When sintered without additives (P100) at 950 8C, P glass
led to a glass–ceramic with about 8% total porosity, consistent
with the findings of the above cited previous research [7]. The
main crystal phase, as shown by the diffraction patterns in
Fig. 1, is a solid solution of the melilite group, which features
gehlenite (Ca2Al2SiO7) and akermanite (Ca2MgSi2O7) as main
end members