The Effect of γ-radiation on Mechanical Properties of Model UK Nuclear Waste Glasses

2018

Inorg. Chem.

Hollandite is a class of metal oxide material with the general formula A2B8O16. Several methods have been used in the synthesis of this type of metal oxide, and the synthetic methods reported have typically employed high annealing temperatures between 1200 and 1300 °C. Appropriate synthetic methods must be employed to successfully synthesize these hollandite-type oxides at lower annealing temperatures. Hollandite compounds have been synthesized using ceramic (high annealing temperature only) and coprecipitation (high and low annealing temperatures) methods. Annealing temperatures ranging from 1200 to 700 °C have been employed in the thermal treatment process. Powder X-ray diffraction and X-ray absorption near-edge spectroscopy (XANES) were conducted on hollandite-type oxides (Ba x Al2x Ti8–2x O16−δ; x = 1.2; and Ba x Al x Fe x Ti8–2x O16−δ, Ba x Fe2x Ti8–2x O16−δ; x = 1.16). Structural comparisons between materials annealed in the temperature range from 1200 to 800 °C were made, and an examination of the XANES spectra and powder X-ray diffraction patterns has provided confirmation of the absence of significant structural changes in these hollandite materials. This study has shown that hollandite-type materials can be formed using annealing temperatures as low as 700–800 °C when a coprecipitation method is used, with little change to the local and long-range structures being detected.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Synthetic Method and Annealing Temperature on the Structure of Hollandite-Type Oxides

Ebinumoliseh

2018

Inorg. Chem.

“…4,9,11,13,14 It has been recently demonstrated that the presence of transition metals (e.g., Fe) in the borosilicate glass can lead to an increased resistance to structural defects caused by β-particles or γ-rays. [23][24][25][26] The release of β-particles and γ-rays from radioactive elements can lead to the formation of electron-hole pairs, which can result in a change in the silicate and borate bonding networks. 23,25 Previous reports have suggested that Fe present in the glass matrix can trap the electron-hole pairs because of the redox characteristics of this element.…”

mentioning

confidence: 99%

“…[23][24][25][26] The release of β-particles and γ-rays from radioactive elements can lead to the formation of electron-hole pairs, which can result in a change in the silicate and borate bonding networks. 23,25 Previous reports have suggested that Fe present in the glass matrix can trap the electron-hole pairs because of the redox characteristics of this element. 23,25 Rare-earth titanate pyrochlore-type crystalline oxides have been considered as potential nuclear wasteforms because the crystal structure of these materials can incorporate actinides, with natural samples having been found to contain up to 30 wt% UO 2 .…”

mentioning

confidence: 99%

“…23,25 Previous reports have suggested that Fe present in the glass matrix can trap the electron-hole pairs because of the redox characteristics of this element. 23,25 Rare-earth titanate pyrochlore-type crystalline oxides have been considered as potential nuclear wasteforms because the crystal structure of these materials can incorporate actinides, with natural samples having been found to contain up to 30 wt% UO 2 . 27-30 Pyrochlore-type oxides can be represented by the general formula A 2 B 2 O 7 (Space group: € Fd3m ), where A 3+ and B 4+ -site cations are in eight and six coordinate sites, respectively (see Figure 1).…”

mentioning

confidence: 99%

See 1 more Smart Citation

A study of the electronic structure and structural stability of Gd₂Ti₂O₇ based glass-ceramic composites

Aluri

2015

RSC Adv.

Investigation of CeTi₂O₆- and CaZrTi₂O₇-containing glass–ceramic composite materials

Paknahad

2017

Can. J. Chem.

Glass–ceramic composite materials are being investigated for numerous applications (i.e., textile, energy storage, nuclear waste immobilization applications, etc.) due to the chemical durability and flexibility of these materials. Borosilicate and Fe–Al–borosilicate glass–ceramic composites containing brannerite (CeTi2O6) or zirconolite (CaZrTi2O7) crystallites were synthesized at different annealing temperatures. The objective of this study was to understand the interaction of brannerite or zirconolite-type crystallites within the glass matrix and to investigate how the local structure of these composite materials changed with changing synthesis conditions. Powder X-ray diffraction (XRD) and Backscattered electron (BSE) microprobe images have been used to study how the ceramic crystallites dispersed in the glass matrix. X-ray absorption near edge spectroscopy (XANES) spectra were also collected from all glass–ceramic composite materials. Examination of Ti K-, Ce L3-, Zr K-, Si L2,3-, Fe K-, and Al L2,3-edge XANES spectra from the glass–ceramic composites have shown that the annealing temperature, glass composition, and the loading of the ceramic crystallites in the glass matrix can affect the local environment of the glass–ceramic composite materials. A comparison of the glass–ceramic composites containing brannerite or zirconolite crystallites has shown that similar changes in the long range and local structure of these composite materials occur when the synthesis conditions to form these materials or the composition are changed.