0000000000406802
AUTHOR
M. A. Kojdecki
Crystallite size of kaolinites as indicator of different geochemical types of bauxite
A simple microstructural X-ray diffraction analysis using the Voigt function method reveals differences between bauxite deposits in the Iberian Range Catalanides area (NE, Spain). The highest values of apparent crystallite sizes, measured by volume weighted Dv values from 001 kaolinite reflection, have been found in bauxites of type 1.
Mechanism of Formation of TiO2-Doped Mullites from Heated Single-Phase Gels Investigated by Structural and Microstructural Parameters
An analysis of the microstructure of TiO 2 -doped mullites prepared from monophasic gels thermally treated in the temperature range 900°-1600°C is reported. Two series of gels with nominal compositions 3(Al 2-x Ti x O 3 ) ·2(SiO 2 ) and 2(Al 2-x Ti x O 3 )·(SiO 2 ), in the range 0≤x≤0.15, were prepared. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to follow the structural and textural evolution from gels to the final doped mullites. The crystallite sizes and microstrains were determined by linewidth refinements of XRD patterns using the integral breadth method of Langford and the Warren-Averbach analysis. XRD patterns showed the formation of Al 2 TiO 5 and…