3/8/2023 0 Comments Crystaldiffract 1.4.1The coefficient of thermal expansion decreased initially and then increased with increasing ball milling time. The microhardness of sintered bulks, as well as the thermal conductivity, increased firstly with increasing ball milling time and then decreased. Tb2TiO5 bulks with an orthorhombic structure were obtained. The bulk materials prepared by cold isostatic pressing were sintered at 1300 ☌. After 96 h of ball milling, TiO2 was completely solved in Tb4O7 and the crystal size of Tb4O7 was up to 37 nm. The experiment results showed that the nanocrystalline solid solution was obtained during ball milling. The microhardness, coefficient of thermal expansion and thermal conductivity of sintered bulks were measured. Microstructure character of ball-milled Tb4O7-17.605%TiO2 (mass fraction, %) powders and sintered bulks was analyzed using XRD, SEM and TEM. Tb2TiO5 neutron absorber was synthesized by ball milling and sintering. The effect of crystal structure on ion-irradiation response shown here means Ln2TiO5 compounds can be tailored to give the best possible properties for application. This PhD study provides systematic and comprehensive ion-irradiation experimental data and analysis for a large range of Ln2TiO5 compounds coupled with crystal structure detail. The full range of structure types was fabricated and their crystal structure characterised. In this study all these variables, except pressure, are investigated. The final structure type is dependent on the ionic radius of the lanthanide used, the fabrication regime (temperature and pressure), and whether combinations of lanthanides are used. The Ln2TiO5 series of compounds consist of four major crystallographic structure types orthorhombic (Pnma), hexagonal (P63/mmc), cubic (Fm-3m), and cubic (Fd-3m). In particular, in-situ ion-irradiation coupled with transmission electron microscopy (TEM) and electron diffraction are used for radiation damage measurement. Ion-irradiation is used throughout this study to simulate the damage effects of high-energy particles such as those from alpha-decay. There are two main parts to this study: the characterisation of the crystal structure of a range of compounds, all with the Ln2TiO5 (Ln = lanthanides) stoichiometry, and the testing of their ion-irradiation response. It is the radiation tolerance that is the main focus of this study. This is due to their chemical durability, the ability to incorporate high loadings of radionuclides with minimal leaching, and tolerance to exposure to high-energy particles. Ceramics are a promising candidate for nuclear waste-form matrices, as part of the nuclear fuel matrix, and as cladding for fission or diverters for fusion reactors.
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