Praveen Shahi - Academia.edu (original) (raw)

Papers by Praveen Shahi

Research paper thumbnail of Lanthanide complexes for temperature sensing, UV light detection, and laser applications

Sensors and Actuators A: Physical, 2015

ABSTRACT The Eu(DBM)3Phen complex has been synthesized and dispersed in poly(methyl methacrylate)... more ABSTRACT The Eu(DBM)3Phen complex has been synthesized and dispersed in poly(methyl methacrylate) and polyvinyl alcohol matrices in order to explore its versatile applicability. Excitation spectroscopy monitored at 611 nm show intense ultraviolet-blue spectra (∼250 to 450 nm) pointing to efficient energy transfer from the organic ligands to the central Eu3+ ion. The excellent photoluminescence properties, i.e., broad-band excitation spectra, sharp and intense emission, and long lifetime open the door for appealing multi-applications such as temperature sensing, ultraviolet light detection, and laser applications. Photoluminescence based temperature sensing with a sensitivity of up to 1.75% per K is demonstrated for the temperature range of 50–318 K, and additionally, ultraviolet radiation detection is demonstrated, whilst impinging ultraviolet intensities as weak as 96 nW/cm2 can be detected. The work further reports several essential device characteristics, such as emission dependence on impinging excitation intensity, sensor stability, and photoluminescence response times. Finally, by increasing the optical excitation, amplification in spontaneous emission and decrease of full width at half maximum take place, pointing to stimulated emission. This feature, in conjunction with the stimulated emission cross-section of 3.24 × 10−20 cm2, which is comparable to the Nd-Glass laser, suggests the suitability of the investigated lanthanide-polymer merger for laser realizations.

Research paper thumbnail of Impact of viscosity on photo-induced bimodal emission, decay profile and energy transfer in lanthanide based hybrid nanostructure

Research paper thumbnail of Development of inorganic-organic hybrid nanostructured material for H2O2 sensing application

Materials Research Express

An organic-inorganic hybrid nanoparticle (HNPs) composed of Sm(TTA) 3 Phen, a coordination compou... more An organic-inorganic hybrid nanoparticle (HNPs) composed of Sm(TTA) 3 Phen, a coordination compound, and NaY 0.78 Er 0.02 Yb 0.20 F 4, an upconversion nanoparticles (UCNPs), has been developed and used for H 2 O 2 sensing application. Herein, Sm(TTA) 3 Phen absorbs ultraviolet (UV) light and gives fluorescence in yellow-red-near infrared (NIR) region. Whereas, the UCNPs absorb NIR radiations (980 nm) and consequently emit in green-red region through photon upconversion process. Two important optical phenomena are observed when HNPs are simultaneously excited with UV (266 nm) and NIR (980 nm) laser radiation-(i) an energy transfer from Sm 3+ to Er 3+ ions, and (ii) color tunable emission from red to green, if the power of 980 nm laser is varied. Further, the material is highly competent to sense H 2 O 2 through fluorescence quenching of Sm 3+ emission in presence of H 2 O 2. The nature of quenching is conspicuously different for different concentration/ volume range of H 2 O 2. For lower volume range, the rate of decrease of emission/excitation intensity is linear, while for higher volume range the decay in intensity is exponential. The attained minimum detection limit for H 2 O 2 is 2 μl, which is significant for sensing applications.

Research paper thumbnail of Silver nanoparticles embedded hybrid organometallic complexes: Structural interactions, photo-induced energy transfer, plasmonic effect and optical thermometry

AIP Advances

Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide mat... more Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide matrix AIP Advances 8, 065013 (2018);

Research paper thumbnail of Investigation of optical properties and energy transfer in Eu(III) and Tb(III) based composite compound dispersed in polar, non-polar solvents and polymer matrix

Materials Research Express

Research paper thumbnail of An Assembly and Interaction of Upconversion and Plasmonic Nanoparticles on Organometallic Nanofibers: Enhanced Multicolor Upconversion, Downshifting Emission and Plasmonic effect

