 Temperature dependence of
photoluminescence intensity of the 1,685
nm band obtained from Fig. 3.
Experimental data points were fitted with
curves using Eqn. 1 and 2.
Fig. 13 NIR photoluminescence spectra of
neutron-irradiated (JMTR) spinel single
crystal at temperatures ranging from 13.6
to 300 K. The excitation wavelength was
532 nm

40. ɑ-Alumina (SEM & OM)
Fig. 15 Optical micrographs of unirradiated (a) and fast
neutron-irradiated (b-f) α-Al2O3 samples. Fast Neutron
fluence was 2.8 × 1018 n/cm2.
Fig. 16 SEM images of unirradiated (a) and fast neutron-
irradiated (b-c) α-Al2O3 samples to fluence of 2.8 × 1018
n/cm2 after annealing at 1100˚C.

41. Alumina (NIR PL and UV-Vis)
Fig. 17 NIR PL spectra of (a) unirradiated, fast neutron-
irradiated with fluence of (b) 1.3 ×1017 (c) 2.8 ×1018 (d) 9.8
×1018 (e) 1.2 × 1020 and (f) annealed α-Al2O3 samples.
Excitation source was fixed at 532 nm.
Fig. 18 NIR PL spectra of fast neutron-irradiated α-Al2O3
samples with Gaussian curve fitting. Fast Neutron fluence
was 2.8 × 1018 n/cm2.

42. Fig. 19 NIR PL spectra of neutron-irradiated α-Al2O3 at temperatures
ranging from 13.6 to 300 K. Excitation wavelength was 532 nm.
Fig. 21 Temperature dependence of PL peak energy (a), PL intensity and
FWHM (b) near 1,170 nm emission band in neutron-irradiated α-Al2O3.
Fig. 20 Optical absorption spectra of unirradiated and neutron-
irradiated α-Al2O3 at room temperature.

43. Na2SO4:Sm (SEM & XRD)
Fig. 22 3D crystal structure of Na2SO4.
Fig. 23 SEM image of the Na2SO4:SmF3 phosphor.
Fig. 24 XRD patterns of (a) undoped Na2SO4, (b) Na2SO4:SmF3
and (c) electron-irradiated Na2SO4:SmF3 at room temperature.
Particle size calculation d = 0.9λ/β cos θ

44. Fig. 25 PL spectra of (a) as-synthesized, (b-d) γ-ray-
irradiated (e) electron-irradiated Na2SO4:SmF3 at room
temperature, obtained under 375 nm excitation.
Fig. 26 PL spectra of (a) electron-irradiated, (b-f) γ-ray-
irradiated and (e) as-synthesized Na2SO4:SmF3 at room
temperature, obtained under 570 nm excitation.

45. Fig. 27 PE (left) and PL (right) spectra of -ray (44 kGy)
irradiated Na2SO4:SmF3 at 10 K. PE spectrum was obtained
by monitoring the luminescence at 728.4 nm, and PL
spectrum was obtained under 590 nm excitation.
Fig. 28 Schematic energy levels of (a) Sm2+ and (b) Sm3+
(4f5) in the Na2SO4 lattice. Arrows show the excitation and
emission transitions.

46. Fig. 29 Relative PL intensities of Sm2+ (●) and Sm3+ (o) of γ-ray-
irradiated Na2SO4:SmF3 at room temperature as a function of γ-ray
exposure. PL intensities of Sm2+ band and Sm3+ line at 598 nm were
plotted. Straight line (red) represents the linear t and curved line
(blue) was drawn as guide for an eye.
Fig. 30 PL spectra of electron-irradiated Na2SO4:SmF3 at room
temperature after annealing at various temperatures. These were
obtained under 570 nm excitation.

47. Sm-doped SiO2-Na2SO4 composite
(XRD & SEM)
Fig. 31 XRD spectra of (a) SiO2 (b)SiO2-20%Na2SO4:Sm and (c) Na2SO4.
Fig. 32 SEM images of (a) & (b) SiO2-20%Na2SO4:Sm
composite with scale bar of 50 and 2 μm, respectively. inset
(a): synthesized composite shows red emission under UV
light. SEM images of (c)& (d) SiO2, inset (c) : no emission
from host under UV light.

