Structural Studies of Hollandite-Based Radioactive Waste Forms

摘要

Holiandites with compositions Ba_(1.2-x)Cs_xMg_(1.2-x/2)Ti_(6.8+x/2)O_(16), and Ba_(1.2-x)Cs_xAl_(2.4-x)Ti_(5.6+x)O_(16) (x=0, 0.1,0.25) have been synthesised using a modified alkoxide/acetate precursor route. The samples have been sintered using two procedures; hot isostatic pressing and sintering at ambient pressure. X-ray powder diffraction has shown samples from both systems to form tetragonal holiandites, with little change when pressed by both methods. Cs-133 MAS NMR spectra have been recorded showing the chemical shift in Al containing samples to be ～250ppm, and in Mg holiandites ～175ppm and 200ppm, with little change when prepared by both methods.