Abstract
Abstract Eu-doped barium hafnate powders, BaHfO 3 :Eu, prepared with ceramic method have quite peculiar spectroscopic properties, which can be significantly altered changing the dopant concentration as well as preparation atmosphere. When synthesis is performed in a reducing atmosphere, a fraction of Eu gets reduced and produces a broad-band emission peaking around 480 nm. Due to a partial overlapping of the excitation spectra of Eu 3+ and Eu 2+ luminescence, the emission colour can vary between bluish green, when only Eu 2+ is excited, red when solely Eu 3+ is stimulated and white upon simultaneous excitation of both Eu 3+ and Eu 2+ activator ions around 290 nm. Upon X-ray excitation only Eu 3+ luminescence is produced. Radioluminescence of undoped BaHfO 3 consists of a broad-band peaking around 410 nm, which disappears when Eu enters the host. Materials prepared in a reducing atmosphere do not show any phase separation even for higher Eu concentrations.
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