The Highly Frustrated 5d2 Double Perovskite Doppelgängers, SrLaMgReO6 and SrLaLiOsO6. A Comparison including Isostructural La2LiReO6,Inorganic Chemistry

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The Highly Frustrated 5d2 Double Perovskite Doppelgängers, SrLaMgReO6 and SrLaLiOsO6. A Comparison including Isostructural La2LiReO6
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2021-10-19 , DOI: 10.1021/acs.inorgchem.1c02521
Fang Yuan ₁ , Zachery W Cronkwright ₁ , Joey A Lussier ₂ , Christopher R Wiebe ₂ , Paul A Dube ₁ , Corey M Thompson ₁ , Timothy J S Munsie ₃ , Graeme M Luke _{1,

3} , John E Greedan _{1,

4}

Affiliation

The synthesis and characterization of the double perovskite SrLaLiOsO₆ is presented. It is isostructural (P2₁/n) and isoelectronic (5d²) with SrLaMgReO₆, which has been reported previously. The cell volumes are the same to within 1.4%: i.e., these perovskites are doppelgängers. In a previous study SrLaMgReO₆ showed no sign of spin order to 2 K. New data at lower temperatures disclose a maximum in the dc susceptibility near 1.5 K. As the Curie–Weiss (C-W) temperature (Θ) for this material is −161 K, an enormous frustration index, f ≈ 100, is implied (f = |Θ|/T_ord). On the other hand, SrLaLiOsO₆ does not follow the C-W law over the investigated susceptibility range, 2–300 K. Fitting with an added temperature independent term (TIP) gives μ_eff = 1.96 μ_B, Θ = −102 K, and TIP = 1.01 × 10^–3 emu/mol. A clear zero-field-cooled (ZFC), field-cooled (FC) divergence in the dc data occurs at ∼10 K, suggesting a much reduced frustration index, f ≈ 10, relative to SrLaMgReO₆. The real part of the ac susceptibility data, χ′_max, shows a frequency shift that is consistent with a spin glass ground state according to the Mydosh criterion. Heat capacity data for SrLaLiOsO₆ show no sign of a λ peak at 10 K and a linear dependence on temperature below 10 K, also supporting a spin glass ground state. A spin frozen ground state for SrLaMgReO₆ could not be established from χ′ data due to a much weaker signal. Nonetheless, the 10-fold difference in f between these doppelgänger materials is remarkable. It is possible that the enhanced covalency with the oxide ligands for Os⁶⁺ relative to Re⁵⁺ plays a major role here. Finally, a comparison with isostructural La₂LiReO₆ (with a much smaller f ≈ 4) is made and a correlation between the frustration level and the sense of the local distortion of the Re(Os)–O octahedron is pointed out.

中文翻译：

高度沮丧的 5d2 双钙钛矿双体，SrLaMgReO6 和 SrLaLiOsO6。包括同构 La2LiReO6 的比较

介绍了双钙钛矿 SrLaLiOsO ₆的合成和表征。它与 SrLaMgReO ₆具有同构 ( P 2 ₁ / n ) 和等电子性 (5d ² ) ，这在之前已有报道。电池体积相同，误差在 1.4% 以内：即，这些钙钛矿是二重体。在之前的一项研究中，SrLaMgReO ₆没有显示出自旋顺序到 2 K 的迹象。较低温度下的新数据揭示了 1.5 K 附近直流磁化率的最大值。因为该材料的居里-魏斯 (CW) 温度 (Θ) 为 -161 K，一个巨大的挫折指数，f ≈ 100，被暗示（f = |Θ|/ T _ord）。另一方面，SrLaLiOsO ₆在所研究的磁化率范围 2–300 K 内不遵循 CW 定律。使用附加的温度无关项 (TIP) 拟合得出 μ _eff = 1.96 μ _B、Θ = -102 K 和 TIP = 1.01 × 10 ^–3 emu/mol。直流数据中明显的零场冷却 (ZFC)、场冷却 (FC) 发散发生在 ~10 K，表明相对于 SrLaMgReO ₆大大降低了挫败指数f ≈ 10 。交流磁化率数据的实部 χ' _max显示了与根据 Mydosh 准则的自旋玻璃基态一致的频移。SrLaLiOsO _{6 的}热容量数据在 10 K 处没有显示 λ 峰的迹象，并且在 10 K 以下与温度呈线性相关，这也支持自旋玻璃基态。由于信号弱得多，无法从 χ' 数据建立SrLaMgReO _{6 的}自旋冻结基态。尽管如此，这些 doppelgänger 材料之间f的 10 倍差异是显着的。Os ⁶⁺相对于Re ⁵⁺的氧化物配体增强的共价性可能在这里起主要作用。最后，与等结构的 La ₂ LiReO ₆（f ≈ 4小得多）进行了比较，并指出了挫败水平与 Re(Os)-O 八面体的局部畸变感之间的相关性。

更新日期：2021-11-01

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