Journal Pre-proof 3+ Photoluminescence and photocatalytic properties of novel Bi2O3:Sm nanophosphor S Ashwini, S.C Prashantha, Ramachandra Naik, Yashwanth V Naik, H Nagabhushana, K.N Narasimhamurthy PII: S2468-2179(19)30219-9 DOI: https://doi.org/10.1016/j.jsamd.2019.09.001 Reference: JSAMD 250 To appear in: Journal of Science: Advanced Materials and Devices Received Date: May 2019 Revised Date: 18 August 2019 Accepted Date: September 2019 Please cite this article as: S Ashwini, S.C Prashantha, R Naik, Y.V Naik, H Nagabhushana, 3+ K.N Narasimhamurthy, Photoluminescence and photocatalytic properties of novel Bi2O3:Sm nanophosphor, Journal of Science: Advanced Materials and Devices, https://doi.org/10.1016/ j.jsamd.2019.09.001 This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain © 2019 Publishing services by Elsevier B.V on behalf of Vietnam National University, Hanoi Photoluminescence and photocatalytic properties of novel Bi2O3:Sm3+ nanophosphor S Ashwini a,b , S.C Prashantha b*, Ramachandra Naik c*, Yashwanth V Naikd, H Nagabhushanad, K.N Narasimhamurthye a Department of Physics, Channabasaveshwara Institute of Technology, Gubbi-572216, India b Research Center, Department of Science, East West Institute of Technology, VTU, Bengaluru-560091, India c Department of Physics, New Horizon College of Engineering, Bengaluru-560103, India d Prof CNR Rao Center for Advanced Materials, Tumkur University, Tumkur, 572103, India e Department of Physics, Government First Grade College, Tumkur, 572102 India Photoluminescence and Photocatalytic properties of novel Bi2O3:Sm3+nanophosphor Abstract The current work involves studies of the synthesis, characterization and photoluminescence for Sm3+ (1-11 mol %) doped Bi2O3 nanophosphors (NPs) by a solution combustion method The average particle size was determined using powder X-ray diffraction (PXRD) and found to be in the range of 13- 30 nm The Kubelka-Munk (K-M) function was used to assess the energy gap of Sm3+ doped Bi2O3 nanophosphors which was found to be 2.92- 2.96 eV From the Emission spectra, the Judd–Ofelt parameters (Ω2 and Ω4), the transition probabilities (AT), the quantum efficiency (η), the luminescence lifetime (τr), the colour chromaticity coordinates (CIE) and the correlated colour temperature (CCT) values were estimated and discussed in detail The CIE chromaticity co-ordinates were close to the NTSC (National Television Standard Committee) standard value of Orange emission Using the LangmuirHinshelwood model and Acid Red-88, the photocatalytic activity results showed that Bi2O3: Sm3+ NPs are potential materials for the development of an efficient photocatalyst for environmental remediation The obtained results prove that the Bi2O3:Sm3+ nanophosphors synthesised by this method can potentially be used for Solid State display and Photocatalyst Keywords: Bi2O3:Sm3+, Photoluminescence, Judd- Ofelt, CIE and CCT * Corresponding authors E-mail: scphysics@gmail.com (Prashantha S.C), Tel.: +91 9886021344, email: rcnaikphysics@gmail.com (Ramachandra Naik), Tel.:+91 7204408041 1 Introduction Lanthanide ions doped (Ln3+) nanophosphors (NPs) have gained massive attention owing to their potential applications in various fields ranging from display [1], solar cells [2], bioimaging [3], solid state lasers [4], remote photo activation [5], temperature sensors [6] and drug release [7] Furthermore, NPs should possess superior physicochemical characteristics, such as long lifetimes, large anti- Stokes shifts, high penetration depth, low toxicity, as well as high resistance to photo bleaching [8] Bismuth is the only nontoxic heavy metal that can easily be purified in large quantities [9] The semiconductors such as Bi2MoO6 , BiOX (X=Cl, Br, I), BiVO4 and Bi2O3 have a high refractive index and excellent