Ion exchange in glasses

One question I have in mind for quite some time:

Ion exchange in glasses leads to higher strength, because literally speaking “bigger” ions are incorporated into the glass network and build up compressive stresses.

Has there ever been the idea of incorporating ions to induce a different coefficient of thermal expansion (CTE) which then, when cooling the glass, will lead to compressive stresses, because of different CTE between inner and outer of the glass?

For some reason, I have not seen the Wikipedia site:'strength of glass' before tonight. I think it would be a good idea for us to contribute to it.

Chuck

Inorganic glasses are one of the strongest known materials.

Strength of Inorganic Glasses

The intrinsic inert strength of oxide glasses is among the highest of any known materials:

silica ~ 14 GPa

'window glass' - soda lime silica ~ 10 GPa.

The above is not commonly known or appreciated.
What is commonly known is that the 'practical', or commonly encountered strength of both of these glasses is ~ 50-70 MPa.

On the other hand, the now well-known lightguide fibers being installed in local telephone networks, does have and extremely high strength: ~5.5 GPa over MOST of its length.

It is clear that the reason for this enormous 'discrepancy' is that at some point, the glass surface has been 'mechanically damaged'.

Our task is then 3-fold:

1. Understand the fundamental parameters (composition, etc.) that control the inert intrinsic strength.

2. Understand the factors that influence the susceptibility or resistance to mechanical damge (composition, etc.).

3. Understand/develop techniques to 'protect' the glass surface from this mechanical damage (coatings, chemical and thermal tempering, cladding, lamination).