thermal hysteresis in some applications an even wider range of temperatures may be tolerated the beta eucryptite material is based on a highly ordered lithium aluminosilicate glass ceramic which is in itself a stuffed derivative of beta quartz containing aluminum and lithium significant titania for example gt 2 wt is also required to be present as a nucleating agent to induce crystallization of the solid solution in order to minimize grain size and reduce hysteresis due to inter granular micro cracking the beta eucryptite solid solution of preference lies between stoichiometric lialsio 4 li 2 o al 2 o 3 2sio 2 1 1 2 and li 2 al 2 si 3 o 10 li 2 o al 2 o 3 3sio 2 1 1 3 and the nucleating agents tio 2 and optionally zro 2 are added in such a way as to produce accessory phases al 2 tio 5 or zrtio 4 preferably the former for the lowest thermal expansion coefficients this glass ceramic has a true negative expansion micro crystalline phase strongly along one axis c axis mildly positive along the other a axis and is mechanically stable over a wide temperature range showing little hysteresis or physical property degradation in weight percent.