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Application of KBaYSi2O7:Bi3+,Eu3+ Phosphor for White Light-Emitting Diodes with Excellent Color Quality Loan, Nguyen Thi Phuong; Thuy, Le Xuan; Thai, Nguyen Le; Lee, Hsiao Yi; Cong, Pham Hong
Science and Technology Indonesia Vol. 9 No. 3 (2024): July
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.2024.9.3.756-765

Abstract

This paper examines the properties of two phosphor materials synthesized via utilizing the sol gel method: KBaYSi2O7:Bi3+ (KBYS:Bi) phosphor providing cyan/deep-blue emission and KBaYSi2O7:Bi3+,Eu3+ (KBYS:Bi,Eu) phosphor exhibiting tunable emission from near-UV to red. The optimal doping concentrations for Bi3+ and Eu3+ are 0.2% and 3.5%, respectively. It is found that the ability to give discrepant emission peaks under different excitation sources of the KBYS:Bi phosphor is attributed to the occupancy of Bi3+ in different cation hosts. Meanwhile, co doping the Eu3+ and Bi3+ into the KBYS host leads to red and cyan emission regions, enabling the emission tunability of the KBYS:Bi,Eu phosphor. KBYS:Bi,Eu phosphor was then used in combination with YAG:Ce3+ and blue chips to fabricate a white light emitting diode (LED) model. The particle sizes of KBYS:Bi,Eu phosphor are adjusted to examine its influences on the LED properties. With increasing particle sizes (≥12 µm), the KBYS:Bi,Eu phosphor can improve the scatter efficacy, transmission power, lumen output, and color performance (rendition and uniformity). Both KBYS:Bi and KBYS:Bi,Eu phosphors are promising luminescent phosphors that can be combined with other phosphor with different emission colors to obtain the full-spectrum or tunable white light for LEDs.
A Variable Step Size of the LMS Algorithm for System Identification Thai, Nguyen Le; Son, Hoang Hai
Engineering Science Letter Vol. 3 No. 03 (2024): Engineering Science Letter
Publisher : The Indonesian Institute of Science and Technology Research

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56741/esl.v3i03.559

Abstract

The Least Mean Square (LMS) algorithm and adaptive filter techniques have been used in system identification.  However, their effectiveness may degrade due to the learning gain in the LMS algorithm is a constant. In this paper, a variable step-size learning parameter (VSSP) is proposed to improve the performance of the unknown system identification. The proposed algorithm is implemented without any offline learning phase, while faster convergence can be achieved. Moreover, the computational complexities of different methods are compared. Comparative simulation results demonstrate the validity of the proposed method.
Impacts of Eu2+ -doped K3LuSi2O7 phosphor and a scattering particle on conventional white light emitting diodes Duy, Le Doan; Thai, Nguyen Le; Cong, Pham Hong; Tran, Thinh Cong
Indonesian Journal of Electrical Engineering and Computer Science Vol 35, No 2: August 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v35.i2.pp743-750

Abstract

The K3LuSi2O7 phosphor doping Eu2+ rare-earth ions (KLS:Eu) was reported to possess broad emission band from near-ultraviolet to nearinfrared. Additionally, this phosphor showed a wide absorption band of 250-600 nm, allowing it to be excited by blue-light chip of 460 nm, making it one of the suitable phosphor materials for a light emitting diode (LED). Besides, the scattering particle material CaCO3 is incorporated into the yellow phosphor layer to serve the scattering-enhancement purpose. The combination of both materials aims at accomplishing improvements in performance of commercial LED package. The concentration of KLS:Eu is constant while that of CaCO3 is modified. As a result, the scattering factor is regulated and become the key factor influencing the optical outputs of the simulated LED. The increasing CaCO3 concentration enhances the phosphor scattering efficiency of light, helping to improve the lumen output and color-temperature consistency of the LED. However, the color rendering performance declines as a function of the CaCO3 growing amount, despite the presence of a KLS:Eu phosphor layer. Further works should be done to optimize the application of KLS:Eu in cooperation with scattering particles for a higher-quality LED device.