The Effect of Mechanical Activation on the Synthesis and Properties of Multiferroic Lead Iron Niobate
The present work studies the effect of high-energy mechanical activation using the planetary-centrifugal ball mill AGO-2 and subsequent annealing on the synthesis and magnetic properties of PbFe0.5Nb0.5O3 (PFN). This technique enables one to perform the mechanically activated synthesis of PFN at much shorter time. The results of X-ray phase analysis, electron microscopic studies and transmission Mossbauer 57Fe spectra measurement are presented and discussed. Mossbauer studies show that the temperature of magnetic phase transition in PbFe0.5Nb0.5O3 powders can be changed by mechanical activation and subsequent annealing.
Electron microscopy, XRD, dielectric, and Mossbauer studies of Li-doped Pb(Fe0.5Nb0.5)O3 ceramics sintered from mechanically activated powders
ABSTRACT X-ray diffraction (XRD) studies of the phases formed on the surface of the Li-doped PbFe0.5Nb0.5O3 (PFN) ceramics sintered under different conditions from the mechanically activated mixture of oxides and Li2CO3 have been carried out. At sintering temperatures exceeding 800°C a partial evaporation of PbO leads to the formation of pyrochlore Pb2Fe4Nb4O21 and lithium ferrites LiFeO2 and LiFe5O8 phases in the surface layer about 100 μm thick. An increase of the Neel temperature by more than 40 K, as compared to single crystal, was achieved in the mechanically activated PFN powder sintered at 600°C.
Monitoring and Optimization of Internal Grinding Process
Summary The grinding process is influenced by many factors such as grinding wheel characteristics, dressing conditions and, course, grinding conditions. Therefore, it is difficult to perform the grinding operation in an optimum state. In this study, in-process monitoring methods using power and acoustics emission sensors are proposed to detect malfunctions in the internal grinding process. In addition, a new internal grinding cycle featuring rapid indeed is proposed to minimize the grinding cycle time.