Identification of phases in partially crystallised Ti-, Sr- and Zn-containing sodium calcium phosphates by two-dimensional NMR

31P and 23Na one-dimensional MAS NMR, as well as two-dimensional 31P refocused INADEQUATE and 23Na multiple quantum (MQ) MAS, experiments have been used in combination with powder XRD to identify various phases present in three metal-containing sodium calcium phosphate ceramics of interest as potential biomaterials. Each sample is shown to consist of multiple phases (at least seven in the case of the Zn-containing sample), several of which were identified by NMR, but not by XRD. Solid-state NMR is thus demonstrated to be an important characterisation tool in studying multi-phase phosphate ceramics, especially those containing a mixture of crystalline and amorphous components.