Mm-sized LiMn1−xFexPO4 single crystals with 0≤x≤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 mm3 of volume were used for magnetic studies which imply an antiferromagnetic ground state for all compositions. The N\'eel-temperature changes from TN = 32.5(5) K in LiMnPO4 to 49.5(5) K in LiFePO4 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.
@article{arxiv.1702.01138,
title = {High-pressure optical floating-zone growth of Li(Mn,Fe)PO$_4$ single crystals},
author = {Christoph Neef and Hubert Wadepohl and Hans-Peter Meyer and Rüdiger Klingeler},
journal= {arXiv preprint arXiv:1702.01138},
year = {2017}
}