Development of energy-saving methods of synthesis of monodisperse particles of rare-earth oxides with 
improved luminescent properties is very vital task. In present work we’ve developed new method of microwave-assisted synthesis of Y2-xGdxO3:Eu solid solutions, performed a study of influence of Y:Gd ratio on 
morphology and luminescent properties of monodisperse oxide particles. We’ve established monotonous 
dependence of mean size of particles on Y:Gd ratio. On the other hand dependence of intensity of luminescence on Y:Gd ratio has a clear maximum.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3490

Chuvashova, I.G.

Gaitko, O.M.

Vanetsev, A.S.

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 1, 01PCN27(2pp) (2012) 
 
 
2304-1862/2012/1(1)01PCN27(2) 01PCN27-1  2012 Sumy State University 
Preparation of Monodisperse Luminescent Particles of Y2-xGdxO3:Eu  
by Microwave-assisted Hydrolysis 
 
A.S. Vanetsev1,*, I.G. Chuvashova1,2,†, O.M. Gaitko1,2 
 
1 Kurnakov Institute of General and Inorganic Chemistry RAS, 31, Leninskii pr-kt, 119991 Moscow, Russia 
2 Lomonosov Moscow State University, 1, Leninskie Gory, 119992 Moscow, Russia 
 
(Received 21 June 2012; published online 24 August 2012) 
 
Development of energy-saving methods of synthesis of monodisperse particles of rare-earth oxides with 
improved luminescent properties is very vital task. In present work we’ve developed new method of micro-
wave-assisted synthesis of Y2-xGdxO3:Eu solid solutions, performed a study of influence of Y:Gd ratio on 
morphology and luminescent properties of monodisperse oxide particles. We’ve established monotonous 
dependence of mean size of particles on Y:Gd ratio. On the other hand dependence of intensity of lumines-
cence on Y:Gd ratio has a clear maximum. 
 
Keywords: Microwave Synthesis, Monodisperse Particles, Luminescent Materials, Rare Earth Oxides 
 
  PACS numbers: 81.20.Fw, 78.55. – m 
 
 
                                                          
* vanetsev@gmail.com  
† irina.chuvashova@gmail.com 
1. INTRODUCTION 
 
New methods of synthesis of monodisperse colloidal 
particles is one of the crucial steps on the way to pro-
duction of various commercial materials including ink, 
cosmetics, different types of coatings and lubricants, 
paper products etc. One of the most important applica-
tions of monodisperse particles is luminescent coatings 
and highly efficient light sources. Among these lumi-
nescent materials, rare earth doped phosphors, for ex-
ample, red luminescent phosphors doped with trivalent 
europium (Eu3+) ions are of technological importance 
because they are widely used in color displays and fluo-
rescent lamps [1]. Microcrystalline yttrium oxide doped 
with Eu3+ (Y2O3:Eu) represents a typical example and 
is considered to be one of the best red phosphors cur-
rently available [2]. These most promising luminescent 
materials at the same time require the largest amounts 
of energy during synthesis. Therefore, development of 
energy-saving methods of synthesis of monodisperse 
particles of rare-earth oxides with improved lumines-
cent properties is very vital task.  
Microwave treatment possesses many advantages 
in comparison with conventional heating methods, in-
cluding higher velocity of heating, homogeneity of heat 
distribution and lower power inputs. One of the main 
merits of microwave treatment, especially in applica-
tion to monodisperse particles synthesis, is volumetric 
and uniform heating which could be used to obtain ma-
terials with controlled morphology and functional prop-
erties. Earlier  we’ve developed method of microwave-
assisted synthesis of monodisperse RE-doped yttria 
powders consisting of spherical particles and pos-
sessing strong luminescence [3]. Comparing to conven-
tional methods of synthesis microwave-assisted process 
allows increasing the yield of reaction dramatically. 
In present work we’ve developed new method of mi-
crowave-assisted synthesis of Y1.95-xGdxEu0.05O3 solid 
solutions and performed a study of influence of Y:Gd 
ratio on morphology and luminescent properties of 
monodisperse oxide particles.  
2. EXPERIMENTAL 
 
