Prof. B.Sudhakar Reddy
@gcmkadapa.ac.in
Professor of Physics, Department of Physics
Government College for Men (Autonomous), Kadapa
Dr B.Sudhakar Reddy has born in 1st July 1969 at Gudavandla Palli village of C.K.Dinne Mandal, Kadapa District Andhra Pradesh, India. His parents were Smt. B.Mallamma and Late B.Malla Reddy. Dr B.Sudhakar Reddy obtained M.., and Ph.D. Degrees in Physics from S.V. University, Tirupati, India in 1992, 2005 and 2008 respectively. Dr. Dr B.Sudhakar Reddy is presently working as Professor at Department of Physics, Government College for Men(A), Kadapa, India. He has a teaching experience of 28 years and 15 years research experience. has published 68 research papers in International Journals of high repute and carried out 5 Major Research Projects funded by UGC and CSIR. produced 6 and 1 M.Phil degrees. Presently 3 Research Scholars are pursuing Ph.D. for their doctoral degree.
EDUCATION
Ph.D : Doctor of Philosophy (Physics)
University : Sri Venkateswara University, Tirupati.
Thesis Title : Optical Characterization of certain
Transition Metal (Cu2+, Mn2+) & Rare-Earth Ions (Eu3+, Tb3+, Nd3+, Er3+, Pr3+, Tm3+) Doped Boro-Fluoro-Phosphate Glasses
Year of Award : February 2008.
M.Phil : Master of Philosophy (Physics),
Spectroscopy (EPR Studies)
University : Sri Venkateswara University, Tirupati. India
Dissertation Title : EPR and Optical Spectral Studies on Mn2+ Ions Doped in Potassium Thiourea Bromide Single Crystals
Year of Passing : January 2005
M.Sc : Master of Science (Physics),
University : Sri Venkateswara University, Tirupati.
India
Year of Passing : October 1992
RESEARCH INTERESTS
Over the past one decade of rich experience in the preparation, characterization and optimization of variety of rare-earth ions doped glasses, glass-ceramics and nanocrystalline materials for the development of laser systems, optical fiber amplifiers and WLEDs
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
G. Moulika, S. Sailaja, J. Santhoshi Vijetha, S. Hajira, B. Naveen kumar Reddy, C. Nageswara Raju, and B. Sudhakar Reddy
Informa UK Limited
Abstract This article presents synthesis of mixed boro flouro phosphate glasses doped with trivalent samarium and dysprosium ions by melt quenching technic and the luminescent spectra of the glasses and their modifications by altering alkali oxides. Fourier transform infrared spectroscopy (FTIR) tool is used to detect various functional groups their bonding nature in host glasses .The luminescent spectrum of Sm3+ exhibits Orange-Red emission at wavelength of 599 nm due to transition from 4G5/2 →6H7/2 and Dy3+ spectrum has shown yellow emission at wavelength of 575 nm from 4F9/2 →6H13/2 by strong excitation at 403 nm and 388 nm 6H5/2 →4F7/2 transition of Samarium (Sm3+) ion and 6H15/2→4I13/2 transition of Dysprosium (Dy3+) ion respectively. In this article, by altering the three different alkali oxides (Li2O/Na2O/K2O) with the same concentration (0.5%) of Dy3+ ions and Sm3+. The change in the luminescent intensities were studied.
Guduru Moulika, Sannapureddy Sailaja, Jillela Santhosh Vijitha, Putluru Bayapu Reddy, Kondala Shanthi Latha, Gasthi Venkata Chalapathi, and Busireddy Sudhakar Reddy
Wiley
B. Naveen Kumar Reddy, S. Sailaja, K. Thyagarajan, and B. Sudhakar Reddy
Elsevier
B. Naveen Kumar Reddy, S. Sailaja, K. Thyagarajan, M. V. Ramanaiah, and B. Sudhakar Reddy
Informa UK Limited
Abstract Using the melt quenching technique, a new Dy3+-doped alkali and mixed alkali based borosilicate glasses were prepared and characterized for spectroscopic properties to be used to assess the potentiality for the laser gain media. The FTIR, absorption and fluorescence spectra were investigated. According to the Judd-Ofelt theory, from the absorption spectra, the oscillator strengths were computed for the observed bands of Dy3+-doped borosilicate glasses. The spectroscopic properties, J–O intensity parameters and luminescence intensity of Dy3+-ions are compared in alkali and mixed alkali based borosilicate glasses. By the comparison, low δrms (0.323), high Ω2 (11.98 × 10−20 cm2), high Ω4/Ω6 (1.164) and enhanced luminescence intensity indicates that Dy3+-ions doped mixed alkali borosilicate (especially MgNaKBSi) glasses are potentially useful candidates for laser gain media.
