Thermodynamic properties and enhancement of diamagnetism in nitrogen doped lutetium hydride synthesized at high pressure
Thermodynamic properties and enhancement of diamagnetism in nitrogen doped lutetium hydride synthesized at high pressure
复制标题
高压合成氮掺杂氢化镥的热力学性质及增强抗磁性
DOI：
10.1073/pnas.2321540121
复制
发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Wang, Meng
中科院分区：
文献类型：
--
作者：
Han, Yifeng;Ou, Yunbo;Sun, Hualei;Kopaczek, Jan;Leonel, Gerson J.;Guo, Xin;Brugman, Benjamin L.;Leinenweber, Kurt;Xu, Hongwu;Wang, Meng
掺氮氢化镥在室温下的超导电性研究中引起了全球的关注。然而，可变的合成技术和氮浓度的不确定性导致了科学界对这种材料及其性质的广泛辩论。采用高温高压固相法合成了掺氮氢化镥，并对残余原料进行了分析，确定了其氮含量。高温氧化物熔融溶液量热法测定LuH1.96N0.02（LHN）由LuH 2和LuN生成的生成焓为−28.4 ± 11.4 kJ/mol。磁性测量表明，抗磁性增加氮含量。环境压力下的电导率测量观察到金属行为从5至350 K，和恒定和抛物线的磁阻随温度的升高而变化。高压电导率测量表明，LHN不表现出超导性高达26.6 GPa。我们在金刚石压砧室中将LHN压缩到13.7 GPa，并在每一步测量拉曼信号，没有任何相变的证据。尽管没有超导性，但随着压力的增加，观察到从蓝色到紫色再到红色的颜色变化。因此，我们的研究结果证实了LHN的热力学稳定性，不支持超导性，并提供了对其抗磁性起源的见解。
Nitrogen doped lutetium hydride has drawn global attention in the pursuit of room-temperature superconductivity near ambient pressure and temperature. However, variable synthesis techniques and uncertainty surrounding nitrogen concentration have contributed to extensive debate within the scientific community about this material and its properties. We used a solid-state approach to synthesize nitrogen doped lutetium hydride at high pressure and temperature (HPT) and analyzed the residual starting materials to determine its nitrogen content. High temperature oxide melt solution calorimetry determined the formation enthalpy of LuH1.96N0.02(LHN) from LuH2and LuN to be −28.4 ± 11.4 kJ/mol. Magnetic measurements indicated diamagnetism which increased with nitrogen content. Ambient pressure conductivity measurements observed metallic behavior from 5 to 350 K, and the constant and parabolic magnetoresistance changed with increasing temperature. High pressure conductivity measurements revealed that LHN does not exhibit superconductivity up to 26.6 GPa. We compressed LHN in a diamond anvil cell to 13.7 GPa and measured the Raman signal at each step, with no evidence of any phase transition. Despite the absence of superconductivity, a color change from blue to purple to red was observed with increasing pressure. Thus, our findings confirm the thermodynamic stability of LHN, do not support superconductivity, and provide insights into the origins of its diamagnetism.