As starting compounds for preparation of 
Y1.95-xGdxEu0.05O3 samples (x  0, 0.4, 0.8, 1, 1.2, 1.6, 
1.95) were used Y(NO3)3•6H2O (Aldrich, 99.9  purity), 
Gd(NO3)3•6H2O (Aldrich, 99.9  purity), 
Eu(NO3)3•6H2O (Aldrich, 99.9  purity), urea 
(KhimMed, 99  purity). 0.5 L of solutions with 0.03 M 
total concentration of Y3+, Gd3+ and Eu3+ (in various 
proportions depending on the composition of desired 
product) in deionized water were prepared.  
Water solutions were transferred in 0.5 l flasks and 
exposed to microwave treatment for 3 hours using 
Panasonic NN-SD556M inverter microwave oven (2.45 
GHz, 150 W minimum output power). During the mi-
crowave treatment process of precipitation of solid so-
lution of rare-earth hydroxocarbonates proceeded as 
described in equation (1). 
 
 (Y3+ + Gd3+ + Eu3+) + (NH2)2CO +(3+x)H2O    
   (Y, Gd, Eu)(OH)CO3·xH2O  + 2NH4+ + Н+ (1) 
 
After treatment all samples were centrifuged, 
washed several times with deionized water and air-
dried at 50 C for 10 hours. 
Resulting powders were annealed in laboratory fur-
nace at 700 C for 2 hours to form corresponding oxide 
solid solutions. 
XRD analysis of synthesized samples was pre-
formed using Rigaku D/MAX 2500 diffractometer 
(CuKα-emission). Identification of diffractions peaks 
was carried out using JCPDS PDF2 database. Mor-
phology of samples were studied using Leo Supra 50 
VP scanning electron microscope with acceleration 
voltage 1-10 kV. Photoluminescent properties were 
studied using Perkin Elmer LS-55 spectrometer with 
Xenon lamp as a source of excitation. Powdered sam-
ples were placed on copper carrier. Registration of 
emission was performed using photoelectron multiplier 
in the range of 400-900 nm. 
 
 A.S. VANETSEV, I.G. CHUVASHOVA, O.M. GAITKO PROC. NAP 1, 01PCN27 (2012) 
 
 
01PCN27-2 
3. RESULTS AND DISCUSSION  
 
XRD-analysis showed that all synthesized powders 
after annealing represent corresponding 
Y1.95-xGdxEu0.05O3 solid solution with value of x very 
close to the one put during synthesis. Analysis of shift of 
(222) diffraction peak with increase of x (Fig. 1) allows 
one to see that synthesized solutions obey Vegard’s law. 
As it is known that such solutions of yttrium and gado-
linium oxides are disordered and radii of Y3+ and Gd3+ 
are not very different, this seems to be reasonable result. 
 
 
 
Fig. 1 – Dependence of position of (222) diffraction peak on 
composition of solid solution 
 
Scanning electron microscopy (SEM) showed that all 
synthesized samples consist of spherical particles with 
very narrow size distribution. On Fig. 2 presented typi-
cal micromorphology for synthesized powders. 
 
 
 
Fig. 2 – Morphology of Y1.55Gd0.4Eu0.05O3 particles 
 
Dependence of mean size of spherical particles on 
composition of solid solution (Fig. 3) derived from SEM 
data shows that from pure yttrium oxide to pure gadolini-
um oxide mean size of particles decreases monotonously.  
 
 
Fig. 3 – Dependence of mean size of spherical monodisperse 
particles on composition of solid solution 
 
This most likely is related to the difference in solubility of 
corresponding hydroxocarbonates and, therefore, velocity 
of growth of precipitating particles. 
As Eu3+ ion main luminescent emission band refers 
to symmetry forbidden transition its intensity is very 
sensitive to local symmetry. This most likely is the rea-
son why relative intensity of 5D0  7F2 to 5D0  7F1 for 
these solid solutions has clear maximum near x = 0.5 
(Fig. 4) as this composition corresponds to the most dis-
torted local surrounding of Eu3+ ion in crystal lattice. 
 
 
 
Fig. 4 – Dependence of mean size of spherical monodisperse 
particles on composition of solid solution 
 
Therefore it is possible to state that developed meth-
od of synthesis of Y1.95-xGdxEu0.05O3 solid solutions al-
lows producing powders consisting of monodisperse 
spherical particles which size depends on composition of 
solid solution. Obtained results also show that use of 
solid solutions of yttrium and gadolinium instead of pure 
yttria as luminescent matrix will allow increasing the 
efficiency of luminescence significantly. 
 
AKNOWLEDGEMENTS 
 
The work was supported by Scientific Program for 
Fundamental Research of Presidium of RAS №8 and 
grant of President of Russian Federation for support of 
young scientists (MK-2607.2011.3). 
 
