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DOE OSTI2021

Ca2+-Doped CeBr3 Scintillating Material

2021 ANS Annual Meeting Conference Papers; June 13-16, 2021 | Omni / Convention Center | Providence, RI; https://epsr.ans.org/meeting/?m=310

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Active Tuning of Optical Constants in the Visible–UV: Praseodymium-Doped Ceria—a Model Mixed Ionic–Electronic Conductor

Mixed ionic-electronic conductors offer chemical and electrical means for active tuning of their optical constants, e.g. with variations in oxygen non-stoichiometry in Pr 0.1 Ce 0.9 O 2-δ , enabling implementation of adaptive thin film optical devices. Here, we demonstrate in-situ chemo-tuning of the extinction coefficient in Pr 0.1 Ce 0.9 O 2-δ at elevated temperatures and provide a tuning model that treats the interdependence of mobile oxygen vacancies and small polarons coupled to variations in optically active praseodymium ions. Further, a new means for electro-tuning of the optical constants of mixed ionic-electronic conductors was demonstrated experimentally and modeled for Pr 0.1 Ce 0.9 O 2-δ thin films deposited on grid-like electrode structures. Modeling of non-steady state optical transmittance modulations in the latter allows for estimation of oxygen vacancy mobility that determines the switching speed of the device. Quenched-in values of nr and k to room temperature become nonvolatile, providing a modulation range in the extinction coefficient of Δk ~0.1 (change of ~800%) and in the refractive index of Δn r ~0.1 (relative to initial n r of ~2.35). Key figures of merit including, transmission optical modulation of ~0.04 per 1 mV nm -1 , switching energy per area of 670 pJ μm -2 and switching times of seconds, were demonstrated, with further improvements possible.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Sn doping on partially dealuminated Beta zeolite by solid state ion exchange for 5‐hydroxymethylfurfural ( 5‐HMF ) production from glucose

Abstract BACKGROUND The conversion of glucose into 5‐hydroxymethylfurfural (5‐HMF) involves the isomerization of glucose to fructose catalyzed by Lewis acid and subsequent dehydration of fructose catalyzed by Brönsted acid. In this work, in order to obtain a high yield of 5‐HMF, a series of Sn‐Al‐Beta catalysts containing both Lewis and Brönsted acid sites were prepared by a convenient solid state ion exchange (SSIE) method using partially dealuminated Beta zeolite and tin(II) acetate. RESULTS The obtained bifunctional catalysts were investigated for one‐pot production of 5‐HMF from glucose in the ionic liquid (IL) [C 4 mim]Cl. Among various catalysts, Sn‐Al‐Beta‐ 4 ‐ 8 exhibited the best catalytic performance, giving a 5‐HMF yield of 54% under optimal reaction conditions (393 K, 2 h), along with a glucose conversion of 81%. The Sn‐Al‐Beta‐ 4‐8 catalyst and IL were regenerated by the extraction of 5‐HMF, and the reactivity was reserved after five runs of recycling. In addition to glucose, the Sn‐Al‐Beta‐ 4‐8 /[C 4 mim]Cl system was also proven to have the potential to effectively convert other carbohydrates into 5‐HMF. CONCLUSION The results suggested that the catalyst is convenient to prepare and has preferable efficiency and stability in the conversion of carbohydrates into 5‐HMF. © 2022 Society of Chemical Industry (SCI).

Zhang, Wei↗
DOE OSTI2024

Atomically Dispersed Ru-doped Ti 4 O 7 Electrocatalysts for Chlorine Evolution Reaction with a Universal Activity

Chlorine has been supplied by the chlor-alkali process that deploys dimensionally stable anodes (DSAs) for the electrochemical chlorine evolution reaction (ClER). The paramount bottlenecks have been ascribed to an intensive usage of precious elements and inevitable competition with the oxygen evolution reaction. Herein, a unique case of Ru 2+ -O 4 active motifs anchored on Magnéli Ti 4 O 7 (Ru-Ti 4 O 7 ) via a straightforward wet impregnation and mild annealing is reported. The Ru-Ti 4 O 7 performs radically active ClER with minimal deployment of Ru (0.13 wt%), both in 5 m NaCl (pH 2.3) and 0.1 $\tiny{M}$ NaCl (pH 6.5) electrolytes. Scanning electrochemical microscopy demonstrates superior ClER selectivity on Ru-Ti 4 O 7 compared to the DSA. Operando X-ray absorption spectroscopy and density functional theory calculations reveal a universally active ClER (over a wide range of pH and [Cl - ]), through a direct adsorption of Cl - on Ru 2+ -O 4 sites as the most plausible pathway, together with stabilized ClO* at low [Cl - ] and high pH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Modulational instability in oppositely doubled-doped directed couplers with a non-kerr-like nonlinear refractive-index change

We theoretically investigate modulation instability (MI) in a two-core nonlinear oppositely directed coupler with a negative-index material channel in the presence of a non-kerr-like nonlinear refractive-index change. Using linear stability analysis, we obtain an expression for the instability gain. It is found that the MI in the nonlinear two-core oppositely directed coupler is significantly influenced by the ratio of the forward- to backward-propagating wave power, nonlinearity, power and saturation. In the normal dispersion regime, the septic nonlinearity is found to suppress the MI by reducing both the gain and width of the instability nonlinearity. But in anomalous dispersion regime, the situation is different because septic nonlinearity enhances the MI by increasing both the gain and width of MI. The increase of septic nonlinearity both in normal and anomalous dispersion regimes increases the gain of the instability nonlinearity. Thus, we report new ways to generate and manipulate the MI and solitons in two-core oppositely directed couplers with a particular emphasis on a negative-index material (NIM) channel in presence of septic nonlinearity.

36 MATERIALS SCIENCE↗