CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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Rhabdophane) and the other is monoclinic CePO 4 [108, 109]. CePO 4 / LaPO 4 nanorods as well as CePO 4 :Tb 3+ -LaPO 4 core-shell nanorods were synthesised and characterised by Cao, et al. [110] and Zhu, et al. [111] under hydrothermal condition in presence of surfactants and ultra-sonication respectively. Li and Yam [112] have prepared CePO 4 :Tb 3+ nanowires in aqueous medium at room temperature by the reaction between Ce 3+ / Tb 3+ ions and NH 4 H 2 PO 4 in presence of cyclodextrin. Kompe, et al.[113] employing co-precipitation in presence of coordinating ligands like tributyl phosphate (TBP) and trihexyl amine, prepared CePO 4 :Tb 3+ core and CePO 4 :Tb 3+ -LaPO 4 core – shell nanoparticles in water free environments at 200°C. These studies revealed that luminescence property of CePO 4 :Tb 3+ nanorods/ nanoparticles get significantly improved when covered by a shell of LaPO 4 . Improved dispersability of nanoparticles/ wires in alcohols and water is extremely important for making good quality silica sols and xero-gels incorporated with nanoparticles. Such sols and xero-gels, when immobilized with proteins and enzymes, combines the advantages of biological inertness, biodegradability and compatibility with bio-molecules at the same time, can also act as efficient luminescence based biosensors for monitoring the protein and enzyme activities in biological systems. Gulnar, et al. [114] have prepared crystalline CePO 4 , CePO 4 :Tb 3+ and CePO 4 :Dy 3+ nanoleaves with monoclinic structure. These nanomaterials are dispersible in solvents like water and methanol and can be incorporated in silica sols based on sol-gel method. Such nanoleaves incorporated silica sols have improved luminescence properties compared to silica sols directly doped with lanthanide ions. 1.7 Scope of present work: In the present investigation, a variety of inorganic matrices varying from oxides (Ga 2 O 3 , Sb 2 O 3 ), phosphates (SbPO 4 , BiPO 4 , GaPO 4 ), gallate (ZnGa 2 O 4 ) to tungstates (CaWO 4 , SrWO 4 , BaWO 4 ) both undoped and doped with lanthanide ions have been synthesised and their luminescent properties are investigated. Even though number of reports are available on the luminescence properties of both undoped and lanthanide ions 28
doped nanomaterials of the above mentioned systems, very few studies have been reported on the variation of synthesis conditions and the nature of precursor on the luminescence properties of the above nanomaterials. For example, GaOOH is a precursor material for Ga 2 O 3 nanomaterials. Understanding the morphology and luminescence properties of GaOOH prepared under different experimental conditions is essential for adapting the right synthesis procedure for making Ga 2 O 3 nanomaterials with required optical properties. This aspect is not properly addressed in previous studies. Similarly, in the case of Sb 2 O 3 nanomaterials, effect of morphology on its luminescence properties is not known so far. This aspect is investigated in detail in the present work. Luminescence properties of hosts like SbPO 4 , BiPO 4 and GaPO 4 both undoped and doped with lanthanide ions are investigated for the first time with a view to develop new and robust phosphor materials having multi functional applications. Off late, considerable attention is paid to develop efficient blue light emitting nanomaterials for incorporating them in polymers and sol-gel films. Such polymers/ sol-gel films are suitable candidates for the fabrication of economic and cheap white light display devices. Compounds like ZnGa 2 O 4 , CaWO 4 , etc. have host emission in the visible region over the range of 400-550 nm. Hence, it is expected that suitable modification in the synthesis procedure as well doping them with lanthanide ions can give efficient luminescent materials which can have multi colour emission. With this in mind, the luminescence properties of these nanomaterials have been investigated during the course of the present investigation. 29
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SYNTHESIS AND CHARACTERIZATION OF L
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STATEMENT BY AUTHOR This dissertati
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Dedicated to ……… My beloved b
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also thankful to all the members of
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2.3 Synthesis of binary oxide nanom
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CHAPTER 5: Zinc Gallate ...........
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imaging, scintillators, lasers, etc
Page 15 and 16: morphology by heating at 500 and 90
Page 17 and 18: nanoparticles having hexagonal stru
Page 19 and 20: 100°C and 185°C, respectively in
Page 21 and 22: into poly methyl methacryllate (PMM
Page 23 and 24: 3. N. M. Dimitrijevic, Z. V. Saponj
Page 25 and 26: Fig.13: Fig.14: (a) Simplified ray
Page 27 and 28: Eu 3+ ions after heat treatment at
Page 29 and 30: 615 nm Fig.50: FT-IR patterns (a) a
Page 31 and 32: area electron diffraction pattern a
Page 33 and 34: different amounts of Eu 3+ . Fig.86
Page 35 and 36: and 545 nm, respectively. Fig.106:
Page 37 and 38: List of Tables: Table 1: Variation
Page 39 and 40: CHAPTER 1: Introduction 1.1 Histori
Page 41 and 42: Rods, cylinders, wires and tubes ar
Page 43 and 44: must be supersaturated either by di
Page 45 and 46: - + - + charge stabilized nanoparti
Page 47 and 48: exothermic reaction between the met
Page 49 and 50: constant, ħ is h/2π, e is the ele
Page 51 and 52: these platinum complexes have been
Page 53 and 54: (IR), visible and ultra-violet (UV)
Page 55 and 56: in Ce 3+ , Pr 3+ , Tb 3+ and CT abs
Page 57 and 58: assisted by lattice phonons of appr
Page 59 and 60: decay-time reduction is much easier
Page 61 and 62: nanocrystals is shown in Fig.10 [58
Page 63 and 64: depends strongly on the nature of t
Page 65: corresponding emission and excitati
Page 69 and 70: will be formed and subsequently it
Page 71 and 72: Eu 3+ ions were also subjected to s
Page 73 and 74: transferred into a two-necked RB fl
Page 75 and 76: Where λ is the wavelength of X-ray
Page 77 and 78: Micro-structural characterization b
Page 79 and 80: electrons (i.e. diffraction mode).