Nanotechnology, Jan 18, 2017

We herein present a novel inorganic-organic hybrid nanoparticle (HNPs) constituted of inorganic N... more We herein present a novel inorganic-organic hybrid nanoparticle (HNPs) constituted of inorganic NPs, NaY0.78Er0.02Yb0.2F4, and organometallic nanofiber, Tb(ASA)3Phen (TAP). The X-ray diffraction, Fourier transform infrared absorption and TEM analyse reveal that, the prepared ultrafine upconversion nanoparticles {UCNPs (6-9 nm)} are dispersed on the surface of TAP nanofibers. We observe that addition of TAP in UCNPs, effectively prevents the surface quenching to boost the UC intensity and enables tuning of UC emission from green to red region by controlling the phonon frequency around Er3+ ion. On the other hand, TAP is an excellent source of green emission under UV exposure. Therefore prepared HNPs not only give the enhanced and tunable UC but also emit strong green color in downshifting process. To further enhance the dual mode emission of HNPs, AgNPs has been introduced. The emission intensity of UC as well as DS emission was found to be strongly modulated in the presence of AgNPs...

Research paper thumbnail of Sunlight activated lanthanide complex for luminescent solar collector applications: effect of waveguide matrix

Journal of Physics D: Applied Physics, 2017

Research paper thumbnail of A strategy to achieve efficient dual-mode luminescence in lanthanide-based magnetic hybrid nanostructure and its demonstration for the detection of latent fingerprints

Journal of Colloid and Interface Science, 2017

We have synthesized a novel inorganic-organic hybrid nanostructure (IOHN) composed of fluoride na... more We have synthesized a novel inorganic-organic hybrid nanostructure (IOHN) composed of fluoride nanophosphor (NaGd0.78Er0.02Yb0.2F4) and β-diketones complex (Eu(DBM)3Phen). The Le Bail fitting of X-ray diffraction data suggests that the nanophoshor crystallizes in a hexagonal structure (P63/m space group). The TEM studies reveal that the nanophosphor and the IOHN both have average particle size of 6-8nm. The Eu(DBM)3Phen and NaGd0.78Er0.02Yb0.2F4 show characteristic down-shifting (DS) and up-conversion (UC) emission, under UV and NIR excitation, respectively. The IOHN comprises an excellent dual-mode optical features (DS and UC) of both the phases. Energy transfer from Er(3+) (doped in inorganic phase) to Eu(3+) (coordinated in organic phase) clearly demonstrates for a viable coupling between both the phases. IOHN material was found to be unique for the visualization of latent fingermarks. Because of ultrafine particle size the surface to volume ratio is relatively higher which improves the attachment of particles with the fingermarks. On the other hand, the strong paramagnetic property helps to remove excess material with magnetic wand easily. These properties provide an opportunity to probe even very weak fingermarks. Notwithstanding this, the dual-mode emission is useful for the visualization of latent fingermarks on multi-color surfaces as well.

Research paper thumbnail of Lanthanide doped ultrafine hybrid nanostructure: Multicolour luminescence, upconversion based energy transfer and luminescence solar collector application

Nanoscale, 2016

We herein demonstrate novel inorganic-organic hybrid nanoparticles (HNPs) composed of inorganic N... more We herein demonstrate novel inorganic-organic hybrid nanoparticles (HNPs) composed of inorganic NPs, NaY0.78Er0.02Yb0.2F4, and an organic β-diketonate complex, Eu(TTA)3Phen, for energy harvesting applications. Both the systems maintain their core integrity and remain entangled through weak interacting forces. HNPs incorporate the characteristic optical behaviour of both the systems i.e. they give an intense red emission under UV excitation, due to Eu(3+) in organic complexes, and efficient green upconversion emission of Er(3+) in inorganic NPs for NIR (980 nm) excitation. However, (i) an energy transfer from Er(3+) (inorganic NPs) to Eu(3+) (organic complex) under NIR excitation, and (ii) an increase in the decay time of (5)D0 → (7)F2 transition of Eu(3+) for HNPs as compared to the Eu(TTA)3Phen complex, under different excitation wavelengths, are added optical characteristics which point to an important role of the interface between both the systems. Herein, the ultra-small size (6-9 nm) and spherical shape of the inorganic NPs offer a large surface area, which improves the weak interaction force between both the systems. Furthermore, the HNPs dispersed in the PMMA polymer have been successfully utilized for luminescent solar collector (LSC) applications.

