OBSERVATION OF A 2ND STAGE COMPOUND IN THE INTERCALATION OF N-2 IN C24RB - A NEUTRON-DIFFRACTION STUDY

Upon cooling a single-phase sample of C24Rb under N-2 pressure, interc alation of N-2 into C24Rb starts immediately below RT. A single phase of C24Rb(N-2)(x) is formed, where N-2 resides at every Rb layer, and x increases monotonically as temperature decreases. In the temperature range 175 > T > 140K a phase transition occurs, and for T less than or equal to 140K three phases co-exist: C24Rb,C24Rb(N-2)(x) and C48Rb2(N -2)(x). The third phase, has a stacking where N-2 resides at every sec ond Rb layer, hence, it is second stage compound in the intercalation of N-2 in C24Rb.