Positron Annihilation Spectroscopy of KCl (Zn) crystals

• Published in: Applied radiation and isotopes Vol. 166; p. 109330
• Main Authors: Biganeh, A., Kakuee, O., Rafi-Kheiri, H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2020
• Subjects: Cation vacancy; Positron annihilation spectroscopy (PAS); Potassium chloride; Cation vacancy; Potassium chloride; Positron annihilation spectroscopy (PAS)
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2020.109330

Four samples of nominally pure KCl crystals and doped with Zn2+ impurities are grown by the Czochralski method and characterized by X-ray diffraction and Proton Induced X-ray Emission techniques. Positron Annihilation Lifetime Spectroscopy (PALS) is performed to obtain information on the cation vacancy type defects and their evolution under doping. The results of the PALS experiment indicate that doping KCl by Zn2+ ions, at first increases the concentration of mono vacancies and in the second stage leads the creation of divacancy sites. Coincidence Doppler Broadening Spectroscopy (CDBS) is carried out to obtain the chemical environment of positron annihilation sites. The results of CDBS show that cation vacancies have a significant role in the annihilation process. An interesting observation is the participation of Zn2+ cations in the positron annihilation process which confirms that positrons are not completely localized on the anion sites. The internal consistency between the results of PALS and CDBS experiments is also clarified.
•PAS demonstrates the formation of cation vacancy sites in KCl (Zn2+) crystals.•PAS parameters which are related to the cation vacancies are determined.•Evolution of the cation vacancies under doping is investigated by PALS technique.•CDBS reinforces on the extended rather than localized positron in ionic crystals.