Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7993041 | Journal of Alloys and Compounds | 2018 | 13 Pages |
Abstract
The sodium intercalation of mixed - valence iron phosphate Fe32+Fe43+(PO4)6 results in drastic transformation of its physical properties. The parent compound Fe7(PO4)6 reaches magnetically ordered state through succession of phase transitions at TN1â¯=â¯45.5â¯K and TN2â¯=â¯16â¯K marked by sharp singularities in both specific heat Cp and magnetic susceptibility Ï. The introduction of sodium suppresses the formation of antiferromagnetic state down to TNâ¯=â¯33â¯K in Na0.65Fe7(PO4)6. The low temperature phase transition in this compound smears being substituted by broad anomalies in magnetization and specific heat related to the spin/charge disorder effects. The sharp well resolved electron spin resonance spectra in parent material transform into asymmetric broad line in sodium - intercalated substance. The dielectric permittivity ε of Fe7(PO4)6 demonstrates a kink at TN2, while no singularity marks TN1. No features accompany magnetic phase transition in dielectric property of Na0.65Fe7(PO4)6 but ε reaches the relaxation maxima at high temperatures which can be attributed to the freezing of sodium ions.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
Ekaterina Kozlyakova, Igor Danilovich, Anatoliy Volkov, Konstantin Zakharov, Olga Dimitrova, Elena Belokoneva, Larisa Shvanskaya, Elena Zvereva, Dmitry Chareev, Olga Volkova, Alexander Vasiliev,