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V. Annapu Reddy,N.P. Pathak,R. Nath 한국물리학회 2012 Current Applied Physics Vol.12 No.2
The ferroelectric properties of BiFeO3 (BFO) films spray deposited on porous silicon have been studied. The analysis of XRD and FESEM investigations show that the crystalline strain in the BFO films increases with pore size. The BFO films on porous silicon substrate showed improvement in ferroelectric fatigue behavior, remanent polarization and ferroelectric switching time. A maximum memory window of 5.54 V at 1 MHz and a large remanent polarization (Pr) of 13.1 mC/cm2 have been obtained at room temperature. The improvement in the ferroelectric properties of these films has been correlated to the crystalline strain. The ferroelectric properties of BiFeO3 (BFO) films spray deposited on porous silicon have been studied. The analysis of XRD and FESEM investigations show that the crystalline strain in the BFO films increases with pore size. The BFO films on porous silicon substrate showed improvement in ferroelectric fatigue behavior, remanent polarization and ferroelectric switching time. A maximum memory window of 5.54 V at 1 MHz and a large remanent polarization (Pr) of 13.1 mC/cm2 have been obtained at room temperature. The improvement in the ferroelectric properties of these films has been correlated to the crystalline strain.
Singh, V.,Sivaramaiah, G.,Rao, J. L.,Singh, N.,Mohapatra, M.,Singh, P. K.,Pathak, M. S.,Dhoble, S. J. Minerals, Metals & Materials Society and the Insti 2017 Journal of Electronic Materials Vol. No.
<P>LiAl5O8 doped with Fe was synthesized by a propellant combustion route at furnace temperature of 773 K. The phosphor was characterized using powder x-ray diffraction, optical absorption, electron paramagnetic resonance (EPR) and photoluminescence spectroscopic techniques. The optical absorption spectrum exhibits a broad band at 242 nm characteristic of charge transfer between Fe3+-O2-. On excitation with 293 nm, emission band for the Fe3+ ion was observed at 687 nm. The CIE (International Commission on Illumination or Commission Internationale de l'Elcairage) coordinates for the system were evaluated adopting standard procedure which suggested that the system can be effective as a deep red emitting phosphor. The EPR spectrum of this phosphor exhibits a number of resonance signals characteristic of Fe3+ ions. The resonance signals at g = 3.16, 2.27 are attributed to Fe3+ present at tetrahedral site with an axial symmetry. The resonance signals at g = 1.98 and 1.43 are attributed to Fe3+ ions in octahedral site with an axial symmetry. Various EPR parameters such as the number of spins, Gibbs free energy, magnetic susceptibility, Curie constant and effective magnetic moment values are calculated and compared at room temperature and 110 K.</P>
Cr3+-Doped Yb3Ga5O12 Nanophosphor: Synthesis, Optical, EPR, Studies
Singh, V.,Sivaramaiah, G.,Rao, J. L.,Singh, N.,Pathak, M. S.,Jirimali, H. D.,Singh, P. K.,Srivastava, A. K.,Dhoble, S. J.,Mohapatra, M. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.8
<P>Gallium garnets of lanthanides are multifunctional materials especially known for their complicated structure and magnetic properties. In addition, with a suitable transition metal dopant ion, these matrices have been proved to be excellent materials for lasers. In particular, gallium garnet of ytterbium (Yb3Ga5O12) is known to possess excellent properties with regards to these applications. In this connection, Yb3Ga5O12 doped with Cr3+ nanophosphors were synthesized by a solution combustion route. The synthesized material was characterized by powder x-ray diffraction and scanning electron microscopy for phase purity and homogenous morphology. In order to ascertain the oxidation state of the doped ion, diffuse reflectance (DRF), photoluminescence (PL) and electron paramagnetic resonance (EPR) experiments were performed on the sample. The DRF and PL data suggested the stabilisation of the trivalent Cr ion in the matrix. The EPR spectra exhibited two resonance signals with effective g values at g approximate to 7.6 and 4. The EPR data corroborated the DRF and PL results, suggesting the stabilisation of Cr3+ in the matrix at octahedral-type geometries.</P>
Singh, N.,Singh, V.,Sivaramaiah, G.,Rao, J.L.,Singh, P.K.,Pathak, M.S.,Dhoble, S.J.,Mohapatra, M. Elsevier [etc.] 2016 Journal of luminescence Vol.178 No.-
<P>Strong blue-green light emitting MgSrAl10O17:Eu2+,Mn2+ phosphor was synthesized by a low temperature initiated, self-propagating and gas producing combustion process in a very short time (< 5 min). Structural characterization of the luminescent material was studied with X-ray diffraction analysis and energy-dispersive X-ray analysis. The absorption spectrum exhibits bands due to Eu2+ and Mn3+ ions. The excitation spectrum shows a peak at 337 nm. Upon excitation at 337 nm, the emission spectrum exhibits an intense band centered at 462 nm due to transitions from the 4f(6)5d(1) to the 4f(7) configuration of the Eu2+ ions, whereas sharp peak at 513 nm attributed to T-4(1) -> (6)A(1) transition of Mn2+ ions. The X-band EPR spectra of MgSrAl10O17:Eu2+,Mn2+ showed the presence of Eu2+ and Mn2+ ions. (C) 2016 Elsevier B.V. All rights reserved.</P>
