“…MoO4 2-tends to form alkali or alkaline earth molybdate crystals on separating out from the glass network and therefore the molybdate solubility can be related to the cations with which the MoO4 2-tetrahedra are associated. Tailoring glass composition so as to improve molybdate solubility in borosilicate glasses has been undertaken by a number of workers [2,[14][15][16][17]; however, the solubility is still low. For example, Caurant and co-workers [14,17] have found that increasing the B2O3 level in a Ca-Na borosilicate glass, which is supposed to consume more Na + cations thereby enabling more MoO4 2-units to be connected with Ca 2+ , does not enhance molybdate capacity in glass in reality.…”