There is disclosed a method for preparing a thin ceramic and/or metallic solid-state composition consisting of three phases: a material (A), a material (B) and pores. The concentration of each phase varies continuously from one face of the article to the other in a continuous and controlled gradient. The porous matrix of material (A) has a porosity gradient of 0% to about 80%, the pores being completely or partly filled with material (B). The concentration of material (B) in the article therefore varies from 80% to 0% of small thicknesses.