It was shown that a simple model that treated La ions as independent harmonic (Einstein) oscillators embedded in a Debye framework of boron ions successfully accounted for anomalies in the specific heat and resistivity. One of the features of the model was that the Einstein temperature of the La atoms and the Debye temperature of the boron framework were derived from room-temperature X-ray crystallography data. This feature made the model easy to apply to other hexaborides and other materials that could be treated as inclusion compounds. The results implied that local modes were likely to be important for understanding the physical properties of all of the hexaborides.

Localized Vibrational Mode Analysis of the Resistivity and Specific Heat of LaB6. Mandrus, D., Sales, B.C., Jin, R.: Physical Review B, 2001, 64[1], 123021