The (Na,Li)FeGe2O6 clinopyroxene-type series: a temperature-dependent single-crystal X-ray diffraction and 57Fe Mössbauer spectroscopic study

Redhammer, Günther J.; Tippelt, Gerold

doi:10.1007/s00269-015-0769-2

Cited by 12 publications

(14 citation statements)

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“…3). The observation is very similar and in line with the one of Redhammer and Tippelt (2016) at 298 K, however shifted to higher Na contents at 20 K.…”

Section: Low-temperature Neutron Diffractionsupporting

confidence: 88%

“…the crystallographic structure remains the same. Thus at 20 K, the change in space group symmetry takes place at x(Na) ~0.76-0.77 apfu, at lower contents as extrapolated in Redhammer and Tippelt (2016). This indicates a sharp drop of the P2 1 /c phase stability (as for x(Na) = 0.74, the transition temperature was determined to be 104 K, Redhammer and Tippelt 2016).…”

Section: Low-temperature Neutron Diffractionmentioning

confidence: 92%

“…For magnetometry and calorimetric measurements, sample material of the study of Redhammer and Tippelt (2016) was used. For neutron diffraction experiments, additional samples along the Li 1-x Na x FeGe 2 O 6 series with x(Na) = 0.7-0.9 were synthesized using a ceramic sintering route.…”

Section: Materials Synthesismentioning

confidence: 99%

“…Data treatment was performed using the FullProf Suite of programs (Rodríguez-Carvajal, 2001). The structural data of (Redhammer and Tippelt, 2016) were taken as starting parameters in Rietveld refinements. During refinements, we became aware of very small amounts of hematite, which are <0.3 wt%, but detectable in the neutron diffraction data, while not in the X-ray powder diffraction data.…”

Section: Neutron Diffraction Experimentsmentioning

confidence: 99%

“…The crystal structures of (Na,Li)FeGe 2 O 6 solid solution compounds were investigated in detail by Redhammer and Tippelt (2016) using single-crystal X-ray diffraction. The P2 1 /c structure is conserved over a wide range of compositions at 100 K. From extrapolation of available data, a change of symmetry is expected between Na contents of x(Na) ~0.85-0.90 for temperatures of about 20 K. In a very recent study of Drokina et al (2016), the change in symmetry from C2/c to P2 1 /c in the Li x Na 1-x FeGe 2 O 6 system in the 100 K to 800 K region, found by Redhammer and Tippelt (2016), was fully confirmed.…”

Section: Introductionmentioning

confidence: 99%

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A neutron diffraction study of crystal and low-temperature magnetic structures within the (Na,Li)FeGe2O6 pyroxene-type solid solution series

et al. 2017

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an antiferromagnetic (AFM) coupling within the Fe 3+ O 6 octahedra zig-zag chains and an alternating AFM and ferromagnetic (FM) interaction between the chains, depending on the nature of the tetrahedral GeO 4 chains. The magnetic structure can be described in magnetic space group P a 2 1 /c. Close to the structural phase transition for sample with x(Na) = 0.75, magnetic ordering is observed below 15 K; however, it becomes incommensurately modulated with k = (0.344, 0, 0.063). At 4 K, the magnetic spin structure best can be described by a cycloidal arrangement within the M1 chains, the spins are within the a-c plane. Around 12 K the cycloidal structure transforms to a spin density wave (SDW) structure. For the C2/c structures, a coexistence of a simple collinear and an incommensurately modulated structure is observed down to lowest temperatures. For 0.78 ≤ x(Na) ≤ 0.82, a collinear magnetic structure with k = (0 1 0), space group P C 2 1 /c and an AFM spin structure within the M1 chains and an FM one between the spins is dominating, while the incommensurately modulated structure becomes dominating the collinear one in the samples with x(Na) = 0.88. Here the magnetic propagation vector is k = (0.28, 1, 0.07) and the spin structure corresponds again to a cycloidal structure within the M1 chains. As for the other samples, a transition from the cycloidal to a SDW structure is observed. Based on the neutron diffraction data, the appearance of two peaks in the heat capacity of Na-rich samples can now be interpreted as a transition from a cycloidal magnetic structure to a spin density wave structure of the magnetically ordered phase for the Na-rich part of the solid solution series.Keywords Clinopyroxenes · LiFeGe 2 O 6 · NaFeGe 2 O 6 · Neutron diffraction · Magnetic ordering · Cycloidal incommensurate structure · Spin density wave Abstract Solid solution compounds along the Li 1-x Na x FeGe 2 O 6 clinopyroxene series have been prepared by solid state ceramic sintering and investigated by bulk magnetic and calorimetric methods; the Na-rich samples with x(Na) > 0.7 were also investigated by lowtemperature neutron diffraction experiments in a temperature range of 4-20 K. For samples with x(Na) > 0.76 the crystal structure adopts the C2/c symmetry at all measuring temperatures, while the samples display P2 1 /c symmetry for smaller Na contents. Magnetic ordering is observed for all samples below 20 K with a slight decrease of T N with increasing Na content. The magnetic spin structures change distinctly as a function of chemical composition: up to x(Na) = 0.72 the magnetic structure can be described by a commensurate arrangement of magnetic spins with propagation vector k = (½, 0 0), Electronic supplementary material The online version of this article

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“…3). The observation is very similar and in line with the one of Redhammer and Tippelt (2016) at 298 K, however shifted to higher Na contents at 20 K.…”

Section: Low-temperature Neutron Diffractionsupporting

confidence: 88%

Section: Low-temperature Neutron Diffractionmentioning

confidence: 92%

Section: Materials Synthesismentioning

confidence: 99%

Section: Neutron Diffraction Experimentsmentioning

confidence: 99%