Research paper thumbnail of Host-Sensitized NIR Quantum Cutting Emission in Nd3+Doped GdNbO4Phosphors and Effect of Bi3+Ion Codoping

Inorganic Chemistry, 2016

Host-sensitized near-infrared quantum cutting (QC) emission has been demonstrated in Nd(3+) doped... more Host-sensitized near-infrared quantum cutting (QC) emission has been demonstrated in Nd(3+) doped Gd(1-x)Nd(x)NbO4 phosphors for various x values. Further, the effect of Bi(3+) ion addition as a sensitizer on near-infrared QC is studied in detail. X-ray diffraction confirms a monoclinic structure for pure and Nd(3+) doped phosphors. Pulsed laser excitation at 266 nm of Gd(1-x)Nd(x)NbO4 and Gd(0.99-x)Nd(x)Bi(0.01)NbO4 causes efficient room-temperature energy transfer from the NbO4(3-) to the Nd(3+) ions and the NbO4(3-) and Bi(3+) ions to the Nd(3+) ions, respectively, which emits more than one near-infrared photon for single impinging ultraviolet photon. The emission band of Nd(3+) shows unusual character where the intensity of the (4)F(3/2)-(4)I(9/2) transition at 888 nm is higher than the intensity of the transition (4)F(3/2)-(4)I(11/2) at 1064 nm, due to energy transfer from GdNbO4 host to Nd(3+) ion. Using photoluminescence lifetime studies, the quantum cutting efficiencies are found to be the maximum 166% and 172% for Gd(0.95)Nd(0.05)NbO4 and Gd(0.94)Nd(0.05)Bi(0.01)NbO4, respectively. The present study could establish Nd(3+) ion as an alternative of Yb(3+) ion for near-infrared quantum cutting. This work facilitates the probing of Nd(3+) ions doped phosphor materials for next generation Si-solar cells.

Research paper thumbnail of Revelation of the Technological Versatility of the Eu(TTA) 3 Phen Complex by Demonstrating Energy Harvesting, Ultraviolet Light Detection, Temperature Sensing, and Laser Applications

ACS Applied Materials & Interfaces, 2015

We synthesized the Eu(TTA)3Phen complex and present herein a detailed study of its photophysics. ... more We synthesized the Eu(TTA)3Phen complex and present herein a detailed study of its photophysics. The investigations encompass samples dispersed in poly(vinyl alcohol) and in ethanol in order to explore the versatile applicability of these lanthanide-based materials. Details upon the interaction between Eu, TTA, and the Phen ligands are revealed by Fourier transform infrared and UV-visible absorption, complemented by steady state and temporally resolved emission studies, which provide evidence of an efficient energy transfer from the organic ligands to the central Eu(3+) ion. The material produces efficient emission even under sunlight exposure, a feature pointing toward suitability for luminescent solar concentrators and UV light sensing, which is demonstrated for intensities as low as 200 nW/cm(2). The paper further promotes the complex's capability to be used as luminescence-based temperature sensor demonstrated by the considerable emission intensity changes of ∼4.0% per K in the temperature range of 50-305 K and ∼7% per K in the temeperature range 305-340 K. Finally, increasing the optical excitation causes both spontaneous emission amplification and emission peak narrowing in the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) - features indicative of stimulated emission. These findings in conjunction with the fairly large stimulated emission cross-section of 4.29 × 10(-20) cm(2) demonstrate that the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) could be a very promising material choice for lanthanide-polymer based laser architectures.

Research paper thumbnail of Host matrix impact on Er3+ upconversion emission and its temperature dependence

RSC Advances

By synthesizing Y(1.9-2x)Yb0.1Er2xO3, Y(0.95-x)Yb0.05ErxVO4 and Y(0.95-x)Yb0.05ErxPO4 phosphors, ... more By synthesizing Y(1.9-2x)Yb0.1Er2xO3, Y(0.95-x)Yb0.05ErxVO4 and Y(0.95-x)Yb0.05ErxPO4 phosphors, with phonon frequency maxima at 560, 826 and 1050 cm-1, respectively, we present the impact of phonon energy and crystal structure of the host matrix on upconversion and temperature sensing behavior. The spectral upconversion characteristics of all three phosphors reveal noticeably differences. The temperature sensing studies reveal that the phosphors have maximum sensitivity ~490K, which is found to be highest (0.0105K-1) in Y0.947Yb0.05Er0.003VO4 followed by Y1.894Yb0.1Er0.006O3 and Y0.947Yb0.05Er0.003PO4 phosphors. We found that the temperature sensitivity basically depends on intensity ratio of two thermally coupled emission bands, 2H11/2→4I15/2 and 4S3/2→4I15/2, of Er3+. Further, the intensity ratio depends on phonon energy of the host lattice, crystal structure, surface quenching centers and the temperature dependence of non-radiative decay rate.

