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Blue-yellow emissive LaAlO3:Dy3+ phosphor for high bright white light-emitting diodes Tung, Ha Thanh; Dang, Huu Phuc
Bulletin of Electrical Engineering and Informatics Vol 12, No 3: June 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i3.4949

Abstract

LaAlO3:Dy3+ (LAO:Dy3+) with blue-yellow emission for brilliant white light of light-emitting diodes (LEDs) was prepared using gel-combustion process. The chemical content of the created material was confirmed using energy dispersive X-ray analysis (EDX). The transmission electron microscopy was used to examine the phosphor crystal size and morphology. The luminescence analysis showed that LAO:Dy3+ phosphors exhibited peaks at 482 nm (blue) and 574 nm (yellow), attributed to the transitions 4F 9/2à6H 15/2 and 4F 9/2à6H 13/2, respectively. The investigating of correlated color temperature (CCT) and Commission International de L'Eclairage (CIE) described that the phosphor LAO:Dy3+ helped to attained good CCT coordination and bright cool-white emission under ultraviolet (UV) stimulation. However, when using in white LED fabrication, the concentration of LAO:Dy3+ should be modified to fulfill the need from manufactures. According to results from this work, the white light luminescence intensity and color rendering performance may be reduced if the LAO:Dy3+ is high (10%) because of too much scattering. On the other hand, such scattering improvements offered by LAO:Dy3+ phosphor is beneficial to reduce the color deviance for better color uniformity of light.
Enhancing Scattering Strength Improvement and Color Uniformity in White Light-Emitting Diodes Using High Concentration of Yttrium Oxide Cong, Pham Hong; Loan, Nguyen Thi Phuong; Tung, Ha Thanh
Science and Technology Indonesia Vol. 11 No. 1 (2026): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.1.174-181

Abstract

This study investigates the effect of yttrium oxide (Y2O3) doping on the phase evolution of barium titanate (BaTiO3), a key dielectric material used in multilayer ceramic capacitors (MSCCs). Two types of starting powders were examined: pure BaTiO3 and a commercial X7R composition containing 1 wt% Y2O3. Using the solid-state method under high temperature, Y2O3 was added in varying amounts, and the powders were processed under controlled sintering conditions to evaluate its influence on phase formation. The resulting ceramics were characterized to determine formational alterations as well as the potential generation of secondary phases. Increasing Y2O3 content led to a transmutation from the tetragon structure to a merger between tetragon as well as cubic phases. The commercial X7R powder exhibited greater densificating process, surpassing pure BaTiO3 and formed a cuboid formation under greater Y2O3 concentrations. Notably, the sample doped with 20 wt% Y2O3 produced the Ba6Ti17O40 phase, augmenting scattering capacity and color uniformity. These findings clarify the role of Y2O3 in phase evolution and highlight its implications for optimizing BaTiO3-based MSCC materials.