Search

We have explored the effect of magnetic rare-earth dopants substitutionally incorporated on the Ba sites of BaSnO3 in terms of electronic transport, magnetism, and optical properties. We show that for Ba0.92R0.08SnO3 thin films (where R=La,Pr,Nd,Gd), there is a linear increase of mobility with carrier concentration across all doping schemes. La-doped films have the highest mobilities, followed by Pr- and Nd-doped films. Gd-doped samples have the largest ionic size mismatch with the Ba site and correspondingly the lowest carrier concentrations and electron mobilities. However, crystallinity does not appear to be a strong predictor of transport phenomena; our results suggest that point defects more than grain boundaries are key ingredients in tuning the conduction of BaSnO3 films grown by pulsed laser deposition. Pronounced, nonhysteretic x-ray magnetic dichroism signals are observed for Pr-, Nd-, and Gd-doped samples, indicating paramagnetism. Finally, we probe the optical constants for each of the BaSnO3 doping schemes and note that there is little change in the transmittance across all samples. Together these results shed light on conduction mechanisms in BaSnO3 doped with rare-earth cations.

The discovery of new transition metal (TM) oxide cathodes which can act as intercalation hosts for Mg2+ ions is critical for the development of high energy density Mg-ion batteries. In Li-ion batteries, disordered rocksalts with sufficiently high Li+ charge carrier ion concentration, i.e. Li : TM >1.1, can support fast Li+ diffusion and therefore deliver high capacities (∼300 mA h g−1) and rate performance. Here, we investigate a range of simple Mg-rich disordered rocksalt cathodes, Mg2TMO3 (TM = Mn, Ni, Co), which possess similar charge carrier ion concentrations and similar ratios between the ion size and interstitial tetrahedron height to Li-rich disordered rocksalts. However, even with high carbon loadings, elevated cycling temperatures and reduced particle and crystallite size, no significant Mg2+ deintercalation was observed, indicating that conventional design rules established for Li-rich DRS cannot be simply translated to Mg-rich systems. Despite the lack of activity in Mg-rich oxides, we demonstrate that Mg2+ intercalation into close-packed cubic disordered rocksalts, such as Li2−xMnO2F (x = 1), is possible, opening possible routes to activating Mg-rich systems. [ABSTRACT FROM AUTHOR]

Lithium-rich disordered rocksalts such as Li1.3Nb0.3Mn0.4O2 and Li2MnO2F are being investigated as high energy density cathodes for next generation Li-ion batteries. They can support the (de) lithiation of lithium ions over large compositional ranges while preserving the same overall structure. Here, we present a new Ni-rich oxyfluoride cathode, Li2NiO2F, with a disordered rocksalt structure. Li2NiO2F and can deliver a discharge capacity of 200 mAh g-1 at an average voltage of 3.2 V. [ABSTRACT FROM AUTHOR]