  A brief overview of changes in the superconducting transition temperature
under pressure and evolution of specific heat capacity jump at Tc for two
related families of iron - based superconductors, Ba{1-x}KxFe2As2 (0.2 < x <
1.0) and Ba{1-x}NaxFe2As2 (0.2 < x < 0.9) will be given. For Ba{1-x}KxFe2As2
the specific heat capacity jump at Tc measured over the whole extent of the
superconducting dome shows clear deviation from the empirical, Delta Cp (Tc) ~
Tc^3, scaling (known as the BNC scaling) for x > 0.7. At the same
concentrations range apparent equivalence of effects of pressure and K-
substitution on Tc fails. These observations suggests a significant change of
the superconducting state for x > 0.7. In contrast, the data for the large
portion of Ba{1-x}NaxFe2As2 (0.2 < x < 0.9) series follow the BNC scaling.
However, the pressure dependence of Tc (measured up to ~ 12 kbar) have clear
non-linearities for Na concentration in 0.2 - 0.25 region, that may be
consistent with Tc crossing the phase boundaries of the emergent, narrow,
antiferromagnetic/tetragonal phase. Results will be discussed in context other
studies of these two and related families of iron-based superconductors.
