Low-temperature thermal expansion and specific heat of KBr containing CN

Thermal expansion coefficients and specific heats are reported for orientationally disordered KBr samples containing CN concentrations ranging from 0.03 to 50 mol %, and within a temperature range of 0.08--10 K. With increasing CN concentration, a broad spectrum develops in the coupling parameter between the tunneling excitations and lattice strains. As with other properties reported previously, the thermal expansion for 50 mol % CN in KBr is similar to that of an amorphous solid.