Abstract: A glass ceramic substrate includes: an inner layer part having a first thermal expansion coefficient; and a surface layer part having a second thermal expansion coefficient smaller than the first thermal expansion coefficient. The inner layer part contains a first glass matrix and flat alumina particles. The flat alumina particles are dispersed in the glass matrix in a direction in which individual thickness directions are substantially perpendicular to a surface direction of one of main surfaces of the inner layer part. Further, a mean aspect ratio of the flat alumina particles is 3 or more in one of cross sections along the thickness directions of the flat alumina particles out of cross sections of the inner layer part.

Abstract: A glass ceramic substrate includes: an inner layer part having a first thermal expansion coefficient; and a surface layer part having a second thermal expansion coefficient smaller than the first thermal expansion coefficient. The inner layer part contains a first glass matrix and flat alumina particles. The flat alumina particles are dispersed in the glass matrix in a direction in which individual thickness directions are substantially perpendicular to a surface direction of one of main surfaces of the inner layer part. Further, a mean aspect ratio of the flat alumina particles is 3 or more in one of cross sections along the thickness directions of the flat alumina particles out of cross sections of the inner layer part.

Abstract: There are provided a glass ceramic body having a sufficiently high strength and having a high degree of flexibility in shape which can correspond to a three-dimensional shape, and a layered body having the glass ceramic body. In a glass ceramic body in which flat alumina particles are dispersed in a glass matrix constituted of a glass with a crystallinity of 25% or less, a total cross-sectional area of the flat alumina particles, having a cross section with a thickness of 0.2 ?m or more, a maximum diameter of 8 ?m or less, and an aspect ratio in a range of 3 to 18 in one of cross sections along the thickness directions of the flat alumina particles in the glass ceramic body, is 20% or more relative to a total area of the cross section, and an open porosity is 5% or less.