Nanoscale physics

Nanoscale multi-experimental investigation of Eu3+ and Mn2+ co-doped ZnGa2O4 and MgGa2O4 phosphors
O. Kravets1, O. Zaremba1, Ya. Shpotyuk1,2, A. Luchechko1, 
K. Szmuc2, J. Cebulski2, A. Ingram3, O. Shpotyuk4,5
1 Ivan Franko National University of Lviv, Universytetska Str., 1, Lviv 79000, Ukraine. E-mail: oleh.kravets@lnu.edu.ua
2 University of Rzeszow, Rzeszow, 35-959, Poland.
3 Opole University of Technology, 75, Ozimska str., 45370, Opole, Poland
4 Jan Dlugosz University, al. Armii Krajowej, 13/15, 42201, Czestochowa, Poland
5 Vlokh Institute of Physical Optics, 23, Dragomanov str., 79005, Lviv, Ukraine

Recently, the spinel oxide ceramics have attracted much attention due to advantageous properties allowing application in many prospective fields. Gallate spines doped with rare-earth elements is used as a high-spot in display, WLED and solid state lasers technologies [1]. Biocompatibility of oxide phosphors makes ZnGa2O4 and MgGa2O4 nanoparticles promising biomarker materials [2]. Unfortunately, only a few papers published on the fundamental relations of structure defects and optical-luminescence properties of the ZnGa2O4 and MgGa2O4 spinel type ceramics.
In this work, MgGa2O4 and ZnGa2O4 ceramics co-doped with Mn2+ and Eu3+ ions were prepared via high-temperature solid-state reaction and studied using a multi-experimental approach. X-ray diffraction method with Rietveld refinements testified successful formation of the spinel structure in ceramic samples. TEM and EDX investigations showed grains of irregular shape with a homogeneous distribution of Eu3+ ions. Positron annihilation lifetime spectroscopy and optical-luminescent measurements were employed to characterize both ceramics. The influence of Eu3+ doping and vacancy-type defects on luminescence properties is shown. 

1.	Luchechko A., Kravets O. Novel visible phosphors based on MgGa2O4-ZnGa2O4 solid solutions with spinel structure co-doped with Mn2+ and Eu3+ ions // J. Lumin.-2017.-192.-P. 11-16. 
2.	S. K. Sharma et al. Persistent luminescence of AB2O4:Cr3+ (A = Zn, Mg, B = Ga, Al) spinels: New biomarkers for in vivo imaging // Opt. Mater.-2014.-36.-P. 1901-1906.