D. P. Bisen | Pt. Ravishankar Shukla University (original) (raw)

Papers by D. P. Bisen

Research paper thumbnail of Luminescent properties of R+ doped Sr2MgSi2O7:Eu3+ (R+ = Li+, Na+ and K+) orange–red emitting phosphors

Journal of Materials Science: Materials in Electronics, 2016

Research paper thumbnail of Influence of Er 3+ concentration on the photoluminescence characteristics and excitation mechanism of Gd 2 O 3 :Er 3+ phosphor synthesized via a solid-state reaction method

Luminescence, 2014

An Er(3+) -doped phosphor of Gd2 O3 (Gd2 O3 :Er(3+) ) was prepared using a conventional solid-sta... more An Er(3+) -doped phosphor of Gd2 O3 (Gd2 O3 :Er(3+) ) was prepared using a conventional solid-state reaction method. The structure and particle size were determined from X-ray powder diffraction measurements. The average particle size of the phosphor was in between 20 and 50 nm. The particle size and structure of the phosphor were further confirmed by transmission electron microscopy (TEM) analysis. Luminescence spectra were recorded under excitation wavelengths of 275, 380, 515 and 980 nm. The visible upconversion and downconversion luminescence spectra of the Gd2 O3 :Er(3+) phosphor were investigated as a function of Er(3+) ion concentration. The upconverted emission at 980 nm excitation shows enhanced red emission with respect to green emission as the dopant concentration increased. Similar results were observed for downconversion emission under 275 and 380 nm excitation wavelengths. The mechanisms responsible for populating the (4) S3/2 and (4) F9/2 levels, for green and red emissions, respectively, are different for different excitations and for different concentrations of Er(3+) . Copyright © 2014 John Wiley & Sons, Ltd.

Research paper thumbnail of Enhanced long-persistence of Ca2Al2SiO7:Ce3+ phosphors for mechanoluminescence and thermoluminescence dosimetry

Journal of Materials Science: Materials in Electronics, 2016

Research paper thumbnail of Photoluminescence and thermoluminescence properties of Eu(2) (+) doped and Eu(2+) ,Dy(3) (+) co-doped Ba2 MgSi2 O7 phosphors

Luminescence : the journal of biological and chemical luminescence, Jan 25, 2016

In this work, we report the preparation, characterization, comparison and luminescence mechanisms... more In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu(2) (+) -doped and Eu(2) (+) ,Dy(3) (+) -co-doped Ba2 MgSi2 O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2 MgSi2 O7 :Eu(2) (+) showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2 MgSi2 O7 :Eu(2) (+) Dy(3) (+) showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f(6) 5d(1) to 4f(7) transition of Eu(2) (+) . T...

Research paper thumbnail of Ca2Al2SiO7:Ce3+phosphors for mechanoluminescence dosimetry

Luminescence, 2016

A series of Ce(3+) ion single-doped Ca2 Al2 SiO7 phosphors was synthesized by a combustion-assist... more A series of Ce(3+) ion single-doped Ca2 Al2 SiO7 phosphors was synthesized by a combustion-assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X-ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV-irradiation excitation, the TL and ML emission spectra of Ca2 Al2 SiO7 :Ce(3+) phosphor showed the characteristic emission of Ce(3+) peaking at 400 nm (UV-violet) and originating from the Ce(3+) transitions of 5d-4f ((2) F5/2 and (2) F7/2 ). The photoluminescence (PL) emission spectra for Ca2 Al2 SiO7 :Ce(3+) were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca2 Al2 SiO7 :Ce(3+) phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Research paper thumbnail of INVESTIGATION OF THERMOLUMINESCENCE CHARACTERISTICS OF Y2O3:Er3+ NANOPHOSPHORS

