Excellent Red Phosphors of Eu3+ Activated Double Perovskite Structured Series NaSrBi1-xEuxMoO6 (x = 0.0-0.24) Prepared by Citrate-Gel Method K. Koteswara Rao, B. Nagamani Naidu Asian Journal of Chemistry, 2022 In this work, a double perovskite structured series was prepared by using simple citrate sol-gel method at 700 ºC for 5 h of sintering. The concentrated sample of x = 0.12 exhibits more intensity than all other concentration in their emission spectra for every series. Particle size, thickness of the particle, distance between particles and its surface morphology were identified by scanning electron microscopy. The size and distance between particles in each series lies in between the range of 1 μm-50 nm and 20-50 nm, respectively. Many voids with strong agglomerations were also observed. In addition, the absorption of light capacity for each series investigated through diffuse reflectance spectra method. All the samples of double perovskite structures exhibit a sharp cut-off of absorption light in the UV-visible regions of diffuse reflectance spectra. Predominantly, all the samples shows a very good charge transfer band in their excitation spectra that leads to more absorption of light correspondingly emits high intensity in emission spectra at 395, 464 and 545 nm. All the samples of every series emit main peaks in the range of 550-700 nm in their emission spectra. Out of all four main peaks, 614 nm peak represents the red phosphor with 5D0-7F2 transition in the emission spectra. The prepared double perovskite structure compound CRI coordinates were almost close to commercially available red phosphor i.e. Y2O2S(0.67,0.33) as per NTSC. Hence, the prepared red phosphors can be used in order to display devices, luminescent materials and WLEDs.
Mechanism of Luminescence Enhancement in Eu3+ Activated Double Perovskite Phosphors Bi2-xEuxWO6 (x = 0-0.24) Prepared by Sol-Gel Method K. Koteswara Rao, B. Nagamani Naidu Asian Journal of Chemistry, 2022 A double perovskite structured series Bi2–xEuxWO6 (x = 0.03-0.24) was prepared by using simple citrate sol-gel method at 700 ºC for 5 h of sintering. The double perovskite structure and its lattice parameters were analyzed by the XRD technique and found to be pure orthorhombic phase. The concentrated sample of x = 0.12 exhibits more intensity than all other concentration in their emission spectra. Particle size, thickness of the particle, distance between particles and its surface morphology were identified by scanning electron microscopy. The size and distance between particles lies in between the range of 1-50 nm and 20-50 nm, respectively. In addition to this the absorption of light capacity for every sample was investigated through diffuse reflectance spectra method. All the samples of double perovskite structures exhibit a sharp cut-off of absorption light in the UV and visible regions of diffuse reflectance spectra. Predominantly, sample x = 0.12 shows very good charge transfer band in their excitation spectra that leads to more absorption of light correspondingly emits high intensity in emission spectra. All the samples of series emit main peaks in the range of 550-700 nm in their emission spectra. Out of all four main peaks, 614 nm peak represents the red phosphor with 5D0−7F2 transition in the emission spectra. The prepared double perovskite structure compound CRI co-ordinates (0.6254, 0. 3739) are almost close to commercially available red phosphor i.e. Y2O2S (0.67, 0.33) as per NTSC. Hence, the prepared red phosphors can be used in order to display devices, luminescent materials and WLEDs.
Sol-gel synthesis, crystal structure and luminescence properties of Eu3+ doped double perovskite molybdates NaCaBi1-xEuxMoO6 (x = 0-0.27) B Nagamani Naidu, K Koteswara Rao, M P S Murali Krishna Materials Research Express, 2019 Sodium and calcium containing bismuth molybdates of double perovskite structured NaCaBi1−xEuxMoO6 (x = 0.0–0.27) were prepared by a sol-gel combustion method. The samples were finally sintered at 500, 600 & 700 °C/5 h each and characterized by using powder X-ray diffraction (XRD), UV–Visible absorption and fluorescence spectroscopy. The powder XRD patterns indicated a monoclinic phase initially for x = 0 to 0.09 and then a mix of monoclinic and triclinic phases for x = 0.12 to 0.18. For the remaining compositions, i.e. for x = 0.21–0.27 the samples crystallized in triclinic phase only. A corresponding change of lattice parameters and peak positions were observed in powder XRD patterns as the Eu3+ concentration was increased. The powder samples sintered at 700 °C /5 h were excited at 395, 465 & 540 nm and their corresponding emission spectra showed major peaks in the vicinity of 595 & 614 nm for all the excitation wavelengths. The Eu3+ concentration of x = 0.12 gave highest red light emission intensity, related to the transition 5D0–7F2. The morphology of powders showed clear and characteristic nano-flake like structure. The color rendering index (CRI) coordinates of all the samples were calculated and showed values close to National Television Standards Committee (NTSC) coordinates of pure red phosphor showing promise for phosphor converted -white light emitting diodes (pc-WLEDs).
