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Influence of the electron concentration on the superconducting properties of the spinel system Li 1‐ y Ti 2 O 4
Author(s) -
Rygula M.,
KemmlerSack S.,
Nissel T.,
Hübener R. P.
Publication year - 1993
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.19935050803
Subject(s) - spinel , superconductivity , materials science , crystal structure , analytical chemistry (journal) , extraction (chemistry) , electron , ion , lattice (music) , solid solution , transition temperature , oxygen , crystallography , condensed matter physics , physics , chemistry , metallurgy , chromatography , quantum mechanics , acoustics
In the spinel system Li 1‐ y Ti 2 O 4 the Li content was reduced by oxidative extraction by means of a solution of I 2 as well as Br 2 in CH 3 CN or by oxygen. The extraction is associated with a transition of Ti 3+ to Ti 4+ : the system is Li 1‐ y Ti 3+ 1‐ y Ti 4+ 1+ y O 4 . Consequently, with increasing y the charge carrier concentration decreases from the starting value of 0.5 electrons/Ti ion for LiTi 2 O 4 . The extraction proceeds in two steps. At the beginning, the Ti 2 O 4 framework remains intact and the transition to superconductivity increases with decreasing charge carrier concentration to a maximal value of 13.2 K. Separated by a two‐phase region for medium extraction levels for higher y values, a Li depleted material of approximate composition Li 0.3 Ti 2 O 4 is obtained. The crystal structure of Li 0.3 Ti 2 O 4 can be deduced from the original spinel lattice by a partial Ti migration from 16 d to 16 c and 8 a sites (space group Fd3m). Consequently, the Ti 2 O 4 framework of Li 0.3 Ti 2 O 4 is disconnected and the material is no longer superconducting.