Abstract
Rare earth cation segregation in magnesium aluminate spinel has been imaged and analysed in an aberration corrected scanning transmission electron microscope. The SuperSTEM at Daresbury Laboratory provided evidence for monolayer segregation of europium ions along grain boundaries in spinel. EELS spectra confirmed the Eu to be within 0.5 nm of the grain boundary region. Spinel is a candidate material for hard window applications owing to its excellent transparency, intrinsic hardness, fracture toughness and resistance to thermal and chemical erosion. Rare earth cation doped spinel maintains good transparency throughout visible and near infrared wavelengths.
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