Very high-density amorphous characterized

Study of the system dynamics shows that at very low temperatures the diffusion coefficient in the high-density and low-density phases is zero, characterizing solid amorphous phases (LDA and HD A). Thus, starting from zero temperature at fixed chemical potential, the LDL and the HDL emerge continuously from the LDA... 

Then the choice of the type of catalyst (acid or base) determines the structure of the material. The silicas that we prepared are amorphous materials. In the acidic condition, microporous amorphous gels are obtained. The formed gel is clear and trasparent. The similarity in form of the isotherms would indicate similar structure. This structure is characterized by a high bulk density and high surface area. The form of isotherms suggests the presence of rather regular channels having a very smaU diameter (about 1.5 nm). 

Under acidic conditions long shaped siloxane particles were produced and microporous amorphous silicas with high surface area were obtained. The form of isotherms suggests the presence of rather regular channels having a very small diameter (about l.S nm). The base-catalyzed samples exhibited features of colloidal gel. Round-shaped particles were produced and mesoporous amorphous materials woe obtained. The structure is characterized by low bulk density and relatively low surface area with a mean pore diameter of the ortter of 20 nm. 

---