Abstract

High temperature X-ray diffraction studies have been carried out on calcined AlPO4-5 molecular sieve in the temperature range 298-673K in order to study the thermal expansion behavior of this material. Rietveld refinement analysis of AlPO4-5 structure against the powder X-ray diffraction data collected at different temperature were carried out to derive the unit cell dimensions. Unit cell volume increases upto 373K and then remains nearly constant upto 523K and then decreases marginally. The material exhibits a complex thermal behavior viz, it expands initially upto 523 K and then contracts. The strength of expansion is greater than the strength of contraction.

Keywords: Microporous materials; X-ray diffraction; Thermal expansion