キュリウム

化学的特性silvery white, hard brittle metal; chemistry of trivalent state similar to that of trivalent lanthanides; α-emitter; hexagonal, a=0.3496nm, c=1.1331 nm; enthalpy of vaporization 1340 kJ/mol; ionic radius of Cm+++ is 0.0970nm; discovered in 1944; used in generating thermoelectric power for remote locations and in space; β-Cm is fcc, which is stable at

解説キュリウム，Cm．原子番号96の元素．電子配置[Rn]5f 76d17s2の周期表3族アクチノイド元素．95番のAmより数か月先に，3番目に発見された超ウラン元素．キュリー夫妻にちなんで命名された．銀色の金属．密度13.5 g cm－3．融点1613.2 ℃．第一イオン化エネルギー587 kJ mol－1(6.09 eV)．通常の酸化数2～4．水溶液中で Cm3＋ は淡黄色．CmO，Cm2O3，CmO2，CmH2，CmCl3，CmF3が存在する．CmF3の磁化率がGdF3の磁化率と同じであることが1950年に見いだされ，ランタノイドとの類似性が確認された．現在，知られている同位体核種は，232～252の範囲に21種．質量数247の核種がもっとも長寿命で半減期1.56×107 y．半減期162.8 d でα崩壊する．242Cm は，グラム当たり3 W の熱量を発生するので，熱電素子としての利用が考えられる．

用途242Cm は，グラム当たり3 W の熱量を発生するので，熱電素子としての利用が考えられる．

天然物の起源There is no natural curium on Earth. All of its isotopes are man-made and artificiallyproduced through nuclear reactions with other elements. The curium isotope Cm-242 wasfirst produced by bombarding plutonium-239 with helium nuclei (alpha particles), whichcontributed neutrons that changed 94Pu to 96Cm.

使用There are no major commercial uses for curium because of the extremely small amountproduced. In the future, the most important use of curium may be to provide the power forsmall, compact thermoelectric sources of electricity, by generating heat through the nucleardecay of radioisotope curium-241. These small, efficient power sources can be used in individualhomes or remote regions to provide electricity to areas that cannot secure it from othersources. It could also be used as a source of electricity in spacecraft. However, today curium’smain use is for basic scientific laboratory research.