Na3(VO)(PO4)(CO3): a synthetic member of the bradleyite phosphate carbonate family with a new type of crystal structure†
Abstract
The synthesis and characterization of a (VO)2+ representative in the bradleyite family of compounds is reported. The new trisodium vanadyl phosphate carbonate was investigated using scanning electron microscopy, microprobe analysis, low temperature X-ray diffraction, and theoretical calculations of possible pathways of Na migration through the framework. Its crystal structure is assembled from strongly distorted VO6 octahedra, PO4 tetrahedra, and triangular CO3 groups linked into one-periodic ribbons parallel to the b axis of a monoclinic unit cell. Na atoms occupy positions between these ribbons and connect them into a framework. It is shown that the formal exchange of Fe2+ or Mn2+ for (VO)2+ ions leads to the bonshtedtite and sidorenkite crystal structure transformation from layered to chain ones. The character of the Na atom distribution in the structure allows considering Na3(VO)(PO4)(CO3) as a potential electrochemically active material.