B. Naveen Kumar Reddy, S. Sailaja, K. Thyagarajan, Young Dahl Jho, and B. Sudhakar Reddy
Wiley
Four series of borosilicate glasses modified by alkali oxides and doped with Tb3+ and Sm3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B2 O3 + 10SiO2 + 5MgO + R + 0.5(Tb2 O3 /Sm2 O3 ) [where R = 10(Li2 O /Na2 O/K2 O) for series A and C, and R = 5(Li2 O + Na2 O/Li2 O + K2 O/K2 O + Na2 O) for series B and D]. The X-ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5 D4 → 7 F5 (543 nm) transition of the Tb3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm3+ ions with the series C and D glasses showed strong reddish-orange emission at 600 nm (4 G5/2 →6 H7/2 ) with an excitation wavelength λexci = 404 nm (6 H5/2 →4 F7/2 ). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb3+ and Sm3+ ions was studied to optimize the potential alkali-oxide-modified borosilicate glass.
G. Moulika, S. Sailaja, B. Naveen Kumar Reddy, V.Sahadeva Reddy, S.J. Dhoble, and B. Sudhakar Reddy
Elsevier BV
B. Suneetha, S. Sailaja, S.J. Dhoble, and B. Sudhakar Reddy
Elsevier BV
B. Naveen Kumar Reddy, B. Devaprasad Raju, K. Thyagarajan, R. Ramanaiah, Young-Dahl Jho, and B. Sudhakar Reddy
Elsevier BV
K. Mallikarjuna, M. Bhushana Reddy, G. Moulika, B. Naveen Kumar Reddy, R. Ramanaiah, S. J. Dhoble, and B. Sudhakar Reddy
Author(s)
Rare-earth (Tb3+) ions doped zinc lithium bismuth borate (ZLiBiB) glasses have been prepared by melt quenching method. From the FTIR spectrum, the functional groups have been identified. From the measurements of X-ray diffraction (XRD), differential scanning calorimeter (DSC) profiles of these glasses have been carried out. In case of Tb3+:ZLiBiB glasses emission transitions such as 5D4→ 7F6 (489 nm), 5D4→ 7F5 (545 nm), 5D4→ 7F4 (584 nm) and 5D4→ 7F3 (622 nm) have been identified. Among these, the transition at 542 nm has shown a bright green emission. The emission mechanism of Tb3+ doped ZLiBiB glasses has been explained in terms of energy level diagram.
Monali R. Kadukar, P. W. Yawalkar, S. P. Lochab, S. J. Dhoble, and B. Sudhakar Reddy
Informa UK Limited
ABSTRACT In the present article, polycrystalline low Z (Zeff = 8.19) LiAlO2:Dy/Eu phosphor prepared by simple wet chemical method. Thermoluminescence and some of the dosimetric characteristics of Dy/Eu activated LiAlO2 were reported. Samples in powder form were exposed to γ-ray irradiation with 137 Cs source for both LiAlO2:Dy and LiAlO2:Eu phosphors were studied for the first time. In case of LiAlO2:Dy phosphor shows one peak at 287°C and small hump at 335°C. However; LiAlO2:Eu phosphor shows glow peak at 272°C with a shoulder peak around 329°C. The TL sensitivity in both the cases were compared with CaSO4:Dy phosphor.LiAlO2:Dy sample have shown 1.23 times less sensitive than CaSO4:Dy and for LiAlO2:Eu is 5.6 times less sensitive than CaSO4:Dy.The TL response in the 0.001-0.043Gy dose range increased linearly with increase in radiation dose for both the samples. Fading study has been also done for both the samples. In addition to this trap parameters of LiAlO2:Dy/Eu were calculated by using computerized glow curve deconvolution and Chen's peak shape method.