Radiation protection dosimetry, Jan 5, 2016

Thermoluminescence (TL) characteristics of Y2O3:Er(3+) nanophosphor exposed to UV radiations were... more Thermoluminescence (TL) characteristics of Y2O3:Er(3+) nanophosphor exposed to UV radiations were investigated. Combustion synthesis method was employed to synthesise the nanophosphors. The confirmation for the pure cubic phase was done by powder X-ray diffraction. The particles formed were found to have 23.19 nm size and it was calculated by the Debye-Scherrer formula for [222] plane and is in close agreement with those obtained using transmission electron microscopy analysis. scanning electron microscopy micrograph reveals porous, irregular shaped particles with large agglomeration of particles whereas Fourier transform infrared spectroscopy studies confirm the presence of organic residua OH and CO in the samples. TL characteristics of UV irradiated Y2O3:Er(3+) for (1-5) mol % were investigated. All the TL glow curves show almost similar glow curves having a single broad peak at 113.26, 113.82 113.72, 113.74 and 113.72°C for 1, 2, 3, 4 and 5 mol %, respectively, of Er(3+) ions. Th...

Research paper thumbnail of Synthesis and Optical Properties of CaMgSi2O6:Ce3+ Phosphors

Journal of Electronic Materials, 2015

ABSTRACT CaMgSi2O6:Ce3+ phosphors were prepared by the solid state reaction method at a temperatu... more ABSTRACT CaMgSi2O6:Ce3+ phosphors were prepared by the solid state reaction method at a temperature of 1050°C. Structural and morphological studies of the phosphors were carried out using x-ray diffraction (XRD) and scanning electron microscopy. The results of XRD show a monoclinic structure with space group C2/c, and the average crystallite size calculated using Debye-Scherrer’s formula was found to be in the range 36-52 nm. Fourier transform infrared spectra confirmed the proper preparation of the sample. The thermoluminescence (TL) glow curves of CaMgSi2O6:Ce3+ phosphors for different ultra-violet (UV)-radiation times were studied. It was observed that, initially, the TL intensity increases with increasing UV irradiation time and later on it attains a saturation value. The phosphors were characterized using photoluminescence excitation and emission spectra in which the excitation peaks were found at 295 nm and 327 nm, and the emission peak was found at 348 nm. The peak of the mechanoluminescence intensity versus time curve increased linearly with the impact velocity of the piston used to deform the sample. Finally, the optical properties of CaMgSi2O6:Ce3+ phosphors are discussed.

Research paper thumbnail of Mechanoluminescence properties of SrAl2 O4 :Eu(2+) phosphor by combustion synthesis

Luminescence : the journal of biological and chemical luminescence, Jan 21, 2015

In this paper, europium-doped strontium aluminate (SrAl2 O4 :Eu(2+) ) phosphors were synthesized ... more In this paper, europium-doped strontium aluminate (SrAl2 O4 :Eu(2+) ) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2 O4 :Eu(2+) phosphor. The optical properties of SrAl2 O4 :Eu(2+) phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2 O4 :Eu(2+) phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2 O4 :...

Research paper thumbnail of Photoluminescence properties of rare-earth-doped (Er 3+ ,Yb 3+ ) Y 2 O 3 nanophosphors by a combustion synthesis method

Luminescence, 2015

In this work, we report the synthesis of Y2 O3 :Er(3+) , Y2 O3 :Yb(3+) and Y2 O3 :Er(3+) ,Yb(3+) ... more In this work, we report the synthesis of Y2 O3 :Er(3+) , Y2 O3 :Yb(3+) and Y2 O3 :Er(3+) ,Yb(3+) nanophosphors by the combustion synthesis method using urea as fuel. The doping agents were incorporated in the form of erbium nitrate and ytterbium nitrate. X-Ray diffraction (XRD) patterns revealed that the synthesized particles have a body-centered cubic structure with space group Ia-3. The photoluminescence (PL) properties were investigated after UV and infrared irradiation at room temperature. A strong characteristic emission of Er(3+) and Yb(3+) ions was identified, and the influence of doping concentration on the PL properties was systematically studied. Energy transfer from Yb(3+) to Er(3+) ions was observed in Y2 O3 nanophosphors. The obtained result may be useful in potential applications such as bioimaging. Copyright © 2015 John Wiley & Sons, Ltd.

