Silicon Oxide Modified with Gadolinium and Europium Oxides—Synthesis, Properties and Application Prospects

• Published in: Glass physics and chemistry Vol. 49; no. 2; pp. 150 - 159
• Main Authors: Niftaliev, S. I., Kuznetsova, I. V., Zvereva, I. A., Lygina, L. V., Sinelnikov, A. A., Saranov, I. A., Kim, K. B., Chernenko, S. S.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-04-2023; Springer Nature B.V
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Desiccants; Europium; Europium compounds; Excitation spectra; Gadolinium; Gadolinium oxides; Glass; Kaolin; Materials Science; Moisture effects; Nanoparticles; Natural Materials; Particle size; Photon correlation spectroscopy; Physical Chemistry; Polysaccharides; Silicon dioxide; Silicon oxides; Synthesis; Tetraethyl orthosilicate; Transmission electron microscopy; tetraethoxysilane; silicon oxide; kaolin; gadolinium oxide; europium oxide
• ISSN: 1087-6596; 1608-313X
• DOI: 10.1134/S108765962260096X

The SiO
2
, Gd
2
O
3
–SiO
2
and Eu
2
O
3
–SiO
2
were synthesized by two ways: using the silicon oxide isolated from kaolin and using the silicon oxide obtained by hydrolysis of tetraethoxysilane. Agar-agar (polysaccharide) was added as a structure-forming agent and the freeze-drying was used for obtaining powders. DSC and TG up to 700°С revealed endothermic effects corresponding to the loss of free moisture, the decomposition of metal hydroxide and hydroxogroups (≡Si–OH) from the silica surface. The powders calcined at 700°С are X-ray amorphous. The morphology of the samples was studied using transmission electron microscopy (TEM) and dynamic light scattering (DLS). The hydrodynamic size of the particles synthesized from kaolin, determined using DLS method, exceeds the particle size established by TEM. The hydrodynamic size of the nanoparticles obtained from tetraethoxysilane is within the particle size determined by TEM. The agglomerates formed by particles synthesized from tetraethoxysilane are less strong than those obtained from kaolin. In the Eu
2
O
3
–SiO
2
system obtained using tetraethoxysilane, nanocrystallinity with a particle size of 8–40 nm was detected. The luminescence excitation spectra for the Eu
2
O
3
–SiO
2
samples synthesized by both ways differ in the ratio of the supersensitive
5
D
0
–
7
F
2
and magnetodipole
5
D
0
–
7
F
1
transition bands. For the Gd
2
O
3
–SiO
2
nanopowder obtained from tetraethoxysilane, an increase in the
5
D
0
–
7
F
2
intensity, as well as the appearance of a second
5
D
0
–
7
F
1
peak were observed.