Syntheses of all the three groups of materials (NZP, CZP and Perovskite) have been successfully carried out by solid state ceramic route resulting in the formation of single phase high density material in all the cases. Preliminary characterization was carried out by X-ray diffraction followed by complete crystal characterization by Rietveld method. Their crystal chemistry has been investigated using software’s like CRYSFIRE, Check cell, Winploter etc. Finally, structures have been refined to a satisfactory convergence using GSAS software. The structure model in each case has been given with the help of graphics software’s like PLATON, Crystal maker, Diamond and ORTEP etc.
Particle size calculation using Scherrer’s formula suggest that crystallite size along prominent reflections belongs to nano range in most of the synthetic phases. On the basis of results emerged after Rietveld refinement of each group of materials.
Table of Contents
CHAPTER- 1
Introduction and Survey of Literature
1.1 Definition
1.2 Structure and properties of ceramic materials
1.3 Advanced ceramics and their applications
1.4 Scope of the present work
1.5 Survey of relevant literature
Substituted sodium zirconium phosphate (NZP)
Substituted perovskites
Substituted calcium titanate
Substituted barium titanate
Substituted zirconolites
CHAPTER- 2
Instrumental Techniques and Structure refinement
2.1 X-ray Diffraction method
2.2 Structure Determination
2.3 Software applications in solving structures
2.3.1 Indexing programs
2.3.2 GSAS - Rietveld refinement
2.4 Scanning Electron Microscopy (SEM)
2.5 Energy Dispersive X-ray microanalysis (EDAX)
2.6 Impedance Spectroscopy
2.7 Infrared Spectroscopy
2.8 Magic Angle Spinning NMR
CHAPTER-3
Experimental procedures and data
3.1 Methods of synthesis and materials characterization
3.2 Characterization of ceramic phases
3.2.1 XRD: Phase analysis and Rietveld refinement
3.2.2 SEM/EDAX: Grain size, morphology and elemental analysis
3.3 Impedance Study: Electrical behavior
3.3.1 Dielectric measurements
3.4 Infrared Spectroscopy
3.5 MAS-NMR Spectroscopy
3.6 Experimental data
CHAPTER-4
Results and Discussion
4.1 Substituted Sodium Zirconium Phosphates (NZP)
4.1.1 Antimony substituted sodium zirconium phosphate: Na1+xZr2-xSbxP3O12 (where x=0.05-0.2)
4.1.2 Aluminum/ Chromium substituted sodium zirconium phosphate: Na1+xZr2-x (Al/Cr)xP3O12 (where x=0.1)
4.1.3 Molybdenum substituted sodium zirconium phosphate: Na1-xZr2(PO4)3-x(MoO4)x (where x=0.1& 0.15)
4.1.4 NZP ceramic waste forms
TYPE-I:Na1.49Zr1.56Sn0.02Fe0.28Cr0.07Ni0.07P3O12
TYPE-II:Na1.35Ba0.14Zr1.56Sn0.02Fe0.28Cr0.07Ni0.07P2.86Si0.14O12
0-35wt% WOx loaded waste forms
4.2 Perovskites
4.2.1 Calcium Yttrium Titanate: Ca1-xYxTiO3 (where x=0.1- 0.3)
4.2.2 Calcium Iron Niobium Titanate: CaTi1-x(Fe0.5Nb0.5)xO3 (x=0.1- 0.1.0)
4.2.3 Substituted Barium Titanate: BaTi1-(x+y)ZrxMnyO3 (0≤x<0.1, 0.01 4.3 Zirconolite 4.3.1 Substituted Calcium zirconium Titanate: Ca1-xMxZrTi2O7 (M=Y, La and x=0.1) The primary research objective of this work is the synthesis, crystallographic characterization, and electrical property analysis of titania and zirconia-based ceramic materials to evaluate their potential as matrix materials for the management of radioactive waste. 1.1 Definition of ceramics Ceramics can be defined as inorganic, non-metallic materials that are produced using clays and other minerals from the earth or chemically processed powders. These materials are typically crystalline in nature and are formed between metallic and non-metallic elements such as aluminium and oxygen (alumina- Al2O3), silicon and nitrogen (silicon nitride- Si3N4), silicon and carbon (silicon carbide-SiC) etc. Glass is often considered a subset of ceramics. Glass is somewhat structurally different than ceramics in the sense that it is amorphous or has no long range crystalline order. These materials are an important class of compounds which have found numerous applications in science, technology and Industry. Besides their well-known applications in ceramic-ware, there several new applications have been discovered. They are often used to make insulators, electrical, electronic devices and hardware components. Their behavior as super conducting materials has opened up a completely new area of research. One of the applications of titania, zirconia and phosphate based ceramic precursors is in immobilization and solidification of radioactive isotopes occurring in waste effluents coming out of nuclear establishments and power plants. Since ancient times, the technology and applications of ceramics (including glass) have steadily increased. CHAPTER- 1 Introduction and Survey of Literature: Provides a comprehensive definition of ceramics, an overview of their structural and physical properties, and a literature survey on relevant ceramic families like NZP and Perovskites. CHAPTER- 2 Instrumental Techniques and Structure refinement: Details the scientific methodologies used, including X-ray diffraction, structural refinement via GSAS, microscopy, and spectroscopic techniques like NMR and Impedance analysis. CHAPTER-3 Experimental procedures and data: Outlines the systematic synthetic routes used to prepare ceramic precursors and the specific experimental data sets obtained for characterization. CHAPTER-4 Results and Discussion: Analyzes the experimental findings, focusing on the structural analysis, bond distortions, and electrical properties of synthesized Substituted Sodium Zirconium Phosphates, Perovskites, and Zirconolites. Ceramics, Radioactive Waste, Zirconolite, Perovskites, NZP, Rietveld refinement, X-ray diffraction, Impedance spectroscopy, SEM, EDAX, MAS-NMR, Dielectric constant, Solid state reaction, Ionic substitution, Structural analysis. The work focuses on the synthesis and characterization of ceramic materials (titania and zirconia-based) to assess their suitability as durable waste forms for the immobilization of high-level nuclear waste. The study investigates three main groups of materials: Sodium zirconium phosphates (NZP), Perovskites, and Zirconolites. The goal is to understand the structural complexity and atomistic interactions within these ceramic precursors using powder X-ray diffraction data and Rietveld refinement techniques. The research employed a range of techniques including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), Impedance Spectroscopy, Infrared (IR) Spectroscopy, and Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). Electrical investigations were conducted to explore potential applications in electronic materials, insulators, and sensor technologies, specifically looking at how structural substitutions affect dielectric behavior. Refinement provides lattice parameters, atomic positions, site occupancies, interatomic distances, and thermal parameters, which help in verifying the stability and phase purity of the synthesized materials. Substitution of elements like Nd or Yb in Zirconolite influences the formation of different polytypes (e.g., 3T, 2M) depending on the level of substitution and synthesis temperature, which is critical for waste encapsulation. Perovskites are identified as key components for synthetic rock (synroc) precursors because they can accommodate a wide range of radionuclides in their lattice structure through flexible chemical doping.Research Objectives and Topics
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- Citar trabajo
- Ashish Bohre (Autor), 2012, Synthesis crystallographic characterization and electrical properties of titania and zirconia based ceramic materials, Múnich, GRIN Verlag, https://www.grin.com/document/233302
