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arXiv · 1702.01138

High-pressure optical floating-zone growth of Li(Mn,Fe)PO$_4$ single crystals

Christoph Neef·Hubert Wadepohl·Hans-Peter Meyer·Rüdiger Klingeler
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Abstract

Mm-sized LiMn$_{1-x}$Fe$_x$PO$_4$ single crystals with $0\leq x \leq 1$ were grown by means of the traveling floating-zone technique at elevated Argon pressure of 30~bar. For the various doping levels, the growth process was optimized with respect to the composition-dependant effective light absorption and transparency of the materials. A convex crystal/melt interface, determined by the angle of incident light, was identified to be particularly crucial for a successful growth. The resulting large single crystalline grains are stoichiometric. Structure refinement shows that lattice parameters as well as the atomic positions and bond lengths linearly depend on the Mn:Fe-ratio. Oriented cuboidal samples with several mm$^3$ of volume were used for magnetic studies which imply an antiferromagnetic ground state for all compositions. The N\'eel-temperature changes from $T_N$ = 32.5(5) K in LiMnPO$_4$ to 49.5(5) K in LiFePO$_4$ while the easy magnetic axis in the ordered phase flips from the crystallographic $a$- to the $b$-axis upon Fe-doping of $x<0.2$.

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Christoph Neef, Hubert Wadepohl, Hans-Peter Meyer, Rüdiger Klingeler. 2017-02-03. High-pressure optical floating-zone growth of Li(Mn,Fe)PO$_4$ single crystals. https://doi.org/10.1016/j.jcrysgro.2017.01.046

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