Zero stress-optic barium tellurite glass

Zero stress-optic glasses are achieved traditionally through a high content of lead oxide or other closely related p-block metal oxide. We have found that the underlying cause for this behavior is the combination of high metallicity and low coordination numbers adopted by compounds such as lead oxide. Here we test this idea by showing that barium tellurite glasses also show zero stress-optic and negative stress-optic response, at very low barium content. This response results from the fact that barium oxide bonds have very high metallicity, and at the same time barium modifies tellurite by lowering the Te coordination number. The two effects together are sufficient to produce zero stress optic response.