RARE EARTHS CHEMISTRY: SCIENTIFIC, TECHNOLOGICAL AND ...
Transcript of RARE EARTHS CHEMISTRY: SCIENTIFIC, TECHNOLOGICAL AND ...
Faculty of Chemistry, Sofia University, Bulgaria
M. Milanova, D. Todorovsky, N. Minkova, A. Terziev, M. Getsova, G. Tzvetkov, N. Petrova, M. Uzunova,
S. Anastasova, J. Zaharieva, R. Kralchevska,R. Todorovska
RARE EARTHS CHEMISTRY: SCIENTIFIC, TECHNOLOGICAL AND PRODUCTION ACTIVITIES
AT THE DEPARTMENT OF INORGANIC CHEMISTRY, SOFIA UNIVERSITY
Group of Rare and Rare Earth Elements, Est. 1984
Faculty of Chemistry, Sofia University, Bulgaria
Chemistry of rare earth elements
SOLID SOLUTIONS
COORDINATION COMPOUNDS
MECHANOCHEMISTRY
Leaching,separation,purification
Materials,based on REE
SilicatesPolymetallic oxidesModified photocatalystsThin films Optical sensors
RE products
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Plan
Materials based on REE
RE products
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Polymerized complex method, PCM
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Polymerized complex method Problems
Reaction CA /EG Factors influencing the complex compositionsNature of the complexes in bimetallic systems Alcoholic group deprotonationThermochemical behaviour of the complexes; nature of the final precursorApplication of the solutions of complexes for thin film deposition
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Synthesized and characterisedmaterials
Buffer layers for high temperature superconductors (Y2O3, CeO2, YSZ)
Materials of high magnet restriction (LaMnO3, pure/doped with Ca)
Magnet materials (Fe2O3, Y3Fe5O12,(granite), YFeO3, Y3Fe5O12 doped with Al or Се)
Ferroelectrics ( La2Ti2O7, Nd2Ti2O7)
Ionic conductors (Y2Ti2O7 )
Oxygen sensors based on YSZ, doped with Pt nanoparticles (Assoc. Prof. Dimitrov, Assoc. Prof. Dushkin)
Optical oxygen sensors
Photocatalysts based on TiO2, including modified by doping with Lа or by mechanochemical treatment (Assoc. Prof. Dimitrov)
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Deposition of thin films Spray-pyrolysis /PCM (mixed-metal citrates)
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SEM images (8 mol% Y) Т substrate 350oC;additionally annealed at 750оС
On fused quarz On glass
Thin films of Y-stabilized ZrO2 Buffer layers for high temperature superconductors (YBCO)
film on quarz
film on fused silica
powder
XRD
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AFM (5x5 μm), from Ce(Cl)Cit (fused quarz)
AFM (10x10 μm), from Ce(N)Cit (fused quarz)
Thin films of CeO2Buffer layers for high temperature superconductors
size of the grains (250-400)x(120-240) nm from Ce(N)Cit,
Т substrate 500оСfrom Ce(N)Tar
Т substrate 350оС
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Thin films of LaMnO3Materials of high magnet restriction
SEM of manganite films with thickness ~150 nm on SrTiO3, x20 000).
LaMnO3La0,7Ca0,3MnO3
XRD
AFM (6,5x6,5 μm) of LaMnO3 film on SrTiO3
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Thin films of YFeO3Ferromagnetic behaviour,potential UV-Vis photocatalyst
AFM (5x5 μm) of
YFeO3 film on SrTiO3
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Thin films of La-doped TiO2Photocatalysts
SEM images, post deposition heating at 400ºC (a), 500ºC (b,c).
