CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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nanomaterials prepared at different temperatures and their insets show the corresponding SAED patterns. % of transmittence (arb.units) 100 75 50 25 RT 100 125 185 0 400 800 1200 Wavenumber (Cm -1 ) Fig.78. FT-IR spectra of BiPO 4 samples prepared at room temperature, 100, 125 and 185°C (a) (b) (c) (d) Fig.79. TEM images of BiPO 4 samples prepared at (a) room temperature, (b) 100, (c) 125 and (d) 185°C. Inset shows the SAED patterns of corresponding samples. 136
Room temperature and 100°C synthesized samples showed particles with size in the range of 50-80 nm and 70-100 nm, respectively. BiPO 4 samples prepared at 125 and 185°C shows rod shaped morphology with lengths in the range ~ 450-750 and 1000-1200 nm with corresponding widths ~ 50-120 and 100-170 nm, respectively. The SAED patterns show that these nanomaterials are single crystalline in nature and their crystallinity increases with increase in the reaction temperature. The possible reason for change in morphology with increase in temperature is the increasing concentration of nuclei and associated anisotropic growth brought about by the reaction temperature. 3+ 4.4.2 Effect of particle size and crystal structure on Eu emission from BiPO 4 :Eu 3+ nanomaterials: Figure 80 (a) shows the emission spectra of Eu 3+ doped hydrated hexagonal BiPO 4, anhydrous hexagonal BiPO 4, and monoclinic BiPO4 nanomaterials on 270 nm excitation. The intensity of Eu 3+ luminescence increases with increase in the reaction temperature. It has been attributed to the combined effect of improved crystallinity and removal of water molecules present in the lattice. Water molecules quench the excited state of Eu 3+ , thereby reducing its luminescence intensity. Europium ions in the BiPO 4 lattice show four intense emission peaks at 590, 615, 650 and 700 nm and are due to 5 D Æ 7 F , 5 D 0 1 0 Æ 7 5 7 5 7 3+ F 2, D0 Æ F3 and D0 Æ F 4 transitions of Eu . Improved crystallinity of BiPO4 samples with increase in temperature of synthesis is also clear from the fine structure of the emission spectrum (Fig 80 (a)), particularly for the 185°C heated samples. The corresponding excitation spectra monitored at 615 nm emission from the samples is shown in Fig.80 (b). It shows broad intense band centered at 270 nm with a shoulder at 255 nm along with many sharp peaks in the wavelength range of 310 - 420 nm. The broad band centered at 270 nm is due to the Eu-O charge transfer process and the shoulder at 255 nm is due to host absorption. Observation of host excitation peak while monitoring Eu 3+ emission from the sample confirm that the energy transfer takes place from host to Eu 3+ ions. The sharp peaks in the wavelength 137
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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
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morphology by heating at 500 and 90
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nanoparticles having hexagonal stru
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100°C and 185°C, respectively in
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into poly methyl methacryllate (PMM
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3. N. M. Dimitrijevic, Z. V. Saponj
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Fig.13: Fig.14: (a) Simplified ray
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Eu 3+ ions after heat treatment at
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615 nm Fig.50: FT-IR patterns (a) a
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area electron diffraction pattern a
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different amounts of Eu 3+ . Fig.86
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and 545 nm, respectively. Fig.106:
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List of Tables: Table 1: Variation
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CHAPTER 1: Introduction 1.1 Histori
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Rods, cylinders, wires and tubes ar
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must be supersaturated either by di
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- + - + charge stabilized nanoparti
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exothermic reaction between the met
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constant, ħ is h/2π, e is the ele
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these platinum complexes have been
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(IR), visible and ultra-violet (UV)
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in Ce 3+ , Pr 3+ , Tb 3+ and CT abs
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assisted by lattice phonons of appr
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decay-time reduction is much easier
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nanocrystals is shown in Fig.10 [58
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depends strongly on the nature of t
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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
Page 123 and 124: Similar results are also observed f
Page 125 and 126: intensity of XRD peaks correspond t
Page 127 and 128: compared to the bulk material and a
Page 129 and 130: is almost 1½ times that of peak B1
Page 131 and 132: 3.8 Interaction of Eu 3+ ions with
Page 133 and 134: The spectrum shows strong emission
Page 135 and 136: The decay curves are found to be bi
Page 137 and 138: As prepared undoped Sb 2 O 3 sample
Page 139 and 140: Intensity(arb.units) 1.0 0.8 0.6 0.
Page 141 and 142: 3+ having surface lanthanide ions.
Page 143 and 144: diffraction patterns from the GaPO
Page 145 and 146: 5 D 0 7 F 2 level to 7 F 7 7 1 , F
Page 147 and 148: The second possibility is the excha
Page 149 and 150: chemical shift anisotropy is much h
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Page 153 and 154: (001) (110) (011) (101) (020) (101)
Page 155 and 156: growth centre compared to higher vi
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Page 159 and 160: 3+ 3+ concentration quenching. Tb l
Page 161 and 162: Compared to the selected area elect
Page 163 and 164: lattice. Lanthanide ions occupying
Page 165 and 166: obtained after 275 nm excitation is
Page 167 and 168: The luminescence dynamics associate
Page 169 and 170: that the broad peak can be resolved
Page 171 and 172: espectively. Value of this integral
Page 173: ethylene glycol moiety (stabilizing
Page 177 and 178: heavier metal ion as compared to La
Page 179 and 180: Similar studies were also carried o
Page 181 and 182: 3+ 3+ faster decay component is ass
Page 183 and 184: the other hand the Eu 3+ lifetime h
Page 185 and 186: 3+ 4.4.8 Luminescence studies on Sm
Page 187 and 188: CHAPTER 5: Zinc gallate (ZnGa 2 O 4
Page 189 and 190: In pure EG an amorphous product is
Page 191 and 192: water content in the reaction mediu
Page 193 and 194: nucleation, thereby leading to incr
Page 195 and 196: particles. Thus the TEM studies als
Page 197 and 198: value. The lattice parameters calcu
Page 199 and 200: Quantum yield of the blue emission
Page 201 and 202: 5.5.2. Eu 3+ doped ZnGa 1.5 In 0.5
Page 203 and 204: CHAPTER 6: Tungstates [MWO 4 (M = C
Page 205 and 206: ionic radius of the metal cation ca
Page 207 and 208: lattice. Asymmetric ratio is ~ 12 f
Page 209 and 210: 700 Intensity (arb.units) 600 λ ex
Page 211 and 212: Intensity (arb.units) 25000 20000 1
Page 213 and 214: Strong green emission has been obse
Page 215 and 216: consists of strong band at 255 nm a
Page 217 and 218: peak can be attributed to the cryst
Page 219 and 220: nm) is observed from Er 3+ doped Ga
Page 221 and 222: and Dy 3+ doped CaWO 4 nanoparticle
Page 223 and 224: 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
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130. F. Li, W. Jianhuai, L. Jiongti
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166. L. Fu, Z. Liu, Y. Liu, B. Han,
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205. R. Sasikala, V. Sudarsan, C. S
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238. E. Oldfield, R. A. Kinsey, K.
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271. B. G. Hyde, S. Andersson, ”I
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B. S. Naidu, B. Vishwanadh, V. Suda
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9. Room temperature synthesis of mu
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CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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