Crystallite size characterization of mechanically alloyed of (Ba,Sr) hexaferrite and (Ba,Sr) titanate composite system

Barium - Strontium Hexaferrite and Barium - Strontium Titanate are both well established materials which widely used respectively as permanent magnets and piezoelectric devices. As the properties are a structure sensitive, materials structure as well as crystal structure must be properly designed to meet a specific application. In this paper, we report our recent investigation on material structure analysis of Ba_0.3Sr_0.7Fe₁₂O₁₉ and Ba_0.7Sr_0.3TiO₃ composite system prepared by a mechanical alloying process to promote feroic properties. The average of particle size for composites system was found initially increased to a large size of 9 μm after mechanically milled for 30 hours and then start to decreased to smaller size of ~ 5μm when the milling time was extended to 80 hours and showing trend toward further reduction in mean particle sizes. In the latter case, the XRD trace for milled powders showed broadened diffracted peaks pattern due to deformation during mechanically milling. After sintering at a temperature of 1050 °C much finer crystallites of 7-13 nm size in a dense pellet were observed. Hence, sintering to the milled particles has promoted formation of nanocrystal containing particles. The mean crystallite size for magnetic phase was about more than 350 times smaller than the mean particle size of composite particles. Finer crystallite sizes were found in B₃SF in which the mean was about 700 times smaller than the mean particle size. The magnetic and electric properties of the composite system are also discussed.