glass graphite stainless steel
Degradation of methylene blue, TiO2:5 mol% La
Ti-coated steel
silica
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Silanes
Tetraethoxy silane(TEOS)
Methyl triethoxysilane(MTEOS)
Octyl-triethoxysilane(OtEOS)
Ru(dpp)32+
Thin films based on SiO2Optical oxygen sensors
[ ]20 1 OКII
SV+=
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SiO2-based filmsEffect of sonication
0
200
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1000
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TEOS TEOS +OtEOS
TEOS +MtEOS
TEOS TEOS +OtEOS
TEOS +MtEOS
Ster
n-V
olm
er c
onst
ants
(n.1
0-3 %
-1)
No sonication Sonication
Gas phase Water
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PMMA films Optical oxygen sensors
SEM
MMA polymerized
PMMA solution
PMMA solution
AFM
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PMMA filmsOxygen in the gas phase
0 20 40 60 80 1000,0
0,5
1,0
1,5
2,0 Ksv = 0,0105
1
I 0/I
Concentration of O2, %0 20 40 60 80 100
0,0
0,5
1,0
1,5
2,0
Ksv = 0,0017
I 0/IConcentration of O2, %
film preparedvia PMMA solution
film prepared via in situpolymerization of MMA
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PMMA filmsDissolved oxygen in water
0 10 20 30 40 50 600,9
1,0
1,1
1,2
1,3I 0/I
Concentration O2, ppm
film preparedvia PMMA solution
KSV=0,0062
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Hybrid matrix, SiO2/polyester Optical oxygen sensors
TEOS/CA/EG = 4 : 1 : 1
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Hybrid matrix, SiO2/polyester
0 20 40 60 80 1000
1
2
3
4
5
I 0/I
Concentration of O2
Ksv =0,0302
0 5 10 15 20 25 30 350,0
0,2
0,4
0,6
0,8
1,0
Concentration of O2, ppmIn
tens
ity, a
. u.
Ksv 0,0198
Oxygen in the gas phase Oxygen dissolved in water
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Ksv, comparison
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
PMMA MMA Hybrid
Ksv
Gas Water
Eu β-diketonates
Immobilization in PMMA matrix
DBM
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Eu(DBM)3oxygen sensitive
500 550 600 650 7000
10
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30
40
50
60
70
80
Inte
nsity
, a. u
.
Wavelenght, nm550 600 650 700 750
0
50
100
150
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250
300
350
400
450
Inte
nsity
, a. u
.
Wavelength, nm
265 μs 75 μs
Powder Immobilized in matrix
AFM ,Eu(DBM)3 in PMMA
AFM ,Eu(DBM)3 in PMMA
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Eu(DBM)3.Phen
500 550 600 650 700 7500
50
100
150
200
Inte
nsity
, a.u
.
W avelength, nm550 600 650 700 750
0
50
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150
200
250
300
350
400
450
Inte
nsity
, a. u
.
Wavelength, nm
Powder Immobilized in matrix
530 μs363 μs
Phen – 1,10-phenathroline
AFM ,Eu(DBM)3.phen in PMMA
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Methods of RE recovery from waste and by-productsProduction routes for some RE compoundsdeveloped and carried out in practice
REE products, Technology and production activities
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Phosphogypsum H3PO4
Mechanochemical RE concentratetreatment
Ca separation
RE concentrate, low Ca
non-RE sepn
REO
RE sources
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Ce separation
Mechano-chemistry
Selective dissolution
Selective precipitation
Ln2O3CeO2
REO treatment
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Solid statecomplexes,
DEHPA
REO/Ln2O3
REO Ln2O3
Extraction
La-Nd Didymium Heavy RE,Eu
LME
La2O3
Nd2O3
Prconcentrate
Concentrate, Eu enriched
Eu2O3
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Pilot facilities
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Some of the products
Product REE yield, % Purity
REE concentrate of low Са content 99 Са<1,5%
RE oxide mixture 98 95-99%
СеО2 94-98 Ln2O3: < 10-2%, other impurities: < 0.1%
Oxide mixture, Се-free Се < 1,5%
Nd2O3 50 99.5%
20 99.9%
Eu2O3 25 99.8%
70 98.5%
Y2O3 70 99.999%
Y2O3 (from YAG) 85 Impurities of Аl
Polishing material 85 Cerox quality
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Thank you!
Dr. Maria Milanova, Assoc. Prof.,
+ 359-2-8161217