Singh, V.,Sivaramaiah, G.,Mohapatra, M.,Rao, J. L.,Singh, N.,Pathak, M. S.,Singh, P. K.,Dhoble, S. J. Springer Science + Business Media 2017 Journal of Electronic Materials Vol.46 No.2
<P>GdAlO3 phosphor samples have been prepared by a solution combustion method. X-ray diffraction analysis revealed that the GdAlO3 phosphor stabilized in orthorhombic phase. The optical absorption spectrum showed bands due to Gd3+ ions as well as defect level in the host. The excitation spectrum exhibited a dominant band with maximum at 273 nm. Upon excitation at 273 nm, ultraviolet-B (UV-B) emission with maximum at 312 nm was observed from the undoped sample, being attributed to P-6(7/2) -> S-8(7/2) transition of Gd3+ ion. The UV-B emission was enhanced at liquid-nitrogen temperature (77 K), most probably due to increased ground-state population according to the Boltzmann distribution law. Electron spin resonance spectra of samples at both room and liquid-nitrogen temperature exhibited resonance signals at g ae 2, attributed to Gd3+ ions arranged with octahedral symmetry linked via oxygen bridges. Various magnetic and thermodynamic parameters for the phosphor system were evaluated by standard procedures. Correlation of these values with the optical properties suggested that the GdAlO3 phosphor can be effectively used as an UV-B light source for industrial applications at room temperature.</P>
Studies of Radiation-Induced Defects in Li2SiO3:Sm Phosphor Material
Singh, N.,Singh, V.,Watanabe, S.,Gundu Rao, T. K.,Chubaci, J. F.,Cano, N. F.,Pathak, M. S.,Singh, P. K.,Dhoble, S. J. Springer Science + Business Media 2017 Journal of electronic materials Vol.46 No.1
<P>Li2SiO3:Sm was synthesized by the solution combustion method. Powder x-ray diffraction technique was used to find the phase formation. Li2SiO3:Sm exhibits thermoluminescence (TL) peaks at approximately 140 degrees C, 155 degrees C, 190 degrees C, 250 degrees C, and 405 degrees C. Three defect centers contribute to the observed electron spin resonance spectrum from the gamma irradiated phosphor. Center I with principal g-values g(parallel to) = 2.0206 and g(perpendicular to) = 2.0028 is identified as an O-2(-) ion while center II, with an isotropic g-factor 2.0039, is assigned to an F+-type center. Center III is assigned to a Ti3+ center. The Ti3+ center is related to the 250 degrees C TL peak while the O-2(-) ion also correlates with the main TL peak at 250 degrees C. An additional defect center is observed during thermal annealing experiments, and the center (assigned to F+ center) seems to originate from an F center. The F center appears to be associated with the high temperature TL peak in a Li2SiO3: Sm phosphor. The luminescence spectrum reveals the dominant emission peaks at 605 ((4)G(5/2) -> H-6(7/2)) nm under the excitation wavelength of 402 nm.</P>
R.B.L. 굽타,V.N. 파닥,O.P. 베르마,Gupta, R.B.L.,Pathak, V.N.,Verma, O.P. Korean Society of Applied Entomology 1985 한국식물보호학회지 Vol.24 No.3
Influence of temperature, relative humidity, spore washing and spore drying on conidial germination of Alternaria porri(Ell.) Cif. was studied. Maximum conidial germination occurred at 100% relative humidity prevailing for 6 hours or more at $25^{\circ}C$. Conidial germination decreased with increase in number of spore washings. Drying of conidia for more than half an hour caused significant decrease in germination. In all the experiments, conidial germinatio increased with increase in incubation period.
Effect of Subclinical Mastitis on Milk of Cross Bred Sahiwal × Jersey Cows: A Biochemical Study
Kalorey, D.R.,Kurkure, N.V.,Nigot, N.K.,Patil, M.P.,Pathak, V.P. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.3
The experiment was undertaken to study the effect of subclinical mastitis on the biochemical parameters of milk in crossbred (Sahiwal $\times$ Jersey) cows. Subclincial mastitis was judged using California Mastitis Test and graded on a scale of 0 to 2. Twenty six milk samples of each grade were subjected to somatic cell count. Separated milk whey was analysed for total protein, immunoglobulin and trace mineral content. Results indicate linear increases in somatic cell count, total protein and immunoglobulin concentrations in milk with increase in grade of subclinical mastitis. However, copper, zinc, manganese and iron concentration in milk was not affected by grade of mastitis.
R.B.L. GUPTA,V.N. PATHAK,O.P. VERMA 한국응용곤충학회 1985 한국응용곤충학회지 Vol.24 No.3
Influence of temperature, relative humidity, spore washing and spore drying on conidial germination of Alternaria porri(Ell.) Cif. was studied. Maximum conidial germination occurred at 100% relative humidity prevailing for 6 hours or more at . Conidial germination decreased with increase in number of spore washings. Drying of conidia for more than half an hour caused significant decrease in germination. In all the experiments, conidial germinatio increased with increase in incubation period.