Research paper thumbnail of Fracto-mechanoluminescence and thermoluminescence properties of UV and γ-irradiated Ca2 Al2 SiO7 :Ce(3+) phosphor

Luminescence : the journal of biological and chemical luminescence, Jan 23, 2015

Ce(3+) -doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an... more Ce(3+) -doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an initiating temperature of 600°C. Structural characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2 Al2 SiO7 :Ce(3+) showed an absorption edge at 230 nm. The optical characterization of Ca2 Al2 SiO7 :Ce(3+) phosphor was investigated in a fracto-mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2 Al2 SiO7 :Ce(3+) was recorded for different exposure times of UV and γ-irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a γ-dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82°C, 125°C and 203°C. Also the TL intensity had a single peak at 152°C for γ-irradiation. The TL and ML emission spectra of Ca2 Al2 Si...

Research paper thumbnail of UV excited green luminescence of SrAl2O4:Eu2+, Dy3+ nanophosphor

Research on Chemical Intermediates, 2015

Research paper thumbnail of Experimental and Theoretical Study of the Mechanoluminescence of ZnS:Mn Nanoparticles

Journal of Electronic Materials, 2015

Research paper thumbnail of Effect of capping agent concentration on thermoluminescence and photoluminescence of copper-doped zinc sulfide nanoparticles

Luminescence : the journal of biological and chemical luminescence, Jan 5, 2014

Copper-doped zinc sulfide (ZnS:Cu) nanoparticles with varying concentrations of capping agent wer... more Copper-doped zinc sulfide (ZnS:Cu) nanoparticles with varying concentrations of capping agent were prepared using a chemical route technique. These particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy and X-ray diffraction (XRD). Optical absorption studies showed that the absorption edge shifted towards the blue region as the concentration of the capping agent increased. Using effective mass approximation, calculation of the nanoparticle size indicated that effective band gap energy increases with decreasing particle size. The thermoluminescence (TL) properties of sodium hexameta phosphate (SHMP)-passivated ZnS:Cu nanoparticles were investigated after UV irradiation at room temperature. The TL glow curve of capped ZnS:Cu showed variations in TL peak position and intensity with the change in capping agent concentration. The photoluminescence (PL) spectra of ZnS:Cu nanoparticles excited at 254 nm exhibited a broad green emission band pea...

Research paper thumbnail of Thermoluminescence of mercaptoethanol-capped ZnS:Mn nanoparticles

Luminescence, 2014

The thermoluminescence (TL) of nanoparticles has become a matter of keen interest in recent times... more The thermoluminescence (TL) of nanoparticles has become a matter of keen interest in recent times and is rarely reported. This article reports the synthesis of ZnS:Mn nanocrystals using the chemical route technique, with mercaptoethanol (ME) used as the capping agent. The particle sizes for the nanocrystals were measured by X-ray diffraction (XRD) and also by studying transmission electron microscopy (TEM) patterns. The particle sizes of the synthesized samples were found to be between 1 and 3 nm. For samples with different concentrations of the capping agent, it was found that the TL intensity of the ZnS:Mn nanoparticles increased as the particle size decreased. A shift in the peak position of the TL glow curve was also seen with decreasing particle size. The TL intensity was found to be maximal for samples with 1.2% of Mn. A change in the peak position was not found for samples with different concentrations of Mn. The half-width glow peak curve method was used to determine the trap-depth. The frequency factor of the synthesized samples was also calculated. The stability of the charge carriers in the traps increases with decreasing nanoparticle size. The higher stability may be attributed to the higher surface/volume ratio and also to the increase in the trap-depth with decreasing particle size.

Research paper thumbnail of Theoretical Approach to the Mechanoluminescence of Thermoluminescent Crystals

Physica Status Solidi (a), 1989

ABSTRACT No abstract is available for this article.