Monali R.Kadukar, S. J. Dhoble, A. K. Sahu, V. Nayar, S. Sailaja, and B. Sudhakar Reddy
Wiley
This article reports on the luminescence properties of rare earth (Dy3+ and Tm3+ )ions doped SrGa2 Si2 O8 phosphor were studied. SrGa2 Si2 O8 phosphors weresynthesizedby employing solid state reaction method.From the measured X-ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ-ray irradiated samples have been studied. Photoluminescence spectra of Dy3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 348 nm,and it shows two emission bands at 483 and 574 nm due to 4 F9/2 → 6 H15/2 and 4 F9/2 → 6 H13/2 transitions respectively. Whereas the photoluminescence spectra of Tm3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 359 nm and it exhibits two emission bands at 454 and 472 nm due to 1 D2 → 3 F4 and1 G4 → 3 H6 transitions respectively. In thermoluminescence study, γ-irradiatedthermoluminescence glow curve of SrGa2 Si2 O8 :Dy3+ phosphor shows two well defined peaks at 293 °C (peak1)and 170 °C (peak2) whereas thermoluminescence glow curve of SrGa2 Si2 O8 :Tm3+ phosphor shows peaks at 292 °C (peak1) and 184 °C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa2 Si2 O8 :Dy3+ and SrGa2 Si2 O8 :Tm3+ are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd.
P. Giridhar, M. Bhushana Reddy, G. Neelima, R. Ramanaiah, K. Nagamuni Reddy, V. Sahadeva Reddy, and B. Sudhakar Reddy
Wiley
This article reports on the optical characterization of Pr(3) (+) -, Er(3) (+) - and Nd(3) (+) -doped cadmium lead boro tellurite (CLBT) glasses prepared using the melt quenching method. The visible-near infrared (Vis-NIR) absorption spectra of these glasses were analyzed systematically. On measuring the NIR emission spectra of Er(3) (+) :CLBT glasses, a broad emission band centered at 1536 nm ((4) I13 /2 → (4) I15 /2 ) was observed, as were three NIR emission bands at 900 nm ((4) F3 /2 → (4) I9 /2 ), 1069 nm ((4) F3 /2 → (4) I11 /2 ) and 1338 nm ((4) F3 /2 → (4) I13 /2 ) from Nd(3) (+) :CLBT glasses and an NIR emission band at 1334 nm ((1) G4 → (3) H5 ) from Pr(3) (+) :CLBT glasses at an excitation wavelength (λex ) of 514.5 nm (Ar(+) laser). Copyright © 2016 John Wiley & Sons, Ltd.
S. A. Fartode, B. Sudhakar Reddy, V. Nayar, and S.J. Dhoble
Informa UK Limited
ABSTRACT This paper reports on the BaSi6N8O:Eu3+ phosphor were prepared via modified two steps solid state diffusion technique in open air atmosphere and material was quenched at 1200°C for four hours. Eu3+ activated BaSi6N8O phosphor was characterized by XRD, which confirms the formation of the sample. From the Scanning electron microscope (SEM) images, the surface morphology of the sample has been studied. The photoluminescence (PL) spectra of BaSi6N8O:Eu3+ phosphor exhibits two emission bands at 614 nm (5D0→7F2) and at 587 nm (5D0→7F1) with an excitation wavelength of 396 nm. From the FTIR spectrum, bonding of atoms to each other and vibrational motions of molecules has been studied. ML was studied by dropping a piston on irradiated sample. From the ML glow curves single peak has been observed. ML intensity increases with activator concentration. Optimum ML has been observed for the sample having 1mole % of Eu ions.
Urlagaddala Rambabu, Nagegownivari Ramachandra Munirathnam, Busireddy Sudhakar Reddy, and Sandip Chatterjee
Wiley
Red emission intensity was optimized in three stages, by investigating the effects of: (i) host composition (Gd, Y and Gd/Y), (ii) codoping Li(+) as a sensitizer and, finally, (iii) with a SiO2 shell coating as a protecting layer. Lanthanide vanadate powder phosphors were synthesized using a modified colloidal precipitation technique. The effects of SiO2 coating on phosphor particles were characterized using scanning electron microscopy (SEM)-EDAX, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and photoluminescence (PL) measurements. An improvement in the PL intensity on Li codoping was due to improved crystallinity, which led to higher oscillating strengths for the optical transitions, and also a lowering of the inversion symmetry of Eu(3+) ions. Red emission intensity due to (5)D0 → (5)D2 transition of the phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01 was enhanced by 22.28% compared with Y0.95VO4:Eu(3+)0.05, and was further improved by 58.73% with SiO2 coating. The luminescence intensity (I) and colour coordinates (x, y) of the optimized phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01@SiO2, where I = 13.07 cd/m(2) and (x = 0.6721, y = 0.3240), were compared with values for a commercial red phosphor (Y2O2S:Eu(3+)), where I = 27 cd/m(2) and (x = 0.6522, y = 0.3437). The measured colour coordinates are superior to those of the commercial red phosphor, and moreover, match well with standard NTSC values (x = 0.67, y = 0.33).
