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Preparation of potassium tungsten bronze (KxWO3) for near-infrared shielding application via high-energy ball milling: Effect of milling time
(2026-07-15)
Pinthong, Phonlawee
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Kansaard, Thanaphon
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Songpanit, Maneerat
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Jayasankar, C. K.
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Mekprasart, Wanichaya
Potassium tungsten bronze (K<inf>x</inf>WO<inf>3</inf>), one of Near-infrared shielding application, with superior visible transmittance and near-infrared. In this work, potassium tungsten bronze particles were prepared by high energy ball milling method. X-ray diffraction technique was used to identify crystal structure of KWO powder. the morphology was observed with FE-SEM and TEM. The chemical state of tungsten was use XPS, and UV-vis-NIR spectrophotometer for optical property. The effect of prolongated milling time is effect on crystal structure change from starting materials to potassium tungsten bronze materials, particles size and optical property including Near infrared shielding and photochromic property.
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Optimization of Pr3+-doped glasses for photonic applications: an overview and challenges in Judd–Ofelt analysis
(2026-07-17)
Kesavulu, C. R.
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Soumya, S.
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Saikia, Darshana
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Jayasankar, Deviprasad Chalicheemalapalli
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Pecharapa, Wisanu
Characteristics (optical, luminescence, up-conversion, etc.) of triply ionized Praseodymium (Pr3+) ions doped glasses, glass-ceramics, phosphors and crystals have been widely studied for the development of photonic devices. Most of these characteristics are mainly based on Judd–Ofelt (JO) theory to interpret transition intensities and in turn to simulate radiative properties of Pr3+ ions based optical materials. However, JO analysis provides inconsistent results for Pr3+:glasses. Further, besides no review is available focusing on uneven findings of Pr3+:glasses. Therefore, a comprehensive data on Pr3+:glasses have been collected (490 Pr3+:glasses) and compared, besides labeling glass compositions systematically. The properties that are reviewed include, Nephelauxetic effect, optical energy gap, thermal, JO parameters, radiative properties, etc. It has been noticed that the systematic study either in preparation or optimization of characteristic properties are very much missing. Moreover, large number of data sets of literature are presented at one place which is very much useful for predictive modeling approaches. Also, the primary focus of the present review is not to provide a comprehensive summary of all studies conducted so far or to discuss new findings, but rather to highlight the challenges associated with JO parameters for Pr3+ ions that influence the development of optical materials, components, and applications.
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Optical and emission Spectroscopy and radiation shielding properties of Sm3+-Doped P2O5 + BaO + La2O3 glasses
(2026-01-01)
Kesavulu, C. R.
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Masthanaiah, E.
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Basavapoornima, Ch
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Depuru, Shobha Rani
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Pecharapa, Wisanu
Within lanthanide series, Sm3+(4f5) ion is relatively very complex electronic structure and similar to Dy3+(4f9) ion but both ions exhibit visible and infrared emissions. As such, characteristics (structural, thermal, optical, luminescence, etc.) of Sm3+ ion doped crystals, glass-ceramics, phosphors and glasses have been widely investigated for development of visible photonic devices, scintillators and magnetic components. In this paper, studies carried out so far on physical, structural, luminescence and optical characteristics of Sm3+-embedded glasses have been collected, tabulated and re-analysed in a systematic procedure besides our own work on P<inf>2</inf>O<inf>5</inf> + BaO + La<inf>2</inf>O<inf>3</inf> + Sm<inf>2</inf>O<inf>3</inf> (PBaLaSm) glasses. All the quantified properties have also been reviewed besides the labeling of glass compositions in a meaningful way. The properties that are reviewed include, optical energy gap, Judd-Ofelt (JO), radiative, etc. The obtained JO parameters ( × 10−20 cm2) for the present glasses are Ω<inf>2</inf> = 5.57, Ω<inf>4</inf> = 5.22 and Ω<inf>6</inf> = 3.37. In the case of Sm3+ ion, it has been noticed that the JO analysis found to be not only sensitive to the co-ordination geometry of the surrounded glass composition but also on the number of absorption levels that are used for the JO analysis. Theoretical radiation shielding results for the studied glass found to be better than the RS-253-G18, RS-360, lead and ordinary concrete at 30 and 40 KeV. The decay rates for 4G<inf>5/2</inf> level of Sm3+ ions in the PBaLaSm glasses have been measured and are found to exhibit single exponential nature at lower concentration and turns into non-exponential at higher concentrations (≥1.0 mol % Sm<inf>2</inf>O<inf>3</inf>-doped glasses). The experimental lifetimes for 4G<inf>5/2</inf> level of Sm3+ ions are found to decrease from 2413, 2383, 2129, 2039, 1299 and 259 μs when concentration increases from 0.01, 0.05, 0.1,0.5, 1.0 and 2.0 mol % due to cross-relaxation energy transfer. The non-exponential decay rates are well-fitted to Inokuti-Hirayama model for S = 6, indicates that the energy transfer is of dipole-dipole type. However, the overall observations outlined in this study for 48 Sm3+:glasses may be quite useful for those who are interested in this thrust area to plan and carryout systematic study to get constructive conclusion besides predictive nature.