properties for visible light absorb ion, photoluminescence, dielectric permittivity, photoconductivity, large oxygen ion conductivity, and, noteworthy, for photocatalytic activity [10-12] At present, the photocatalysis technology has been anticipated to be a perfect “green” technology by the usage of solar energy in many fields such as, water-splitting [13], solar cell [14], water and air purification, organic waste degradation [15], CO2 reduction [16] etc The decomposition of dye contaminants in contaminated water, as a branch of photocatalysis, has attracted great attention To date, with the exception of intensive research on conventional photocatalysts such as TiO2, ZnO, ZrO2 and other semiconductors with a wide band gap [17], the finding out of new photocatalysts with sturdy degradation abilities has become additionally important Thus, we can consider Bi2O3 as a suitable host material, which is having all these features Bismuth oxide (Bi2O3) is a semiconductor with attractive optical and electronic properties Because of these properties, Bi2O3 has become an important material for several applications such as fuel cells [18], photocatalysts [19], gas sensors [20], and electronic components [21] Another significant characteristic of Bi2O3 is its polymorphism, which results in polymorphic forms (α, β, γ, δ and ω) with different structures and properties [22], among them monoclinic α which is stable at room temperature and face-centered cubic δ that is stable at high temperature There are various methods available for the synthesis of Bi2O3 nanophosphors viz., sonochemical, microwave irradiation, hydrothermal, chemical vapour deposition, micro-emulsion, surfactant thermal strategy, sol-gel approach, solution combustion and electro-spinning [23, 24] In this work we report the synthesis of Bi2-xO3: Smx (x= 0.01 to 0.11) NPs via a simple low temperature solution combustion method Compared with the conventional methods adopted for synthesis, the solution combustion method is advantageous in view of its low temperature and reduced time consumption which result in a high degree of crystallinity and homogeneity The synthesised nanophosphor is characterized by PXRD and DRS The effect of Sm3+ doping on the photoluminescence properties were studied in detail for their possible usage in display applications Experimental Synthesis of Bi2-xO3: Smx (x= 0.01 to 0.11) The synthesis of Bi2-xO3: Smx (x= 0.01 to 0.11) via solution combustion method was made using analytical grade Bismuth nitrate (Bi(NO3)3.5H2O: 99.99%, Sigma Aldrich Ltd.), Samarium nitrate ( Sm(NO3)3.6H2O: 99.99%, Sigma Aldrich Ltd) as dopant and Urea as fuel In a cylindrical Petri dish (300 ml), the aqueous solution containing stoichiometric quantity of reactants were taken such that Oxidizer (Bi (NO3)3.5H2O) to Fuel (Urea) ratio is (O/F=1) [25] and introduced into a pre heated muffle furnace at temperature of 400 ±10 oC Thermal dehydration of the reaction mixture takes place and auto-ignites with liberation of gaseous products resulting in the nano powders Finally, the so-prepared powders were calcined at 600 oC for h The theoretical equation, assuming complete combustion of the redox mixture used for the synthesis of Bi2O3, can be written as: +5 → +8 +5 + 20 — Photocatalytic Activity of Bi2O3:Sm3+ At room temperature, the experiment was conducted in a reactor by utilizing a 125 W mercury vapour lamp as the UV light source (λ=254nm) Using Acid red dye 88 (AR-88) as a model dye, the UV light photocatalytic activities of Bi2O3:Sm3+ NPs were evaluated In this experiment, 30 mg of synthesized Bi2O3:Sm3+ NPs was dissolved completely into 10 ppm of AR-88 dye solution and stirred continuously to form a uniform solution At each 15 min, ml of the dye solution was inhibited and tested by a UV-Vis