Elgaml Mahmoud, Dey Sunita, Cen Jiayi, Avdeev Maxim, Scanlon David O, Grey Clare P, Clarke Simon J
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, U.K.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
Inorg Chem. 2024 Jan 15;63(2):1151-1165. doi: 10.1021/acs.inorgchem.3c03524. Epub 2024 Jan 4.
The NbPdS ( ≈ 0.74) superconductor with a of 6.5 K is reduced by the intercalation of lithium in ammonia solution or electrochemically to produce an intercalated phase with expanded lattice parameters. The structure expands by 2% in volume and maintains the 2/ symmetry and rigidity due to the PdS units linking the layers. Experimental and computational analysis of the chemically synthesized bulk sample shows that Li occupies triangular prismatic sites between the layers with an occupancy of 0.33(4). This level of intercalation suppresses the superconductivity, with the injection of electrons into the metallic system observed to also reduce the Pauli paramagnetism by ∼40% as the bands are filled to a Fermi level with a lower density of states than in the host material. Deintercalation using iodine partially restores the superconductivity, albeit at a lower of ∼5.5 K and with a smaller volume fraction than in fresh NbPdS. Electrochemical intercalation reproduces the chemical intercalation product at low Li content (<0.4) and also enables greater reduction, but at higher Li contents (≥0.4) accessed by this route, phase separation occurs with the indication that Li occupies another site.
临界温度(T_c)为6.5K的NbPdS（(T_c\approx0.74)）超导体通过在氨溶液中插入锂或电化学方法进行还原，以产生晶格参数膨胀的插层相。由于连接各层的PdS单元，该结构的体积膨胀了2%，并保持了2/ 对称性和刚性。对化学合成的块状样品进行的实验和计算分析表明，锂占据层间的三角棱柱位置，占据率为0.33(4)。这种插层程度抑制了超导性，随着电子注入金属系统，观察到泡利顺磁性也降低了约40%，因为能带被填充到费米能级，其态密度低于母体材料。使用碘进行脱插层部分恢复了超导性，尽管临界温度较低，约为5.5K，且体积分数比新鲜的NbPdS小。电化学插层在低锂含量（<0.4）时再现了化学插层产物，并且还能实现更大程度的还原，但通过该途径达到较高锂含量（≥0.4）时，会发生相分离，这表明锂占据了另一个位置。
