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Singh, Vijay,Pathak, M.S.,Singh, N.,Singh, Pramod K.,Jirimali, H.D. Elsevier 2018 OPTIK -STUTTGART- Vol.168 No.-
<P><B>Abstract</B></P> <P>A series of Tb<SUP>3+</SUP> doped Sr<SUB>2</SUB>La<SUB>8</SUB>(SiO<SUB>4</SUB>)<SUB>6</SUB>O<SUB>2</SUB> phosphors were successfully synthesized via sol-gel method. The formations of sol-gel phosphors were confirmed using powder X-ray diffraction studies. The emission intensity shows the 544 nm (<SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>5</SUB>) maximum that was obtained for the prepared samples using the 233 nm excitation. Luminescence quenching was not observed for the prepared series of the Tb<SUP>3+</SUP> doped Sr<SUB>2</SUB>La<SUB>8</SUB>(SiO<SUB>4</SUB>)<SUB>6</SUB>O<SUB>2</SUB> phosphors. The addition of the Tb<SUP>3+</SUP> concentration greatly improved the photoluminescent properties of the present phosphors.</P>
Visible upconversion in Er<sup>3+</sup>/Yb<sup>3+</sup> co-doped LaAlO<sub>3</sub> phosphors
Singh, Vijay,Rai, V.K.,Singh, N.,Pathak, M.S.,Rathaiah, M.,Venkatramu, V.,Patel, Rahul V.,Singh, Pramod K.,Dhoble, S.J. Elsevier 2017 Spectrochimica acta. Part A, Molecular and biomole Vol.171 No.-
<P><B>Abstract</B></P> <P>The Er<SUP>3+</SUP> doped and Er<SUP>3+</SUP>/Yb<SUP>3+</SUP> co-doped LaAlO<SUB>3</SUB> phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb<SUP>3+</SUP> ions into Er<SUP>3+</SUP>:LaAlO<SUB>3</SUB>, the blue, green and red upconversion emissions of Er<SUP>3+</SUP> ions have been enhanced about ~20, ~54 and ~22 times, under 978nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er<SUP>3+</SUP>:LaAlO<SUB>3,</SUB> whereas energy transfer is dominant mechanism in Er<SUP>3+</SUP>/Yb<SUP>3+</SUP>:LaAlO<SUB>3</SUB> phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb<SUP>3+</SUP> ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> By facile combustion synthesis, Er<SUP>3+</SUP> and Er<SUP>3+</SUP>/Yb<SUP>3+</SUP> doped LaAlO<SUB>3</SUB> phosphors are obtained. </LI> <LI> Phosphor was characterized using XRD, SEM-EDX, FTIR and Up-conversion spectroscopy. </LI> <LI> Upon excitation at 978nm, intense up-conversion emission is observed. </LI> <LI> Prepared materials could be suitable for up-conversion lasers and green display device. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>
Plasticizer doped ionic liquid incorporated solid polymer electrolytes for photovoltaic application
Pramod K. Singh,B. Bhattacharya,R.M. Mehra,이희우 한국물리학회 2011 Current Applied Physics Vol.11 No.3
Polyethylene oxide base polymer electrolyte has been modified by doping of EMImDCN and PEG as plasticizers. Doping by IL resulted to enhanced conductivity and improved DSSC response. The DSSC using the modified electrolyte showed 3.02% efficiency at 1 sun condition.