spectrophotometer by means of the typical adsorption band at 510 nm after centrifugation for the computation of the disintegration of dye [26] Characterization Crystal morphology of the synthesised NPs was determined by PXRD using X-ray diffractometer (Shimadzu) (V-50 kV, I-20 mA, λ-1.541Å, scan rate of 2o min-1) Photoluminescence studies are made using Horiba, (model fluorolog-3, xenon-450 W) Spectroflourimeter at Room Temperature Fluor Essence™ software is used for spectral analysis DRS studies of the samples were performed using Shimadzu UV- 2600 in the range 200–800 nm Results and Discussion 3.1 PXRD studies Fig shows the Powder X-ray diffraction (PXRD) pattern of undoped and Sm3+ (1-11 mol %) doped Bi2O3 NPs All the recorded peaks were indexed to the Cubic phase of Bi2O3 (JCPDS card No.52-1007, Space Group: Fm-3m (no.225)), suggesting high purity and crystallinity of the synthesized powders As the acceptable percentage difference Dr (ionic radii) [27] is less than 15% between Bi3+ and Sm3+ ions, Sm3+ ions substitute the Bi3+ ions in the Bi2O3 host − = −−− For Coordination number CN equal to 6, the radius of the host cation Rh(CN) is1.03 Å, and the radius of the doped ion Rd(CN) is 0.958 Å The calculated Dr is found to be 6.99 % [28] The average crystallite size (D) was calculated by using Scherer’s formula [29] = 0.9 −−− !" where λ represents the wavelength of X-rays (1.54 Ǻ), θ the incident angle, and β the full width at half maximum (FWHM) of the XRD peaks Table1 gives the crystallite sizes of the Bi2O3:Sm3+ (1-11 mol %) samples These are in the range of13-30 nm which indicates that, as doping concentration increases, crystallite sizes decrease 3.2 Diffuse Reflectance Spectroscopy studies To evaluate the energy band gap, the diffuse reflectance spectra (DRS) of Bi2O3: Sm3+NPs were carried out and shown in Fig The spectra mainly exhibit absorption at ~410 nm which is the characteristic for the absorption of Sm3+ ions [30] The Kubelka- Munk relation was adopted to calculate the band gap of the NPs [31], $ where $ ∞ ∞ h& = C h& − () * −−− is the Kubelka-Munk function, ℎ& the photon energy, C a constant, () the optical energy band gap, n an exponent which value depends on the nature of the inter band electronic transition, viz., n = ½ ( direct allowed transition), n = (indirect allowed transition), n = 3/2 (direct forbidden transition) and n = (indirect forbidden transition) [24] Direct or indirect transitions are ''allowed'' transitions, if the momentum matrix element characterizing the transition is different from zero This means that the transition can hold for sure if sufficient energy is given to the particle (e.g electron) involved in the process Direct or indirect transitions are ''forbidden'' transitions, if the momentum matrix element characterizing the transition is equal to zero The transition cannot hold even if sufficient energy is given However, a forbidden transition can sometimes become allowed Sometimes a transition can be forbidden in first order (first order perturbation theory) but it becomes allowed in second order (second order perturbation theory) [32] As Bi2O3 is a direct band gap material, from the extrapolation of the line [$ ∞ ℎ&] to zero (Fig 3), the () of the synthesised NPs was found to be in the range of 2.92–2.96 eV, indicating that the present material can be a promising photocatalyst since it can absorb UV as well as the visible region of solar light 3.3 Photoluminescence studies Fig shows the excitation spectra of Bi2O3: Sm3+NPs for 3, and 7mol% The spectra were taken in the range of 360 nm to 500 nm and exhibit bands at 365 nm (6H5/2→4D3/2, 5/2), at 395 nm (6H5/2→4F7/2), at 418 nm(6H5/2→4M19/2), at 448 nm(6H5/2→4G9/2), at 465 nm(6H5/2→4I13/2) and at 488 nm(6H5/2→4I11/2) attributed to the 4f-4f transition