The thermal conductivity of argon crystals with a nitrogen impurity of
concentrations ranged from 0.05 to 1% is measured in a temperature re
gion of 2 to 20 K. An additional thermal resistance due to the nitroge
n impurity is proportional to T-2 with a linear concentration dependen
ce. Possible mechanisms of phonon scattering by the impurity is discus
sed.