Research paper thumbnail of Effect of Molar Concentration on Optical Absorption Spectra of ZnS:Mn Nanoparticles

E-Journal of Chemistry, 2010

The present paper reports the synthesis and characterization of luminescent nanocrystals of manga... more The present paper reports the synthesis and characterization of luminescent nanocrystals of manganese doped zinc sulphide. Nanocrystals of zinc sulphide were prepared by chemical precipitation method using the solution of zinc chloride, sodium sulphide, manganese chloride and mercaptoethanol was used as the capping agent. It was found that change in the molar concentration changes the particle size. The particle size of such nanocrystals was measured using XRD pattern and it is found to be in between 3 nm -5 nm. The blue-shift in absorption spectra was found with reducing size of the nanoparticles

Research paper thumbnail of Luminescence properties of Eu2+, Dy3+-doped Sr2MgSi2O7, and Ca2MgSi2O7 phosphors by solid-state reaction method

Research on Chemical Intermediates, 2014

ABSTRACT Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors was synthesized by the high te... more ABSTRACT Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors was synthesized by the high temperature solid state reaction method. The phase structure of the prepared phosphors was akermanite type structure which belongs to the tetragonal crystallography. The EDX and FTIR spectra confirm the present elements in prepared phosphors. Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors would emit blue and green light; the main emission peak appeared at 465 nm and 535 nm belonging to the broad emission band ascribed to the 4f65d1→4f7 transition. Decay graph indicate that the both phosphors contains the fast decay and slow decay. Investigation on afterglow property shows that the Sr2MgSi2O7:Eu2+, Dy3+ phosphor held better afterglow than Ca2MgSi2O7:Eu2+, Dy3+ phosphor. The peak of ML intensity increases linearly with increasing impact velocity of the moving piston.

Research paper thumbnail of Electronic Excitation during Elastic Deformation of γ-Irradiated LiF Single Crystals

Physica Status Solidi (a), 1992

Research paper thumbnail of Photoluminescence and electroluminescence studies of polyvinyl carbazole films

Journal of Luminescence, 2008

Polyvinyl carbazole (PVK) film has been prepared by solution method. Its absorption, photolumines... more Polyvinyl carbazole (PVK) film has been prepared by solution method. Its absorption, photoluminescence (PL) and electroluminescence (EL) have been studied. For PL and absorption studies, film of PVK was prepared by spreading PVK solution on clean glass plate. The dried film was taken out of the glass plate and used for absorption, thickness measurement and PL studies. The film is

Research paper thumbnail of Mechanoluminescence and thermoluminescence of Mn doped ZnS nanocrystals

Journal of Luminescence, 2011

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Research paper thumbnail of Luminescent properties of R+ doped Sr2MgSi2O7:Eu3+ (R+ = Li+, Na+ and K+) orange–red emitting phosphors

Journal of Materials Science: Materials in Electronics, 2016

Research paper thumbnail of Influence of Er 3+ concentration on the photoluminescence characteristics and excitation mechanism of Gd 2 O 3 :Er 3+ phosphor synthesized via a solid-state reaction method

Luminescence, 2014

An Er(3+) -doped phosphor of Gd2 O3 (Gd2 O3 :Er(3+) ) was prepared using a conventional solid-sta... more An Er(3+) -doped phosphor of Gd2 O3 (Gd2 O3 :Er(3+) ) was prepared using a conventional solid-state reaction method. The structure and particle size were determined from X-ray powder diffraction measurements. The average particle size of the phosphor was in between 20 and 50 nm. The particle size and structure of the phosphor were further confirmed by transmission electron microscopy (TEM) analysis. Luminescence spectra were recorded under excitation wavelengths of 275, 380, 515 and 980 nm. The visible upconversion and downconversion luminescence spectra of the Gd2 O3 :Er(3+) phosphor were investigated as a function of Er(3+) ion concentration. The upconverted emission at 980 nm excitation shows enhanced red emission with respect to green emission as the dopant concentration increased. Similar results were observed for downconversion emission under 275 and 380 nm excitation wavelengths. The mechanisms responsible for populating the (4) S3/2 and (4) F9/2 levels, for green and red emissions, respectively, are different for different excitations and for different concentrations of Er(3+) . Copyright © 2014 John Wiley & Sons, Ltd.