Polymer electrolyte with ionic liquid for DSSC application
Singh, Pramod K.,Kim, Ki-Il,Lee, Jae-Wook,Rhee, Hee-Woo WILEY-VCH Verlag 2006 Physica status solidi. PSS. A, Applications and ma Vol.203 No.11
<P>We have investigated the structural and ionic conductivity properties of the polymer electrolyte PEO:KI/I<SUB>2</SUB> doped with an ionic liquid 1-ethyl 3-methylimidazolium thio-cyanate (EMImSCN). Incorporation of the ionic liquid (IL) reduced the crystallinity, and enhanced the ionic conductivity. Optimized conductivity was found at 80 wt% of ionic liquid composition. This high electrical conductivity was suitable for dye sensitized solar cell (DSSC) application. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Singh, Pramod K,Kim, Kang-Wook,Nagarale, R K,Rhee, Hee-Woo Institute of Physics [etc.] 2009 Journal of physics. D, applied physics Vol.42 No.12
<P>Solid polymer electrolyte membranes of polyethylene oxide, KI and I<SUB>2</SUB> doped with low viscosity ionic liquid (IL) are developed and used in dye sensitized solar cells. Free charge carriers and reduced crystallinity of polymer electrolyte matrix provided by IL assist in ionic conductivity (σ) enhancement, and the maximum σ is 4.72 × 10<SUP>−4</SUP> S cm<SUP>−1</SUP> at 40 wt% IL concentration. XRD and DSC results affirm the reduction of crystallinity while AFM suggests the good incorporation of IL. The fabricated solar cells with IL-doped polymer electrolytes show improved efficiency (2%) in comparison with solar cells without IL. This improvement is due to the high σ by IL doping.</P>
Pramod K. Rajak,Vijay K. Singh,Asha L. Singh,Narendra Kumar,Om P. Kumar,Vishvajeet Singh,Aniruddha Kumar,Rai Ankita,Shweta Rai,Amiya S. Naik,Prakash K. Singh 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.4
The present study is an attempt to know the temporal and spatial distribution of geochemical components in the lignite deposit of Kapurdi, Barmer Basin (Rajasthan). Lignite samples have been subjected to proximate, ultimate and elemental analyses, and determination of mineral carbon (MINC%). Besides, various minerals and functional groups have been analyzed through X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). Selected environmentally sensitive and potential hazardous elements like Cu, Cd, Zn, Ni, Cr, Pb, Mn, Al, Fe and Co are determined using atomic absorption spectrophotometer (AAS). To know the association of minerals with organic matter, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) has also been carried out. The concentration of Co, Ni, Cd, Pb, Na, and K is high when compared with world average and is main concern for the environmental and health hazards. The elements like Fe, Ca, Mg, Zn, and Pb have shown increasing trend from top to bottom of the lignite seam with some fluctuations in the values in few bands whereas others do not follow a definite trend of variation along the seam profile.
Singh, Vijay,Seshadri, M.,Singh, N.,Pathak, M.S.,Kumaran, R. Senthil,Choi, Yong-Keun,Singh, Pramod K.,Dhoble, S.J.,Srivastava, Anoop K. Elsevier 2016 Journal of luminescence Vol.176 No.-
<P><B>Abstract</B></P> <P>Combustion derived In<SUB>2</SUB>O<SUB>3</SUB>:Er<SUP>3+</SUP>, co-doped with Yb<SUP>3+</SUP>phosphor powders have been prepared. Powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy methods are used to characterize the prepared phosphor powders. The intensity parameters (<I>Ω<SUB>λ</SUB> </I>, <I>λ</I>=2, 4 and 6), radiative transition probabilities (<I>A<SUB>R</SUB> </I>), radiative lifetime (<I>τ<SUB>R</SUB> </I>) and branching ratios (<I>β</I>) of certain emission transition of Er<SUP>3+</SUP>ions for In<SUB>2</SUB>O<SUB>3</SUB>:Er<SUP>3+</SUP>and In<SUB>2</SUB>O<SUB>3</SUB>:Er<SUP>3+</SUP>/Yb<SUP>3+</SUP>phosphors have been estimated in the framework of the model given by Judd–Ofelt. Upon excitation at 978nm, upconversion luminescence properties of Er<SUP>3+</SUP>and Er<SUP>3+</SUP>/Yb<SUP>3+</SUP>doped In<SUB>2</SUB>O<SUB>3</SUB> phosphors are investigated. The results obtained from optical study confirm the existence of an effective Yb<SUP>3+</SUP>to Er<SUP>3+</SUP>energy transfer process and it also predict possible mechanisms to populate the <SUP>4</SUP>S<SUB>3/2</SUB> and <SUP>4</SUP>F<SUB>9/2</SUB> levels. The possible upconversion mechanisms are discussed for Er<SUP>3+</SUP>and Yb<SUP>3+</SUP>ions with energy level diagram.</P>
PL and ESR of Gd3+ in LaMgAl11O19 phosphors
Singh, Vijay,Singh, N.,Pathak, M. S.,Watanabe, S.,Gundu Rao, T. K.,Singh, Pramod K.,Kwon, Young-Wan Springer-Verlag 2018 Journal of materials science Materials in electron Vol.29 No.6
<P>LaMgAl11O19 doped with different concentrations of gadolinium phosphors were synthesized by combustion and characterized using X-Ray diffraction to identify the crystalline phase. Photoluminescence studies on the sample showed emission peaks at 313 and 306 nm with lambda(exi) = 273 nm corresponding to the P-6 (J) -> S-8(7/2) transitions of Gd3+ ions. In phosphors with low dopant concentrations, dominant electron spin resonance lines are observed with g (eff) similar to 1.96, 1.98, 4.2, and 6.0. With increasing concentrations, the spectrum appears to be U-shaped, and main lines are seen at g (eff) similar to 1.98, 2.04, 2.8, 4.1 and 6.2. Distortions in the immediate environment of Gd3+ ions lead to relatively strong crystal fields and the appearance of lines in the low field region of the spectrum.</P>