λ-Transition in AgNO3 at high pressures

Abstract

Investigation of AgNO₃ at high pressures, by differential thermal analysis in piston-cylinder apparatus, has shown the existence of a phase transition which is almost certainly a λ-transition, akin to that of NaNO₃. The transition occurs stably over the range from 97 ± 2°C and 7.0 ± 0.5 kbar to ∼130°C and ∼35 kbar; the p,T trajectory may be described by a power series with the 1-bar values: intercept ≈81.5°C, slope dT_λ/dp= 2.5 ± 0.3 K kbar^–1, curvature, -d²T_λ/dp²= 0.06 ± 0.02 K kbar^–2. Appropriate thermodynamic data for the lower pressure solid-solid transitions are re-evaluated and volume against temperature data at 1 bar are examined in view of this λ-transition.