of Sm3+ [33] Among these, the prominent transition at 465 nm (6H5/2→4I13/2) was taken to explicate the emission spectra of the NPs Fig shows the emission spectra of Bi2-xO3: Smx (x= 0.01 to 0.11) calcined at 600 oC excited under 465 nm The spectra consist of four typical transition emission bands centered at 565 nm(yellow), 616 nm(orange), 653 nm(orange red) and 713 nm(red) which are due to G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 respectively Actually at excitation, the doped ions are excited to the higher energy state 4H9/2 from which they relax nonradiatively to the metastable state 4G5/2 through the4F7/2, 4G7/2, and 4F3/2 levels But 4H9/2 and G5/2 correspond to very close and fast non-radiative relaxations So the spectra will have the four transition bands from 4G5/2 Among all the emitted transitions, 4G5/2→6H7/2 (616 nm) is the most prominent one with strong orange emission which is partly magnetic dipole and partly electric dipole.4G5/2→6H9/2 (653 nm) is purely electric dipole and in this study the intensity of the electric dipole transition is less compared to that of the magnetic dipole one, indicating the symmetry behaviour of Sm3+ ions in the host Bi2O3 [34, 35] The variation of the PL intensity with respect to the Sm3+ dopant concentration is shown in Fig The PL intensity at 616 nm emission increases up to 5mol% with the increase of Sm3+ content and, subsequently, it decreases owing to concentration quenching The energy of the phosphor is lost due to non-radiative (or also multi phonon-assisted non-radiative) transitions by the incorporation of Sm3+ in the host or Sm3+-Sm3+ interaction when excited through vacancies 3.4 Judd Ofelt (J-O) analysis Quantum efficiency is an important parameter which determines the efficiency of nanophosphors for the applications of display devices The electric-dipole (ED) and magnetic-dipole (MD) transitions are generally used in the investigation of rare earth ions doped luminescent materials However, it is challenging to calculate the J-O intensity Ωt (t = 2, 4, 6) parameters for powder materials because the absorption spectra of powder materials can hardly be recorded The radiative transition probabilities (/0 ) from an excited state 2 43 to the final state 24 are related to forced electric dipole transitions and they may be written as a function of the J–O intensity parameters: /0 23 43 − 24 = 646 7̅ : : +2 3ℎ 24 + ;< + : ;= > − − − − Where, ;< and ;= are the electric and magnetic dipole strengths, respectively, J is the wavenumber of the respective electronic transition, h is Planck’s constant, n is the effective refractive index of the nanophosphor [36] The total radiative transition probability (/? ) for an excited state 23 43 is transition [37] given by formula: /? 24 = @ /0 23 43 − 24 − − − − − − − − − AB The radiative lifetime C of the excited state 43 can be obtained by [38] C 43 = −−−−−−−−−−−−− /0 24 The luminescence quantum efficiency (E) can be calculated by the relation [39] and was found to be ~ 75 % for the present phosphor: E = /0 /0 = −−−−−−−−−−−− /0 + /F0 /? Table gives the results of J-O intensity parameters (Ω2 and Ω4) and radiative properties of Bi2O3:Sm3+ nanophosphors that are calculated from the emission spectra From the results it is clear that the Ω2 and Ω4values are comparatively high due to the fact that the samples generally possess higher fractions of the rare earth ions on the surface of the nano crystals compared to the bulk counterparts [40] The parameter Ω2 is related to the short range impact in the vicinity of the rare earth Sm3+ ion and Ω4 is related to the long range impact AR and τr were calculated from the emission spectra The quantum efficiency (η) is calculated with equation (8) and found to be equal to 74.8% as shown in Table An increase