Fujihisa Hiroshi, Nakamoto Yuki, Shimizu Katsuya, Yabuuchi Takahiro, Gotoh Yoshito
National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
Phys Rev Lett. 2008 Aug 29;101(9):095503. doi: 10.1103/PhysRevLett.101.095503.
High-pressure phases IV and V of calcium discovered in 2005 have the highest superconducting transition temperature of 25 K among all the elements; however, their crystal structures have not been determined. From the x-ray powder diffraction data, both Ca IV and V have been found to form unique and complex structures with a coordination number of 7. They were confirmed to be identical to the theoretical models that were recently predicted [Ishikawa, Phys. Rev. B 77 020101(R) (2008)].
2005年发现的钙的高压相IV和V在所有元素中具有最高的超导转变温度，为25K；然而，它们的晶体结构尚未确定。从X射线粉末衍射数据来看，已发现钙IV和V都形成了配位数为7的独特而复杂的结构。它们被证实与最近预测的理论模型相同[石川，《物理评论B》77 020101(R) (2008)]。
