Vibrational and structural properties of the RFe4Sb12 (R = Na, K, Ca, Sr, Ba) filled skutterudites

Author(s)

de Abrantes, Juliana G. ; Cantarino, Marli R. ; da Silva Neto, Wagner R. ; Freire, Victoria V. ; Figueiredo, Alvaro G. ; Germano, Tarsis M. ; Mounssef, Bassim, Jr. ; Bittar, Eduardo M. ; Leithe-Jasper, Andreas ; Garcia, Fernando A.

• Document type: Journal article
• Source: PHYSICAL REVIEW MATERIALS; v. 6, n. 8, p. 10-pg., 2022-08-16.

Abstract

Vibrational and elastic properties of the RFe4Sb12 skutterudites are investigated by, respectively, temperature (T) dependent extended x-ray absorption fine structure (EXAFS) and pressure (P) dependent x-ray diffraction (XRD) experiments. The Fe K-edge EXAFS experiments of the R = K, Ca, and Ba materials were performed in the T interval 6 < T < 300K and XRD experiments of the R = Na, K, Ca, Sr, and Ba materials were performed in the P interval 1 atm < P < 16 GPa. From EXAFS, we obtained the correlated Debye-Waller parameters that were thus analyzed to extract effective spring constants connected with the Fe-Y (where Y = either R, Fe or Sb) scattering paths. Our findings suggest that in the case of the light cations, R = K or Ca, the R atoms are relatively weakly coupled to the cage, in a scenario reminiscent to the Einstein oscillators. From the XRD experiments, we obtained the bulk modulus B0 for all R = Na, K, Ca, Sr, and Ba materials, with values ranging from 77 GPa (R = K) to R = 99 GPa (R = Ba) as well as the compressibility ss as a function of P. The trend in ss as a function of the R filler is discussed and it is shown that it does not correlate with simple geometrical considerations but rather with the filler-cage bonding properties. (AU)

• FAPESP's process: 19/05150-7 - Electronic structure and magnetic excitations of magnetic superconductors
• Grantee: Marli dos Reis Cantarino
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 20/13701-0 - ARPES study of the electronic structure in iron-based superconductors
• Grantee: Marli dos Reis Cantarino
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/25665-1 - Charge and spin instabilities in unconventional superconductors
• Grantee: Fernando Assis Garcia
• Support Opportunities: Regular Research Grants