CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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ions. SbPO 4 : Eu 3+ and SbPO 4 : Tb 3+ nanoribbons/ nanoparticles showed bright red and green emissions, respectively after excitation at 220 nm due to energy transfer from host to Eu 3+ /Tb 3+ ions. Detailed vibrational and luminescence studies on these samples established that these lanthanide ions were incorporated at Sb 3+ site of the SbPO 4 lattice. Co-doping of SbPO 4 : Tb 3+ nanoparticles/nanoribbons with Ce 3+ , resulted in improved luminescence due to energy transfer from Ce 3+ to Tb 3+ ions. The excitation spectrum corresponding to the Tb 3+ emission and the excited state lifetime of the 5 D 4 level of Tb 3+ ions in the sample further confirmed energy transfer from Ce 3+ to Tb 3+ ions in the SbPO 4 host. Dispersion of these nanomaterials in silica matrix effectively shields the lanthanide ions at the surface of the nanoribbons/nanoparticles from vibrations of stabilizing ligands resulting in the reduction in extent of vibronic quenching of the excited state. The results showed significant reduction in surface contribution to the decay curve corresponding to the 5 D 4 level of the Tb 3+ ions after incorporating the nanoribbons/ nanoparticles in silica matrix. Figure 3. TEM image SbPO 4 nanoparticles and nanoribbons. In the third section deals with the synthesis, characterization and luminescence properties of nanocrystalline lanthanide ions doped hexagonal BiPO 4 .xH 2 O, hexagonal BiPO 4 and monoclinic BiPO 4 . All the three forms of BiPO 4 were prepared at room temperature, xviii
100°C and 185°C, respectively in ethylene glycol medium. XRD patterns of as synthesized samples confirmed the existence of different phases (Fig. 4). Hydrated BiPO 4 phase exists as nanoparticles having size ~50-80 nm. Unlike this, anhydrous hexagonal and monoclinic phases of BiPO 4 exist in the form of nanorods. 185°C Monoclinic BiPO 4 Intensity (arb.units) 125°C Hexagonal BiPO 4 + Monoclinic BiPO 4 100°C Hexagonal BiPO 4 RT Hydrated BiPO 4 10 20 30 40 50 60 70 2θ/ o Figure 4. XRD patterns of BiPO 4 sample prepared at different temperatures Nanorods of hexagonal BiPO 4 and monoclinic BiPO 4 were isolated having length / width in the ranges of 80-110/ ~ 20-30 nm and ~ 500-2000/ ~ 30-80 nm, respectively. BiPO 4 nanorods showed host absorption ~250 nm and energy transfer from host to lanthanide ions was observed in both Eu 3+ and Tb 3+ doped BiPO 4 nanorods. The optimum emission characteristics have been observed for 2.5 at % lanthanide ions doped BiPO 4 . The emission intensity systematically increases starting from hydrated hexagonal BiPO 4 to anhydrous hexagonal BiPO 4 and then to monoclinic BiPO 4 . Strong multi colour emissions have been observed from nanorods after doping with Dy 3+ (blue, yellow), Tb 3+ (green), Sm 3+ (orange) and Eu 3+ (red) ions. Based on the shift in the XRD peak maxima and line shape changes in xix
Page 1 and 2: SYNTHESIS AND CHARACTERIZATION OF L
Page 3 and 4: STATEMENT BY AUTHOR This dissertati
Page 5 and 6: Dedicated to ……… My beloved b
Page 7 and 8: also thankful to all the members of
Page 9 and 10: 2.3 Synthesis of binary oxide nanom
Page 11 and 12: CHAPTER 5: Zinc Gallate ...........
Page 13 and 14: imaging, scintillators, lasers, etc
Page 15 and 16: morphology by heating at 500 and 90
Page 17: nanoparticles having hexagonal stru
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 and 66: corresponding emission and excitati
Page 67 and 68: doped nanomaterials of the above me
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will be formed and subsequently it
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Eu 3+ ions were also subjected to s
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transferred into a two-necked RB fl
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Where λ is the wavelength of X-ray
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Micro-structural characterization b
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electrons (i.e. diffraction mode).
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diffraction spots. By tilting a cry
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surface. The contact mode can obtai
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three types lines in the scattered
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solids tend to be broadened because
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sample fluoresce. The fluorescent l
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pulse frequency) as excitation sour
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Lanthanide ions doped Ga 2 O 3 nano
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atoms at three corners and the lone
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Figure 19 (a-d) shows SEM images of
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Based on these results, it can be i
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almost normal to the equatorial pla
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Table 2. Summary of important modes
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systematic disappearance of these t
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comparison, Eu 3+ ions alone in wat
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the samples, suggesting that Eu 3+
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These inferences are further substa
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Similar DTA peaks have been reporte
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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
Page 225 and 226:
32. K. A. Gschneidner, Jr., L. Eyri
Page 227 and 228:
65. Z. Deng, F. Tang, D. Chen, X. M
Page 229 and 230:
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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