Local structure around phosphorus and silicon in the CaO-SiO2-PO2.5 system

► Local structures of phosphorus and silicon are examined by MAS-NMR. ► In the CaO-SiO2-PO2.5 system, phosphorus mainly exists as monophosphate ion. ► Local structure of phosphorus is independent on the phosphate content and basicity. ► Non-bridging oxygen around silicon decreases with increase in the PO2,5 content. ► Basicity equalization concept can explain basicity dependence of local structures.