Ceramic is generally more brittle than glass. This is due to the differences in their chemical compositions and crystal structures. Ceramics are inorganic, non-metallic materials that are typically composed of a mixture of metallic and non-metallic elements. They often have a crystalline structure with a high degree of anisotropy, meaning that their properties can vary depending on the direction of measurement. This anisotropy contributes to their brittleness, as stress is not distributed evenly across the material.

Glass, on the other hand, is an amorphous solid, meaning it lacks a regular, repeating pattern of atoms. This amorphous structure allows glass to be more resistant to stress and deformation, making it less brittle than ceramics. The absence of a crystalline structure in glass means that the atoms are not arranged in a way that promotes the propagation of cracks.

Data from the American Ceramic Society indicates that ceramics typically have a tensile strength of around 100 to 500 MPa, while glass has a tensile strength of around 50 to 200 MPa. This lower tensile strength in glass is a direct result of its amorphous structure, which limits its ability to withstand tensile stresses without fracturing.

In addition, the hardness of ceramics is often higher than that of glass. Ceramics can have a hardness ranging from 5 to 9 on the Mohs scale, while glass typically ranges from 5.5 to 6.5. The higher hardness of ceramics makes them more prone to fracturing under stress, further contributing to their brittleness.

In summary, ceramic is more brittle than glass due to its crystalline structure, anisotropy, and higher tensile strength. The amorphous nature of glass, along with its lower tensile strength and hardness, makes it less prone to fracturing under stress.