Coherent solvus of disordered alkali feldspar: experiment, atom probe tomography and thermodynamic model.

ABSTRACT: At temperatures above about 600 °C, alkali feldspar forms a continuous solid solution between the Na and K end members. Towards lower temperatures a miscibility gap opens, and alkali feldspar of intermediate composition exsolves, forming an intergrowth of relatively more Na-rich and K-rich lamellae. During exsolution, the crystal structure usually remains coherent across the lamellar interfaces, a feature that may be preserved over geological times. Due to the compositional dependence of the lattice parameters, coherent intergrowth requires that the lamellae are elastically strained. The associated elastic strain energy counteracts exsolution, and the solvus delimiting the misciblity gap for coherent intergrowth lies below the solvus for strain free phase equilibria. To determine the coher

SUBMITTER: Heuser D 

PROVIDER: S-EPMC11636987 | biostudies-literature | 2024

REPOSITORIES: biostudies-literature