1. Glass structure

1.1 Glass formation

Throughout history, several hypotheses have been put forward to explain the formation of glass.

In 1932, William Zachariasen established a theory for understanding the structure of glass, a random construction also known as a "disordered network".

This hypothesis is based on simple rules of accounting and geometry:

• 1. Forming atoms (Si, B, As, Ge...) are small and can only be surrounded by a small number of oxygen atoms (3 or 4). This number is called the coordinacy of the forming atom and induces the existence of a small number of privileged directions (three or four) ensuring the loose structure;

• 2. Each oxygen atom is bound to a maximum...