Electrochemical synthesis of alkali-intercalated iron selenide superconductors

Abstract

Electrochemical method has been used to insert K/Na into FeSe lattice to prepare alkali-intercalated iron selenides at room temperature. Magnetization measurement reveals that KxFe2Se2 and NaxFe2Se2 are superconductive at 31 K and 46 K, respectively. This is the first successful report of obtaining metal-intercalated FeSe-based high-temperature superconductors using electrochemical method. It provides an effective route to synthesize metal-intercalated layered compounds for new superconductor exploration.

FeSe-based superconductors with a superconducting transition temperature of 50 K

“…Under ambient pressure, the key factor to improve the T c of FeSe-based superconductors is to dope electrons to the FeSe plane to form intercalated structure or charge-transfer interface. The former includes the AFe 2 Se 2 (A is alkaline metals) obtained by high temperature solid state reaction [4], A x (NH 3 ) y Fe 2 Se 2 obtained by liquid-ammonia method [5][6][7], (Li, Fe)OHFeSe obtained by hydrothermal method [8][9][10], A x (M) y Fe 2 Se 2 (M is the organic solvent molecule, C 6 H 16 N 2 or C 2 H 8 N 2 ) obtained by electrochemical intercalation method [11][12][13] and alkaline metals and organic amine co-intercalated FeSe obtained by sonochemical insertion method [14]. The latter includes FeSe/SrTiO 3 interface [3,15], potassium coating at ultrahigh vacuum [16,17], and gating method [18][19][20].…”

β-FeSe nanorods composited g-C 3 N 4 with enhanced photocatalytic efficiency

“…b-FeSe has a layered structure, which consists of a quasi-two-dimensional layer composed of edge-sharing FeSe 4 tetrahedra stacking along the c-axis. Intercalating metal ions or even neutral molecules into [Fe 2 Se 2 ] layers will transfer electrons to [Fe 2 Se 2 ] layer, [21][22][23][24] which indicates that b-FeSe has excellent ability to capture electrons. Moreover, b-FeSe nanoparticles, [25] nanoflakes [26] and nanorods [27,28] have been synthesized through various preparation methods.…”

Electrochemical Synthesis and Crystal Structure of the Organic Ion Intercalated Superconductor (TMA)0.5Fe2Se2 with Tc = 43 K

“…26 Another promising approach is the electrochemical intercalation of alkali metal ions. After the first report in 2010, 30 several studies state the formation of superconducting electrochemically intercalated FeSe compounds with critical temperatures around 40±5 K. [31][32][33] A close inspection reveals that almost all of these materials suffer either from inhomogeneity, small superconducting volume fractions, or incomplete conversion of the host β-FeSe.…”

“…Another promising approach is the electrochemical intercalation of alkali metal ions. Several studies reported electrochemically intercalated FeSe compounds with critical temperatures at ∼40 ± 5 K. − Almost all of these materials suffer either from inhomogeneity, small superconducting volume fractions, or incomplete conversion of the host β-FeSe. Only recently, Shi et al reported the intercalation of large cetyltrimethylammonium ions (CTA + ) , and tetrabutylammonium ions (TBA + ) in individual β-FeSe crystals with superconducting transitions up to 50 K. A drawback of this method is the tiny sample amount, consisting of one tiny crystal on the tip of an indium wire.…”