Crystal and magnetic structures, phase transitions in quasi-one-dimensional pyroxenes Na0.5Li0.5FeGe2O6

Drokina, T. V.; Petrakovskiı̌, G. A.; Мolokeev, Maxim S.; Misyul, S. V.; Бондарев, В. С.; Velikanov, D. A.; Frontzek, Matthias; Schefer, J.

doi:10.1016/j.jmmm.2015.03.016

Cited by 7 publications

(12 citation statements)

References 19 publications

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“…The magnetic moments are oriented along the a axis, with insignificant components along b and c. Also with temperature, this arrangement is not changing. The obtained magnetic structure for Li 0.31 Na 0.69 FeGe 2 O 6 is consistent with the one determined by Drokina et al (2015). Here, also the magnetic moment is aligned along the a axis with negligible components along b and c. However, it is different to some details to the magnetic structure of the pure Li-end-member compound.…”

Section: Sample LI 031 Na 069 Fege 2 O 6 (P2 1 /C)supporting

confidence: 88%

“…The total magnetic moment M amounts to 3.70(6) μB at 4 K. This is a distinct reduction to the spin only value of Fe 3+ (5.92 μB) and also is lower than the value found for LiFeGe 2 O 6 (4.48(5) μB), and 4.30 μB for Li 0.5 Na 0.5 FeGe 2 O 6 (Drokina et al 2015). This reduction may be interpreted as increasing magnetic frustration with increasing Na + content and correlates well with the increasing chain separation.…”

Section: Sample LI 031 Na 069 Fege 2 O 6 (P2 1 /C)mentioning

confidence: 64%

“…This alternating FM and AFM coupling between the M1 chains is responsible for the doubling of a in the magnetic unit cell. Very recently Drokina et al (2015) found a magnetic structure for the intermediate compound Li 0.5 Na 0.5 FeGe 2 O 6 with P2 1 /c symmetry at low temperature and found a very similar magnetic structure to the one of the LiFeGe 2 O 6 endmember. In contrast NaFeGe 2 O 6 shows complex magnetic ordering with a cycloidal incommensurate ordering of spins within the M1-chains and k = (0.323 1.0 0.080) (Drokina et al 2011;Redhammer et al 2011a).…”

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confidence: 86%

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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

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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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Section: Sample LI 031 Na 069 Fege 2 O 6 (P2 1 /C)supporting

confidence: 88%

Section: Sample LI 031 Na 069 Fege 2 O 6 (P2 1 /C)mentioning

confidence: 64%

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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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“…In the case of LiFeGe 2 O 6 and Na 0.5 Li 0.5 FeGe 2 O 6 compounds the changes in symmetry from a low temperature P 2 1 /c to a high temperature C2/c structure were observed at a transition temperature T tr = 789 K and 276 K correspondingly [10,13]. NaFeGe 2 O 6 compound exhibits C2/c symmetry between 1.6 and 1000 K [10].…”

Section: Resultsmentioning

confidence: 96%

“…We have recently studied the crystal and magnetic structures of the Na 0.5 Li 0.5 FeGe 2 O 6 compound [13]. The room crystal structure of Na 0.5 Li 0.5 FeGe 2 O 6 is monoclinic C2/c (high temperature parameters of the cell: a = 10.0333(1), b = 8.8136(1), c = 5.5295(9)Å, β = 108.921(1)…”

Section: Introductionmentioning

confidence: 99%