Nano bismuth molybdate for photo-catalytic synthesis of imidazo [1, 2-a] pyridines using 2-aminopyridines and phenacyl bromide in aqueous conditions International Journal of Mechanical Engineering and Technology, 2018
Nano SiO 2 catalyzed synthesis of Imidazo[1,2-a]pyridines Tejeswararao DHARMANA, Koteswara Rao KOLA Annales De Chimie Science Des Materiaux, 2018 A facile microwave assisted reaction of phenacyl bromide and 2-amino pyridine is catalyzed by Nano SiO2 under solvent free conditions to give corresponding Imidazo[1,2a]pyridines in good yields. Reactions proceed with high efficiency and good functional group tolerance. This approach provides a useful protocol for the preparation of highly substituted Imidazo[1,2-a]pyridine derivatives. RÉSUMÉ. Une réaction facile assistée par micro-ondes du bromure de phénacyle et de la 2amino pyridine est catalysée par du Nano SiO2 dans des conditions sans solvant pour donner les Imidazo[1,2-a]pyridines correspondantes avec de bons rendements. Les réactions se déroulent avec une efficacité élevée et une bonne tolérance fonctionnelle du groupe. Cette approche fournit un protocole utile pour la préparation de dérivés d’Imidazo[1,2-a]pyridine hautement substitués.
Silica@PMA core-shell structure as recyclable catalyst for the synthesis of quinolines Der Pharma Chemica, 2016
Mechanism of luminescence Enhancement in Eu3+ activated Double perovskite phosphors Bi2-xEuxWO6 (x= 0 - 0.24) prepared by semi sol-gel Method KKRBN Naidu Asian Journal of Chemistry 34 (9), 2205-2210 , 2022 2022
Excellent red phosphors of Eu3+ activated Double perovskite structured series NaSrBi1-xEuxMoO6(x=0.0-0.24) prepared by citrate-gel method KKRBN Naidu Asian Journal of Chemistry 34 (11), 2806-2812 , 2022 2022
Growth of silver nanowires on anatase structured TiO2 thin films by thermal reduction method KKRBN Naidu NeuroQuantology 20 (8), 8637-8645 , 2022 2022
Bismuth and Europium - based double perovskite nanoscale motifs as support media for the Synthesis of Quinoline KK Rao Turkish Journal of Physiotherapy and Rehabilitation 32 (2) , 2021 2021
Fabrication Of TiO2 Nanorod & Nanotube Arrays by Electrochemical Anodization – Influence of Process Parameters KKRVD Rao Turkish Journal of Physiotherapy and Rehabilitation 32 (3) , 2021 2021
Sol-gel synthesis, crystal structure and luminescence properties of Eu 3+ doped double perovskite molybdates NaCaBi 1−x Eu x MoO 6 (x = 0–0.27) B Nagamani Naidu, K Koteswara Rao, MPS Murali Krishna Materials Research Express 6 (11), 116210 , 2019 2019 Citations: 4
Red Mud & Graphene Oxide Blend As An Effective Coagulant and Adsorbent for the Treatment of Waste Water from Various Industries KG Naidu, KV Krishna, KK Rao International Journal of Mechanical Engineering and Technology 10 (3) , 2019 2019 Citations: 2
Semi sol-gel synthesis and red luminescence studies of Eu3+ activated Double perovskite phosphors Bi2-xEuxMoO6 (x= 0.0–0.24) BN Naidu, KK Rao, MPSM Krishna Optik 182, 565-570 , 2019 2019 Citations: 5
Nano SiO 2 catalyzed synthesis of Imidazo[1,2-a]pyridines. T Dharmana, KR Kola, NN Bonnada Annales de Chimie Science des Matériaux 42 (4) , 2018 2018 Citations: 1
Reactively sputtered InVO 4 thin films: effect of non-stoichiometric composition on photocatalytic activity. KK Rao 2018
