Two novel phosphates Na2Mg2Fe(PO4)3 and Ag2Mg2Fe(PO4)3 with alluaudite structure: Synthesis, crystal structure and electrical properties - Laboratoire de Matériaux Céramiques et de Mathématiques - Ceramaths Accéder directement au contenu
Article Dans Une Revue Journal of Solid State Chemistry Année : 2022

Two novel phosphates Na2Mg2Fe(PO4)3 and Ag2Mg2Fe(PO4)3 with alluaudite structure: Synthesis, crystal structure and electrical properties

Résumé

Single crystals and powders of the orthophosphates A2Mg2Fe(PO4)3 with A ​= ​Na+ or Ag+ have been synthesized by solid-state reaction. The X-ray diffraction diagrams of Na2Mg2Fe(PO4)3 and Ag2Mg2Fe(PO4)3 were refined by pattern matching method. The two compounds crystallize in C2/c space group adopting the alluaudite type structure. Refinement of the crystal structure of the silver-containing compound leads to the non-stoichiometric chemical formula Ag1·67Mg2·33Fe0·89(PO4)3 while that of the sodium-containing compound leads to the stoichiometric chemical formula Na2Mg2Fe(PO4)3. The complex impedance plots are obtained in frequency range from 0.1 ​Hz to 1 ​MHz, between 573 ​K and 823 ​K Na2Mg2Fe(PO4)3 presents a conductivity of 0.25 ​× ​10−5 ​S ​cm−1 at 773 ​K, with Ea ​= ​0.81 ​eV. For Ag2Mg2Fe(PO4)3, a better ionic conductivity of 1.8 ​× ​10−3 ​S ​cm−1 ​has been observed at the same temperature with Ea ​= ​0.47 ​eV. The two alluaudite compounds present an intrinsic cationic conductivity type resulting from Na+ or Ag+ ions movement.

Domaines

Chimie

Dates et versions

hal-03656806 , version 1 (02-05-2022)

Identifiants

Citer

Ahmed Ould Saleck, Cyrille Albert-Mercier, Claudine Follet-Houttemane, Abderrazzak Assani, Mohamed Saadi, et al.. Two novel phosphates Na2Mg2Fe(PO4)3 and Ag2Mg2Fe(PO4)3 with alluaudite structure: Synthesis, crystal structure and electrical properties. Journal of Solid State Chemistry, 2022, 312 (2), pp.123139. ⟨10.1016/j.jssc.2022.123139⟩. ⟨hal-03656806⟩
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