Influence of titanium doping on the structure and properties of hollow glass microspheres for inertial confinement fusion

Titanium doped hollow glass microsphere has been fabricated by dried gel method for inertial confinement fusion application. Spheres with same titanium doping level were classified into two classes based on the absorption of different visible light wavelengths. Influences of titanium doping on the structure, strength and half-life of deuterium retention of spheres, as well as differences on the structure and property between the two classes of spheres were investigated. Results showed that titanium doping of gel precursors led to formation of oxygen vacancy during shell-forming process. Besides, the uniformity of the spheres decreased with increasing titanium content. Although gas retention and mechanical strength of titanium doped spheres satisfied the requirements of fuel containers, change in the composition and deterioration in the glass structure resulted in degradation of these performances. For five batches of spheres, viz. 0%, 8%(B), 8%(A), 15%(B) and 15%(A), the average Young's moduli were 52.14, 36.68, 41.41, 33.99 and 34.72 GPa, respectively, and the average half-lives of deuterium retention were 513, 41, 470, 62, and 327 d, respectively. Class B spheres possessed thinner walls and lower titanium concentrations than class A spheres. This facilitated the formation of dense oxygen vacancies, which disrupted the continuity of glass network. Due to an inferior structure, the performance of class B spheres was not as well as that of class A spheres. Nevertheless, oxygen vacancies can be compensated via heat treatment in air. (C) 2016 Elsevier B.V. All rights reserved.