Nanoscale composition fluctuations and crystallization process: Case study in Li 2 O–SiO 2 ‐based glasses

Abstract Nanoscale composition fluctuations in Li 2 O–SiO 2 ‐based glasses were analyzed and discussed from the data on the structure and crystallization process reported so far to enter deeply into the medium‐range ordered structure of multicomponent oxide glasses. Li 2 O is proposed to have a strong tendency for dynamical heterogeneous structure, that is, the formation of fragile Li 2 O‐rich regions with small SiO 2 contents, resulting in the initial crystallization of metastable Li 2 SiO 3 prior to the formation of stable Li 2 Si 2 O 5 in Li 2 O–2SiO 2 ‐based glasses. Li 2 O–Ga 2 O 3 /Nb 2 O 5 –SiO 2 glasses are proposed to have nanoscale composition fluctuations of Li 2 O–Ga 2 O 3 /Nb 2 O 5 ‐rich regions, resulting in the initial formation of LiGa 5 O 8 and LiNbO 3 nanocrystals. In Li 2 O–Al 2 O 3 –SiO 2 glasses, the distribution width of composition fluctuations is proposed to be narrow, resulting in the initial crystallization of metastable β‐quartz solid solutions Li 2 O·Al 2 O 3 · n SiO 2 ( n = 6–8). Additive P 2 O 5 and NiO leading to an enhanced nucleation are proposed to be present in fragile Li 2 O‐rich regions.