Eu3+-activated SrY2O4:Ce4+/3+ red-phosphor for WLEDs: Structural and luminescent insights from experimental and theoretical approaches

• Published in: Journal of alloys and compounds Vol. 938; p. 168595
• Main Authors: Saraiva, Leonardo F., Bispo-Jr, Airton G., Lima, Sergio A.M., Pires, Ana M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-03-2023
• Subjects: Cerium(IV/III); Eu(III) activator ion; Luminescence spectroscopy; Single and multireference calculations; Strontium and yttrium oxide; Cerium(IV/III); Luminescence spectroscopy; Eu(III) activator ion; Single and multireference calculations; Strontium and yttrium oxide
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.168595

Herein, single-phase Eu3+-activated SrY2O4:Ce4+/3+ red-emitting phosphor was produced by an adapted Pechini route under softer synthesis conditions (1100 °C in CO reducing atmosphere) compared to those reported so far. A detailed structural study conducted by Rietveld refinement and DFT calculations confirmed the presence of two hexa-coordinated Y3+ sites that are occupied by Eu3+. Cerium is present in a mixed oxidation state, where the proportion of Ce4+/Ce3+ was determined as 70/30% by X-ray photoelectron spectroscopy (XPS), and this influences the SrY2O4 phase stabilization by increasing the point defect concentration. A thorough analysis of the photoluminescent features of Eu3+-activated phosphor revealed its occupancy in at least two non-equivalent local sites belonging to the C1 point group. Furthermore, the excited state dynamics of the phosphors were enlightened by the theoretical band structure determination. Finally, 3%-doped sample exhibited the highest intrinsic quantum yield (81%), which qualifies these materials to be used as red-emitting components for solid-state lighting.
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•Luminescent behavior of Eu3+-activated SrY2O4:Ce4+/3+ under near-UV excitation.•The structural and photophysical properties were thoroughly investigated.•The Ce4+/Ce3 + ratio ratio plays a key role in the obtention of the desired phase.•The SrY2O4:Ce4+/3+,Eu3+(3%) phosphor exhibits a high intrinsic quantum yield of 81%.•All the acquired data qualify this phosphor to be used as red-emitting components.