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Stritzinger, Jared T.

Publications and source records attributed to Stritzinger, Jared T..

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

X-ray diffraction, differential scanning calorimetry and evolved gas analysis of aged plutonium tetrafluoride (PuF4)

A 30 year-old PuF4 sample consisting of brown powder (PuF4-b) and pink granules (PuF4-p) was analyzed. X-ray difraction shows the bulk is comprised of three compounds: PuF4, PuO2, and PuF4·1.6H2O. Broadening of PuF4 XRD peaks suggests possible a-damage. After annealing at 650 °C, crystalline PuF4 and PuO2 remain. Thermogravimetric analysis and diferential scanning calorimetry—with simultaneous evolved gas analysis—of the separated PuF4-p and PuF4-b components reveal a distinct sequence of reactions. Dehydration occurs between~90 and 300 °C. Exothermic annealing of the a-damage occurs in two stages: at 350–355 °C and at 555–558 °C. Hydrofuoric acid, fuorine and helium desorb during the frst exotherm. Above 700 °C, PuF4 reacts with PuO2, resulting in oxygen release and mass loss.

PuF4, dsc, differential scanning calorimetry, plut↗
DOE OSTI2019

Origins of the odd optical observables in plutonium and americium tungstates

A series of trivalent f-block tungstates, MW 2 O 7 (OH)(H 2 O) (M = La, Ce, Pr, Nd, and Pu) and AmWO 4 (OH), have been prepared in crystalline form using hydrothermal methods. Both structure types take the form of 3D networks where MW 2 O 7 (OH)(H 2 O) is assembled from infinite chains of distorted tungstate octahedra linked by isolated MO 8 bicapped trigonal prisms; whereas AmWO 4 (OH) is constructed from edge-sharing AmO 8 square antiprisms connected by distorted tungstate trigonal bipyramids. PuW 2 O 7 (OH)(H 2 O) crystallizes as red plates; an atypical color for a Pu( III ) compound. Optical absorption spectra acquired from single crystals show strong, broadband absorption in the visible region. A similar feature is observed for CeW 2 O 7 (OH)(H 2 O), but not for AmWO 4 (OH). Here we demonstrate that these significantly different optical properties do not stem directly from the 5f electrons, as in both systems the valence band has mostly O-2p character and the conduction band has mostly W-5d character. Furthermore, the quasi-particle gap is essentially unaffected by the 5f degrees of freedom. Despite this, our analysis demonstrates that the f-electron covalency effects are quite important and substantially different energetically in PuW 2 O 7 (OH)(H 2 O) and AmWO 4 (OH), indicating that the optical gap alone cannot be used to infer conclusions concerning the f electron contribution to the chemical bond in these systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Cs[Tf 2 N]: a second polymorph with a layered structure

The structural determination of the ionic liquid, caesium bis[(trifluoromethyl)sulfonyl]imide or poly[[μ 4 -bis[(trifluoromethyl)sulfonyl]imido]caesium(I)], Cs[N(SO 2 CF 3 ) 2 ] or Cs[Tf 2 N], reveals a second polymorph that also crystallizes in a layer structure possessing monoclinic P 2 1 / c symmetry at 120 K instead of C 2/ c for the known polymorph [Xue et al. (2002). Solid State Sci. 4 , 1535–1545]. The caesium ions in the cationic layers are coordinated by the sulfonyl groups of the bistriflimide molecules from anion layers while the trifluoromethyl groups are oriented in the opposite direction, forming a non-polar surface separating the layers. The layer direction is (100).

36 MATERIALS SCIENCE↗