Neodymium (III) in Alumino-Borosilicate Glasses
- BATTELLE (PACIFIC NW LAB)
- ASSOC WESTERN UNIVERSITY
- Savannah River Technology Center
Optical spectroscopic measurement was performed on Al2O3-B2O3-SiO2 glasses containing 7 to 25 mol% Nd2O3 (soluble). The local chemical environment of Nd(III) in glass was systematically studied as a function of the Nd2O3 concentration in the glasses using Judd-Ofelt (J-O) optical oscillator parameters, Omega 2 and Omega 6, that are related to the ligand field symmetry (LFS) and the degree of bond covalency (BC), respectively. Two transition points (TP), in terms of the J-O parameter vs. Nd2O3 concentration, were found for Omega 2 that is sensitive to LFS and Omega 6 that is sensitive to the degree of BC. The first TP is defined by Nd:3(B+Al) and the second is by Nd:3(B+Al+Si). Below the first TP, Omega 2 and Omega 6 were nearly independent of Nd concentration. Between the first and the second TP, 2 and 6 increased and then decreased above the second TP. Reviewing literature data of rare earths in Na2O-B2O3, Na2O-SiO2, Na2O-B2O3-SiO2, and Al2O3-B2O3 systems, we proposed that up to the first TP, Nd preferentially dissolves in the borate sites, composed of two trigonal boron, B(III), and one tetrahedral boron B(IV) where Al(IV) substitutes for B(IV). Further increase in Nd2O3 concentration results in the excess Nd cations,[Nd-3(B+Al)], partitioning to the silicate sites possibly in a form of Nd-Q3, and above the second TP, Nd-Q2 could result at the expense of Nd-Q3 (Qn is the number of bridging oxygens per Si tetrahedron) whereas the concentration of Nd cations in the borate-sites is expected to be unchanged. Crystallization of Nd-silicate above its solubility, 25 -30 mol% Nd2O3, indirectly supports the proposed Nd dissolution mechanisms. The dissolution of rare earth elements in aluminoborosilicate may be best described in terms of their partitioning to these structure groups.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15001196
- Report Number(s):
- PNNL-SA-33159; 820101000; TRN: US200401%%505
- Journal Information:
- Journal of Non-crystalline Solids, Vol. 278, Issue 1-3; Other Information: PBD: 1 Nov 1999
- Country of Publication:
- United States
- Language:
- English
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