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Structural and visible-near infrared optical properties of sodium tungsten bronze particles synthesized by one-step ball milling method
(2025-12-01)
Noinonmueng, Tanisara
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Kansaard, Thanaphon
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Pinthong, Phonlawee
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Moonseeda, Watcharakorn
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Songpanit, Maneerat
Near Infrared (NIR) shielding is a challenging issue in developing novel technology for smart building applications. Tungsten bronze-based material is one of the interesting materials for IR absorption and shielding applications. This research work aims to conduct the facile synthesis of sodium tungsten bronze powder (Na<inf>x</inf>WO<inf>3</inf>) via a high energy ball milling technique. The effect of ball milling time on the properties of the prepared product was investigated by relevant characterization techniques including X-ray diffraction technique, electron microscopy, X-ray photoelectron spectroscopy, and UV–vis–NIR spectrophotometry. At certain milling of 2–3 h, the corresponding results exhibited the phase transformation from starting precursor to the Na<inf>0</inf><inf>·</inf><inf>3</inf>WO<inf>3</inf> phase with good near-infrared absorptivity due to localized surface plasmon resonance phenomena of this phase.
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Stokes and anti-Stokes emission characteristics of Er3+/Yb3+ co-doped zinc tellurite glasses under 377 and 1550 nm excitations for solar energy conversion application
(2025-01-01)
Suresh, Keenatampalle
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Kesavulu, C. R.
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Deviprasad, C. J.
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Pecharapa, Wisanu
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Kagola, Upendra Kumar
One of the best rare earth combinations for down- and up-converting the solar photons is Er3+/Yb3+. Therefore, at present, by using the traditional melt quench technique, zinc tellurite glasses doped with Er3+ and Er3+/Yb3+ were characterised. Several methods of down-conversion that result in the emission of 1000 nm from the acceptor (Yb3+) under excitation of donor (Er3+) were studied. On the other hand, the impact of acceptor (Yb3+) concentration and excitation pump power on the excited state absorption and its influence on the up-conversion emission (1000 nm) properties were investigated in detail under 1535 nm excitation. The studies on emission and decay results are discovered to be very significant. Suggesting that these glasses when used as conversion layers, can append the conversion efficiency of Si-based solar cells.
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Sonochemical synthesis, characterization, and infrared-driven photocatalytic performance of 2%Er/x%Yb co-doped BiVO4 nanoparticles (x=2–10%)
(2024-11-01)
Kansaard, Thanaphon
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Noinonmueng, Tanisara
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Boonyarattanakalin, Kanokthip
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Boondok, Dungcharoen
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Wechprasit, Tirapat
This study investigates the influence of Yb co-doping on the photocatalytic performance of 2% Er-doped BiVO<inf>4</inf> nanoparticles under infrared light for wastewater treatment. Er/Yb co-doping induces a phase transformation from monoclinic to tetragonal BiVO<inf>4</inf>, significantly enhancing infrared light absorption and photocatalytic activity. The optimal Yb concentration for maximizing activity is found to be 2%, achieving a one-order-of-magnitude improvement compared to undoped BiVO<inf>4</inf>. Up-conversion processes involving Yb and Er ions play a crucial role in this enhancement, converting low-energy infrared photons into higher-energy visible emissions that drive photocatalysis. These findings demonstrate a promising strategy for developing highly efficient and sustainable photocatalysts for wastewater treatment utilizing the abundant yet underexplored infrared region of the solar spectrum.
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Structural, optical, luminescence spectroscopy and radiation shielding properties of Eu3+:borophosphotellurite glasses
(2024-10-01)
Masthanaiah, E.
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Basavapoornima, Ch
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Lokanadham, R.
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Pecharapa, Wisanu
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Kaewkhao, J.
