竞争多空位团簇、超晶格和畴形成下Na0. 77 CoO 2的钠离子有序
Sodium ion ordering of Na0.77CoO2 under competing multi-vacancy cluster, superlattice and domain formation
摘要：
基于电化学微调单晶的同步辐射X射线劳厄衍射研究，提出了Na $_{0.77}$ CoO $_2$中钠多空位簇有序化形成的异质超晶格.标题化合物位于接近所提出的x ~ 0.77-0.82相分离范围的可混性间隙的下限。在sqrt{19}a*sqrt {19}a*3c的大超晶格尺寸内，平均钠空位簇尺寸估计为每层4.5个Na空位。特别大的Na空位团簇尺寸有利于大的孪生简单六方超晶格sqrt{19}a，与较小的二，三和四空位团簇形成的sqrt{12}a和sqrt{13}a的超晶格竞争。在~ 3 K以下观察到的类似自旋玻璃的磁滞现象以及在273- 373 K热循环过程中的孪晶畴、三畴和单畴转变揭示了竞争的电子关联。
英文摘要：
Hexagonal superlattice formed by sodium multi-vacancy cluster ordering in Na$_{0.77}$CoO$_2$ has been proposed based on synchrotron X-ray Laue diffraction study on electrochemically fine-tuned single crystals. The title compound sits closely to the proposed lower end of the miscibility gap of x ~ 0.77-0.82 phase separated range. The average sodium vacancy cluster size is estimated to be 4.5 Na vacancies per layer within a large superlattice size of sqrt{19}a*sqrt{19}a*3c. The exceptionally large Na vacancy cluster size favors large twinned simple hexagonal superlattice of sqrt{19}a, in competition with the smaller di-, tri- and quadri-vacancy clusters formed superlattices of sqrt{12}a and sqrt{13}a. Competing electronic correlations are revealed by the observed spin glass-like magnetic hysteresis below ~ 3K and the twin, triple and mono domain transformations during thermal cycling between 273-373K.
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