Laboratory parallel-beam transmission X-ray powder diffraction investigation of the thermal behavior of calcite: comparison with X-ray single-crystal and synchrotron powder diffraction data
DOI:
https://doi.org/10.2451/2011PM0010Keywords:
high-temperature X-ray powder diffraction, Rietveld method, calcite, nitratine, order/disorder phase transition, spontaneous strainAbstract
Periodico di Mineralogia (2011), 80, 1 (Special Issue), 123-134 - DOI: 10.2451/2011PM0010
Special Issue in memory of Sergio Lucchesi
Laboratory parallel-beam transmission X-ray powder diffraction investigation of the thermal behavior of calcite: comparison with X-ray single-crystal and synchrotron powder diffraction data
Paolo Ballirano
Dipartimento di Scienze della Terra, Sapienza Università degli Studi di Roma, Italy
paolo.ballirano@uniroma1.it
Abstract
Thermal behavior of calcite has been analyzed in the 303-1098 K thermal range by laboratory parallel-beam transmission X-ray powder diffraction. Present results provide a clear indication of the possibility to extract high-quality structural data from such instrumental set up. Such quality has been proved to be at the same level of a mid eighties X-ray single crystal investigation. Analysis of the spontaneous strain e33 provides a critical exponent Β of 0.2499(5) consistent with the value of ¼ expected for a tricritical behavior. Structure refinements seemengly support the Ising model of disorder.
Key words: high-temperature X-ray powder diffraction; Rietveld method; calcite; nitratine; order/disorder phase transition; spontaneous strain.