A STUDY ON THE SOLAR HYDROGEN PRODUCTION BY DIFFERENT HETERO STRUCTURED PHOTOCATALYSTS: A STATE-OF THE-ART REVIEW M Karthik, SSP Tej, IJ Madhuri, KK Rao International Journal of Research In Science & Engineering , 2018 2018
Nano bismuth molybdate for photo-catalytic synthesis of imidazo [1, 2-a] pyridines using 2-aminopyridines and phenacyl bromide in aqueous conditions KKR D.Tejeswararao, B.Nagamani Naidu International Journal of Mechanical Engineering and Technology 9 (11), 2181-2188 , 2018 2018
Nano flakes of NaMgBi0.85Eu0.15WO6 as catalyst for simple and efficient green synthesis of Dihydropyridines K Koteswara Rao, D Tejeswara Rao, B Nagamani Naidu International Journal for Research in Applied Science & Engineering … , 2017 2017
Silica@PMA core-shell structure as recyclable catalyst for the synthesis of Quinolines D Tejeswararao, K Koteswara Rao, B Nagamani Naidu Der Pharma Chemica 8 (17), 181-185 , 2016 2016
Nano-scale mechanical properties of polymer/fullerene bulk hetero-junction films and their influence on photovoltaic cells HC Li, KK Rao, JY Jeng, YJ Hsiao, TF Guo, YR Jeng, TC Wen Solar energy materials and solar cells 95 (11), 2976-2980 , 2011 2011 Citations: 39
A wide-ranging review on Nasicon type materials NA Anantharamulu, K Koteswara Rao, G Rambabu, B Vijaya Kumar, ... Journal of materials science 46 (9), 2821-2837 , 2011 2011 Citations: 739
Investigation of nitrogen doped diamond like carbon films as counter electrodes in dye sensitized solar cells SF Wang, KK Rao, TCK Yang, HP Wang Journal of Alloys and Compounds 509 (5), 1969-1974 , 2011 2011 Citations: 50
Synthesis, crystal structure and optical properties of quasi-one-dimensional lead (II) iodide: C14H18N2Pb2I6 K Pradeesh, M Agarwal, KK Rao, GV Prakash Solid state sciences 12 (1), 95-98 , 2010 2010 Citations: 41
Structural Characterization and Luminescent Properties of a Red Phosphor Series: Y 2− x Eu x (MoO 4 ) 3 (x=0.4–2.0) SF Wang, K Koteswara Rao, YR Wang, YF Hsu, SH Chen, YC Lu Journal of the American Ceramic Society 92 (8), 1732-1738 , 2009 2009 Citations: 69
Synthesis and Characterization of Ce 3+ :YAG Phosphors by Heterogeneous Precipitation Using Different Alumina Sources SF Wang, KK Rao, YC Wu, YR Wang, YF Hsu, CY Huang International Journal of Applied Ceramic Technology 6 (4), 470-478 , 2009 2009 Citations: 18
MOST CITED SCHOLAR PUBLICATIONS
A wide-ranging review on Nasicon type materials NA Anantharamulu, K Koteswara Rao, G Rambabu, B Vijaya Kumar, ... Journal of materials science 46 (9), 2821-2837 , 2011 2011 Citations: 739
Preparation and characterization of bulk and nano particles of La2Zr2O7 and Nd2Zr2O7 by sol–gel method KK Rao, T Banu, M Vithal, G Swamy, KR Kumar Materials Letters 54 (2-3), 205-210 , 2002 2002 Citations: 186
Influence of crystallinity and carbon content on visible light photocatalysis of carbon doped titania thin films MS Wong, SW Hsu, KK Rao, CP Kumar Journal of Molecular Catalysis A: Chemical 279 (1), 20-26 , 2008 2008 Citations: 112
A novel core–shell like composite In2O3@ CaIn2O4 for efficient degradation of methylene blue by visible light WK Chang, KK Rao, HC Kuo, JF Cai, MS Wong Applied Catalysis A: General 321 (1), 1-6 , 2007 2007 Citations: 82
Structural Characterization and Luminescent Properties of a Red Phosphor Series: Y 2− x Eu x (MoO 4 ) 3 (x=0.4–2.0) SF Wang, K Koteswara Rao, YR Wang, YF Hsu, SH Chen, YC Lu Journal of the American Ceramic Society 92 (8), 1732-1738 , 2009 2009 Citations: 69
