title: Temperature and pressure evolution of the crystal structure of A(x)(Fe(1-y)Se)2 (A = Cs, Rb, K) studied by synchrotron powder diffraction.
abstract: Temperature-dependent synchrotron powder diffraction on Cs(0.83)(Fe(0.86)Se)(2) revealed first-order I4/m to I4/mmm structural transformation around 216 °C associated with a disorder of the Fe vacancies. Irreversibility observed during the transition is likely associated with a mobility of the intercalated alkali atoms. Pressure-dependent synchrotron powder diffraction on Cs(0.83)(Fe(1-y)Se)(2), Rb(0.85)(Fe(1-y)Se)(2), and K(0.8)(Fe(1-y)Se)(2) (y ~ 0.14) indicated that the I4/m superstructure reflections are present up to pressures of 120 kbar. This may indicate that the ordering of the Fe vacancies is present in both superconducting and nonsuperconductive states.
authors: Swiss-Norwegian Beamlines at European Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France. svitlyk@esrf.fr
authors: V
authors: V
authors: Svitlyk
authors: D
authors: D
authors: Chernyshov
authors: E
authors: E
authors: Pomjakushina
authors: A
authors: A
authors: Krzton-Maziopa
authors: K
authors: K
authors: Conder
authors: V
authors: V
authors: Pomjakushin
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authors: V
authors: Dmitriev