Research paper thumbnail of Enhanced long-persistence of Ca2Al2SiO7:Ce3+ phosphors for mechanoluminescence and thermoluminescence dosimetry

Journal of Materials Science: Materials in Electronics, 2016

Research paper thumbnail of Photoluminescence and thermoluminescence properties of Eu(2) (+) doped and Eu(2+) ,Dy(3) (+) co-doped Ba2 MgSi2 O7 phosphors

Luminescence : the journal of biological and chemical luminescence, Jan 25, 2016

In this work, we report the preparation, characterization, comparison and luminescence mechanisms... more In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu(2) (+) -doped and Eu(2) (+) ,Dy(3) (+) -co-doped Ba2 MgSi2 O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2 MgSi2 O7 :Eu(2) (+) showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2 MgSi2 O7 :Eu(2) (+) Dy(3) (+) showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f(6) 5d(1) to 4f(7) transition of Eu(2) (+) . T...

Research paper thumbnail of Ca2Al2SiO7:Ce3+phosphors for mechanoluminescence dosimetry

Luminescence, 2016

A series of Ce(3+) ion single-doped Ca2 Al2 SiO7 phosphors was synthesized by a combustion-assist... more A series of Ce(3+) ion single-doped Ca2 Al2 SiO7 phosphors was synthesized by a combustion-assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X-ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV-irradiation excitation, the TL and ML emission spectra of Ca2 Al2 SiO7 :Ce(3+) phosphor showed the characteristic emission of Ce(3+) peaking at 400 nm (UV-violet) and originating from the Ce(3+) transitions of 5d-4f ((2) F5/2 and (2) F7/2 ). The photoluminescence (PL) emission spectra for Ca2 Al2 SiO7 :Ce(3+) were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca2 Al2 SiO7 :Ce(3+) phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Research paper thumbnail of INVESTIGATION OF THERMOLUMINESCENCE CHARACTERISTICS OF Y2O3:Er3+ NANOPHOSPHORS

Radiation protection dosimetry, Jan 5, 2016

Thermoluminescence (TL) characteristics of Y2O3:Er(3+) nanophosphor exposed to UV radiations were... more Thermoluminescence (TL) characteristics of Y2O3:Er(3+) nanophosphor exposed to UV radiations were investigated. Combustion synthesis method was employed to synthesise the nanophosphors. The confirmation for the pure cubic phase was done by powder X-ray diffraction. The particles formed were found to have 23.19 nm size and it was calculated by the Debye-Scherrer formula for [222] plane and is in close agreement with those obtained using transmission electron microscopy analysis. scanning electron microscopy micrograph reveals porous, irregular shaped particles with large agglomeration of particles whereas Fourier transform infrared spectroscopy studies confirm the presence of organic residua OH and CO in the samples. TL characteristics of UV irradiated Y2O3:Er(3+) for (1-5) mol % were investigated. All the TL glow curves show almost similar glow curves having a single broad peak at 113.26, 113.82 113.72, 113.74 and 113.72°C for 1, 2, 3, 4 and 5 mol %, respectively, of Er(3+) ions. Th...

Research paper thumbnail of Synthesis and Optical Properties of CaMgSi2O6:Ce3+ Phosphors

Journal of Electronic Materials, 2015

ABSTRACT CaMgSi2O6:Ce3+ phosphors were prepared by the solid state reaction method at a temperatu... more ABSTRACT CaMgSi2O6:Ce3+ phosphors were prepared by the solid state reaction method at a temperature of 1050°C. Structural and morphological studies of the phosphors were carried out using x-ray diffraction (XRD) and scanning electron microscopy. The results of XRD show a monoclinic structure with space group C2/c, and the average crystallite size calculated using Debye-Scherrer’s formula was found to be in the range 36-52 nm. Fourier transform infrared spectra confirmed the proper preparation of the sample. The thermoluminescence (TL) glow curves of CaMgSi2O6:Ce3+ phosphors for different ultra-violet (UV)-radiation times were studied. It was observed that, initially, the TL intensity increases with increasing UV irradiation time and later on it attains a saturation value. The phosphors were characterized using photoluminescence excitation and emission spectra in which the excitation peaks were found at 295 nm and 327 nm, and the emission peak was found at 348 nm. The peak of the mechanoluminescence intensity versus time curve increased linearly with the impact velocity of the piston used to deform the sample. Finally, the optical properties of CaMgSi2O6:Ce3+ phosphors are discussed.

