Poster presented at the International Symposium on Advanced Complex Inorganic Nanomaterials (ACIN 2011), September 11-14, 2011 - Namur, Belgiu

Barroso, Ignacio

Gómez, Luz Stella

Milošević, Olivera

Rabanal, Maria Eugenia

English

Milošević, Olivera (PhD)

Digital Repository of the Institute of Technical Sciences of SASA

The investigations in the nanoscaled oxide materials doped with rare earths have received great attention in the recent decades because of their huge possibilities in application of Field Emission
Displays (FEDs), Plasma Displays (PDs) and cathode Ray Tubes (CRT). The interest of such materials originates from their extraordinary luminescence, magnetic and catalytic properties.
The processing of europium-doped gadolinia (Gd2O3:Eu) nanostructured particles has been realized using the bottom-up chemical approache by a hot-wall spray pyrolysis technique (SP),
starting from the aerosol of common nitrates precursors. This method offers the possibility for reaching high-purity nanostructured non-agglomerated particles having spherical morphology and
high chemical homogeneity. Moreover, because of extreme synthesis conditions (high heating and cooling rates) the metastable structures can be obtained, as well.
Introduction
I. Barroso a, L. S. Gómez b, M. E. Rabanal a, O. Milosevic c 
aMaterials Science and Engineering and Chemical Engineering Dept. and IAAB, University Carlos III Madrid, Avd. Universidad 30, 
28911 Leganes, Madrid, Spain
bInstitute for the Economic Geology, (CSIC-UCM), Faculty for Geology, Petrology and Geochemical Dept.,  Complutence
University, José Antonio Nováis, 2, 28040, Madrid, Spain
cInstitute of Technical Sciences of the Serbian Academy of Sciences and Arts, K. Mihailova 35/IV, 11000 Belgrade, Serbia
Optical properties of nanostructured particles synthesized
by Spray Pyrolysis route
The particles obtained have a spherical morphology with rough surfaces.
The dense particles are non-aglomerated and have a mean crystallite
and particle size of 20 and 500nm, respectevely.
With increasing temperature of thermal treatments, it is evident the
increase the size of the primary particles.
The detailed study of the crystalline structure and luminescent properties were proceeded for the different europium concentrations (1, 2 and 6at%) by means of XRD, SEM and steady state-
fluorescent spectroscopy. The phase development and structural changes implied the nanocrystalline inner structure (crystallites < 20 nm) and the coexistence of the following crystal phases
for as-synthesized SP samples: two cubic phases, having either a bcc (SG: Ia3) or a fcc (SG: Fm-3m) structure, and a monoclinic phase with the space group (SG) C2/m. In the cubic Ia3
phase the cell parameter was affected by the europium concentration and the thermal treatment temperature, followed with progressive increase in crystallite size. On the other side, the
monoclinic phase concentration decreased after additional thermal treatments. Luminescence measurements have detected the presence of divalent europium near to 480 nm, aside to the
typical trivalent europium spectra. This behavior could explain the increase in the emission intensity in the blue spectral region due to the divalent europium.
Objectives
Experimental
Results
Precursor  common nitrates
solution (0,1M)
Aerosol formation via
ultrasonic atomization
(Three piezoelectric
transducers , 2.1 MHz) -
700ºC, air atmosphere
As-prepared nanoparticles
Thermally treated particles
(800-1100ºC)+  +
300 400 500 600 700 800
0,0
0,2
0,4
0,6
0,8
1,0
5
D
1
-7
F
1
5D0-
7F4
5
D
0
-7
F
3
5D0-
7F2
5
D
0
-7
F
1
5
D
0
-7
F
0
2T2g-
8S7/2
7F0-
5L6
260 280 300
0,000
0,005
0,010
0,015
In
te
n
s
ity
 (
n
o
rm
a
liz
e
d
)
 (nm)
In
te
n
si
ty
 (
n
o
rm
a
liz
e
d
)
 (nm)
 nn0.25 as-prepared
300 400 500 600 700 800
0,0
0,2
0,4
0,6
0,8
1,0
7F0-
5L6
280 300
0,000
0,005
0,010
0,015
In
te
n
si
ty
 (
n
o
rm
a
liz
e
d
)
 (nm)
5 D
1-
7 F
1
5D0-
7F4
5 D
0-
7 F
3
5D0-
7F2
5 D
0-
7 F
1
5 D
0-
7 F
0
2T2g-
8S7/2
In
te
n
si
ty
 (
n
o
rm
a
liz
e
d
)
 (nm)
 nn0.50 as-prepared
300 400 500 600 700 800
0,0
0,2
0,4
0,6
0,8
1,0
5 D
0-
7 F
4
5 D
0-
7 F
3
5 D
0-
7 F
1
5 D
0-
7 F
2
5 D
0-
7 F
1
5 D
0-
7 F
0
2T2g-
8S7/2
260 280 300 320 340
0,0
7F0-
5L6
In
te
ns
ity
 (
n
o
rm
a
liz
e
d
)
 (nm)
In
te
ns
ity
 (
no
rm
al
iz
ed
)
X Axis Title
 nn1.5 as-prepared
The emission spectra show typical Eu3+ 5Do-7Fj (j=0,1,2,3,4) transitions
with dominant red emission at 610nm in addition to a 480 nm peak
attributed to a Eu2+ 2T2g-8S7/2.
Fluorescence measurements have shown the existence of a
crystallographic phase of monoclinic symmetry (C2 / m) centered around
629 nm, which did not appear in XRD measurements.
1000 oC
2% atomic Of Eu
10 20 30 40 50 60 70 80 90
1000ºC
900ºC
800ºC
 
