The phase composition and development of calcium aluminates (CA, CA2, and CA6) processed by in-situreaction sintering of AI203 and CaC03 have been studied by Rietveld refinement technique. The formation of calciumaluminates is temperature-dependent. X-ray diffraction result revealed that the CA, CA2, and CA6 phases starts todevelop at approximately 1000 DC,1100 °c and 1375 DC,respectively. The relative phase compositions obtained from x-raydiffraction patterns for the a-A1203 phase decreased markedly with increasing temperature, Le. from 86.0(1.1) wt %at 1000 °c to 34.7(0.4) wt % at 1400 DC.The wt % of CA decreased from 10.9(0.3) - 1.9(0.2) wt % at 1100 - 1200 °cbut disappeared at 1300 DC.The wt % of CA2 reached 36.0(0.7) wt % at 1300 °c and decreased to 18.5 (0.5) wt % at1400°C. The wt % CA6 increased markedly from 1375 to 1400DC,i.e. 12.80(0.6)- 47.3(0.9) wt %. The goodness of fitvalues is relatively low and the fluctuation in the difference plots shows a reasonable fit between the observed and thecalculated plot.Keywords: X-ray diffraction, Rietveld technique, calcium aluminates (CA, CA2, and CA6).PACS: 61.10.Nz. I. Ridwan and D. Asmii Department of Physics, Faculty of Mathematics and Natural Sciences, University of Lampung, Il.Sumantri Brojonegoro No.1, Bandar Lampung 35145, Indonesia
