Mechanical properties of PbWO4 scintillating crystals

After confirming the tetragonal structure of PbWO4, we measured the cleavage plane, thermal expansion coefficient and fracture strength. The cleavage of PbWO4 occurs in the (101) and the identical (011) plane but it is weaker than that of CdWO4. The average linear coefficient of thermal expansion between 25-900 degrees C is 29.5 X 10(-6) degrees C-1 along the [001] axis and 12.8 X 10(-6) degrees C-1 along the [100] and [010] axes with an anisotropy of 2.3. The fracture strength is between 26.8 and 31.7 MPa for the [010] and [001] tensile direction, and about 30% smaller (18.5 MPa) for the direction normal to the cleavage plane (011).