in quantum efficiency indicates a better applicability for display devices It was observed that G5/2→6H7/2transition of Sm3+ doped Bi2O3 NPs dominates the intensity emitted by the NPs in the emission spectra The results infer that the current NPs can be utilized for display devices [38] 3.5 CIE and CCT analysis “Commission International de i’Eclairage (CIE) 1931 standards” were used to calculate the colour coordinates of Bi2-xO3: Smx (x= 1-11 mol %) from the emission spectra In the colour space, coordinates (x, y) are used to specify the colour quality and to evaluate the phosphors performance these coordinates are the most prominent parameters Fig 7(a) shows the CIE 1931 chromaticity diagram for Bi2-xO3:Smx (x= 1- 11 mol%) NPs excited at 365 nm and 465 nm The CIE colour coordinates so calculated for Bi2-xO3: Smx (x= 1-11 mol%) are summarized in Fig 7(a) It is clear that all the samples fall into the scope of orange red light emission Fig 7(b) show CCT of Bi2-xO3:Smx (x= 1-11 mol%) and the average value was found to be 1758 K [41] Hence, it is obvious that the NPs can be used as an Orange red light source to meet the needs of the illustrated applications 3.6 Photocatalytic Activity of AR-88 Dye Acid Red-88(AR-88) is an azo dye Due to its intense colour, Ar-88 was used to dye cotton textiles red and used for Photocatalytic studies The PCA of Bi2-xO3: Smx (x= 1- 11 mol %) were analysed for the decolourization of AR-88 in aqueous solution under UV light irradiation for a time duration of 60min The UV visible absorption spectra of the dye for various concentrations of Bi2-xO3: Smx (x= 1- 11 mol %) are shown in Fig 8(a-f) To know about the response kinetics of AR-88 Dye decolourization, the Langmuir-Hinshelwood model was adopted which follows the equation, ln(C/C0) = kt + a, where, k is the reaction rate constant, C0 the preliminary attention of AR-88, C the attention of AR-88 on the response time t [22, 42] Fig9 shows the plot of ln(C/C0) photo decolourization of all catalysts Bi2O3:Sm3+ under UV light irradiation As the doping concentration increases, the photo decolourization efficiency decreases and after 60 irradiation it was found that the photo decolourization efficiency was 98.57% which is the maximum for mol% (Fig 10) This might be due to the fact that at mol%, Sm3+ ions on the host Bi2O3 behave as electron trapper to detach the electron-hole pairs which is much needed for PCA At other molar concentrations, the catalyst may behave as recombination centres and this leads to less PCA efficiency 3.7 Conclusions The present Bi2O3:Sm3+ nanophosphors were prepared by a solution combustion method The crystallite size was found to be in the range 13-30 nm The phosphors upon exciting at comparably low energy of 465 nm, emit orange colour with all characteristic transitions of Sm3+ ions CCT of 1758 K shows that the phosphors are potential materials for warm white light emitting display devices Further, it shows an excellent photocatalytic activity which proofs the multi functionality of the prepared nanophosphors References [1] R Deng, F Qin, R Chen, W Huang, M Hong, X Liu, “Temporal full-colour tuning through non-steady-state upconversion”, Nat Nanotechnol., 10 (2015) 237 [2] J de Wild, A Meijerink, J K Rath, W G J H M van Sark and R E I Schropp, “Upconverter solar cells: materials and applications”, Energy Environ Sci., (2011) 4835 [3] Jing Zhou, Zhuang Liu, Fuyou Li, “Upconversion nanophosphors for small-animal imaging”, Chem Soc Rev., 41 (2012) 1323–1349 [4] G Rumbles, “Synthesis and upconversion 3+ 3+ BaY2F8:Yb /Er nanobelts”, Nature, 409 (2001) 572-573 [5] Jayakumar MK, Idris NM, Zhang Y, “Remote activation of biomolecules in deep tissues using near-infrared-to-UV upconversion nanotransducers”, Proc Natl Acad Sci U S A 109 (2012)8483-8 [6] Fischer LH, Harms GS, Wolfbeis OS, “Upconverting nanoparticles for nanoscale thermometry”, Angew Chem Int Ed Engl 50 (2011) 4546-51 [7] Shen J, Zhao L, Han G, “Lanthanide-doped upconverting luminescent nanoparticle platforms for optical imaging-guided drug delivery and therapy”, Adv Drug Deliv Rev., 65 (2013)744-55 [8] Huang P, Zheng W, Zhou S, Tu D, Chen Z, Zhu H, Li R, Ma E, Huang M, Chen X, “Lanthanide-doped LiLuF(4) upconversion nanoprobes for the detection of disease biomarkers”, Angew Chem Int Ed Engl., 53 (2014)1252-7 [9] P Lei, X Liu, L Dong, Z Wang, S Song, X Xu, Y Su, J Feng and H Zhang, “Lanthanide doped Bi2O3 upconversion luminescence nanospheres for temperature sensing and optical imaging”, Dalton Trans 45 (2016) 2686 luminescence of [10] Buagun Samran,Sumneang lunput, Siriporn Tonnonchiang,Saranyoo Chaiwichian, “BiFeO3/BiVO4 nanocomposite photocatalysts with highly enhanced photocatalytic activity for rhodamine B degradation under visible light irradiation”, Physica B, 561, ( 2019) 23-28 [11] J.Yesuraj, S.Austin Suthanthiraraj, O.Padmaraj, “Synthesis, characterization and electrochemical performance of DNA-templated Bi2MoO6 nanoplates for supercapacitor applications”, Mater Sci Semicond Process., 90 (2019) 225-235 [12] Aleksandra Bielicka Giełdoń, Patrycja Wilczewska, Anna Malankowska et al., “Morphology, surface properties and photocatalytic activity of the bismuth oxyhalides semiconductors prepared by ionic liquid assisted solvothermal method”, Sep Purif Technol., 217 (2019) 164-173 [13] S.U.M Khan, M Al-Shahry, W.B Ingler Jr., “Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2”, Science, 297 (2002) 2243-2245 [14] O K Varghese, M Paulose, C.A Grimes, “Long vertically aligned titania nanotubes on transparent conducting oxide for highly efficient solar cells”, Nature Nanotech, 4, (2009) 592 - 597 [15] N.N.Rao, V.Chaturvedi, G.L Puma, “Novel pebble bed photocatalytic reactor for solar treatment of textile wastewater”, Chem Engg J, 184 (2012) 90–97 [16] A Dhakshinamoorthy, S Navalon, A.Corma, H Garcia, “Photocatalytic CO2 reduction by TiO2 and related titanium containing solids”, Energy Envi Scie, (2012) 9217-9233 [17] L Renuka, K.S Anantharaju, S.C Sharma, H Nagabhushana, Y.S Vidya, H.P.Nagaswarupa, S.C Prashantha, “A comparative study on the structural, optical, electrochemical and photocatalytic properties of ZrO2nanooxide synthesized by different routes”, J Alloys Compd, 695 (2017) 382-395 [18] W zuo, W Zhu, D Zhao, Y Sun, Y Li, J Liu and X W D Lou, “Bismuth oxide: a versatile high-capacity electrode material for rechargeable aqueous metal-ion batteries”, Energy Environ Sci., (2016) 2881 [19] Hassan Najafiana, Faranak Manteghia, Farshad Beshkarb, Masoud Salavati-Niasaric, “Enhanced photocatalytic activity of a novel NiO/Bi2O3/Bi3ClO4 nanocomposite for the degradation of azo dye pollutants under visible light irradiation”, Sep Purif Technol, 209 (2019) 6–17 [20] H Takeda, T Ueda, K Kamada, K Matsuo, T Hyodo, Y Shimizu, “CO-sensing properties of a NASICON-based gas sensor attached with Pt mixed with Bi2O3 as a sensing electrode”, Electrochim Acta, 155(2015) 8-15 [21] L Li, X Zhang, Z Zhang, M Zhang, L Cong, Y Pan, S Lin, J Mater Chem A, (2016) 16635 [22] Yanlin Huang , Jie Qin, Xuanxuan Liu , Donglei Wei, Hyo Jin Seo, “Hydrothermal synthesis of flower-like Na-doped α-Bi2O3 and improved photocatalytic activity via the induced oxygen vacancies”, J Taiwan Inst Chem Eng., 96 (2019) 353-360 [23] Ashwini S, Prashantha SC, Naik R, Nagabhushana H, “Enhancement of luminescence intensity and spectroscopic analysis of Eu3+ activated and Li+ charge-compensated Bi2O3 nanophosphors for solid-state lighting”, J Rare Earths, 37 (2019) 356-364 [24] S Ashwini, S.C Prashantha, Ramachandra Naik, Yashwanth V Naik, H Nagabhushana, D.M