Crystal structure of (Na<sub>0.70</sub>)(Na<sub>0.70</sub>,Mn<sub>0.30</sub>)(Fe<sup>3+</sup>,Fe<sup>2+</sup>)<sub>2</sub>Fe<sup>2+</sup>(VO<sub>4</sub>)<sub>3</sub>, a sodium-, iron- and manganese-based vanadate with the alluaudite-type structure
Acta crystallographica. Section E, Crystallographic communications