B. Sudhakar Reddy, Monali R. Kadukar, Hyeong-Yong Hwang, Byoung Seung Ham, S. Sailaja, U. Rambabu, S.J. Dhoble, and Young-Dahl Jho
Elsevier BV
B. Sudhakar Reddy, Hyeong-Yong Hwang, Young-Dahl Jho, Byoung Seung Ham, S. Sailaja, C. Madhukar Reddy, B. Vengala Rao, and S.J. Dhoble
Elsevier BV
S.Hemasundara Raju, K.Thyagarajan, B.Sudhakar Reddy, and C.Nageswara Raju
Elsevier BV
B Sankara Reddy, S Venkatramana Reddy, P Venkateswara Reddy, N Koteeswara Reddy, and R P Vijayalakshmi
IOP Publishing
Pure ZnO and co-doped (Mn, Ag) ZnO nanoparticles have been successfully prepared by chemical co-precipitation method without using a capping agent. X-ray diffraction (XRD) studies confirms the presence of wurtzite (hexagonal) crystal structure similar to undoped ZnO, suggesting that doped Mn, Ag ions are substituted to the regular Zn sites. The morphology of the samples were studied by scanning electron microscopy (SEM). The chemical composition of pure and co-doped ZnO nanoparticles were characterized by energy dispersive X-ray analysis spectroscopy (EDAX). Optical absorption properties were determined by UV-vis Diffuse Reflectance Spectrophotometer. The incorporation of Ag+, Mn2+ in the place of Zn2+ provoked to decrease the size of nanocrystals as compared to pure ZnO. Optical absorption measurements indicates blue shift in the absorption band edge upon Ag, Mn ions doped ZnO nanoparticles.
A.N. Yerpude, S.J. Dhoble, and B. Sudhakar Reddy
Elsevier BV
S. Hemasundara Raju, B. Muni Sudhakar, B. Sudhakar Reddy, S. J. Dhoble, K. Thyagarajan, and C. Nageswara Raju
Wiley
Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 →(7)F2) with an excitation wavelength λ(exci) = 408 nm ((7)F0 → (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 → (7)F5) with an excitation wavelength λ(exci) = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.
S. Hemasundara Raju, B. Muni Sudhakar, B. Sudhakar Reddy, S. J. Dhoble, K. Thyagarajan, and C. Nageswara Raju
Informa UK Limited
This article reports on the synthesis, photoluminescence and thermoluminescence properties of samarium and dysprosium ions doped barium gadolinium titanate powder ceramics. The prepared samples were characterized by X- ray diffraction spectrum and it is observed that Sm3+ and Dy3+ ions doped barium gadolinium titanate powder ceramics are orthorhombic structure. From the SEM images of Sm3+ and Dy3+: BaGd2Ti4O12 ceramics, it is observed that the average grain size in the range ∼200-300 nm. The elements present in the composition are confirmed by the EDAX profiles and functional groups have been identified by using Fourier Transform Infrared spectroscopy. Photoluminescence spectra of Sm3+: BaGd2Ti4O12 ceramics have shown strong reddish- orange emission at 598 nm (4G5/2→6H7/2) with an excitation wavelength λexci = 408 nm (6H5/2→4F7/2) and Dy3+: BaGd2Ti4O12 ceramics have shown yellow emission at 587 nm (4F9/2→ 6H13/2) with an excitation wavelength λexci = 427 nm (6H15/2 → 4G11/2). Thermoluminescence (TL) nature of Sm3+ and Dy3+ ions doped BaGd2Ti4O12 ceramics has been observed with gamma ray irradiation.
M. Bhushana Reddy, S. Sailaja, C. Nageswara Raju, and B. Sudhakar Reddy
Springer Science and Business Media LLC
C. Nageswara Raju, S. Sailaja, S. Hemasundara Raju, S.J. Dhoble, U. Rambabu, Young-Dahl Jho, and B. Sudhakar Reddy
Elsevier BV
O. Ravi, C. Madhukar Reddy, B. Sudhakar Reddy, and B. Deva Prasad Raju
Elsevier BV
U. Rambabu, N.R. Munirathnam, D.P. Amalnerkar, T.L. Prakash, B. Sudhakar Reddy, and S. Chatterjee
Elsevier BV
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