Magnetic study of intermetallic Ce_1-xTb_xMn₂Ge₂(0 ≤ x ≤ 1) compounds

Abstract

Temperature dependence of microstructure of titanium oxide, TiO 2 , and the phase transition of anatase (A) to rutile (R) were studied by in situ X-ray powder diffraction and Raman spectroscopy, as well as by TEM and SAED techniques.The as-synthesized TiO 2 p.a. showed a gradual transition A R during the temperature increase from 1200 K to 1570 K and during the temperature decrease to 600 K. High-energy ball-milling at room temperature induced a partial transition A R. The transition continued during the temperature increase to 1370 K and during the temperature decrease, and is accompanied by sharpening of diffraction lines.Anisotropy of thermal expansion was noticed for both A and R. In the transition A R, the nuclei of R are formed either throughout the A crystallites ( in case of as-synthesized TiO 2 p.a.) or mainly in the interior of the A crystallites ( in case of milled TiO 2 p.a.).These nuclei grow in number and size with a prolonged time of thermal agitation.