Novel approaches to crystallize materials with narrow liquidus lines: Application to spin ladder compound La_4+4nCu_8+2nO_14+8n (n = 2,3) and high-T_c cuprate Bi-2223

We propose two novel approaches, a modified slow cooling (MSC) method and an improved traveling solvent floating zone (I-TSFZ) method, to crystallize materials with narrow liquidus lines. The MSC method uses a flux-poor starting composition to attain sufficient supersaturation, and involves a rapid cooling from high temperature to a proper crystallization temperature to avoid the formation of unwanted phases. The I-TSFZ method uses a very slow growth velocity to grow crystals under small supersaturation, and a steep temperature gradient to precisely control the growth temperature. The MSC method and the I-TSFZ method have been successfully applied to grow spin ladder compounds La_{4 + 4n}Cu_{8 + 2n}O_{14 + 8n} (n = 2,3) and a high-T_c cuprate Bi₂Sr₂Ca₂CU₃O_{10 + δ} respectively.