Short‐Range Structure of Yttrium Alumino‐Silicate Glass for Cancer Radiotherapy: Car–Parrinello Molecular Dynamics Simulations

Abstract We present Car–Parrinello molecular dynamics (CPMD) simulations of yttrium alumino‐silicate (YAS) glass. Alumino‐silicate glass microspheres are used as vectors of yttrium radioisotopes in cancer radiotherapy; understanding in detail how yttrium is bound within the glass network is important to control the unwanted release of radioactive yttrium in the bloodstream. Our simulations, focused on a specific composition relevant to practical applications, show that silicon and aluminum form a disordered glass network, where Si is mainly four‐coordinated, whereas, Al is mainly four‐ and five‐coordinated. Yttrium cations have a network‐modifying role, disrupting the alumino‐silicate network by breaking Si(Al)O bonds and coordinating the resulting non‐bridging oxygens (NBO). The local environment of yttrium in the glass turns out to be rather flexible: between five and eight oxygen atoms, with a marked predominance of NBO, are found coordinated to a central Y cation, leading to a corresponding broad and multimodal distribution of OYO angles.