Phonons are vibrational quanta whose energy is quantized using the Planck constant h in its reduced form ћ (ћ = h/2π), which gives the phonons energy: E = ћω (frequency: ω). The thermodynamic properties of the new qtz phases were calculated from the phonon frequencies using the statistical thermodynamic approach on a high-precision sampling mesh in the Brillouin zone. The temperature dependencies of the heat capacity at constant volume (C v ) and entropy (S) of qtz BP and qtz AlP are shown in Fig. in comparison with experimental C p data for zb-BP and zb-AlP . It is easy to see that the heat capacity of zb-BP is higher than that of qtz BP in the whole temperature range studied, while the heat capacity of zb-AlP in the range 300-1000 K practically coincides with the heat capacity of qtz AlP. Experimental data on the lowtemperature heat capacity of zb-AlP are not available in the literature.