48. Fig 33 (a) PE (left) and PL spectra (right) of Na2SO4:Sm. (b) PE (left)
and PL (right) spectra of SiO2-20%Na2SO4:Sm. Excitation and
emission spectra (red line) for SiO2 was given for comparison.
Observation wavelength: 644 nm. Excitation wavelength: 375 nm.
Fig. 35 (a) PL spectra of SiO2-x%Na2SO4:Sm (x=0,5,10,20) under
excitation at 402 nm. (b) Schematic energy levels of Sm3+ (4f5) in
composite materials. Arrows show the excitation and emission
transitions.
Fig. 34 (a) PL spectra of 644 nm band
under 402 nm excitation for SiO2
and SiO2-x%Na2SO4:Sm (x=5,10,20).
(b) Relative PL intensities of the 644
nm band.

49. LDPE-Na2SO4:Sm composite (XRD, SEM & EDX)
Fig. 36 Photograph of synthesized Sm-doped LDPE-Na2SO4
composite, pure and commercial LDPE. .
Fig. 37 XRD patterns of LDPE- xwt%Na2SO4:Sm composites
(x =0, 5, 10, and 20) and pure Na2SO4:Sm.
Fig. 38 SEM images of a: Na2SO4:Sm3+ phosphor powders b: the pure
LDPE; c: LDPE-5% phosphor composite; d: LDPE-10% phosphor
composite; e: LDPE-20% phosphor composite; f: EDX of LDPE-20%
Na2SO4:Sm3+ composite.

50. Fig. 39 Excitation spectra (left) and emission spectra
(right) of a: pure LDPE; b: LDPE-5%Na2SO4:Sm
composite. c: LDPE-10%Na2SO4:Sm; d : LDPE-
20%Na2SO4:Sm composite.
Fig. 40 (a) PL spectra of the 644nm band for LDPE-
x%Na2SO4:Sm3+ composite (x =0, 5, 10, 20). (b) Relative
intensities of the 644 nm peak in the composites.

51. Outline of the report
• Acknowledgement
• Introduction
• Purposes of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

52. Conclusions
Main Findings of this study are as follow:
• New vibronic photoexcitation band was observed in neutron- and electron-
irradiated MgO.nAl2O3 single crystals.
• New NIR emission band at a range of 0.8 to 3.0 μm was observed in neutron-
irradiated α-Al2O3 and MgAl2O4which was suggested as F aggregate centers.
The band appeared only after neutron-irradiation at a temperature above room
temperature.
• Anomalous temperature dependence was also observed for the new NIR
emission band in neutron-irradiated α -Al2O3.
• Synthesis of samarium-doped SiO2-Na2SO4 and LDPE-Na2SO4 luminescent
composite was done successfully. Luminescence properties of these new
luminescent composites were also investigated.

53. Outline of the report
• Acknowledgement
• Introduction
• Purposes of the study
• Experimental
• Results and discussion
• Conclusions
• Research accomplishment

