Abstract Large, high quality single crystals of Li-ion battery cathode material LiCoO2 have been grown using the optical floating zone technique employing a four-mirror furnace. Several growth experiments reveal that the calcination temperature, quantity of excess Li in the starting feed rod, the atmosphere in the growth chamber, and the growth speed are crucial parameters that govern the stability of the molten zone and in turn the phase purity, stoichiometry and crystallinity of the grown crystal. It is observed that high-quality, phase pure single crystals can only be grown in an Ar-atmosphere of 9 bar and using slow growth speeds of 1–2 mm/h, using feed rods containing 15% excess Li content. The structural refinement of the powder x-ray diffraction data along with the Laue diffraction patterns confirms a rhombohedral crystal structure (space group R 3 ¯ m) and the presence of a single grain along the length (~2.5 cm) of the grown crystal. Atomic emission spectrometry (ICP-AES) ascertained the uniformity in stoichiometry along the length of the grown crystals. The x-ray rocking curve of the crystal has a resolution limited full-width at half-maximum (FWHM) of 0.22°, confirming the high single crystalline quality of the sample.

中文翻译：

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锂离子电池材料 LiCoO2 单晶的光学浮区生长

摘要 使用四镜炉的光学浮区技术已经生长了大型、高质量的锂离子电池正极材料 LiCoO2 单晶。几项生长实验表明，煅烧温度、起始进料棒中过量锂的数量、生长室中的气氛和生长速度是控制熔融区稳定性的关键参数，进而影响相纯度、化学计量和生长晶体的结晶度。据观察，高质量、相纯单晶只能在 9 bar 的 Ar 气氛中生长，使用 1-2 mm/h 的缓慢生长速度，使用含有 15% 过量锂的进料棒。粉末 X 射线衍射数据的结构细化以及劳厄衍射图证实了菱面体晶体结构（空间群 R 3 ¯ m）和沿生长晶体长度（~2.5 cm）的单个晶粒的存在。原子发射光谱法 (ICP-AES) 确定了沿生长晶体长度的化学计量的均匀性。晶体的 X 射线摇摆曲线具有 0.22° 的分辨率限制半峰全宽 (FWHM)，证实了样品的高单晶质量。