Abstract We elucidate the local distribution and aggregated structure of iron oxide nanoparticles (IONPs; 6 nm in diameter) doped in the matrix of a nematic liquid crystal (LC), 4-cyano-4'-pentylbiphenyl, utilizing in situ cryogenic transmission electron microscopy and polarized light microscopy. We show that tens of IONPs aggregate into a sphere-like morphology, and the aggregates combine into elongated clusters with a length of hundreds of nm. With the IONP-doped LC matrix confined to a thin glass cell, we study the nematic-isotropic (N-I) phase transition, and suggest that local heterogeneity of LC textures as seen in polarized microscopy is caused by the existence of IONP aggregate clusters. These clusters act also as nuclei for the formation of isotropic domains upon heating.

中文翻译：

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掺杂氧化铁纳米颗粒的热致液晶的非均匀向列-各向同性相变

摘要 我们利用原位低温透射电子显微镜阐明了掺杂在向列液晶 (LC)、4-氰基-4'-戊基联苯基质中的氧化铁纳米粒子 (IONPs; 直径 6 nm) 的局部分布和聚集结构。和偏光显微镜。我们展示了数十个 IONP 聚集成球状形态，并且聚集体结合成长度为数百纳米的细长簇。将 IONP 掺杂的 LC 基质限制在薄玻璃单元中，我们研究了向列各向同性 (NI) 相变，并表明在偏光显微镜下看到的 LC 纹理的局部异质性是由 IONP 聚集体簇的存在引起的。这些簇还充当加热时形成各向同性域的核。