Synthesis of large FeSe superconductor crystals via ion release/introduction and property characterization

Yuan Dongna¹, Huang Yulong¹, Ni Shunli¹, Zhou Huaxue¹, Mao Yiyuan¹, Hu Wei¹, Yuan Jie¹, Jin Kui¹, Zhang Guangming³, Dong Xiaoli^{1, 2, †,}, Zhou Fang^{1, 2, ‡,}

(a) Illustration of the hydrothermal K/Fe release/introduction synthesis of the superconducting FeSe crystal from the insulating K_0.8Fe_1.6Se₂ matrix. (b) and (c) XRD patterns of the crystal samples of the matrix K_0.8Fe_1.6Se₂ and the hydrothermally derived FeSe, respectively, all showing single preferred orientations of the (001) planes. The insets are the photographs for the two crystals.