Research paper thumbnail of Lanthanide complexes for temperature sensing, UV light detection, and laser applications

Sensors and Actuators A: Physical, 2015

ABSTRACT The Eu(DBM)3Phen complex has been synthesized and dispersed in poly(methyl methacrylate)... more ABSTRACT The Eu(DBM)3Phen complex has been synthesized and dispersed in poly(methyl methacrylate) and polyvinyl alcohol matrices in order to explore its versatile applicability. Excitation spectroscopy monitored at 611 nm show intense ultraviolet-blue spectra (∼250 to 450 nm) pointing to efficient energy transfer from the organic ligands to the central Eu3+ ion. The excellent photoluminescence properties, i.e., broad-band excitation spectra, sharp and intense emission, and long lifetime open the door for appealing multi-applications such as temperature sensing, ultraviolet light detection, and laser applications. Photoluminescence based temperature sensing with a sensitivity of up to 1.75% per K is demonstrated for the temperature range of 50–318 K, and additionally, ultraviolet radiation detection is demonstrated, whilst impinging ultraviolet intensities as weak as 96 nW/cm2 can be detected. The work further reports several essential device characteristics, such as emission dependence on impinging excitation intensity, sensor stability, and photoluminescence response times. Finally, by increasing the optical excitation, amplification in spontaneous emission and decrease of full width at half maximum take place, pointing to stimulated emission. This feature, in conjunction with the stimulated emission cross-section of 3.24 × 10−20 cm2, which is comparable to the Nd-Glass laser, suggests the suitability of the investigated lanthanide-polymer merger for laser realizations.

Research paper thumbnail of Impact of viscosity on photo-induced bimodal emission, decay profile and energy transfer in lanthanide based hybrid nanostructure

Research paper thumbnail of Development of inorganic-organic hybrid nanostructured material for H2O2 sensing application

Materials Research Express

An organic-inorganic hybrid nanoparticle (HNPs) composed of Sm(TTA) 3 Phen, a coordination compou... more An organic-inorganic hybrid nanoparticle (HNPs) composed of Sm(TTA) 3 Phen, a coordination compound, and NaY 0.78 Er 0.02 Yb 0.20 F 4, an upconversion nanoparticles (UCNPs), has been developed and used for H 2 O 2 sensing application. Herein, Sm(TTA) 3 Phen absorbs ultraviolet (UV) light and gives fluorescence in yellow-red-near infrared (NIR) region. Whereas, the UCNPs absorb NIR radiations (980 nm) and consequently emit in green-red region through photon upconversion process. Two important optical phenomena are observed when HNPs are simultaneously excited with UV (266 nm) and NIR (980 nm) laser radiation-(i) an energy transfer from Sm 3+ to Er 3+ ions, and (ii) color tunable emission from red to green, if the power of 980 nm laser is varied. Further, the material is highly competent to sense H 2 O 2 through fluorescence quenching of Sm 3+ emission in presence of H 2 O 2. The nature of quenching is conspicuously different for different concentration/ volume range of H 2 O 2. For lower volume range, the rate of decrease of emission/excitation intensity is linear, while for higher volume range the decay in intensity is exponential. The attained minimum detection limit for H 2 O 2 is 2 μl, which is significant for sensing applications.

Research paper thumbnail of Silver nanoparticles embedded hybrid organometallic complexes: Structural interactions, photo-induced energy transfer, plasmonic effect and optical thermometry

AIP Advances

Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide mat... more Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide matrix AIP Advances 8, 065013 (2018);

Research paper thumbnail of Investigation of optical properties and energy transfer in Eu(III) and Tb(III) based composite compound dispersed in polar, non-polar solvents and polymer matrix

Materials Research Express

Research paper thumbnail of An Assembly and Interaction of Upconversion and Plasmonic Nanoparticles on Organometallic Nanofibers: Enhanced Multicolor Upconversion, Downshifting Emission and Plasmonic effect

Nanotechnology, Jan 18, 2017

We herein present a novel inorganic-organic hybrid nanoparticle (HNPs) constituted of inorganic N... more We herein present a novel inorganic-organic hybrid nanoparticle (HNPs) constituted of inorganic NPs, NaY0.78Er0.02Yb0.2F4, and organometallic nanofiber, Tb(ASA)3Phen (TAP). The X-ray diffraction, Fourier transform infrared absorption and TEM analyse reveal that, the prepared ultrafine upconversion nanoparticles {UCNPs (6-9 nm)} are dispersed on the surface of TAP nanofibers. We observe that addition of TAP in UCNPs, effectively prevents the surface quenching to boost the UC intensity and enables tuning of UC emission from green to red region by controlling the phonon frequency around Er3+ ion. On the other hand, TAP is an excellent source of green emission under UV exposure. Therefore prepared HNPs not only give the enhanced and tunable UC but also emit strong green color in downshifting process. To further enhance the dual mode emission of HNPs, AgNPs has been introduced. The emission intensity of UC as well as DS emission was found to be strongly modulated in the presence of AgNPs...

