Structural Phase Transitions in SrRh2As2

Abstract

SrRh2As2 exhibits structural phase transitions reminiscent to those of BaFe2As2, but crystallizes with three polymorphs derived from the tetragonal ThCr2Si2-type structure. The structure of α-SrRh2As2 is monoclinic with a = 421.2(1) pm, b = 1105.6(2) pm, c = 843.0(1) pm and β= 95° and was refined as a partially pseudo meroedric twin in the space group P21/c with R1 = 0.0928. β-SrRh2As2 crystallizes with a modulated structure in the (3+1) dimensional superspace group Fmmm(10γ)σ00 with the unit cell parameters a = 1114.4(3) pm, b = 574.4(2) pm and c = 611.5(2) pm and an incommensurable modulation vector q = (1, 0, 0.3311(4)). High temperature single crystal diffraction experiments confirm the tetragonal ThCr2Si2-type structure for γ-SrRh2As2 above 350°C. Electronic band structure calculations indicate that the structural distortion in alpha-SrRh2As2 is caused by strong Rh-Rh bonding interactions and has no magnetic origin as suggested for isotypic BaFe2As2.

16 pages, 10 Figures

References in corpus (7)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• Fermi surface nesting and the origin of Charge Density Waves in metals
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• Structural and magnetic phase transitions in the ternary iron arsenides SrFe2As2 and EuFe2As2
• Fermi surface nesting in several transition metal dichalcogenides

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