Recently much effort is being paid to study the rare earth ions in multi component glass formers as they exhibit high enhancement in the efficiency of luminescence properties. In this direction, the present study focuses on the preparation and analysis of novel glass batches with composition of (in mol %) BPTCZEu: 40B<inf>2</inf>O<inf>3</inf>+20P<inf>2</inf>O<inf>5</inf>+15TeO<inf>2</inf>+ 10CaO+(15−x)ZnO + xEu<inf>2</inf>O<inf>3</inf>, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5. The important spectroscopic techniques such as optical absorption, luminescence, excitation and decay curves are taken to analyse the BPTCZEu glasses. Luminescence spectrum of BPTCZEu comprise of emission from excited (5D<inf>0</inf>) to the lower multiplets (7F<inf>J</inf> (J = 0−4)), among these, 5D<inf>0</inf> → 7F<inf>2</inf> (red luminescence) at 612 nm found to be very intense. Judd−Ofelt characteristics, Ω<inf>2</inf>, Ω<inf>4</inf> and Ω<inf>6</inf>, were derived from different constraints. To know the site symmetry around Eu3+, the fluorescence intensity ratio of 5D<inf>0</inf> → 7F<inf>2</inf> vs. 5D<inf>0</inf> → 7F<inf>1</inf> were analysed. Exciting 7F<inf>0</inf> → 5L<inf>6</inf> and monitoring 5D<inf>0</inf> → 7F<inf>2</inf>, the lifetime of 5D<inf>0</inf> level is determined to be 2 ms which is independent of Eu3+ content. The colour coordinates for all the Eu3+ concentrations are estimated to fall in the reddish−orange region. Theoretical radiation shielding results showed that substituting Eu<inf>2</inf>O<inf>3</inf> for ZnO in the glasses lowers photon number that can pass via the material, enhancing the glass system's trend to shield high energy radiation. These stimulated results are compared with experimental measurements of mass attenuation coefficient with respect to energy up to 662 KeV using Cs−137 source. All these findings obtained from title glasses are compared and discussed with respect to reported Eu3+:glasses and no systematic variation has been noticed either with single, bi− or multi−component glass formers and therefore needs further systematic work to relate Eu−radiation−ligand interaction.
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Spectroscopic investigation and local structure of Eu3+ ions in lead phosphate glasses for optical device applications
(2024-04-01)
Basavapoornima, Ch
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Masthanaiah, E.
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Vijaya, N.
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Depuru, Shobha Rani
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Kaewkhao, J.
Phosphate-based glasses are promising materials which are being employed for broad range of applications whereas Eu3+ is an efficient activator due to its predominant 5D<inf>0</inf> →7F<inf>2</inf> emission (red region). In this direction, an attempt has been made to investigate the effect of Eu3+ ions doped lead phosphate glasses (PPbKANEu: P<inf>2</inf>O<inf>5</inf>+PbO+K<inf>2</inf>O+Al<inf>2</inf>O<inf>3</inf>+Na<inf>2</inf>O+Eu<inf>2</inf>O<inf>3</inf>) to explore possible photonic device applications. Optical absorption, excitation, photoluminescence and decay rates are used to characterize the PPbKANEu glasses. The photoluminescence spectrum of Eu3+:PPbKAN glasses exhibit emission channels from the first excited (5D<inf>0</inf>) to the ground (7F<inf>J</inf> (J =0–4)) multiplets. To determine the local site symmetry of surrounding Eu3+ ions, the relative fluorescence intensity ratio of 5D<inf>0</inf>→7F<inf>1</inf> versus 5D<inf>0</inf>→7F<inf>2</inf> emission channels has been analyzed. The emission spectrum of PPbKANEu glasses exhibits a comprehensive lifting of degeneracy of 5D<inf>0</inf>→7F<inf>2</inf> and 5D<inf>0</inf>→7F<inf>1</inf> emission channels. By considering C<inf>2v</inf> symmetry for Eu3+ ions, the second (B<inf>0</inf>2= −406 and B<inf>2</inf>2=−158) and fourth (B<inf>0</inf>4=980, B<inf>2</inf>4=297 and B<inf>4</inf>4=926 cm–1) rank crystal–field (CF) characteristics were estimated along with CF strength factor (S= 402 cm–1). The lifetime of 5D<inf>0</inf> state is estimated to be 2.09, 2.23, 2.21 and 2.21 ms for 0.1, 0.5, 1.0 and 2.0 mol% of Eu3+ ions, respectively. The analysis of the decay times reveals that the lifetime of 5D<inf>0</inf> state is less affected by the concentration of the Eu3+ ion. The results are compared and discussed with reported values and confirm the potentiality of the PPbKANEu glasses for optical device applications in visible regions.
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Investigation of structural, optical and luminescence characteristics of Dy3+-embedded alkaline heavy metal zincfluoroborophosphate glasses
(2024-03-01)
Basavapoornima, Ch
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Chandrappa, V.
