Abstract and subjects
Synthetic anorthite (CaAl2Si2O8) powder was prepared through solid-state synthesis and compacts were consolidated through pressure-less sintering as well as uniaxial hot-pressing. Calcium oxide (CaO), aluminum oxide (Al2O3), and silicon oxide (SiO2) powders were mixed in a stoichiometric ratio of CaO:Al2O3:SiO2 = 1:1:2 and reacted at 1500 degrees C to form bulk anorthite powder. Consolidation through pressure-less sintering at 1300 degrees C resulted in highly-porous compacts with bulk densities of 1.80 g/cm(3), while uniaxial hot-pressing at 1300 degrees C achieved highly-dense compacts with bulk densities of 2.74 g/cm(3). Anorthite compacts were determined to be nominally phase-pure through X-ray diffraction (XRD), although the absence of (h+k+l=odd) reflections suggest Al-Si site disorder. Additionally, hkl-dependent intensity variations in the XRD patterns of uniaxial hot-pressed anorthite indicated crystallographic texturing occurred. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDXS) revealed the formation of an Al-depleted phase not evident in the XRD patterns and minor Zr contamination. Nominally phase-pure, highly dense anorthite was achieved through solid-state synthesis and uniaxial hot-pressing, demonstrating a route to fabricate artificial mineralogical specimens for laboratory studies.