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μSR comparison of two rare-earth oxides: Lu2O3 and Nd2O3

Authors: R. C. Vilao, Marco C. Alberto, Helena Vieira Alberto, Joao M. Gil, Ricardo B. L. Vieira, Alois Weidinger, James S. Lord

Ref.: 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017) (2017)

Abstract: The broad technological significance of rareearth oxides spans from their role in ceramics technologies [1] up to their use in optical [2] and electronic [3] devices. Hydrogen has an important impact in the properties of oxides, affecting for example the electrical properties by acting as an active dopant or by compensation/passivation. Muonium, as a light pseudoisotope of hydrogen, has become a standard tool to characterize microscopically hydrogen levels and configurations in the several charge states (positively charged, neutral, negatively charged). Rareearth oxides are mostly paramagnetic, and that introduces an additional aspect to the interpretation of the data. Lu O constitutes a notable exception, due to the complete filling of the fshell. The main goal of the present study is the comparison of a magnetic and nonmagnetic material with otherwise similar properties. We present an investigation of the muon spectroscopy data in Nd O (which is paramagnetic) and in Lu O (which is diamagnetic). Transversefield measurements (B=100G) were undertaken at the ISIS Facility from T=8K up to T=650K. A slowlyrelaxing component s dominates in both materials and is assigned to muons thermalizing as at the donor oxygenbound position. The relaxation is consistent with nuclear broadening. There are, however, additional components which clearly differ in the two materials. We investigate these findings with respect to the magnetic/nonmagnetic property as well as under the aspect of slightly different structural properties of the two materials. As will be shown in an accompanying paper to this conference [4], the formation of the final muon configuration is very sensitive to slight differences in the lattice rearrangement following the muon stopping. The conversion of stopped muonium to the final bound configuration may e.g. proceed via an energy barrier and may by slight changes of the barrier height lead to different results. [1] P. Simoncic and A. Navrotsky, J. Am. Ceram. Soc. 90, 2143 (2007) [2] M. Bosund et al., App. Surf. Science 256, 847 (2009) [3] R. Gillen, J. Robertson, Microelectronic Eng. 109, 72 (2013) [4] R. C. Vilao et al., abstract 75 (this conference)