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  • TITLE
  • CERTIFICATE-1
  • CERTIFICATE-2
  • DECLARATION
  • ACKNOWLEDGEMENT
  • PREFACE
  • PUBLICATIONS / PRESENTATIONS IN SEMINARS /CONFERENCES /JOURNALS
  • ABSTRACT
  • CONTENTS
  • LIST OF FIGURES
  • LIST OF TABLES
  • 1. THEORIES AND TECHNIQUES OF CRYSTAL GROWTH
  • 1.1 Introduction
  • 1.2 Thermodynamics of crystal growth
  • 1.3 Nucleation
  • 1.4 Theories of crystal growth
  • 1.4.1 Surface Energy Theory
  • 1.4.2 Diffusion Theories
  • 1.4.3 The Surface Nucleation Models
  • 1.4.4 Screw Dislocation Theory
  • 1.5 Crystal growth techniques
  • 1.5.1 Growth from Solid
  • 1.5.2 Growth from Solution
  • 1.5.3 Growth from Vapour
  • 1.5.4 Melt Growth Techniques
  • 1.6 References
  • 2. GEL METHOD AND RARE EARTH OXALATE CRYSTALS
  • 2.1 Introduction
  • 2.2 The structure and properties of gel
  • 2.3 Preparation of hydro silica gel
  • 2.4 Gelation mechanisms and gel structure
  • 2.5. Crystallization in gel medium
  • 2.6 Nucleation control in gel
  • 2.7 Nature of the gel grown crystals
  • 2.8 Rare earth oxalate crystals
  • 2.9 Advantages of gel technique
  • 2.10 References
  • 3. CHARACTERIZATION TECHNIQUES
  • 3.1 Introduction
  • 3.2 X-Ray Diffractometry
  • Fig 3.1: Bruker AXS D8 Advance X-ray Diffractometer
  • 3.3 Fourier transform infra red spectroscopy
  • 3.4 Thermal Analysis – TG/DTA
  • 3.5 Thermal Analysis –DSC
  • 3.6 Elemental analysis using inductively coupledplasma atomic emission spectrometer (ICP –AES)
  • 3.7 Microhardness measurements
  • 3.8 Electrical conductivity measurements usingimpedance analyzer
  • Fig. 3.6. HP4192A Impedance Analyzer
  • 3.9 Photoconductivity
  • 3.10 Microwave dielectric studies
  • 3.11 Energy dispersive analysis by x-rays (EDAX)
  • 3.12 Reference
  • 4. GROWTH STUDIES
  • 4.1 Introduction
  • 4.2 Chemistry associated with growth of rare earth oxalate crystals
  • 4.3 Hydro silica gel as growth medium
  • 4.4 Preparation of hydro silica gel
  • 4.5 Preparation of supernatant solution
  • 4.6 Growth of rare earth oxalate crystals
  • Fig.4.3 Yttrium Oxalate tetragonal crystals heaped on a glass plate in redbackground (left) Crystallization of the Yttrium Oxalate crystalsin the dissolution area – magnified (right) .
  • Fig. 4.4 A well faceted Yttrium Oxalate crystal (x20)
  • Fig. 4.5 An enlarged Yttrium Oxalate crystal with its growth layers (x50)
  • Fig.4.6 Microscopic view of Yttrium Oxalate crystals (*20 magnification) Single, multi nucleated, branched, additional growth can beobserved.
  • 4.7 Growth kinetics
  • Fig. 4.7 Growth system of Yttrium mixed Oxalate crystals
  • Fig. 4.8 Growth system of NdBaCuOx, PrBaCuOx, GdBaCuOx crystals
  • 4.8 Conclusion
  • 4.9 References
  • 5. SPECTROSCOPIC AND THERMAL CHARACTERIZATION
  • 5.1. Introduction
  • 5.2. X-ray Analysis
  • 5.3 Analysis Infrared
  • 5.4 Analysis Using Inductively Coupled Plasma Atomic EmissionSpectrometer (ICP –AES)
  • 5.5 Energy dispersive X-ray analysis
  • 5.6 THERMAL ANALYSIS
  • 5.7 Differential scanning calorimetry (DSC)
  • 5.8 Conclusion
  • 5.9 References
  • 6. MICROHARDNESS
  • 6.1 Introduction
  • 6.2 Vickers hardness test method
  • 6.3 Microhardness measurements of the pure and mixed rare earth oxalate crystals
  • 6.4 Discussion on microhardness studies
  • 6.5 Conclusion
  • 6.6 Reference
  • 7. ELECTRICAL AND OPTICAL PROPERTIES OF RARE EARTH MIXED OXALATE CRYSTALS
  • 7.1 Introduction
  • 7.2 Frequency dependence on dielectric constant and dielectric loss rare
  • 7.3 Frequency and Temperature Dependence of Conductivity
  • 7.4 Activation energy of Rare Earth Oxalate Crystals
  • 7.5 Photoconductivity
  • 7.6. Conclusion
  • 7.7. References
  • 8. MICROWAVE DIELECTRIC STUDIES ON RARE EARTH MIXED OXALATE CRYSTALS
  • 8.1 Introduction
  • 8.2. Microwave experimental set up