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Materials Data on NbS3 by Materials Project

NbS3 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one NbS3 sheet oriented in the (1, 0, -1) direction. there are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 8-coordinate geometry to eight S+1.67- atoms. There are a spread of Nb–S bond distances ranging from 2.52–2.61 Å. In the second Nb5+ site, Nb5+ is bonded in a 8-coordinate geometry to eight S+1.67- atoms. There are a spread of Nb–S bond distances ranging from 2.49–2.85 Å. In the third Nb5+ site, Nb5+ is bonded in a 8-coordinate geometry to eight S+1.67- atoms. There are a spread of Nb–S bond distances ranging from 2.52–2.63 Å. There are nine inequivalent S+1.67- sites. In the first S+1.67- site, S+1.67- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and one S+1.67- atom. The S–S bond length is 2.11 Å. In the second S+1.67- site, S+1.67- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and one S+1.67- atom. In the third S+1.67- site, S+1.67- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and one S+1.67- atom. The S–S bond length is 2.08 Å. In the fourth S+1.67- site, S+1.67- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and one S+1.67- atom. In the fifth S+1.67- site, S+1.67- is bonded in a 4-coordinate geometry to four Nb5+ atoms. In the sixth S+1.67- site, S+1.67- is bonded in a distorted L-shaped geometry to two equivalent Nb5+ atoms. In the seventh S+1.67- site, S+1.67- is bonded in a distorted trigonal non-coplanar geometry to three Nb5+ atoms. In the eighth S+1.67- site, S+1.67- is bonded in a distorted trigonal non-coplanar geometry to three Nb5+ atoms. In the ninth S+1.67- site, S+1.67- is bonded in a 4-coordinate geometry to four Nb5+ atoms.

36 MATERIALS SCIENCE↗

Synergy in Materials: Leveraging Phosphosilicate Waste Forms for Electrochemical Salt Waste

Here, waste forms containing glassy and crystalline phosphate and silicate phases were produced to immobilize salt waste simulants from pyroprocessing and characterized by using Raman spectroscopy, Mössbauer spectroscopy, X-ray diffraction, scanning electron microscopy, heat capacity, and chemical durability measurements. In this work, a phosphosilicate waste form is presented to leverage the benefits of both borosilicate glasses and iron phosphate glasses. To improve waste loading, prior to immobilization, salt simulants were successfully dechlorinated using ammonium dihydrogen phosphate, mixed with a borosilicate frit (5–30 wt %) and Fe 2 O 3 , and vitrified. Additions of 2.5–15 wt % borosilicate glass (NBS3) improved normalized release rates for Cs relative to iron-phosphates without NBS3, resulting in chemical durabilities similar to high-level waste borosilicate glass reference materials. The release rates of the alkalis (i.e., Li, Na, K, Cs) were the lowest with the addition of 5 wt % NBS3. Although Sr was not specifically targeted in this study, evidence exists that it preferentially partitioned with Si to form an amorphous droplet phase within the iron phosphate glass matrix.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