The f -electron contribution to the elastic property of Ce 3 S 4

The elastic constant, C’, of Ce3S4 has been measured as a function of temperature. It is shown that the curve is markedly different from that of La3S4. Since the only basic difference between the two compounds is the existence of a f-electron in Ce, we propose a theoretical scheme in which the f-electron plays a crucial role. It is shown that the existence of the f-electron in Ce3S4 prevents the band Jahn–Teller type structural transition when the temperature is lowered. The theory is consistent with the experiment and also with the theoretically predicted instability of cubic f-electronelements at zero temperature.