Research paper thumbnail of Sunlight activated lanthanide complex for luminescent solar collector applications: effect of waveguide matrix

Journal of Physics D: Applied Physics, 2017

Research paper thumbnail of A strategy to achieve efficient dual-mode luminescence in lanthanide-based magnetic hybrid nanostructure and its demonstration for the detection of latent fingerprints

Journal of Colloid and Interface Science, 2017

We have synthesized a novel inorganic-organic hybrid nanostructure (IOHN) composed of fluoride na... more We have synthesized a novel inorganic-organic hybrid nanostructure (IOHN) composed of fluoride nanophosphor (NaGd0.78Er0.02Yb0.2F4) and β-diketones complex (Eu(DBM)3Phen). The Le Bail fitting of X-ray diffraction data suggests that the nanophoshor crystallizes in a hexagonal structure (P63/m space group). The TEM studies reveal that the nanophosphor and the IOHN both have average particle size of 6-8nm. The Eu(DBM)3Phen and NaGd0.78Er0.02Yb0.2F4 show characteristic down-shifting (DS) and up-conversion (UC) emission, under UV and NIR excitation, respectively. The IOHN comprises an excellent dual-mode optical features (DS and UC) of both the phases. Energy transfer from Er(3+) (doped in inorganic phase) to Eu(3+) (coordinated in organic phase) clearly demonstrates for a viable coupling between both the phases. IOHN material was found to be unique for the visualization of latent fingermarks. Because of ultrafine particle size the surface to volume ratio is relatively higher which improves the attachment of particles with the fingermarks. On the other hand, the strong paramagnetic property helps to remove excess material with magnetic wand easily. These properties provide an opportunity to probe even very weak fingermarks. Notwithstanding this, the dual-mode emission is useful for the visualization of latent fingermarks on multi-color surfaces as well.

Research paper thumbnail of Lanthanide doped ultrafine hybrid nanostructure: Multicolour luminescence, upconversion based energy transfer and luminescence solar collector application

Nanoscale, 2016

We herein demonstrate novel inorganic-organic hybrid nanoparticles (HNPs) composed of inorganic N... more We herein demonstrate novel inorganic-organic hybrid nanoparticles (HNPs) composed of inorganic NPs, NaY0.78Er0.02Yb0.2F4, and an organic β-diketonate complex, Eu(TTA)3Phen, for energy harvesting applications. Both the systems maintain their core integrity and remain entangled through weak interacting forces. HNPs incorporate the characteristic optical behaviour of both the systems i.e. they give an intense red emission under UV excitation, due to Eu(3+) in organic complexes, and efficient green upconversion emission of Er(3+) in inorganic NPs for NIR (980 nm) excitation. However, (i) an energy transfer from Er(3+) (inorganic NPs) to Eu(3+) (organic complex) under NIR excitation, and (ii) an increase in the decay time of (5)D0 → (7)F2 transition of Eu(3+) for HNPs as compared to the Eu(TTA)3Phen complex, under different excitation wavelengths, are added optical characteristics which point to an important role of the interface between both the systems. Herein, the ultra-small size (6-9 nm) and spherical shape of the inorganic NPs offer a large surface area, which improves the weak interaction force between both the systems. Furthermore, the HNPs dispersed in the PMMA polymer have been successfully utilized for luminescent solar collector (LSC) applications.