 
In
te
ns
ity
 (a
.u
.)
2 (º)
as prepared
Fm-3m
Ia-3
Two crystalline phases of cubic
symmetry (Ia-3 and Fm-3m)
have been identify in all as-
prepared samples. Additional
thermal treatment lead to the
solely cubic Ia-3 phase.
Europium
content
(% at.)
Stoichiometry Nomenclature Heat
treatment
(ºC/12h)
Ia-3 Fm-3m Crystallite size (Ǻ)
a (Ǻ) a (Ǻ)
1 Gd1.95Eu0.05O3 nn0.25
app 10.8156+0.0060 5.6129+0.0040 115+8
800 10.8154+0.0090 -- 164+14
900 10.8135+0.0013 -- 178+68
1000 10.8140+0.0055 -- 254+24
2 Gd1.90Eu0.10O3 nn0.5
app 10.8448+0.0015 5.5978+0.0027 104+8
800 10.8211+0.0026 -- 154+15
900 10.8176+0.0043 -- 205+17
1000 10.8140+0.0020 -- 359+10
6 Gd1.70Eu0.30O3 nn1.5
app -- -- 118+21
800 -- -- 253+95
900 -- -- 359+26
1000 -- -- 459+24
• Hot-wall aerosol route  (spray pyrolysis) is applied for the synthesis of nanostructured submicronic-sized spherical particles in the Gd2O3:Eu3+ system with 1, 2 and 
6 atomic% of europium.
•Two cubic crystalline phases have been identified in  all as-prepapred samples -Fm-3m and Ia-3; after additional thermal treatment remains only stable cubic phase with
symmetry (Ia-3).
• The use of techniques of steady-state fluorescence emission indicates the coexistence of two different oxidation states for the europium (Eu2+ and Eu3+), fassociated
with the appearance of the monoclinic. Gd2O3:Eu phase that was not identified by XRD measurements. The amount of this phase decreases with the increase of the e of 
heat treatment temperature. 
•The appearance of monoclinic phase is atributed to the extreme synthesis conditions (high heating/cooling rates and short residence time) .
Conclusions
ACKNOWLEDGMENTS: The authors would like to thank the Comunidad Autónoma de Madrid
for the financial support of this work through the ESTRUMAT grant (S2009/MAT-1585), Project
172035, Ministry of Science and Education, Republic of Serbia and University Carlos III-Banco de
Santander, Madrid, Spain Chair of Excellence Grant for 2010 Academic Year.


Optical Properties of Nanostructured Particles Synthesized by Spray Pyrolysis Route

Serbian Academy of Science and Arts Digital Archive (DAIS)

