CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

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3+ range of 310 – 420 nm are assigned to the f-f transitions of Eu ions. It is necessary at this stage to find out whether the Eu 3+ 3+ ions goes to the lattice of BiPO 4 and replaces the Bi ions or exist at the interstitial or surface sites of BiPO 4 nanomaterials. Hence BiPO 4 nanomaterials were prepared with different concentrations of La 3+ ions (Eu 3+ ions are not used as the unpaired electrons in Eu 3+ can broaden the solid state NMR spectrum) and characterized by XRD, FT-IR and 31 P MAS NMR techniques. Intensity (arb.units) 50000 40000 30000 20000 10000 λ exc = 270 nm RT 75 °C 185 °C Intensity (ab.units) 150000 120000 90000 60000 30000 Eu-O charge transfer Host absorption Room temperature 75 °C 185 °C 0 550 600 650 700 750 (a) Wavelength (nm) 0 200 250 300 350 400 Wavelength (nm) (b) Fig.80 (a) Emission spectra of BiPO 4 samples prepared at room temperature, 75 and 185°C after excitation at 270 nm and (b) corresponding excitation spectra monitored at 615 nm emission. 4.4.3 Solid solution formation between bismuth and lanthanide phosphates: XRD patterns corresponding to Bi 1-x LaxPO4 (x = 0, 0.3, 0.5, 0.7, 1) are shown in the Fig.81. All the samples are found to have monoclinic phase. The diffraction peaks have been shifted to lower 2q values with increasing the lanthanum concentration. This has been attributed to the higher 3+ 3+ ionic radius of La compared to the Bi and associated lattice expansion. Figure 82 (a and b) shows the FT-IR spectra of Bi 1-x La PO x 4 (x = 0, 0.3, 0.5, 0.7, 1) nanomaterials prepared at 185°C. The peaks present over the region 480-680 cm -1 (Fig.82 (a)) are mainly due to the PO 4 bending vibrations whereas absorption in the region 750-1330 cm -1 (Fig.82 (b)) is due to PO 4 stretching vibrations. Both the regions show systematic shift towards the higher frequency with increase in the La 3+ content in the lattice. Bismuth is 138
heavier metal ion as compared to La 3+ ion and hence it is expected that as La 3+ replaces Bi 3+ in BiPO lattice there can be a blue shift in the peak maximum corresponding to PO 4 4 vibrations. These results also confirm the solid solution formation between the BiPO 4 and LaPO lattices. 4 LaPO 4 Bi 0.3 La 0.7 PO 4 Intensity (arb.units) Bi 0.5 La 0.5 PO 4 Bi 0.7 La 0.3 PO 4 BiPO4 25 30 35 2θ/° Fig.81. XRD patterns of Bi 1-x LaxPO4 (x = 0, 0.3, 0.5, 0.7, 1) nanomaterials prepared at 185°C. % of transmittence (arb.units) 100 80 BiPO 4 Bi 0.7 La 0.3 PO 4 Bi 0.5 La 0.5 PO 4 Bi 0.3 La 0.7 PO 4 60 LaPO 4 60 LaPO 4 40 40 20 20 480 510 0 540 570 600 630 660 800 900 1000 1100 1200 1300 Wavenumber (Cm -1 ) Wavenumber (Cm -1 ) (a) (b) % of transmittence (arb.units) 100 80 BiPO 4 Bi 0.7 La 0.3 PO 4 Bi 0.5 La 0.5 PO 4 Bi 0.3 La 0.7 PO 4 Fig.82. FT-IR patterns of Bi 1-x LaxPO4 (x = 0, 0.3, 0.5, 0.7, 1) nanomaterials prepared at 185°C showing the regions (a) 480 – 680 cm -1 and (b) 750 – 1300 cm -1 . 139
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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
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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
Page 151 and 152: not have strong interaction with th
Page 153 and 154: (001) (110) (011) (101) (020) (101)
Page 155 and 156: growth centre compared to higher vi
Page 157 and 158: observed after excitation at 250 an
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 and 174: ethylene glycol moiety (stabilizing
Page 175: Room temperature and 100°C synthes
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
Page 225 and 226: 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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