Abstract: A process for producing a glass having a rod refractive index distribution, which includes pressing a glass at a temperature below the glass transition temperature to form a glass having a density increased towards the surface layer thereof, or alternatively includes heating a glass at a temperature around the transition temperature at the lowest to prepare glass having a uniformly enhanced density and heating the treated glass under a pressure lower than the applied pressure at a temperature below the glass transition temperature of the glass to prepare a rod glass having a density increased towards the central portion.

Abstract: A process for producing a rod glass having a refractive index distribution, which includes pressing a glass at a temperature below the glass transition temperature to form a glass having a density increased towards the surface layer thereof, or alternatively includes heating a glass at a temperature around the transition temperature at the lowest to prepare glass having a uniformly enhanced density and heating the treated glass under a pressure lower than the applied pressure at a temperature below the glass transition temperature of the glass to prepare a glass having a density increased towards the central portion.

Abstract: The present invention discloses a lithium ion conductive glass electrolyte including a cationic component and an anionic component, the cationic component including (A) a lithium ion, (B) alkaline earth metal ions and (C) alkali metal ions other than lithium in a percentage composition falling within a region enclosed by the straight lines formed by connecting, in an ionic ratio diagram, points of A(60, 10, 30), B(70, 0, 30), C(40, 0, 60) and D(40, 10, 50) in order, the anionic component being at least one halide ion selected from among chloride, bromide and iodide ions.