The Structure of Cerium at the Temperature of Liquid Air

In a dilatometric investigation of metallic cerium Trombe and Foex observed under certain conditions a transition at 109°K which was accompanied by a 10 percent volume decrease and a decrease in magnetic susceptibility. Professor Linus Pauling suggested to us in 1946 that this transition is caused by the promotion of 4f electron to a bond-forming orbital, and that the dense phase be studied by x-ray diffraction. This investigation described below was completed in 1948. Lawson and Tang have recently produced the transition at 15,000 atmospheres; they found there essentially the same structure which we found at the temperature of liquid air