Luminescence, structure and antiferroelectric-type phase transition in Ca8ZnEu(PO4)7. (August 2018)

• Record Type: Journal Article
• Authors: Lazoryak, Bogdan I.; Zhukovskaya, Evgeniya S.; Baryshnikova, Oksana V.; Belik, Alexei A.; Leonidova, Olga N.; Deyneko, Dina V.; Savon, Alexander E.; Dorbakov, Nikolai G.; Morozov, Vladimir A.
• Is Part Of: Materials research bulletin. Volume 104(2018)
• Page Start: 20
• Page End: 26
• Publication Date: 2018-08
• Subjects: Phosphates -- Luminescence -- Antiferroelectric -- Crystal structure -- Synchrotron radiation; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2018.03.052
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: Thermal, dielectric and luminescence properties were obtained for Ca8 ZnEu(PO4 )7 . Ca8 ZnEu(PO4 )7 belongs to antiferroelectric with Tc = 836 K. First-order antiferroelectric/paraelectric phase transitions have been found. Influence of composition on the luminescence properties has been shown. Structure of Ca8 ZnEu(PO4 )7 was refined by the Rietveld method. Abstract: Photoluminescence excitation and emission spectra of new phosphate Ca8 ZnEu(PO4 )7 have been investigated. The influence of the composition on the luminescence intensity has been shown. The substitution of Zn 2+ for Ca 2+ in Ca9 Eu(PO4 )7 with the formation of Ca8 ZnEu(PO4 )7 leads to the increased emission intensity 5 D0 → 7 F2 by about 1.5 times and to decreased number of bands from three to one in the range of 5 D0 → 7 F0 transition. Conditions of preparation do not influence the luminescent properties and distribution of Eu 3+ cations in the structure. DSC, SHG data and dielectric spectroscopy reveal that Ca8 ZnEu(PO4 )7 belongs to antiferroelectrics (Tc = 836 K). The first-order antiferroelectric/paraelectric transformations are accompanied by a changing symmetry ( R 3 ¯ с to R 3 ¯ m ). The structure of Ca8 ZnEu(PO4 )7 (sp. gr. R 3 ¯ с ) was refined by the Rietveld method. The Zn 2+ cations occupy the M 5 site. The Eu 3+ and Ca 2+ ions are located in the M 1 and M 3 sites of β -Ca3 (PO4 )2 -type structure.