High-temperature X-ray diffraction and specific heat studies on GdAlO3, Gd3Al5O12 and Gd4Al2O9

✍ Scribed by Satyajeet Chaudhury; S.C. Parida; K.T. Pillai; K.D. Singh Mudher

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 241 KB
• Volume: 180
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2007.06.003

✦ Synopsis

Gadolinium aluminates, GdAlO 3 , Gd 3 Al 5 O 12 and Gd 4 Al 2 O 9 were synthesized by the solution combustion method. Very fine particles in the nanoparticle range of $10-20 nm could be prepared by this method as evidenced by surface area measurement by multipoint BET method. Thermal studies on these compounds were carried out using high-temperature X-ray diffraction (HT-XRD) and differential scanning calorimetry (DSC) methods. The thermal expansion coefficients of GdAlO 3 , Gd 3 Al 5 O 12 and Gd 4 Al 2 O 9 were calculated from the lattice parameter data and specific heats were calculated from DSC data. The lattice parameters of GdAlO 3 and Gd 3 Al 5 O 12 were found to increase linearly with temperature whereas Gd 4 Al 2 O 9 did not show a linear trend. The specific heats of these compounds show an increasing trend with increase in aluminum atom fraction. Based on the thermodynamic data available in the literature and the specific heat data obtained in this study, oxygen potential diagram was constructed at 1000 K.