In situ neutron powder diffraction analyses of BaMgAl10O17:Eu2+ phosphor with increasing temperature

In this study, in situ neutron powder diffraction (NPD) analyses were carried out on commercial BaMgAl10O17:Eu2+ (BA M) phosphor with increasing temperature for the first time. The structural parameters of BAM were successfully determined by the Rietveld refinement against NPD data at room temperature, 500, 700, and 900 V, respectively. And nuclear density of 2d site occupying Eu atoms was calculated using maximum entropy method. During the baking process of BAM, it was clear that impurity phase was not identified in BAM up to 900 V. In particular, comparing c/a ratio of BAM before and after in situ measurement, it was certain that c/a ratio obtained after in situ measurement was practically equal to that of the obtained before in situ measurement. That is, after anisotropic thermal expansion of lattice constants with increasing temperature, recovery of c/a ratio has occurred during the cooling period of the baking process. Consequently, remarkable structural change of BAM did not appear tip to 900 degrees C in a structural point of view.