Studies of the specific heat Cp room temperature concentration dependences for the Bi1-xSbx (x = 0–0.12) solid solutions have shown that in the Cp(x) curves, three peaks of Cp are observed near x = 0.015, x = 0.037, and x = 0.07. These peaks are attributed to critical phenomena accompanying second-order concentration phase transitions (PT) from dilute to concentrated solid solutions, to a gapless state, and a semimetal–semiconductor transition, respectively. The numerical values for the critical exponents of the specific heat α for the Cp peaks near x = 0.015 and x = 0.037 have been determined within the framework of fluctuation theory for second-order phase transitions and percolation theory. It was shown that the α values (α = 0.11 ± 0.005) are the same within the margin of error for both peaks and correspond to the values theoretically calculated within the framework of scale-invariant theory for three–dimensional (3D) models and determined experimentally for different physical systems undergoing second-order phase transitions.

In the present work the temperature dependences of pentalead tris(vanadate) chloride heat capacity have been measured for the first time in the range from 7 to 350 K. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity Cp◦ (T), enthalpy H◦(T)−H◦(0), entropy S◦(T)−S◦(0) and Gibbs function G◦(T)−H◦(0), for the range from T→0 to 350 K. The differential scanning calorimetry in temperature interval 298–1473K was applied to measure temperatures of phase transition and melting of compound under study. The high-temperature X-ray diffraction in range 298–1073K was used for the determining thermal expansion coefficients.
Thermochimica Acta. – 2011. – V. 515. – P. 79-83.