Nanocolumnar titania thin films uniquely incorporated with carbon for visible light photocatalysis SH Wang, TK Chen, KK Rao, MS Wong Applied Catalysis B: Environmental 76 (3-4), 328-334 , 2007 2007 Citations: 69
Investigation of nitrogen doped diamond like carbon films as counter electrodes in dye sensitized solar cells SF Wang, KK Rao, TCK Yang, HP Wang Journal of Alloys and Compounds 509 (5), 1969-1974 , 2011 2011 Citations: 50
Synthesis, crystal structure and optical properties of quasi-one-dimensional lead (II) iodide: C14H18N2Pb2I6 K Pradeesh, M Agarwal, KK Rao, GV Prakash Solid state sciences 12 (1), 95-98 , 2010 2010 Citations: 41
Nano-scale mechanical properties of polymer/fullerene bulk hetero-junction films and their influence on photovoltaic cells HC Li, KK Rao, JY Jeng, YJ Hsiao, TF Guo, YR Jeng, TC Wen Solar energy materials and solar cells 95 (11), 2976-2980 , 2011 2011 Citations: 39
Preparation, characterization, impedance and thermal expansion studies of Mn0. 5MSb (PO4) 3 (M= Al, Fe and Cr) N Anantharamulu, KK Rao, M Vithal, G Prasad Journal of alloys and compounds 479 (1-2), 684-691 , 2009 2009 Citations: 35
Electrical conductivity of Ba–Co–Ti hexagonal ferrites D Ravinder, P Shalini, P Mahesh, KK Rao, M Vithal, BS Boyanov Journal of alloys and compounds 364 (1-2), 17-22 , 2004 2004 Citations: 32
Preparation, characterization and impedance study of AgTaMP3O12 (M= Al, Ga, In, Cr, Fe and Y) KK Rao, G Rambabu, M Raghavender, G Prasad, GS Kumar, M Vithal Solid State Ionics 176 (37-38), 2701-2710 , 2005 2005 Citations: 27
Preparation, characterization and ESR studies of bulk and nano sized pyrochlore La2− xGdxZr2O7 (x= 0.025, 0.05, 0.075 and 0.1) KK Rao, N Anantharamulu, M Salagram, M Vithal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 66 (3 … , 2007 2007 Citations: 23
Preparation, infrared and magnetic susceptibility studies of LnB3O6 (Ln= Gd, Eu and Sm) KK Rao, M Vithal, D Ravinder Journal of magnetism and magnetic materials 253 (1-2), 65-71 , 2002 2002 Citations: 23
Co-sputtered carbon-incorporated titanium oxide films as visible light-induced photocatalysts MS Wong, SH Wang, TK Chen, CW Weng, KK Rao Surface and Coatings Technology 202 (4-7), 890-894 , 2007 2007 Citations: 21
Optical, thermal and electrical studies of Nasicon type Na2PbZnMP3O12 (M= Al, Fe and Ga) glasses T Banu, KK Rao, M Vithal Physics and chemistry of glasses 44 (1), 30-35 , 2003 2003 Citations: 19
Synthesis and Characterization of Ce 3+ :YAG Phosphors by Heterogeneous Precipitation Using Different Alumina Sources SF Wang, KK Rao, YC Wu, YR Wang, YF Hsu, CY Huang International Journal of Applied Ceramic Technology 6 (4), 470-478 , 2009 2009 Citations: 18
Powder X-ray diffraction, infrared and conductivity studies of AgSbMP3O12 (M= Al, Ga, Fe and Cr) G Rambabu, N Anantharamulu, KK Rao, G Prasad, M Vithal Materials Research Bulletin 43 (6), 1509-1518 , 2008 2008 Citations: 18
Preparation, characterization, conductivity and thermal expansion studies of Ca 0.5 SbMP 3 O 12 (M = Al, Fe, Cr) G Rambabu, K Koteswara Rao, N Anantharamulu, M Raghavender, ... Journal of materials science 42 (10), 3613-3620 , 2007 2007 Citations: 9
Preparation, characterization, ESR and PAS studies of Cu0. 5NbAlP3O12 and HNbAlP3O12 M Vithal, B Srinivasulu, KK Rao, CM Rao Materials Letters 45 (1), 58-62 , 2000 2000 Citations: 8
