High-Tc Superconducting Hydrides Formed by LaH24 and YH24 Cage Structures as Basic Blocks
High-Tc Superconducting Hydrides Formed by LaH24 and YH24 Cage Structures as Basic Blocks
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DOI：
10.1021/acs.chemmater.1c02371
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发表时间：
2021-03
影响因子：
8.6
通讯作者：
Peng Song;Z. Hou;P. B. Castro;K. Nakano;K. Hongo;Y. Takano;R. Maezono
中科院分区：
文献类型：
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作者：
Peng Song;Z. Hou;P. B. Castro;K. Nakano;K. Hongo;Y. Takano;R. Maezono
基于最近关于高温（高Tc）La-Y三元氧化物的研究（例如，P1-La 2 YH 12，Pm 3-LaYH 12和Pm 3-（La，Y）H10（最大Tc为253 K），我们用遗传算法和从头计算研究了（LaH 6）（YH 6）y系列高Tc三元氢化物的相和结构稳定性。我们的评估表明，在先前的研究中报道的Pm 3 pHm-LaYH 12在分解成R3 pHc-LaH 6 + Im 3 pHm-YH 6的过程中是不稳定的。我们还发现了新的晶体结构，即CmmmLaYH 12（y = 1），R3-LaYH 12（y = 1），Cmmm-LaY 3 H 24（y = 3）和R3-LaY 3 H 24（y = 3），显示出对这种分解的稳定性。R3 ε c（y = 1）和R3 ε c（y = 3）由于费米能级的态密度极低而没有表现出超导电性，而Cmmm相由于极高的电子-声子耦合常数（LaYH 12的λ = 1.876）而在约200 GPa下表现出约140 K的Tc。Cmmm-LaY_3 H_（24）通过两倍长的堆积，由于Y的化学压力，耦合常数增加，导致Tc略微增加。
Based on recent studies regarding high-temperature (high-Tc) La-Y ternary hydrides (e.g., P1̄-La2YH12, Pm3̄m-LaYH12, and Pm3̄m-(La,Y)H10 with a maximum Tc ∼ 253 K), we examined the phase and structural stabilities of the (LaH6)(YH6)y series as high-Tc ternary hydride compositions using a genetic algorithm and ab initio calculations. Our evaluation showed that the Pm3̄m-LaYH12 reported in the previous study was unstable during decomposition into R3̄c-LaH6 + Im3̄m-YH6. We also discovered new crystal structures, namely CmmmLaYH12 (y = 1), R3̄c-LaYH12 (y = 1), Cmmm-LaY3H24 (y = 3), and R3̄-LaY3H24 (y = 3), showing stability against such decomposition. While R3̄c (y = 1) and R3̄ (y = 3) did not exhibit superconductivity owing to the extremely low density of states at the Fermi level, Cmmm phases exhibited a Tc of approximately 140 K at around 200 GPa owing to the extremely high electron–phonon coupling constant (λ = 1.876 for LaYH12). By the twice longer stacking for Cmmm-LaY3H24, the coupling constant increased owing to the chemical pressure of Y, leading to a slightly increased Tc.