Research paper thumbnail of Mechanoluminescence properties of SrAl2 O4 :Eu(2+) phosphor by combustion synthesis

Luminescence : the journal of biological and chemical luminescence, Jan 21, 2015

In this paper, europium-doped strontium aluminate (SrAl2 O4 :Eu(2+) ) phosphors were synthesized ... more In this paper, europium-doped strontium aluminate (SrAl2 O4 :Eu(2+) ) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2 O4 :Eu(2+) phosphor. The optical properties of SrAl2 O4 :Eu(2+) phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2 O4 :Eu(2+) phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2 O4 :...

Research paper thumbnail of Photoluminescence properties of rare-earth-doped (Er 3+ ,Yb 3+ ) Y 2 O 3 nanophosphors by a combustion synthesis method

Luminescence, 2015

In this work, we report the synthesis of Y2 O3 :Er(3+) , Y2 O3 :Yb(3+) and Y2 O3 :Er(3+) ,Yb(3+) ... more In this work, we report the synthesis of Y2 O3 :Er(3+) , Y2 O3 :Yb(3+) and Y2 O3 :Er(3+) ,Yb(3+) nanophosphors by the combustion synthesis method using urea as fuel. The doping agents were incorporated in the form of erbium nitrate and ytterbium nitrate. X-Ray diffraction (XRD) patterns revealed that the synthesized particles have a body-centered cubic structure with space group Ia-3. The photoluminescence (PL) properties were investigated after UV and infrared irradiation at room temperature. A strong characteristic emission of Er(3+) and Yb(3+) ions was identified, and the influence of doping concentration on the PL properties was systematically studied. Energy transfer from Yb(3+) to Er(3+) ions was observed in Y2 O3 nanophosphors. The obtained result may be useful in potential applications such as bioimaging. Copyright © 2015 John Wiley & Sons, Ltd.

Research paper thumbnail of Fracto-mechanoluminescence and thermoluminescence properties of UV and γ-irradiated Ca2 Al2 SiO7 :Ce(3+) phosphor

Luminescence : the journal of biological and chemical luminescence, Jan 23, 2015

Ce(3+) -doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an... more Ce(3+) -doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an initiating temperature of 600°C. Structural characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2 Al2 SiO7 :Ce(3+) showed an absorption edge at 230 nm. The optical characterization of Ca2 Al2 SiO7 :Ce(3+) phosphor was investigated in a fracto-mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2 Al2 SiO7 :Ce(3+) was recorded for different exposure times of UV and γ-irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a γ-dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82°C, 125°C and 203°C. Also the TL intensity had a single peak at 152°C for γ-irradiation. The TL and ML emission spectra of Ca2 Al2 Si...

Research paper thumbnail of UV excited green luminescence of SrAl2O4:Eu2+, Dy3+ nanophosphor

Research on Chemical Intermediates, 2015

Research paper thumbnail of Experimental and Theoretical Study of the Mechanoluminescence of ZnS:Mn Nanoparticles

Journal of Electronic Materials, 2015

Research paper thumbnail of Effect of capping agent concentration on thermoluminescence and photoluminescence of copper-doped zinc sulfide nanoparticles

Luminescence : the journal of biological and chemical luminescence, Jan 5, 2014

Copper-doped zinc sulfide (ZnS:Cu) nanoparticles with varying concentrations of capping agent wer... more Copper-doped zinc sulfide (ZnS:Cu) nanoparticles with varying concentrations of capping agent were prepared using a chemical route technique. These particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy and X-ray diffraction (XRD). Optical absorption studies showed that the absorption edge shifted towards the blue region as the concentration of the capping agent increased. Using effective mass approximation, calculation of the nanoparticle size indicated that effective band gap energy increases with decreasing particle size. The thermoluminescence (TL) properties of sodium hexameta phosphate (SHMP)-passivated ZnS:Cu nanoparticles were investigated after UV irradiation at room temperature. The TL glow curve of capped ZnS:Cu showed variations in TL peak position and intensity with the change in capping agent concentration. The photoluminescence (PL) spectra of ZnS:Cu nanoparticles excited at 254 nm exhibited a broad green emission band pea...

