Narrow low-frequency spectrum and heat management by thermocrystals. 
By transforming heat flux from particle to wave phonon transport, we introduce a new class of engineered material to control thermal conduction.  We show that rationally designed nanostructured alloys can lead to a fundamental new approach for thermal management, guiding heat as photonic and phononic crystals guide light and sound, respectively.  Novel applications for these materials include heat waveguides, thermal lattices, heat imaging, thermo-optics, thermal diodes, and thermal cloaking.