CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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nanorods have orthorhombic structure with length around 3-4 μm and width around 100-200 nm, as revealed by TEM (Fig.2). Luminescence around 390 nm has been observed from these samples. Morphology induced changes in photoluminescence properties of Sb 2 O 3 nanorods both as prepared and the ones annealed at different temperatures have been investigated. A distinct photoluminescence band compared to bulk Sb 2 O 3 has been observed over a region of 500-600 nm from the nanorods and is arising due to the morphology of Sb 2 O 3 nanorods. Changes in the Raman spectrum at ~260 and 445 cm -1 , corresponding to the Sb-O-Sb stretching and bending modes, respectively. Temperature dependence of these bands further confirmed their shape / morphology selective nature. Attempts have been made to dope Ln 3+ ions in these luminescent nanorods. Based on the detailed XRD, luminescence, Raman and infrared studies it has been established that the Eu 3+ ions were not incorporated in the lattice of Sb 2 O 3 instead interacted with Sb 3+ ions in the presence of hydroxyl ions (present in the medium) to form an amorphous antimony-europium hydroxide compound. The amorphous compound on heating at high temperatures leads to formation of hydrated Sb(V) oxide and Eu 2 O 3 as major phases. Figure 2. TEM image of Sb 2 O 3 nanorods Chapter 4 describes the synthesis and characterization of luminescent phosphate nanomaterials and is divided into three sections dealing with GaPO 4, SbPO 4 and BiPO 4 nanomaterials. In the first section, synthesis, structural and luminescence properties of GaPO 4 xvi
nanoparticles having hexagonal structure with different amounts of Eu 3+ doping is discussed. Synthesis has been carried out at 130°C in glycerol medium. The interaction between GaPO 4 nanoparticles and Eu 3+ ions has been investigated using Eu 3+ luminescence and 31 P magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. Based on the studies it has been established that Eu 3+ ions up to 2.5 atom % replaces the protons of the hydroxyl groups attached on Ga 3+ ions present at the surface of the nanoparticles and above this concentration, separation of EuPO 4 phase has been observed. The anisotropy parameters derived from the side band intensities of the 31 P MAS NMR patterns form these samples confirmed the surface ion exchange at low Eu 3+ concentration (2.5 atom % or less) and separation of EuPO 4 at high Eu 3+ concentration (5 atom % and more). The increase in anisotropy at high Eu 3+ contents has been attributed to the presence of paramagnetic europium species in the sample. In the second section, synthesis and characterization of both undoped and lanthanide ions doped SbPO 4 nanomaterial are discussed. Nanoparticles and nanoribbons of SbPO 4 doped with lanthanide ions like Ce 3+ , Eu 3+ and Tb 3+ were prepared at 140°C by coprecipitation method in a solvent mixture of ethylene glycol and glycerol. Nature and relative concentration of the solvents used for the synthesis had a pronounced influence on particle size, crystallinity and morphology of the nanoparticles/ nanoribbons. TEM studies have revealed that the sample prepared in a 2:3 mixture of ethylene glycol-glycerol solvent comprised of predominantly nanoribbons together with a small quantity of nanoparticles having average size less than 10 nm. The length of nanoribbons was in the range of 500-700 nm while the width was around 100 nm (Fig. 3). Solvent molecules (ethylene glycol and glycerol) assisted in stabilizing these nanomaterials, which was confirmed from IR studies on the samples. The SbPO 4 host was characterized by absorption at 220 nm and excitation of SbPO 4 : Ln 3+ samples at this wavelength resulted in energy transfer from host to lanthanide xvii
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: morphology by heating at 500 and 90
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 and 66: corresponding emission and excitati
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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
Page 213 and 214:
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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