Host sensitization of luminescence of lanthanide activators in NaBi(WO 4 ) 2

AbstractThe synthesis and luminescence of a series of NaBi(WO4)2 activated with trivalent lanthanides Tb, Sm and Nd using the solid-state reaction method is reported. All samples were characterised by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL). The XRD study confirmed the tetragonal phase without any secondary phase. Particles of irregular shape ranging between 5 and 20 µm were observed. Elemental composition was obtained from EDAX and results were found consistent with the formula NaBi(WO4)2. The formation of single-phase NaBi(WO4)2 was again confirmed through these results. Elemental mapping indicated that all elements were uniformly distributed. The band gap was evaluated using Tauc's. formula and was found from 5.6 eV to 5.91 eV which is higher than reported values (3.6 eV). For NaBi(WO4)2:Tb, excitation was monitored for 545 nm emission. Emission spectra upon excitation by 488 nm showed prominent lines around 545 and 549 nm. These are due to the transition 5D4 →7F5. 5 mol.% Tb yielded maximum PL intensity. When 405 nm excitation is used for Sm3+ doped phosphor, lines can be seen in three groups around 564, 600 and 647 nm. The highest emission intensity is observed for Sm3+ concentration of 5 mol.% and quenching was observed for high values. A weak band could be seen in the excitation spectra which is distinct from the f-f lines. The position of this band is close to that observed in the reflectance spectra. Hence it is proposed that there is host sensitization, even though weak, of the lanthanide luminescence in this host. Sensitization is most probably due to Bi3+→Ln3+ energy transfer.KEYWORDS: Photoluminescencetungstatelanthanide activatorshost sensitization AcknowledgementsCrystal structure diagrams are prepared using Vesta software (Citation49). Colour coordinates were calculated using the GoCIE programme (Citation50). We are grateful to the copyright owners for permitting free use. Assistance in obtaining the XRD pattern provided by Shri Shivaji Science College, Amaravati, India is gratefully acknowledged.Disclosure statementNo potential conflict of interest was reported by the author(s).Author contributionsSupriya Kshetrapal – Synthesis, Manuscript writing, K.V. Sharma – Synthesis and graph plotting, R. A. Nafdey – Rietveld Refinement and Editing, N.S. Ugemuge- Basic concept, S. V. Moharil – Basic concept and Editing.Data availability statementData will be made available on reasonable request.Additional informationNotes on contributorsSupriya KshetrapalSupriya Kshetrapal presently working as Lecturer in Physics in St. Francis De' sales college, Sadar, Nagpur. cleared SET examination in Physics. Research interest includes Luminescence study of phosphors. Published an international book on 'Basics of Laser' LAP Lambert Academic Publishing-2022 (ISBN: 978-620-5-51779-6). Associated with professional body such as International Association of Engineers (IAeng).N. S. UgemugeDr. N. S. Ugemuge Assistant Professor in the Department of Physics at Anand Niketan College, Anandwan, Warora, India. Recognized Ph. D. Supervisor in Physics and guiding 4 Ph.D. students in the area of Material Science specifically in Luminescence. Published more than 22 books and 25 articles in prestigious journals and 40 articles at International conferences. Awarded Master and Ph.D. in Physics, and Ph.D. in Management from R.T.M. Nagpur University, Nagpur.Khushbu SharmaDr. Khushbu Sharma is an Assistant Professor at Jhulelal Institute of Technology. Her area of interest is luminescence materials. A good number of international publications and 1 Indian patent is towards her contribution.Renuka NafdeyDr. Renuka Nafdey (Ph.D., Physics) is an academician and professor in Shri Ramdeobaba College of Engineering and Management, Nagpur since 20 years. Her area of interest are luminescent materials, conducting polymers, polymer composites and their applications. She has contributed a good number of research publications in International Journals of repute. She has been sponsored by DST, Gov. of India, under young researcher category to present her research work at France in 2009.I. M. NagpureDr. I. M. Nagpure Assistant Professor (Physics) at National Institute of Technology (NIT) Uttarakhand, a Centrally funded reputed Technical Institute by MoE Govt. of India, since 2013. Also, worked as Post-doctoral research fellow for 2.8 years at University of the Free State, South Africa. Published more than 45 articles in prestigious SCI journals and credited 01 International patent. Research profile follows nanomaterials and their applications towards LED, OLED, FED (field emission display) and bio-medical applications.S. V. MoharilS. V. Moharil is a Professor at the Department of Physics, RTM Nagpur University, Nagpur (M.S), India from 1984 to 2014. He has guided 36 Ph.D. students and has 318 publications. He has completed 17 projects and has 5 patents. He is a reviewer for Elsevier, IOP, Wiley, Springer, Electrochemical Society, RSC, and ACS journals.