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The effect of selenium substitution by sulfur or tellurium in the Tl1-yFe2-zSe2 antiferromagnet was studied by x-ray and electron diffraction, magnetization and transport measurements. Tl0.8Fe1.5(Se1-xXx)2 (nominal composition) solid solutions were synthesized in the full x range (0<x<1) for X=S and up to x=0.5 for X=Te, using the sealed tube technique. No superconductivity was found down to 4.2K in the case of sulfur despite the fact that the optimal crystallographic parameters, determined by Rietveld refinements, are reached in the series (i.e. the Fe-(Se,S) interplane height and (Se,S)-Fe-(Se,S) angle for which the critical superconducting transition T$_{c}$ is usually maximal in pnictides). Quasi full Tl site (y=0.05) compared to significant alkaline deficiency (y=0.2-0.3) in analogous A1-yFe2-zSe2 (A = K, Rb, Cs), and the resulting differences in iron valency, density of states and doping, are suggested to explain this absence of superconductivity. Compounds substituted with tellurium, at least up to x=0.25, show superconducting transitions but probably due to tetragonal Fe(Se,Te) impurity phase. Transmission electron microscopy confirmed the existence of ordered iron vacancies network in the samples from the Tl$_{0.8}$Fe$_{1.5}$(Se$_{1-x}$S$_{x}$)$_{2}$ series in the form of the tetragonal $sqrt{5}$ a $times sqrt{5}$ a $times$ c superstructure (textit{I4/m}) (mixed with the orthorhombic $sqrt{2}$ a $times 2sqrt{2}$ a $times$ c form (textit{Ibam}) if the iron vacancies level is increased). The N{e}el temperature (T$_{N}$) indicating the onset of antiferromagnetism order in the $sqrt{5}$ a $times sqrt{5}$ a $times$ c supercell decreases from 450K in the selenide (x=0) to 330K in the sulfide (x=1). We finally demonstrate a direct linear relationship between $T_{Nacute{e}el}$ and the Fe-(Se,S) bond length (or Fe-(Se,S) height).
BaFe$_2$S$_3$ is a quasi-one-dimensional antiferromagnetic insulator that becomes superconducting under hydrostatic pressure. The magnetic ordering temperature, $T_N$, as well as the presence of superconductivity have been found to be sample dependen
We report experimental studies of a series of BaFe$_2$S$_{3-x}$Se$_x$ ($0leq xleq3$) single crystals and powder specimens using x-ray diffraction, neutron diffraction, muon spin relaxation, and electrical transport measurements. A structural transfor
Ce(O,F)Sb(S,Se)2 single crystals were successfully grown using a CsCl/KCl flux method. The obtained crystals have a plate-like shape with the typical size of 1-2 mm and well-developed ab-plane, which enables X-ray single crystal structural analysis.
Isoelectronic substitution is an ideal tuning parameter to alter electronic states and correlations in iron-based superconductors. As this substitution takes place outside the conducting Fe planes, the electronic behaviour is less affected by the imp
We report the pressure dependence of the superconducting transition temperature, $T_c$, in TlNi$_2$Se$_{2-x}$S$_x$ detected via the AC susceptibility method. The pressure-temperature phase diagram constructed for TlNi$_{2}$Se$_{2}$, TlNi$_{2}$S$_{2}$