| Summary: | This study aimed to explore the effects of the full-scale replacement (up to 100%) of Ca<sup>2+</sup> ions with Ag<sup>1+</sup> ions in the structure of brushite (CaHPO<sub>4</sub>·2H<sub>2</sub>O). This substitution has potential benefits for producing monophasic and biphasic Ca<sub>1−x</sub>Ag<sub>x</sub>HPO<sub>4</sub>·nH<sub>2</sub>O compounds. To prepare the starting solutions, (NH<sub>4</sub>)<sub>2</sub>HPO<sub>4</sub>, Ca(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O, and AgNO<sub>3</sub> at different concentrations were used. The results showed that when the Ag/Ca molar ratio was below 0.25, partial substitution of Ca with Ag reduced the size of the unit cell of brushite. As the Ag/Ca molar ratio increased to 4, a compound with both monoclinic CaHPO<sub>4</sub>·2H<sub>2</sub>O and cubic nanostructured Ag<sub>3</sub>PO<sub>4</sub> phases formed. There was a nearly linear relationship between the Ag ion ratio in the starting solutions and the wt% precipitation of the Ag<sub>3</sub>PO<sub>4</sub> phase in the resulting compound. Moreover, when the Ag/Ca molar ratio exceeded 4, a single-phase Ag<sub>3</sub>PO<sub>4</sub> compound formed. Hence, adjusting the Ag/Ca ratio in the starting solution allows the production of biomaterials with customized properties. In summary, this study introduces a novel synthesis method for the mono- and biphasic Ca<sub>1−x</sub>Ag<sub>x</sub>HPO<sub>4</sub>·nH<sub>2</sub>O compounds brushite and silver phosphate. The preparation of these phases in a one-pot synthesis with controlled phase composition resulted in the enhancement of existing bone cement formulations by allowing better mixing of the starting ingredients.
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