摘要
Ti doped hematitea-Fe_(2-x)Ti_(x)O_(3)(x=0.0,0.0206 and 0.0344)samples are synthesized using solid-state ceramic route technique.Single phase and corundum(Al_(2)O_(3))type structure is revealed from the X-ray diffraction(XRD)pattern.On substitution of Ti at Fe site,all Raman active modes are shifted to higher wave numbers.An additional feature of Eu(LO)mode at about 660 cm^(-1)is observed.The E_(u) mode frequency is decreased and pronounced systematically as a function of Ti doping,and it reaches a value of 658 cm^(-1)for x=0.0344.The coercivity Hc(remanence M_(r))for x=0.0,0.0206 and 0.0344 are determined to be 995 Oe(0.44 emu/mg),1404 Oe(0.00019 emu/mg)and 2023 Oe(0.00016 emu/mg),respectively.The larger coercivity for Ti doped samples can be attributed to their enhanced shape and magneto-crystalline anisotropy.The observed isomer shift(d)from room temperature Mössbauer data clearly shows the presence of ferric(Fe^(3+))and Ti^(4+)ordering ofa-Fe_(2-x)Ti_(x)O_(3)for x=0.0344.
