Fig. 3

Summary and comparison of the size and size distribution of CaPs using various synthesis methods (solid-state method [27], mechanochemical method [38], precipitation method [39], sol–gel method [40], molecule direct crystallization method [41,42,43], hydrothermal method [44, 45], hydrothermal decomposition of Ca-chelated complex method [46, 47], biomineralization method [48,49,50], diffusion method [51, 52], gravity-assisted method [53], hydrolysis method [46], microemulsion method [54, 55], hydrothermal microemulsion method [55], sonochemistry assisted method [56,57,58], microwave assisted method [59, 60], sonochemistry-assisted microwave method [57], precursor transformation method [48,49,50, 61], combustion method [62, 63], pyrolysis method [64, 65], molten salt synthesis and flux technique method [66, 67], and spray-drying and flame-spray methods [64, 65].). TCP; tricalcium phosphate, DCPA; dicalcium phosphate anhydrous