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Kesavulu, C. R.
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Lokanadham, R.
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Pecharapa, Wisanu
Dy3+-embedded glasses have been widely considered for light-emitting diode applications as well as optical display devices. Based on this importance, the present study investigates the structural and photoluminescence characteristics of Dy3+-embedded zincfluoroborophosphate glasses. These glasses with molar composition of 35H<inf>3</inf>BO<inf>3</inf> + 10NH<inf>4</inf>H<inf>2</inf>PO<inf>4</inf> + 25BaCO<inf>3</inf> + (5 − N)La<inf>2</inf>O<inf>3</inf> + 25ZnF<inf>2</inf> + NDy<inf>2</inf>O<inf>3</inf> (BPBaLaZfDy<inf>N</inf>), where N = 2.0, 1.0, 0.5, 0.1, and 0.05, were fabricated by the melt and quenching procedure. FTIR spectra show the existence of fundamental groups such as BO<inf>3</inf> and BO<inf>4</inf> units, phosphates as well as OH groups. The criterion of metallization, optical electronegativity and basicity of the fabricated glasses was investigated and presented. The three phenomenological Judd–Ofelt (JO) parameters were estimated with the aid of optical absorption of oscillator strengths by using well-known theoretical JO model and in turn estimated the essential radiative characteristics of excited fluorescent states of Dy3+ ion. Dy3+:BPBaLaZfDy glasses reveal the luminescence levels at 840 nm (infrared: 4F<inf>9/2</inf> → 6H<inf>7/2</inf>), 754 nm (infrared: 4F<inf>9/2</inf> → 6H<inf>9/2</inf>), 664 nm (weak red: 4F<inf>9/2</inf> → 6H<inf>11/2</inf>), 485 nm (blue: 4F<inf>9/2</inf> → 6H<inf>15/2</inf>) and 576 nm (yellow: 4F<inf>9/2</inf> → 6H<inf>13/2</inf>), exciting at 350 nm. Among different concentrations, 0.5 mol% (BPBaLaZfDy<inf>0.5</inf>) glass exhibits relatively more intense emission for 4F<inf>9/2</inf> → 6H<inf>15/2</inf>,<inf>13/2,11/2</inf> transitions. From emission data, colour chromaticity coordinates, yellow/blue emission intensity ratio, colour purity and correlated colour temperatures have been determined. The decay times for BPBaLaZfDy glasses were measured with 350 nm excitation and noticed that the radiative de-excitation from 4F<inf>9/2</inf> → 6H<inf>13/2</inf> state. The fluorescence lifetime values decrease (659 μs to 389 μs) with increase (0.05 to 2.0 mol%) in Dy3+ content. The analysis of the present work confirms the preference of BPBaLaZfDy glasses for the fabrication of optical display components as well as white light luminescence devices.
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Tailoring the Emission Behavior of WO3 Thin Films by Eu3+ Ions for Light-Emitting Applications
(2023-01-01)
Kavitha, V. S.
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Biju, V.
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Gopchandran, K. G.
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Praveena, R.
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Jayasankar, C. K.
The article reports the successful fabrication of Eu3+-doped WO<inf>3</inf> thin films via the radio-frequency magnetron sputtering (RFMS) technique. To our knowledge, this is the first study showing the tunable visible emission (blue to bluish red) from a WO<inf>3</inf>:Eu3+ thin film system using RFMS. X-ray diffractograms revealed that the crystalline nature of these thin films increased upto 3 wt% of the Eu3+ concentration. The diffraction peaks in the crystalline films are matched well with the monoclinic crystalline phase of WO<inf>3</inf>, but for all the films’, micro-Raman spectra detected bands related to WO<inf>3</inf> monoclinic phase. Vibrational and surface studies reveal the amorphous/semi-crystalline behavior of the 10 wt% Eu3+-doped sample. Valence state determination shows the trivalent state of Eu ions in doped films. In the 400–900 nm regions, the fabricated thin films show an average optical transparency of ~51–85%. Moreover, the band gap energy gradually reduces from 2.95 to 2.49 eV, with an enhancement of the Eu3+-doping content. The doped films, except the one at a higher doping concentration (10 wt%), show unique emissions of Eu3+ ions, besides the band edge emission of WO<inf>3</inf>. With an enhancement of the Eu3+ content, the concentration quenching process of the Eu3+ ions’ emission intensities is visible. The variation in CIE chromaticity coordinates suggest that the overall emission color can be altered from blue to bluish red by changing the Eu3+ ion concentration.
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