Molecular orientation in amorphous calcium phosphate-pyrophosphate

Solids in nature typically exist in amorphous or crystalline states depending on the order of their constituent atoms. Generally, the multi-atom molecules (including ions) are highly ordered and oriented in crystals, but their orientation in amorphous solids is disordered except in certain organic materials formed by external regulations. This study finds that the amorphous calcium phosphate-pyrophosphate nanowire (ACPPN), which is prepared without external regulations, displays a molecular orientation of pyrophosphate ions. This discovery broadens our knowledge of the unique structural characteristics of amorphous materials, which would pave a way for further development of advanced solid materials.