Glass–ceramics with zero thermal expansion in the system BaO/Al2O3/B2O3

Nanocrystal Growth in Cordierite Glass Ceramics Studied with X-ray Scattering

“…Once the different crystals impinge upon each other and the surface is completely covered the crystallites with their c-axis pointing into the bulk become the fastest growing species. This has also been observed in other low thermal expansion coefficient glass ceramics 35 . It therefore is no surprise that during this growth process, with a changing texture, the intensity of the diffraction peaks can vary quite erratically even though the position of the diffraction peaks show a much smoother variation.…”

Thermal expansion of glass–ceramics in the system BaO/Al2O3/B2O3

“…As recently reported [1], this is due to a highly negative thermal expansion coefficient in the direction of the crystallographic c-axis of the rhombohedral crystal phase BaAl 2 B 2 O 7 (JCPDS no. 86-2168).…”

“…Glass-ceramics with zero expansion coefficients based on other systems have scarcely been described in the literature. Recently, the crystallization of the bulk glass, the behavior during sintering of glass powder and the effect of platinum as nucleating agent, as well as the resulting thermal expansion in this system have been reported [1,9]. Here, a notable effect of the preparation procedure and hence the microstructure on the thermal expansion was reported.…”

“…This is due to the crystalline phase BaO AE Al 2 O 3 AE B 2 O 3 which, as shown by high temperature X-ray diffraction, possesses a strongly negative expansion coefficient in the direction of the crystallographic c-axis while it is slightly negative with respect to the a-axis [1]. Glass-ceramics with zero thermal expansion coefficients are of great economic importance [2][3][4][5], especially with respect to cook top panels [3,4] and numerous applications in micromechanics.…”

“…Recently, it has been shown [1,2] that glass-ceramics in the system BaO/Al 2 O 3 /B 2 O 3 may possess negative thermal expansion coefficients. This is due to the crystalline phase BaO AE Al 2 O 3 AE B 2 O 3 which, as shown by high temperature X-ray diffraction, possesses a strongly negative expansion coefficient in the direction of the crystallographic c-axis while it is slightly negative with respect to the a-axis [1].…”