Preparation of molecular crystals containing metal elements and their electrical and magnetic properties

本文研究了压力对分子导体α-Et_2Me_2N[Ni（dmit）_2]_2电阻的影响。该盐在低至0.5 K时是分子金属，尽管在250 K时观察到由于Et_2Me_2N^+的有序-无序相变引起的电阻跳变。这种结构相变是如此剧烈，以致于损坏晶体并使电接触从晶体分离。为了避免这种情况，我们用导电的银环氧树脂粘合剂将金线固定在晶体上。然后，设计并构建了系统，该系统能够缓慢冷却样品并对样品进行温和和连续的加压。在室温下施加压力，电阻在0.11 GPa和0.19 GPa之间的压力范围内突然下降。在常压下，在250 K时，电阻发生了剧烈的跃变.然而，这种电阻跳变在压力下消失，而是在0.17 GPa下观察到280 K和0.28 GPa下观察到304 K的小异常。将这些结果绘制在温度-压力相图上。注意，所有四个点都在一条线上。该相图表明，相变温度从250 K升高到室温的速率约为。20 K / 0.1 GPa的压力。在250 K时，这种相变也被观察到为磁化率的异常。本文用SQUID磁强计测量了加压下的磁化率，并根据测量结果完成了相图，制备了（BEDT-TTF）_x[Pd（ox）_2]（ox=草酸盐），2，6-吡啶-双（硝酰基氮氧化物）及其锌盐和铜盐的晶体，研究了它们的电性能和磁性能。

The pressure effect on the electrical resistance of the molecular conductor α-Et_2Me_2N[Ni(dmit)_2]_2 has been studied. This salt is a molecular metal down to 0.5 K, although the resistance jump due to the order-disorder phase transition of Et_2Me_2N^+ is observed at 250 K. This structural phase transition is so drastic as to damage crystals and to detach electrical contacts from a crystal. To avoid that, gold wires were attached on a crystal with a conductive silver epoxy adhesive. Then, the system has been designed and constructed, which enables to cool samples slowly and to pressurise sample gently and continuously. With applying the pressure at room temperature, the resistance dropped suddenly in the pressure range between 0.11 GPa and 0.19 GPa. At ambient pressure, the drastic resistance jump happened at 250 K. However, this resistance jump disappeared under pressures and instead, the small anomalies at 280 K under 0.17 GPa and 304 K under 0.28 GPa were observed. These results were plotted on the temperature-pressure phase diagram. It is noted that all four points are on the one line. This phase diagram shows that the temperature of the phase transition increases from 250 K to room temperature at the rate of ca. 20 K / 0.1 GPa as applying the pressure. This phase transition is also observed as an anomaly on the magnetic susceptibility at 250 K. We shall perform the measurements of magnetic susceptibilities under pressure by use of a SQUID magnetmeter and complete the phase diagram from the results.Crystals of (BEDT-TTF)_x[Pd(ox)_2] (ox=oxalate), 2, 6-pyridine-bis (nitronyl nitroxide) and its Zn and Cu salts were prepared ; their electrical and magnetic properties were examined.