Inorganic oxide articles with thin, durable anti reflective structures

An article comprising:

• an inorganic oxide substrate comprising opposing major surfaces;
• and
• an optical film structure disposed on a first major surface of the inorganic oxide substrate, the optical film structure comprising a physical thickness from about 50 nm to less than 500 nm, a plurality of alternating high index and low index layers with a first low index layer in direct contact with the first major surface of the substrate, and a capping low index layer,
• wherein each low index layer comprises a silicon-containing oxide and each high index layer comprises silicon nitride or silicon oxynitride,
• wherein the article exhibits a hardness of 8 GPa or greater measured at an indentation depth of about 100 nm or a maximum hardness of 9 GPa or greater measured over an indentation depth range from about 100 nm to about 300 nm, the hardness and the maximum hardness measured by a Berkovich Indenter Hardness Test,
• wherein a refractive index of the low index layers is in a range of a refractive index of the inorganic oxide substrate such that the refractive index of the low index layers is less than about 1.8, wherein the high index layer comprises a refractive index that is greater than 1.8, and
• further wherein the total volume of each of the high index layers comprises about 30% to less than 50% of the volume of the optical film structure, and
• further wherein one of the high refractive index layers in the optical film structure is the thickest layer in the layers of the optical film structure below the capping index layer.

An article comprising:

• an inorganic oxide substrate comprising opposing major surfaces;
• and
• an optical film structure disposed on a first major surface of the inorganic oxide substrate, the optical film structure comprising a physical thickness from about 50 nm to less than 500 nm, a plurality of alternating high index and low index layers with a first low index layer in direct contact with the first major surface, and a capping low index layer,
• wherein each low index layer comprises a silicon-containing oxide and each high index layer comprises silicon nitride or silicon oxynitride,
• wherein the article exhibits a hardness of 8 GPa or greater measured at an indentation depth of about 100 nm or a maximum hardness of 9 GPa or greater measured over an indentation depth range from about 100 nm to about 300 nm, the hardness and the maximum hardness measured by a Berkovich Indenter Hardness Test, and
• further wherein one of the high refractive index layers in the optical film structure is the thickest layer in the layers of the optical film structure below the capping index layer.

An article comprising:

• an inorganic oxide substrate comprising opposing major surfaces;
• and
• an optical film structure disposed on a first major surface of the inorganic oxide substrate, the optical film structure comprising a physical thickness from about 50 nm to less than 500 nm, a plurality of alternating high index and low index layers with a first low index layer on the first major surface, and a capping low index layer,
• wherein each low index layer comprises a silicon-containing oxide and each high index layer comprises silicon nitride or silicon oxynitride,
• wherein the article exhibits a hardness of 8 GPa or greater measured at an indentation depth of about 100 nm or a maximum hardness of 9 GPa or greater measured over an indentation depth range from about 100 nm to about 300 nm, the hardness and the maximum hardness measured by a Berkovich Indenter Hardness Test,
• wherein the first low index layer is in direct contact with the first major surface of the substrate,
• wherein a high index layer is adjacent to the capping low index layer and it has an optical thickness from about 45 nm to about 450 nm,
• wherein the plurality of alternating high index and low index layers is six (6) layers or less, wherein a combined physical thickness of the high index layers is from about 30% to 45% of the physical thickness of the optical film structure, and
• further wherein one of the high refractive index layers in the optical film structure is the thickest layer in the layers of the optical film structure below the capping index layer.