The investigations in the nanoscaled oxide materials doped with rare earths have received great attention in the recent decades because of their huge possibilities in application of Field EmissionDisplays (FEDs), Plasma Displays (PDs) and cathode Ray Tubes (CRT). The interest of such materials originates from their extraordinary luminescence, magnetic and catalytic properties.The processing of europium-doped gadolinia (Gd2O3:Eu) nanostructured particles has been realized using the bottom-up chemical approache by a hot-wall spray pyrolysis technique (SP),starting from the aerosol of common nitrates precursors. This method offers the possibility for reaching high-purity nanostructured non-agglomerated particles having spherical morphology andhigh chemical homogeneity. Moreover, because of extreme synthesis conditions (high heating and cooling rates) the metastable structures can be obtained, as well.IntroductionI. Barroso a, L. S. Gómez b, M. E. Rabanal a, O. Milosevic c aMaterials Science and Engineering and Chemical Engineering Dept. and IAAB, University Carlos III Madrid, Avd. Universidad 30, 28911 Leganes, Madrid, SpainbInstitute for the Economic Geology, (CSIC-UCM), Faculty for Geology, Petrology and Geochemical Dept.,  ComplutenceUniversity, José Antonio Nováis, 2, 28040, Madrid, SpaincInstitute of Technical Sciences of the Serbian Academy of Sciences and Arts, K. Mihailova 35/IV, 11000 Belgrade, SerbiaOptical properties of nanostructured particles synthesizedby Spray Pyrolysis routeThe particles obtained have a spherical morphology with rough surfaces.The dense particles are non-aglomerated and have a mean crystalliteand particle size of 20 and 500nm, respectevely.With increasing temperature of thermal treatments, it is evident theincrease the size of the primary particles.The detailed study of the crystalline structure and luminescent properties were proceeded for the different europium concentrations (1, 2 and 6at%) by means of XRD, SEM and steady state-fluorescent spectroscopy. The phase development and structural changes implied the nanocrystalline inner structure (crystallites < 20 nm) and the coexistence of the following crystal phasesfor as-synthesized SP samples: two cubic phases, having either a bcc (SG: Ia3) or a fcc (SG: Fm-3m) structure, and a monoclinic phase with the space group (SG) C2/m. In the cubic Ia3phase the cell parameter was affected by the europium concentration and the thermal treatment temperature, followed with progressive increase in crystallite size. On the other side, themonoclinic phase concentration decreased after additional thermal treatments. Luminescence measurements have detected the presence of divalent europium near to 480 nm, aside to thetypical trivalent europium spectra. This behavior could explain the increase in the emission intensity in the blue spectral region due to the divalent europium.ObjectivesExperimentalResultsPrecursor  common nitratessolution (0,1M)Aerosol formation viaultrasonic atomization(Three piezoelectrictransducers , 2.1 MHz) -700ºC, air atmosphereAs-prepared nanoparticlesThermally treated particles(800-1100ºC)+  +300 400 500 600 700 8000,00,20,40,60,81,05D1-7F15D0-7F45D0-7F35D0-7F25D0-7F15D0-7F02T2g-8S7/27F0-5L6260 280 3000,0000,0050,0100,015Intensity (normalized) (nm)Intensity (normalized) (nm) nn0.25 as-prepared300 400 500 600 700 8000,00,20,40,60,81,07F0-5L6280 3000,0000,0050,0100,015Intensity (normalized) (nm)5 D1-7 F15D0-7F45 D0-7 F35D0-7F25 D0-7 F15 D0-7 F02T2g-8S7/2Intensity (normalized) (nm) nn0.50 as-prepared300 400 500 600 700 8000,00,20,40,60,81,05 D0-7 F45 D0-7 F35 D0-7 F15 D0-7 F25 D0-7 F15 D0-7 F02T2g-8S7/2260 280 300 320 3400,07F0-5L6Intensity (normalized) (nm)Intensity (normalized)X Axis Title nn1.5 as-preparedThe emission spectra show typical Eu3+ 5Do-7Fj (j=0,1,2,3,4) transitionswith dominant red emission at 610nm in addition to a 480 nm peakattributed to a Eu2+ 2T2g-8S7/2.Fluorescence measurements have shown the existence of acrystallographic phase of monoclinic symmetry (C2 / m) centered around629 nm, which did not appear in XRD measurements.1000 oC2% atomic Of Eu10 20 30 40 50 60 70 80 901000ºC900ºC800ºC  Intensity (a.u.)2 (º)as preparedFm-3mIa-3Two crystalline phases of cubicsymmetry (Ia-3 and Fm-3m)have been identify in all as-prepared samples. Additionalthermal treatment lead to thesolely cubic Ia-3 phase.Europiumcontent(% at.)Stoichiometry Nomenclature Heattreatment(ºC/12h)Ia-3 Fm-3m Crystallite size (Ǻ)a (Ǻ) a (Ǻ)1 Gd1.95Eu0.05O3 nn0.25app 10.8156+0.0060 5.6129+0.0040 115+8800 10.8154+0.0090 -- 164+14900 10.8135+0.0013 -- 178+681000 10.8140+0.0055 -- 254+242 Gd1.90Eu0.10O3 nn0.5app 10.8448+0.0015 5.5978+0.0027 104+8800 10.8211+0.0026 -- 154+15900 10.8176+0.0043 -- 205+171000 10.8140+0.0020 -- 359+106 Gd1.70Eu0.30O3 nn1.5app -- -- 118+21800 -- -- 253+95900 -- -- 359+261000 -- -- 459+24• Hot-wall aerosol route  (spray pyrolysis) is applied for the synthesis of nanostructured submicronic-sized spherical particles in the Gd2O3:Eu3+ system with 1, 2 and 6 atomic% of europium.•Two cubic crystalline phases have been identified in  all as-prepapred samples -Fm-3m and Ia-3; after additional thermal treatment remains only stable cubic phase withsymmetry (Ia-3).• The use of techniques of steady-state fluorescence emission indicates the coexistence of two different oxidation states for the europium (Eu2+ and Eu3+), fassociatedwith the appearance of the monoclinic. Gd2O3:Eu phase that was not identified by XRD measurements. The amount of this phase decreases with the increase of the e of heat treatment temperature. •The appearance of monoclinic phase is atributed to the extreme synthesis conditions (high heating/cooling rates and short residence time) .ConclusionsACKNOWLEDGMENTS: The authors would like to thank the Comunidad Autónoma de Madridfor the financial support of this work through the ESTRUMAT grant (S2009/MAT-1585), Project172035, Ministry of Science and Education, Republic of Serbia and University Carlos III-Banco deSantander, Madrid, Spain Chair of Excellence Grant for 2010 Academic Year.

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Optical Properties of Nanostructured Particles Synthesized by Spray Pyrolysis Route

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