Chemical analysis of superconducting phase in K-doped picene.
Potassium-doped picene (K3.0picene) with a superconducting transition temperature (T C) as high as 14 K at ambient pressure has been prepared using an annealing technique. The shielding fraction of this sample was 5.4% at 0 GPa. The T C showed a positive pressure-dependence and reached 19 K at 1.13 GPa. The shielding fraction also reached 18.5%. To investigate the chemical composition and the state of the picene skeleton in the superconducting sample, we used energy-dispersive x-ray (EDX) spectroscopy, MALDI-time-of-flight (MALDI-TOF) mass spectroscopy and x-ray diffraction (XRD). Both EDX and MALDI-TOF indicated no contamination with materials other than K-doped picene or K-doped picene fragments, and supported the preservation of the picene skeleton. However, it was also found that a magnetic K-doped picene sample consisted mainly of picene fragments or K-doped picene fragments. Thus, removal of the component contributing the magnetic quality to a superconducting sample should enhance the volume fraction.
Department of Physics, Okayama University, Okayama 700-8530, Japan.
Takashi
T
Kambe
Saki
S
Nishiyama
Huyen L T
HL
Nguyen
Takahiro
T
Terao
Masanari
M
Izumi
Yusuke
Y
Sakai
Lu
L
Zheng
Hidenori
H
Goto
Yugo
Y
Itoh
Taiki
T
Onji
Tatsuo C
TC
Kobayashi
Hisako
H
Sugino
Shin
S
Gohda
Hideki
H
Okamoto
Yoshihiro
Y
Kubozono