Glass articles with increased hydroxyl group uniformity comprising stack sealed glass substrates, and methods of forming the same

A method of forming a glass article, the method comprising:

• positioning a first glass substrate and a second glass substrate with a first interface surface of the first glass substrate facing a second interface surface of the second glass substrate to produce a glass article precursor, wherein the first interface surface and the second interface surface are spaced apart by a distance greater than or equal to 0 mm and less than or equal to 5 mm;
• heating the glass article precursor in a sealing environment at a sealing temperature and for a time sufficient to stack seal the first glass substrate to the second glass substrate to form the glass article;
• wherein:
• the sealing environment comprises steam, an inert gas, or combinations thereof;
• and
• subsequent to the heating, the second interface surface of the second glass substrate and the first interface surface of the first glass substrate are in direct contact with one another, wherein the direct contact between the first glass substrate and the second glass substrate establishes an interface between the first glass substrate and the second glass substrate;
• wherein the glass article satisfies at least one of (1) or (2) below:
• (1) at least one of a peak-to-valley difference of a hydroxyl group concentration measured along a first line, a peak-to-valley difference of a hydroxyl group concentration measured along a second line, or a peak-to-valley difference of a hydroxyl group concentration measured along a third line is less than or equal to 30 ppm;
• or
• (2) a birefringence of the glass article, as measured at the interface, is less than or equal to 50 nm/cm, less than or equal to 20 nm/cm, or less than or equal to 10 nm/cm;
• wherein:
• the first line is perpendicular to the interface;
• the first line extends between a depth of the first glass substrate of a first distance from the interface and the interface;
• the hydroxyl group concentration is measured along the first line at a spacing of less than or equal to 0.1 mm;
• the second line is perpendicular to the interface;
• the second line extends between a depth of the second glass substrate of a second distance from the interface and the interface;
• the hydroxyl group concentration is measured along the second line at a spacing of less than or equal to 0.1 mm;
• the third line is perpendicular to the interface;
• the third line extends between the depth of the first glass substrate of the first distance from the interface and the depth of the second glass substrate of the second distance from the interface;
• and
• the hydroxyl group concentration is measured along the third line at a spacing of less than or equal to 0.1 mm.