Synthesis and luminescent properties of magnesium gallate spinel doped with Mn²⁺ and Eu³⁺ ions

Abstract

Ceramic samples of pure MgGa2O4, MgGa2O4: 0.05 mol.% Mn and MgGa2O4: 0.05 mol.% Mn, 5 mol.% Eu were synthesized via high‐temperature solid state reaction method. X‐ray diffraction measurements confirmed formation of spinel structure with Fd3m space group in all investigated samples. Clearly polycrystalline nature of ceramic samples with grain distribution from 1 to 5 μm was confirmed with SEM investigations. An intense broad band that excites in fundamental absorption edge has a maximum around 505 nm and corresponds to emission of Mn2+ ions. A charge transfer band (from O2– to Eu3+) with maximum at about 260 nm was found in the excitation spectra of Mn2+ and Eu3+ co‐doped samples. Luminescence band around 430 nm that corresponds to emission from host defects was found in all investigated samples. Excitation and emission of Eu3+ ions is presented by sharp lines with the most intense at 393 and 617 nm which are associated with 7F0→5L6 and 5D0→7F2 transitions in Eu3+ ions, respectively.

Luminescence Properties and Decay Kinetics of Mn2+ and Eu3+ Co-Dopant Ions In MgGa2O4 Ceramics

“…The luminescence of MgGa 2 O 4 :Mn 2+ ,Eu 3+ is represented by the UV-blue host emission and activator ions in green and orangered regions, respectively. The host luminescence originating from structural defects is clearly seen under 360-nm excitation [29]. The decline of the host emission intensity at about 393 and 463 nm is due to reabsorption by Eu 3+ ions in the near-surface ceramics layer [13].…”

“…The europium ions are excited with the charge transfer from oxygen anions to Eu 3+ ions (240-340 nm) and the 4f-4f intra-shell transitions of Eu 3+ ions corresponding to the sharp lines (350-420 nm) under 615 nm registration [13], [29]. The remarkable sharp declines of the excitation intensities in the range of f-f lines on the excitation spectra registered at 440 nm and 502 nm indicate that the energy transfer occurs through excitation mechanisms between host defects and activator ions.…”

“…The concentration of Mn 2+ was set constant at 0.05 mol.% and concentration of Eu 3+ ions was changed from 2 mol.% to 4 mol.%. The phase and structure analysis were described earlier [13], [29].…”

Thermally stimulated luminescence and thermally stimulated depolarization currents in MgGa2o4 spinels

“…2,б). Асиметричний максимум в околi 500 нм вiдповiдає свiченню йонiв активатора Mn 2+ [7,9,10] . Як показано в попереднiх до-1602-2 слiдженнях [7], асиметричнiсть смуги свiчення йонiв Mn 2+ зумовлена її комплексною будовою.…”

“…2,б, леґування йонами Mn 2+ призводить до суттєвого зменшення iнтенсивностi люмiнесценцiї матрицi. Вiдповiдно до результатiв роботи [10] спектри збудження фотолюмiнесценцiї йонiв Mn 2+ та матрицi перекриваються в дiлянцi краю фундаментального поглинання. З огляду на це можна стверджувати, що зменшення iнтенсивностi люмiнесценцiї матрицi пов'язане з перерозподiлом енерґiї збудження мiж йонами активатора Mn 2+ та дефектами кристалiчної ґратки [3].…”