 
REFERENCES 
 
1. G. Blasse, B.C. Grabmaier, Luminescent Materials (Berlin: 
Springer-Verlag: 1994).  
2. C. Feldmann, T. Justel, C.R. Ronda, P. Schmidt, J. Adv. 
Funct. Mater. 13, 511 (2003).  
3. A.S. Vanetsev, E.A. Karpukhina, I.G. Chuvashova, 
O.M. Gaitko, et al., Doklady Chemistry. 435 No1, 289 
(2010). 


English

Preparation of Monodisperse Luminescent Particles of Y2-xGdxO3:Eu  by Microwave-assisted Hydrolysis

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 1, 01PCN27(2pp) (2012)   2304-1862/2012/1(1)01PCN27(2) 01PCN27-1  2012 Sumy State University Preparation of Monodisperse Luminescent Particles of Y2-xGdxO3:Eu  by Microwave-assisted Hydrolysis  A.S. Vanetsev1,*, I.G. Chuvashova1,2,†, O.M. Gaitko1,2  1 Kurnakov Institute of General and Inorganic Chemistry RAS, 31, Leninskii pr-kt, 119991 Moscow, Russia 2 Lomonosov Moscow State University, 1, Leninskie Gory, 119992 Moscow, Russia  (Received 21 June 2012; published online 24 August 2012)  Development of energy-saving methods of synthesis of monodisperse particles of rare-earth oxides with improved luminescent properties is very vital task. In present work we’ve developed new method of micro-wave-assisted synthesis of Y2-xGdxO3:Eu solid solutions, performed a study of influence of Y:Gd ratio on morphology and luminescent properties of monodisperse oxide particles. We’ve established monotonous dependence of mean size of particles on Y:Gd ratio. On the other hand dependence of intensity of lumines-cence on Y:Gd ratio has a clear maximum.  Keywords: Microwave Synthesis, Monodisperse Particles, Luminescent Materials, Rare Earth Oxides    PACS numbers: 81.20.Fw, 78.55. – m                                                             * vanetsev@gmail.com  † irina.chuvashova@gmail.com 1. INTRODUCTION  New methods of synthesis of monodisperse colloidal particles is one of the crucial steps on the way to pro-duction of various commercial materials including ink, cosmetics, different types of coatings and lubricants, paper products etc. One of the most important applica-tions of monodisperse particles is luminescent coatings and highly efficient light sources. Among these lumi-nescent materials, rare earth doped phosphors, for ex-ample, red luminescent phosphors doped with trivalent europium (Eu3+) ions are of technological importance because they are widely used in color displays and fluo-rescent lamps [1]. Microcrystalline yttrium oxide doped with Eu3+ (Y2O3:Eu) represents a typical example and is considered to be one of the best red phosphors cur-rently available [2]. These most promising luminescent materials at the same time require the largest amounts of energy during synthesis. Therefore, development of energy-saving methods of synthesis of monodisperse particles of rare-earth oxides with improved lumines-cent properties is very vital task.  Microwave treatment possesses many advantages in comparison with conventional heating methods, in-cluding higher velocity of heating, homogeneity of heat distribution and lower power inputs. One of the main merits of microwave treatment, especially in applica-tion to monodisperse particles synthesis, is volumetric and uniform heating which could be used to obtain ma-terials with controlled morphology and functional prop-erties. Earlier  we’ve developed method of microwave-assisted synthesis of monodisperse RE-doped yttria powders consisting of spherical particles and pos-sessing strong luminescence [3]. Comparing to conven-tional methods of synthesis microwave-assisted process allows increasing the yield of reaction dramatically. In present work we’ve developed new method of mi-crowave-assisted synthesis of Y1.95-xGdxEu0.05O3 solid solutions and performed a study of influence of Y:Gd ratio on morphology and luminescent properties of monodisperse oxide particles.  2. EXPERIMENTAL  As starting compounds for preparation of Y1.95-xGdxEu0.05O3 samples (x  0, 0.4, 0.8, 1, 1.2, 1.6, 1.95) were used Y(NO3)3•6H2O (Aldrich, 99.9  purity), Gd(NO3)3•6H2O (Aldrich, 99.9  purity), Eu(NO3)3•6H2O (Aldrich, 99.9  purity), urea (KhimMed, 99  purity). 0.5 L of solutions with 0.03 M total concentration of Y3+, Gd3+ and Eu3+ (in various proportions depending on the composition of desired product) in deionized water were prepared.  