Jnaneshwara, “Photoluminescence of a novel green emitting Bi2O3:Tb3+ nanophosphors for display, thermal sensor and visualisation of latent fingerprints”, Optik, 192 (2019) 162956 [25] K.C Patil, M.S Hegde, T Rattan, S.T Aruna, Chemistry of Nanocrystalline Oxide materials, World Scientific Press, Singapore, 2008 [26] QingheQue, Yonglei Xing, Zuoli He, Yawei Yang, Xingtian Yin, WenxiuQue, “Bi2O3/Carbon quantum dots heterostructured photocatalysts with enhanced photocatalytic activity”, Mater Lett,209 (2017) 220-223 [27] B.D Cullity, Elements of X-ray Diffraction, Addison-Wesley, 1956 10 [28] http://abulafia.mt.ic.ac.uk/shannon/ [29] P Klug, L E Alexander, “X-Ray Diffraction Procedure”, Wiley, New York, 1954 [30] A K Bedyal, Vinay Kumar, H C Swart, “A potential green emitting citrate gel synthesized NaSrBO3:Tb3+ phosphor for display application”, Physica B , 535 (2018) 189-193 [31] Kubelka, P and Munk, F, “Ein Beitrag Zur Optik Der Farbanstriche”, Zeitschrift für Technische Physik, 12 (1931) 593-601 [32] http://web.mit.edu/course/6/6.732/OldFiles/www/6.732-pt2.pdf [33] Carnall, W.T., Fields, P.R and Rajanak, K “Electronic Energy Levels in the Trivalent Lanthanide Aquo Ions I Pr3+, Nd3+, Pm3+, Sm3+, Dy3+, Ho3+, Er3+, and Tm3+”, The Journal of Chemical Physics, 49, (1968) 4424-4442 [34] Dieke, G.H Spectra and Energy Levels of Rare Earth Ions in Crystals, (1968) Willey, New York [35] Reddy, C.P., Naresh, V., Babu, B.C and Buddhudu, S “Photoluminescence and Energy Transfer Process in Bi3+/Sm3+ Co-Doped Phosphate Zinc Lithium Glasses”, Advances in Materials Physics and Chemistry, 4, (2014), 165-171 [36] C K Jorgensen and R Reisfeld, “Judd-Ofelt parameters and chemical bonding”, J Less-Common Met., 93(1983), 107-112 [37] S Som, Subrata Das, S Dutta, Hendrik G Visser, et al., “Synthesis of strong red emitting Y2O3:Eu3+ phosphor by potential chemical routes: comparative investigations on the structural evolutions, photometric properties and Judd–Ofelt analysis” RSC Adv (2015) 70887- 70898 [38] G.P Darshan, H.B Premkumar, H Nagabhushana, S.C Sharma, B Daruka Prasad, S.C.Prashantha, “Neodymium doped yttrium aluminate synthesis and optical properties – A blue light emitting nanophosphor and its use in advanced forensic analysis” Dyes Pigm 134 (2016) 227- 233 [39] V Venkataramu, P Babu , C.K Jayasankar, Th Troster, W Sievers, G Wortmann, “Optical spectroscopy of Sm3+ ions in phosphate and fluorophosphate glasses”, Opt Mater 29 (2007)1429-1439 [40] Ramachandra Naik, S.C Prashantha, H Nagabhushana, “Effect of Li+codoping on structural and luminescent properties of Mg2SiO4:RE3+ (RE = Eu, Tb) nanophosphors for displays and eccrine latent fingerprint detection”, Opt Mater, 72 (2017) 295-304 [41] D.L Monika, H Nagabhushana, R Hari Krishna, B M Nagabhushana, S C Sharma, T Thomas, “Synthesis and photoluminescence properties of a novel Sr2CeO4:Dy3+nanophosphor with enhanced brightness by Li+ co-doping”, RSC Adv, (2014) 38655-38662 [42] C Pratapkumar, S.C Prashantha, H Nagabhushana, M.R Anilkumar, C.R Ravikumar, H.P Nagaswarupa, D.M Jnaneshwara, “White light emitting magnesium aluminate nanophosphor: Near ultra violet excited photoluminescence, photometric characteristics and its UV photocatalytic activity”, J Alloy Compd, 728(2017)1124-1138 11 Table1 Crystallite size of Bi2O3 Sl no Compound Bi2O3: Sm3+ : Mol% Crystallite size (nm) 23.535 Bi2O3: Sm3+ : Mol% 22.553 Bi2O3: Sm3+ : Mol% 19.426 Bi2O3: Sm3+ : Mol% 16.640 Bi2O3: Sm3+ : Mol% 13.243 Bi2O3: Sm3+ : 11 Mol% 13.178 Table2 J-O intensity parameters and radiative properties of Sm3+ doped Bi2O3NPs Phosphor Bi2O3:Sm3+ J-O intensity Parameters Transitions (10-20 cm2) mol % Ω2 0.41059 Ω4 0.361985 mol % 0.401301 0.495693 mol % 0.351343 0.323457 mol % 0.386104 0.347901 mol % 0.354646 0.347472 11 mol % 0.392754 0.417446 AR (s-1) ANR (s-1) AT (s-1) τr (ms) η % G5/2→6H5/2 G5/2→6H7/2 G5/2→6H9/2 12 71.316 24.025 95.341 10.489 74.8 69.703 23.482 93.185 10.731 74.8 61.025 20.558 81.584 12.257 74.8 67.063 22.592 89.656 11.154 74.8 61.599 20.752 82.351 12.143 74.8 68.218 22.982 91.199 10.965 74.8 3+ Bi2O3:Sm (11 mol %) 3+ Bi2O3:Sm (9 mol %) 3+ Intensity (a u.) Bi2O3:Sm (7 mol %) 3+ Bi2O3:Sm (5 mol %) 3+ Bi2O3:Sm (3 mol %) 3+ 20 30 40 50 Bi2O3 60 (423) (203) (421) (402) (222) (400) (002) (220) (201) Bi2O3:Sm (1 mol %) 70 2θ (degrees) Fig PXRD pattern of undoped and Sm3+ (1 to 11 mol %) doped Bi2O3NPs 13 80 Diffuse Reflectance (%) 80 3+ Bi2O3:Sm (1-11 mol %) 60 40 20 mol % mol % mol % mol % mol % 11 mol % 200 300 400 500 600 Wavelength (nm) Fig DRS of Sm3+ (1-11 mol %) doped Bi2O3NPs 14 700 800 3+ Bi2O3:Sm (1-11 mol %) [F(R)hν] mol % mol % mol % mol % mol % 11 mol % 2.96 eV 2.92 eV 2.0 2.5 3.0 Energy (eV) Fig Energy gap of Bi2O3 : Sm3+ NPs 15 3.5 2x10 3+ λemi=610 nm H5/2 Bi2O3: Sm Intensity(a u.) 2x10 1x10 5x10 I13/2 mol mol mol D3/2, 5/2 I11/2 G9/2 F7/2 M19/2 360 380 400 420 440 460 480 Wavelength(nm) Fig Excitation spectrum of Bi2O3:Sm3+ (3, & mol %) NPs (λemi= 610 nm) 16 500 PL Intensity(a u.) 1x10 8x10 6x10 G5/2 H7/2 Bi2O3: Sm ; λexc= 465 nm 3+ G5/2 H5/2 G5/2 H9/2 4x10 2x10 mol mol mol mol mol 11 mol G5/2 550 600 650 H11/2 700 Wavelength(nm) Fig Emission spectra of Bi2O3: Sm3+ (1-11 mol %) (λexc= 465 nm) 17 750 PL Intensity (a u.) 1x10 8x10 6x10 4x10 Sm3+ Concentration (mol%) Fig 6.Variation of PL intensity with Sm3+Concentration 18 11 Fig (a) CIE chromaticity diagram Bi2O3: Sm3+ NPs 19 0.6 CCTavg=1758K (b) 0.5 V' 0.4 0.3 3+ Bi2O3:Sm 0.2 mol% U' V' CCT 0.3481 0.54761 1763.302 0.35721 0.54625 1749.885 0.1 0.1 0.2 0.3 0.35126 0.54714 1756.622 11 0.34607 0.54791 1768.730 0.35363 0.54678 1753.001 0.35211 0.54701 1755.186 0.4 U' Fig (b) CCT diagram of Bi2O3: Sm3+ NPs 20 0.5 0.6 0.10 (a) Bi2O3: Sm1mol% Min 15 Min 30 Min 45 Min 60 Min Min 15 Min 30 Min 45 Min 60 Min 0.08 0.06 Absorbance Absorbance 0.08 (b) Bi2O3: Sm3 mol% 0.10 0.04 0.06 0.04 0.02 0.02 0.00 350 0.00 400 450 500 550 600 350 650 400 450 (c) Bi2O3: Sm5mol% Absorbance Absorbance 0.08 0.04 0.06 0.04 0.02 0.02 0.00 0.00 450 500 550 600 350 650 400 450 0.15 (e) Bi2O3: Sm9 mol% Min 15 Min 30 Min 45 Min 60 Min 0.15 0.10 Absorbance Absorbance 500 550 600 650 Wavelength(nm) Wavelength(nm) 0.05 0.00 350 650 Min 15 Min 30 Min 45 Min 60 Min 0.10 0.06 400 600 (d) Bi2O3: Sm7mol% Min 15 Min 30 Min 45 Min 60 Min 0.08 350 550 Wavelength(nm) Wavelength(nm) 0.10 500 Min 15 Min 30 Min 45 Min 60 Min (f) Bi2O3: Sm11 mol% 0.10 0.05 0.00 400 450 500 550 600 650 350 400 450 500 550 600 Wavelength(nm) Wavelength(nm) Fig Absorption Spectra of Acid Red-88 (AR-88) with Bi2O3:Sm3+NPs catalysts under UV light irradiation 21 650 Bi2O3: Sm1 mol % 0.0 Bi2O3: Sm3 mol % Bi2O3: Sm5 mol % Bi2O3: Sm7 mol % Bi2O3: Sm9 mol % -0.5 ln(c/c0) Bi2O3: Sm11 mol % -1.0 -1.5 15 30 45 60 Time(min) Fig 9.Plot of ln (C/Co) photo decolourization of all catalysts Bi2O3:Sm3+NPs under UV light irradiation 100 3+ Bi2O3: Sm Decomposition (%) 80 60 40 mol% mol% mol% mol% mol% 11 mol% 20 0 10 20 30 40 50 Time(min) Fig 10 Percentage decolourization rate of Bi2O3:Sm3+ NPs 22 60 ... region of solar light 3.3 Photoluminescence studies Fig shows the excitation spectra of Bi2O3: Sm3+NPs for 3, and 7mol% The spectra were taken in the range of 360 nm to 500 nm and exhibit bands... ml of the dye solution was inhibited and tested by a UV-Vis spectrophotometer by means of the typical adsorption band at 510 nm after centrifugation for the computation of the disintegration of. .. Discussion 3.1 PXRD studies Fig shows the Powder X-ray diffraction (PXRD) pattern of undoped and Sm3+ (1-11 mol %) doped Bi2O3 NPs All the recorded peaks were indexed to the Cubic phase of Bi2O3 (JCPDS