Environmental barrier coatings for high temperature ceramic components including: a bond coat layer; an optional silica layer; and at least one transition layer including: from about 85% to about 100% by volume of the transition layer of a primary transition material selected from a rare earth disilicate, or a doped rare earth disilicate; and from 0% to about 15% by volume of the transition layer of a secondary material selected from Fe2O3, iron silicates, rare earth iron oxides, Al2O3, mullite, rare earth aluminates, rare earth aluminosilicates, TiO2, rare earth titanates, Ga2O3, rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, Lnb metals, Lnb2O3, Lnb2Si2O7, Lnb2SiO5, borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof; where the transition layer is applied to the component as a slurry including at least water, the primary transition material and at least one slurry sintering aid, and where a reaction between the slurry sintering aid and the primary transition material results in the transition layer having a porosity of from 0% to about 15% by volume of the transition layer.