Research paper thumbnail of Thermoluminescence of mercaptoethanol-capped ZnS:Mn nanoparticles

Luminescence, 2014

The thermoluminescence (TL) of nanoparticles has become a matter of keen interest in recent times... more The thermoluminescence (TL) of nanoparticles has become a matter of keen interest in recent times and is rarely reported. This article reports the synthesis of ZnS:Mn nanocrystals using the chemical route technique, with mercaptoethanol (ME) used as the capping agent. The particle sizes for the nanocrystals were measured by X-ray diffraction (XRD) and also by studying transmission electron microscopy (TEM) patterns. The particle sizes of the synthesized samples were found to be between 1 and 3 nm. For samples with different concentrations of the capping agent, it was found that the TL intensity of the ZnS:Mn nanoparticles increased as the particle size decreased. A shift in the peak position of the TL glow curve was also seen with decreasing particle size. The TL intensity was found to be maximal for samples with 1.2% of Mn. A change in the peak position was not found for samples with different concentrations of Mn. The half-width glow peak curve method was used to determine the trap-depth. The frequency factor of the synthesized samples was also calculated. The stability of the charge carriers in the traps increases with decreasing nanoparticle size. The higher stability may be attributed to the higher surface/volume ratio and also to the increase in the trap-depth with decreasing particle size.

Research paper thumbnail of Theoretical Approach to the Mechanoluminescence of Thermoluminescent Crystals

Physica Status Solidi (a), 1989

ABSTRACT No abstract is available for this article.

Research paper thumbnail of Effect of Molar Concentration on Optical Absorption Spectra of ZnS:Mn Nanoparticles

E-Journal of Chemistry, 2010

The present paper reports the synthesis and characterization of luminescent nanocrystals of manga... more The present paper reports the synthesis and characterization of luminescent nanocrystals of manganese doped zinc sulphide. Nanocrystals of zinc sulphide were prepared by chemical precipitation method using the solution of zinc chloride, sodium sulphide, manganese chloride and mercaptoethanol was used as the capping agent. It was found that change in the molar concentration changes the particle size. The particle size of such nanocrystals was measured using XRD pattern and it is found to be in between 3 nm -5 nm. The blue-shift in absorption spectra was found with reducing size of the nanoparticles

Research paper thumbnail of Luminescence properties of Eu2+, Dy3+-doped Sr2MgSi2O7, and Ca2MgSi2O7 phosphors by solid-state reaction method

Research on Chemical Intermediates, 2014

ABSTRACT Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors was synthesized by the high te... more ABSTRACT Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors was synthesized by the high temperature solid state reaction method. The phase structure of the prepared phosphors was akermanite type structure which belongs to the tetragonal crystallography. The EDX and FTIR spectra confirm the present elements in prepared phosphors. Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors would emit blue and green light; the main emission peak appeared at 465 nm and 535 nm belonging to the broad emission band ascribed to the 4f65d1→4f7 transition. Decay graph indicate that the both phosphors contains the fast decay and slow decay. Investigation on afterglow property shows that the Sr2MgSi2O7:Eu2+, Dy3+ phosphor held better afterglow than Ca2MgSi2O7:Eu2+, Dy3+ phosphor. The peak of ML intensity increases linearly with increasing impact velocity of the moving piston.

Research paper thumbnail of Electronic Excitation during Elastic Deformation of γ-Irradiated LiF Single Crystals

Physica Status Solidi (a), 1992

Research paper thumbnail of Photoluminescence and electroluminescence studies of polyvinyl carbazole films

Journal of Luminescence, 2008

Polyvinyl carbazole (PVK) film has been prepared by solution method. Its absorption, photolumines... more Polyvinyl carbazole (PVK) film has been prepared by solution method. Its absorption, photoluminescence (PL) and electroluminescence (EL) have been studied. For PL and absorption studies, film of PVK was prepared by spreading PVK solution on clean glass plate. The dried film was taken out of the glass plate and used for absorption, thickness measurement and PL studies. The film is

Research paper thumbnail of Mechanoluminescence and thermoluminescence of Mn doped ZnS nanocrystals

Journal of Luminescence, 2011

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