Electronic Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2013
Supplementary Information
Experimental details
Four different routes have been optimized for the particles synthesis using the following compounds: tetraethyl
5 orthosilicate (TEOS), calcium nitrate tetrahydrate (CN), ethanol (EtOH, 95%), ammonium hydroxide solution (28%), nitric
acid (65%), citric acid anhydrous (CA), cyclohexane (CH), hexanol (HX), Triton X-100, and Eu(NO3)3·6H2O. All syntheses
were performed at room temperature. For the molar ratios of the reagents see Table S1.
9
1. SSM method based on the standard Stöber method . The hydrolysis of TEOS (silica precursor) was performed in a
water–alcoholic solution in the presence of NH4OH. The reagents were mixed on the magnetic stirrer for 30 min. Then, CN
10 dissolved in a small amount of water was added and the stirring was continued for 6 h.
2. MSM1 method based on the modified Stöber method. First, TEOS was dispersed in a mixture of water and ethanol
with small amount of HNO3 added to obtain the pH≈2. After 1 h of stirring, the sol (Sol1) was slowly added under vigorous
stirring to the solution of water, ethanol, and ammonia (Sol2, pH≈11.5). Then, CN dissolved in a small amount of water
was added and the reaction was continued for the next 8 h. To prepare europium-doped sample, the same procedure
15 was used and europium nitrate was dissolved in water–alcoholic solution at the beginning of the synthesis. At the final
stage of reaction, the mixture was stirred for 20 h.
10(b)
3. MSM2 method, proceeded according to the method described by Hong et al.,
was similar to MSM1, however,
the CA was used instead of HNO3 and CN was added to Sol1 at the beginning of the reaction. Moreover, the ratio between
reagents and solvents was different (Table S1). When Sol1 was dropped into deionized water, the pH of the solution was
20 kept around 11 by keep adding ammonium hydroxide solution. The stirring of the reaction mixture was continued for
20 h.
4. MEM method based on the reverse microemulsion system. First, aqueous solution of CN was prepared. The waterin-oil microemulsion was obtained by mixing this solution (aqueous phase) with cyclohexane (oil phase), Triton X-100
(surfactant), and n-hexanol (cosurfactant). When the emulsion was formed, TEOS was added and the mixture was
25 vigorous stirred for 3 h. Then, by the addition of NH4OH, the polymerization process began. The reaction was allowed to
continue for 21 h.
After syntheses, all powders were separated from the reaction mixture by centrifugation and were washed at least
two times with ethanol and two times with water. In case of MEM synthesis, the powder was washed six times with
ethanol and then water. The samples were dried at 80 C for 24 h and afterwards annealed at 700 C for 2.5 h.
30
The amorphous character of the samples (Fig. S1) was checked by X-Ray Diffraction on a Philips Xpert diffractometer.
The morphology of the powders was analyzed using field emission scanning electron microscopy (FE-SEM, Zeiss Supra
55VP) operated at an acceleration voltage of 3 kV. For the measurements, the samples were put on a carbon tape and
covered with gold layer. For the confirmation of the powders’ chemical composition, energy dispersive X-ray analysis
(EDS) technique was used at an acceleration voltage of 15 kV. TEM studies were performed with the Philips CM120
35 operated at 120 kV. TEM samples were prepared by dipping carbon-coated copper grids into the dispersion of particles in
ethanol followed by drying at room temperature. The average particle sizes, D, were determined based on the
measurement of more than 120 particles from the TEM/SEM micrographs using ImageJ processing software. The particle
size distribution was also analyzed using dynamic light scattering technique (DLS, Nano-ZS, Malvern Instruments) after
ultrasonication of powders in distilled water. The specific surface area, S BET, measurements were obtained using nitrogen
40 adsorption–desorption (77 K) and the Brunauer–Emmett–Teller (BET) algorithm on the Autosorb 1, Quantachrome
Instruments adsorption analyzer.
45
Electronic Supplementary Material (ESI) for Chemical Communications
Table
of compounds
This journal
is ©S1.
TheMolar
Royalratios
Society
of Chemistryused
2013for syntheses of glass particles.
Sample TEOS H2O EtOH HNO3/CA H2O EtOH NH4OH CN
Sol1 Sol1
Sol2 Sol2
SSM
MSM1
MSM1’
Eu:MSM1
MSM2
1
1
1
1
1
68
37
37
37
93
90
30
30
30
28
–
0.05
0.05
0.05
0.17
–
–
47 55
47 55
47 55
1100 –
CH
HX
X-100
MEM
1
50
206
28
7.7
–
SiO2/CaO
%wt
13
5
5
5
>1.5
0.35 75/25
0.35 75/25
0.57 65/35
0.50 67/31.5
0.35 75/25
1.6
0.35
75/25
5
Fig. S1. XRD pattern of MSM1.
10
Fig. S2. SEM pictures of SSM. The arrows in the inset indicate spherical particles.
Electronic Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2013
Fig. S3. SEM pictures of Eu:MSM1 (a) with results of EDS analysis (Au was detected due to the covering gold layer)
(b) and size distribution of particles determined from micrographs (c).