Positron annihilation in Eu-, Ag-, Er-, and Pr-doped ZnAl₂O₄ studied by modified coincidence Doppler broadening spectroscopy

Modified coincidence Doppler broadening spectroscopy (MCDBS) was used in this study to investigate the electron band structure of zinc aluminate (ZnAl₂O₄/ZAO). The effect of single and co-doping metal elements on the band structure of valence and core electrons was investigated. At the low momenta range, the annihilation of the maximum number of positrons has been done by the electrons of the pure sample, which indicates more annihilation by valence electrons; in contrast, with the addition of metals, the annihilation of positrons is also done by core electrons. The sample containing silver shows the highest participation of core electrons in the process of positron annihilation. If silver and erbium are simultaneously doped in the sample, the highest participation of electrons in the annihilation of positron occurs in values of momentum of about 15 × 10^–3 m_Oc. Using a new arrangement in electronic panels in the MCDBS allows the detection and study of more energetic momentum of core electrons.