54. Research Accomplishment
Publications in Refereed Journal:
10) A. Z. M. S. Rahman, A. S. M. A. Haseeb, Q. Xu, J. Evslin and M. Cinausero, Laser excited novel
near-infrared photoluminescence band in fast-neutron-irradiated MgO.nAl2O3, Radiation Physics
and Chemistry, Vol. 125, pp. 122-126. 2016. doi:10.1016/j.radphyschem.2016.04.001 .
9) A. Z. M. S. Rahman, X. Cao, B. Wang, J. Evslin, Q. Xu and K. Atobe, Synchrotron VUV-UV and
Positron Lifetime Study of Vacancy-Type Defects in Reactor Neutron-Irradiated MgOn Al2O3
(n=2), Cogent Physics, Vol. 3, 1133481, pp. 1-8. 2016. doi:10.1080/23311940.2015.1133481
8) J. Zhang, A. Z. M. S. Rahman, Y. Li, J. Yang, Y. Wu, D. Yuan, X. Cao, R. Yu and B. Wang.
Radiation induced modifications on structural and luminescence properties of LDPE-Na2SO4:Sm3+
composites by gamma-ray, Optical Materials, Vol. 42, pp. 251-255, 2015.
doi:10.1016/j.optmat.2014.12.041
7) A. Z. M. S. Rahman, L. Wei, T. Yang, Q. Xu and K. Atobe, Anomalous temperature dependence of
near infrared photoluminescence band in neutron-irradiated α-Al2O3. Physica Status Solidi A:
Applications and Materials Science, 2014, doi:10.1002/pssa.201330660
6) A. Z. M. S. Rahman, X. Cao, L. Wei, B. Wang, H. Ji, T. Yang, Q. Xu and K. Atobe, Neutron-
irradiation-induced near-infrared emission in ɑ-Al2O3. Philosophical Magazine Letters, Vol. 94,
No. 2, pp. 211-216, 2014. doi:10.1080/09500839.2014.885180.
5) A. Z. M. S. Rahman, Z. Li, X. Cao, B. Wang, W. Long, Q. Xu and K. Atobe, Positron annihilation
study of vacancy type defects in fast neutron-irradiated MgO.n Al2O3. Nuclear Inst. and Methods in
Physics Research B, Vol. 335, pp.70-73, 2014. doi:10.1016/j.nimb.2014.06.002
4) J. Zhang, A. Z. M. S. Rahman, Y. Li, J. Yang, B. Zhao, E. Lu, P. Zhang, X.Cao, R. Yu and B. Wang,
Synthesis and luminescence properties of Sm-doped LDPE-Na2SO4 composite material. Optical
Materials, Vol. 36, Issue 2, pp. 471-475, 2013. doi:10.1016/j.optmat.2013.10.011.

55. 3. A. Z. M. S. Rahman, X. Cao, L. Wei, B. Wang, Y. Tao, Q. Xu and K. Atobe. Vibronic
Photoexcitation Spectra of Irradiated Spinel MgO.nAl2O3 (n=2) at Low Temperatures. Nuclear
Inst. and Methods in Physics Research B, Vol. 305, pp. 33-36. 2013.
doi:10.1016/j.nimb.2013.03.057.
2. A. Z. M. S. Rahman, X. Cao, L.Wei, B.Wang and H.Wu. Luminescence properties of
samarium-doped SiO2-Na2SO4 composite. Materials Letters. Vol. 99, pp. 142-145, 2013.
doi:10.1016/j.matlet.2013.02.078
1. A. Z. M. S. Rahman, X. Cao, L. Wei, B. Wang, R. Yu, Z. Chen, G. An, A. Sidike. Irradiation-
induced valence conversion of samarium ions in Na2SO4. Applied Physics A: Materials Science &
Processing. Vol. 111, Num. 2, pp: 587-591. 2013. doi:10.1007/s00339-012-7266-y
Conference Publications:
2. A. Z. M. S. Rahman, X. Cao, Z. Li, R. Yu, B. Wang, L. Wei, Q. Xu and K. Atobe, VUV-UV
and positron annihilation spectroscopic study of the irradiation induced defects in MgO.nAl2O3
(n=2), 1st China-Japan Joint Workshop on Positron Science, Oral. pp.11-12, Wuhan, China,
October, 2012.
1. A. Z. M. S. Rahman, X. Cao, P. Zhang, Z. Li, R. Yu, B. Wang, L. Wei, T. Awata and Q. Xu.
Possibility of Irradiation induced microstructure formation in α-Al2O3 , 11th Conference of China
Positron Spectroscopy Society, Oral. pp. 72-74, Sichuan, China, September, 2012.

56. Acknowledgements
• Dr. Marco Cinausero, INFN-LNL
• Chinese Academy of Sciences Young
International Scientist Fellowship
• Natural Science Foundation of China
• High Impact research grant, University of
Malaya, Ministry of Higher Education,
Malaysia
• Ministry of Education MEXT, Japan

57. Thank you! Grazie!