White light emitting LaGdSiO₅:Dy³⁺ nanophosphors for solid state lighting applications

详细信息    查看全文

• 作者：Simon N. Ogugua ; Hendrik C. Swart ; Odireleng M. Ntwaeaborwa ; ^{ntwaeab@ufs.ac.za" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Phosphors ; Photoluminescence ; Oxyorthosilicates ; Solid State Lighting
• 刊名：Physica B: Physics of Condensed Matter
• 出版年：2016
• 出版时间：1 January 2016
• 年：2016
• 卷：480
• 期：Complete
• 页码：131-136
• 全文大小：1963 K

文摘

Powdered dysprosium (Dy³⁺) doped Lanthanum gadolinium oxyorthosilicate (LaGdSiO₅) mixed phosphors were synthesized using urea-assisted solution combustion method. The X-ray diffractometer analysis showed that the samples crystalized in the pure monoclinic mixed phase of LaGdSiO₅. The crystallite size and the lattice strain calculated from the X-ray diffraction peaks using Williamson–Hall equation varied from 12 nm to 16 nm and 1.6mmlsi0003" class="mathmlsrc">mulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0921452615302726&_mathId=si0003.gif&_user=111111111&_pii=S0921452615302726&_rdoc=1&_issn=09214526&md5=6e0f9fdf76131b6893bd9d8ce6cc0b57" title="Click to view the MathML source">&times;mathContainer hidden">mathCode"><math altimg="si0003.gif" overflow="scroll"><mo>&times;mo>math>10^&minus;2 to 2.43mmlsi0004" class="mathmlsrc">mulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0921452615302726&_mathId=si0004.gif&_user=111111111&_pii=S0921452615302726&_rdoc=1&_issn=09214526&md5=be35b760ff9c2578653e7c4f1df15f3c" title="Click to view the MathML source">&times;mathContainer hidden">mathCode"><math altimg="si0004.gif" overflow="scroll"><mo>&times;mo>math>10^&minus;2 respectively. The photoluminescence (PL) emission spectra recorded using 425, 454 and 475 nm excitation wavelengths exhibit characteristic similar to the YAG:Ce phosphor pumped InGaN LED system, by absorbing portion of the excitation energy and re-emitting it. The emission spectra were characterized by radiative recombination at 425, 454, 475, 485 and 575 nm depending on the excitation wavelength. These emission line are ascribed to the f→f transitions of Dy³⁺. The peak intensity and hence the color of the emitted visible light were dependent on the concentration of Dy³⁺. The International Commission on Illumination (CIE) color coordinates of (0.336, 0.313) and (0.359, 0.361) were obtained for Dy³⁺ molar concentration of 0.05 and 3.0 mol% when the emission was monitored using 454 nm and 475 nm respectively. The band gap measured from the reflectance curve using Tauc plot initially decreased with increasing Dy³⁺ concentration, but at higher concentration, it started to increase. These materials were evaluated for solid state lighting application.