Figure 4. Thermal expansion of Ba_0.6Sr_0.4Zn₂Si₂O₇.

On the left side, XRD-patterns, recorded at various temperatures are presented in a 2θ range between 18° and 42°. In the lower two diffractograms, the peak positions of Al₂O₃ (internal standard) and Ba_0.6Sr_0.4Zn₂Si₂O₇ are shown. The peaks of Al₂O₃ were taken from ref. 14. In the upper right corner, the cell parameters, determined by X-ray powder diffraction are given as a function of the temperature. In the lower right corner, the dilatometric thermal expansion behavior of bulk ceramics, prepared with different sintering conditions is illustrated: (A) sintered at 1300 °C without compression (B) isostatically pressed with 100 bar and afterwards sintered at 1175 °C; (C) hot pressed at 1100 °C with an uniaxial pressure of 28 MPa; (D) sintered at 1270 °C without compression. Furthermore, the volume of the unit cell is shown (blue symbols).