Superconductivity of fcc fullerides containing off-centered octahedral cations

H. Shimoda; Y. Iwasa; Y. Miyamoto; Y. Maniwa; T. Mitani

doi:10.1103/PhysRevB.54.R15653

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Superconductivity of fcc fullerides containing off-centered octahedral cations

H. Shimoda, Y. Iwasa, Y. Miyamoto, Y. Maniwa, T. Mitani

DOI 10.1103/PhysRevB.54.R15653 · Physical Review B

T1

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Abstract

Low-temperature synthesis in liquid ammonia yielded the superconductors (NH3)xNaA2C60 (0.5<x<1, A=KandRb). These compounds retained the fcc cell with a tunable lattice constant around a=14.37 Å and a=14.52 Å for K and Rb compounds, respectively, by controlling the ammonia concentration x. Tc of both compounds decreases with increasing lattice parameter, in a striking contrast with the empirical correlation. A Na-NH3 cluster occupies the octahedral interstice and remaining K or Rb occupies the tetrahedral site. The Na ion is displaced by 0.4-0.6 Å from the center of the octahedral site.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(NH3)xNaK2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	13	Pressure not reported	onset
(NH3)xNaK2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	11	Pressure not reported	onset
(NH3)xNaK2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8	Pressure not reported	onset
(NH3)xNaRb2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	17	Pressure not reported	onset
(NH3)xNaRb2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	12	Pressure not reported	onset
(NH3)xNaRb2C60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8.5	Pressure not reported	onset
(NH3)4Na2CsC60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	29.6	Pressure not reported	unknown
Na2CsC60 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10.5	Pressure not reported	unknown