Page 81 and 82: diffraction spots. By tilting a cry
Page 83 and 84: surface. The contact mode can obtai
Page 85 and 86: three types lines in the scattered
Page 87 and 88: solids tend to be broadened because
Page 89 and 90: sample fluoresce. The fluorescent l
Page 91 and 92: pulse frequency) as excitation sour
Page 93 and 94: Lanthanide ions doped Ga 2 O 3 nano
Page 95 and 96: atoms at three corners and the lone
Page 97 and 98: Figure 19 (a-d) shows SEM images of
Page 99 and 100: Based on these results, it can be i
Page 101 and 102: almost normal to the equatorial pla
Page 103 and 104: Table 2. Summary of important modes
Page 105 and 106: systematic disappearance of these t
Page 107 and 108: comparison, Eu 3+ ions alone in wat
Page 109 and 110: the samples, suggesting that Eu 3+
Page 111 and 112: These inferences are further substa
Page 113 and 114: Similar DTA peaks have been reporte
Page 115 and 116: GaOOH samples doped with different
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The cell parameters increases with
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strong emission compared to corresp
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curves are shown in Fig.39. Lifetim
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Similar results are also observed f
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intensity of XRD peaks correspond t
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compared to the bulk material and a
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is almost 1½ times that of peak B1
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3.8 Interaction of Eu 3+ ions with
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The spectrum shows strong emission
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The decay curves are found to be bi
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As prepared undoped Sb 2 O 3 sample
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Intensity(arb.units) 1.0 0.8 0.6 0.
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3+ having surface lanthanide ions.
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diffraction patterns from the GaPO
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5 D 0 7 F 2 level to 7 F 7 7 1 , F
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The second possibility is the excha
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chemical shift anisotropy is much h
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not have strong interaction with th
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(001) (110) (011) (101) (020) (101)
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growth centre compared to higher vi
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observed after excitation at 250 an
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3+ 3+ concentration quenching. Tb l
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Compared to the selected area elect
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lattice. Lanthanide ions occupying
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obtained after 275 nm excitation is
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The luminescence dynamics associate
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that the broad peak can be resolved
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espectively. Value of this integral
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ethylene glycol moiety (stabilizing
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Room temperature and 100°C synthes
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heavier metal ion as compared to La
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Similar studies were also carried o
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3+ 3+ faster decay component is ass
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the other hand the Eu 3+ lifetime h
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3+ 4.4.8 Luminescence studies on Sm
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CHAPTER 5: Zinc gallate (ZnGa 2 O 4
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In pure EG an amorphous product is
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water content in the reaction mediu
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nucleation, thereby leading to incr
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particles. Thus the TEM studies als
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value. The lattice parameters calcu
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Quantum yield of the blue emission
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5.5.2. Eu 3+ doped ZnGa 1.5 In 0.5
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CHAPTER 6: Tungstates [MWO 4 (M = C
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ionic radius of the metal cation ca
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lattice. Asymmetric ratio is ~ 12 f
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700 Intensity (arb.units) 600 λ ex
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Intensity (arb.units) 25000 20000 1
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Strong green emission has been obse
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consists of strong band at 255 nm a
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peak can be attributed to the cryst
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nm) is observed from Er 3+ doped Ga
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and Dy 3+ doped CaWO 4 nanoparticle
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REFERENCES 1. D. J. Barber, I. C. F
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32. K. A. Gschneidner, Jr., L. Eyri
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65. Z. Deng, F. Tang, D. Chen, X. M
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100. A. Rouanel, J. J. Serra, K. Al
Page 231 and 232:
130. F. Li, W. Jianhuai, L. Jiongti
Page 233 and 234:
166. L. Fu, Z. Liu, Y. Liu, B. Han,
Page 235 and 236:
205. R. Sasikala, V. Sudarsan, C. S
Page 237 and 238:
238. E. Oldfield, R. A. Kinsey, K.
Page 239 and 240:
271. B. G. Hyde, S. Andersson, ”I
Page 241 and 242:
B. S. Naidu, B. Vishwanadh, V. Suda
Page 243:
9. Room temperature synthesis of mu
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