The thermal expansion of the zeolites MFI, AFI, DOH, DDR, and MTN in their calcined and as synthesized forms
Progress in Zeolite and Microporous Materials, Pts a-C 105: 1989-1994
The thermal expansion coefficients of the silica zeolites MFI, DOH, DDR, and MTN and of the alumophosphate AFI were determined using the X-ray Guinier technique. At low temperatures the as synthesized microporous materials show positive volume expansion coefficients of the order of magnitude of 10 . 10(-6)K(-1) which are in the expected range for silicates or phosphates. After calcination the thermal expansion of these materials is positive below the displacive phase transitions to their high symmetry forms. The high temperature phases, however, contract with increasing temperature. Their volume expansion coefficients are negative and in the order of -10 . 10(-6)K(-1).