Research paper thumbnail of Host-Sensitized NIR Quantum Cutting Emission in Nd3+Doped GdNbO4Phosphors and Effect of Bi3+Ion Codoping

Inorganic Chemistry, 2016

Host-sensitized near-infrared quantum cutting (QC) emission has been demonstrated in Nd(3+) doped... more Host-sensitized near-infrared quantum cutting (QC) emission has been demonstrated in Nd(3+) doped Gd(1-x)Nd(x)NbO4 phosphors for various x values. Further, the effect of Bi(3+) ion addition as a sensitizer on near-infrared QC is studied in detail. X-ray diffraction confirms a monoclinic structure for pure and Nd(3+) doped phosphors. Pulsed laser excitation at 266 nm of Gd(1-x)Nd(x)NbO4 and Gd(0.99-x)Nd(x)Bi(0.01)NbO4 causes efficient room-temperature energy transfer from the NbO4(3-) to the Nd(3+) ions and the NbO4(3-) and Bi(3+) ions to the Nd(3+) ions, respectively, which emits more than one near-infrared photon for single impinging ultraviolet photon. The emission band of Nd(3+) shows unusual character where the intensity of the (4)F(3/2)-(4)I(9/2) transition at 888 nm is higher than the intensity of the transition (4)F(3/2)-(4)I(11/2) at 1064 nm, due to energy transfer from GdNbO4 host to Nd(3+) ion. Using photoluminescence lifetime studies, the quantum cutting efficiencies are found to be the maximum 166% and 172% for Gd(0.95)Nd(0.05)NbO4 and Gd(0.94)Nd(0.05)Bi(0.01)NbO4, respectively. The present study could establish Nd(3+) ion as an alternative of Yb(3+) ion for near-infrared quantum cutting. This work facilitates the probing of Nd(3+) ions doped phosphor materials for next generation Si-solar cells.

Research paper thumbnail of Revelation of the Technological Versatility of the Eu(TTA) 3 Phen Complex by Demonstrating Energy Harvesting, Ultraviolet Light Detection, Temperature Sensing, and Laser Applications

ACS Applied Materials & Interfaces, 2015

We synthesized the Eu(TTA)3Phen complex and present herein a detailed study of its photophysics. ... more We synthesized the Eu(TTA)3Phen complex and present herein a detailed study of its photophysics. The investigations encompass samples dispersed in poly(vinyl alcohol) and in ethanol in order to explore the versatile applicability of these lanthanide-based materials. Details upon the interaction between Eu, TTA, and the Phen ligands are revealed by Fourier transform infrared and UV-visible absorption, complemented by steady state and temporally resolved emission studies, which provide evidence of an efficient energy transfer from the organic ligands to the central Eu(3+) ion. The material produces efficient emission even under sunlight exposure, a feature pointing toward suitability for luminescent solar concentrators and UV light sensing, which is demonstrated for intensities as low as 200 nW/cm(2). The paper further promotes the complex's capability to be used as luminescence-based temperature sensor demonstrated by the considerable emission intensity changes of ∼4.0% per K in the temperature range of 50-305 K and ∼7% per K in the temeperature range 305-340 K. Finally, increasing the optical excitation causes both spontaneous emission amplification and emission peak narrowing in the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) - features indicative of stimulated emission. These findings in conjunction with the fairly large stimulated emission cross-section of 4.29 × 10(-20) cm(2) demonstrate that the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) could be a very promising material choice for lanthanide-polymer based laser architectures.

Research paper thumbnail of Host matrix impact on Er3+ upconversion emission and its temperature dependence

RSC Advances

By synthesizing Y(1.9-2x)Yb0.1Er2xO3, Y(0.95-x)Yb0.05ErxVO4 and Y(0.95-x)Yb0.05ErxPO4 phosphors, ... more By synthesizing Y(1.9-2x)Yb0.1Er2xO3, Y(0.95-x)Yb0.05ErxVO4 and Y(0.95-x)Yb0.05ErxPO4 phosphors, with phonon frequency maxima at 560, 826 and 1050 cm-1, respectively, we present the impact of phonon energy and crystal structure of the host matrix on upconversion and temperature sensing behavior. The spectral upconversion characteristics of all three phosphors reveal noticeably differences. The temperature sensing studies reveal that the phosphors have maximum sensitivity ~490K, which is found to be highest (0.0105K-1) in Y0.947Yb0.05Er0.003VO4 followed by Y1.894Yb0.1Er0.006O3 and Y0.947Yb0.05Er0.003PO4 phosphors. We found that the temperature sensitivity basically depends on intensity ratio of two thermally coupled emission bands, 2H11/2→4I15/2 and 4S3/2→4I15/2, of Er3+. Further, the intensity ratio depends on phonon energy of the host lattice, crystal structure, surface quenching centers and the temperature dependence of non-radiative decay rate.