Hydrogen impurity in yttria: Ab initio and mu SR perspectives
authors Silva, EL; Marinopoulos, AG; Vilao, RC; Vieira, RBL; Alberto, HV; Duarte, JP; Gil, JM
nationality International
journal PHYSICAL REVIEW B
keywords TOTAL-ENERGY CALCULATIONS; AUGMENTED-WAVE METHOD; UNIVERSAL ALIGNMENT; ELECTRICAL-ACTIVITY; MUONIUM STATES; OXIDE MUONICS; BASIS-SET; WIDE-GAP; SEMICONDUCTORS; CRYSTALLINE
abstract The incorporation of interstitial hydrogen in yttria was studied by means of ab initio calculations based on density-functional theory (DFT) and muonium spin polarization spectroscopy (mu SR). The density-functional calculations, based on a semilocal functional within the GGA-PBE and a hybrid functional, uncovered multiple geometrical configurations for the neutral, H-0, and the negatively charged, H-, states of hydrogen, thus demonstrating the existence of metastable minimum-energy sites. It was observed that the low-energy configurations for H-0 and H- are similar: they prefer to relax in deep, interstitial sites, whereas the equilibrium configurations for the positively charged state, H+, were bond-type configurations with the hydrogen forming a covalent O-H bond with an O anion. For all neutral and negative configurations, localized defect levels were found inside the gap. Overall, the results for the formation energies obtained by the two different functionals are qualitatively similar; an amphoteric behavior was found for hydrogen after considering the lowest-energy structures for each charge state. The calculated acceptor transition level, obtained by the hybrid functional and seen near midgap, is consistent with mu SR data from literature. The results are consistent with the present mu SR data, where the observed diamagnetic signal is attributed to a donor-like muonium at the oxygen-bonded configurations and the paramagnetic signal to an acceptor-like deep muonium at the interstitial sites.
publisher AMER PHYSICAL SOC
issn 1098-0121
year published 2012
volume 85
issue 16
digital object identifier (doi) 10.1103/PhysRevB.85.165211
web of science category Physics, Condensed Matter
subject category Physics
unique article identifier WOS:000303309700004
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