Water solutions were transferred in 0.5 l flasks and exposed to microwave treatment for 3 hours using Panasonic NN-SD556M inverter microwave oven (2.45 GHz, 150 W minimum output power). During the mi-crowave treatment process of precipitation of solid so-lution of rare-earth hydroxocarbonates proceeded as described in equation (1).   (Y3+ + Gd3+ + Eu3+) + (NH2)2CO +(3+x)H2O       (Y, Gd, Eu)(OH)CO3·xH2O  + 2NH4+ + Н+ (1)  After treatment all samples were centrifuged, washed several times with deionized water and air-dried at 50 C for 10 hours. Resulting powders were annealed in laboratory fur-nace at 700 C for 2 hours to form corresponding oxide solid solutions. XRD analysis of synthesized samples was pre-formed using Rigaku D/MAX 2500 diffractometer (CuKα-emission). Identification of diffractions peaks was carried out using JCPDS PDF2 database. Mor-phology of samples were studied using Leo Supra 50 VP scanning electron microscope with acceleration voltage 1-10 kV. Photoluminescent properties were studied using Perkin Elmer LS-55 spectrometer with Xenon lamp as a source of excitation. Powdered sam-ples were placed on copper carrier. Registration of emission was performed using photoelectron multiplier in the range of 400-900 nm.   A.S. VANETSEV, I.G. CHUVASHOVA, O.M. GAITKO PROC. NAP 1, 01PCN27 (2012)   01PCN27-2 3. RESULTS AND DISCUSSION   XRD-analysis showed that all synthesized powders after annealing represent corresponding Y1.95-xGdxEu0.05O3 solid solution with value of x very close to the one put during synthesis. Analysis of shift of (222) diffraction peak with increase of x (Fig. 1) allows one to see that synthesized solutions obey Vegard’s law. As it is known that such solutions of yttrium and gado-linium oxides are disordered and radii of Y3+ and Gd3+ are not very different, this seems to be reasonable result.    Fig. 1 – Dependence of position of (222) diffraction peak on composition of solid solution  Scanning electron microscopy (SEM) showed that all synthesized samples consist of spherical particles with very narrow size distribution. On Fig. 2 presented typi-cal micromorphology for synthesized powders.    Fig. 2 – Morphology of Y1.55Gd0.4Eu0.05O3 particles  Dependence of mean size of spherical particles on composition of solid solution (Fig. 3) derived from SEM data shows that from pure yttrium oxide to pure gadolini-um oxide mean size of particles decreases monotonously.    Fig. 3 – Dependence of mean size of spherical monodisperse particles on composition of solid solution  This most likely is related to the difference in solubility of corresponding hydroxocarbonates and, therefore, velocity of growth of precipitating particles. As Eu3+ ion main luminescent emission band refers to symmetry forbidden transition its intensity is very sensitive to local symmetry. This most likely is the rea-son why relative intensity of 5D0  7F2 to 5D0  7F1 for these solid solutions has clear maximum near x = 0.5 (Fig. 4) as this composition corresponds to the most dis-torted local surrounding of Eu3+ ion in crystal lattice.    Fig. 4 – Dependence of mean size of spherical monodisperse particles on composition of solid solution  Therefore it is possible to state that developed meth-od of synthesis of Y1.95-xGdxEu0.05O3 solid solutions al-lows producing powders consisting of monodisperse spherical particles which size depends on composition of solid solution. Obtained results also show that use of solid solutions of yttrium and gadolinium instead of pure yttria as luminescent matrix will allow increasing the efficiency of luminescence significantly.  AKNOWLEDGEMENTS  The work was supported by Scientific Program for Fundamental Research of Presidium of RAS №8 and grant of President of Russian Federation for support of young scientists (MK-2607.2011.3).   REFERENCES  1. G. Blasse, B.C. Grabmaier, Luminescent Materials (Berlin: Springer-Verlag: 1994).  2. C. Feldmann, T. Justel, C.R. Ronda, P. Schmidt, J. Adv. Funct. Mater. 13, 511 (2003).  3. A.S. Vanetsev, E.A. Karpukhina, I.G. Chuvashova, O.M. Gaitko, et al., Doklady Chemistry. 435 No1, 289 (2010). 

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Preparation of Monodisperse Luminescent Particles of Y2-xGdxO3:Eu by Microwave-assisted Hydrolysis

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