Dielectric and magnetic properties of Ba-,La-and Pb-doped Bi_(0.8)Gd_(0.1)M_(0.1)Fe_(0.9)Ti_(0.1)O_(3) perovskite ceramics

The multiferroic Bi_(0.8)Gd_(0.1)M_(0.1)Fe_(0.9)Ti_(0.1)O_(3),(where M=Ba(DB),La(DL)and Pb(DP))has been synthesized by using solid-state reaction technique.Effects of Ba,La and Pb substitution on the structure,electrical and ferroelectric properties of Bi_(0.8)Gd_(0.1)M_(0.1)Fe_(0.9)Ti_(0.1)O_(3) samples have been studied by performing X-ray diffraction,dielectric and magnetic measurements.The crystal structures of the ceramic samples have a tetragonal phase.The vibrating sample magnetometer(VSM)measurement shows a significant change in the magnetic properties of Ba-doped Bi_(0.8)Gd_(0.1)M_(0.1)Fe_(0.9)Ti_(0.1)O_(3) as compared to La-and Pb-doped ceramics.It is seen that coercive field(HC)and remanent magnetization(MR)increases with Ba-doped ceramics but decreases for La-and Pbdoped ceramics.

Magnetic and specific heat studies of the frustrated Er_2Mn_2O_7 compound

A new ErzMn207 compound was synthesized by the ceramic method and its crystal structure was characterized LJsing powder X-ray diffraction （XRD） and observed by scanning electron microscopy （SEM）. The magnetic properties were investigated using a BS2 magnetometer and the heat capacity was studied using a quantum design （PPMS）. The structural study revealed that this compound was monophasic and crystallized in the monoclinic system with the P2/M space group. Magnetization measurements were carried out in the temperature range of 1.8-200 K under an applied magnetic field of 0.05 T. A crossover from a room temperature para- magnetic phase to an antiferromagnetic one at low temperature was detected from the magnetic study. The magnetic susceptibility, in the paramagnetic region above 40 K, was found to present a simple Curie-Weiss type behavior. From the specific heat （G,） measurements in magnetic fields up to 5 T, we noted the presence of a wide peak characteristic of a second order magneto-structural transition.

Dielectric,electrical conduction and magnetic properties of multiferroic Bi_(0.8)Tb_(0.1)Ba_(0.1)Fe_(0.9)Ti_(0.1)O_(3)perovskite compound

This work focuses on the structural,electrical and magnetic properties of Bi_(0.8)Tb_(0.1)Ba_(0.1)Fe_(0.9)Ti_(0.1)O_(3)ceramics,fabricated by solid state reaction procedure.XRD forms of the samples at RT exhibited perovskite phase through the hexagonal structure at room temperature.Dielectric studies of the materials with frequency at different temperatures(25-400℃)exhibit two dielectric anomalies,first at 175℃(ferroelectric-ferroelectric transition)and second at around 320℃(ferroelectric-paraelectric transition).The Curie temperature moved towards the low side temperature with the increase in frequency.The less value of activation energy got for these samples could be attributed to the influence of electronic contribution to the conductivity.A significant change in the magnetic studies was observed for Bi_(0.8)Tb_(0.1)Ba_(0.1)Fe_(0.9)Ti_(0.1)O_(3) ceramic.The impedance analysis confirms the non-Debye type nature of the ceramic and relaxation frequency moved to a higher temperature.The Nyquist plot and conductivity studies showed the NTCR behavior of samples.The highest magnetization field was found at temperature-268.15℃.

Structural,dielectric and magnetic properties of Pr-,Tb-and Dy-doped(Bi_(0.95)RE_(0.05))(Fe_(0.95)Mn_(0.05))O_(3) ceramics synthesized by solid-state reaction method

The multiferroic(Bi_(0.95)RE_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)(where RE=Pr,Tb and Dy)has been synthesized using solid-state reaction technique.Effects of Pr,Tb and Dy substitution on the structure,electrical and ferroelectric properties of(Bi_(0.95)RE_(0.05))(Fe_(0.95)Mn_(0.05))O_(3) samples have been studied by performing X-ray diffraction,dielectric measurements and magnetic measurements.The crystal structure of the ceramic samples have a monoclinic phase.The vibrating sample magnetometer(VSM)measurement shows a significant change in the magnetic properties of Pr-,Tb-and Dy-doped(Bi_(0.9)RE_(0.05))(Fe_(0.95)Mn_(0.05))O_(3).It is seen that coercive field(Hc)and remanent magnetization(Mr)increases for Pr but decreases for Dy and Tb.

FERROELECTRIC AND MAGNETIC PROPERTIES OF PEROVSKITE STRUCTURED Bi_(1-x-y)Gd_(x)Ba_(y)Fe_(1-y)Ti_(y)O_(3)MAGNETOELECTRIC CERAMICS

Ternary solid solutions of BiFeO_(3),GdFeO_(3)and BaTiO_(3)have been prepared by solid-state reaction method.Dielectric properties of these ceramics have been characterized in the tem-perature range between room temperature and 673 K and magnetic properties between 5 K and 300K.For the understanding of the multiferroic property,the relation between the crystal structures,magnetic transition and ferroelectric transitions with increasing temperature have been analyzed.All ceramic samples show single perovskite phase.When Ba content exceeds 0.2 wt%,the sintering ability is weakened and the phase structure of Bi_(1-x-y)Gd_(x)Ba_(y)Fe_(1-y)Ti_(y)O_(3)(with x=0.2 and y=0.1,0.2,0.3,0.4,0.5)solid solution changes from rhombohedral to tetragonal phase.The maximum ferroelectric transition temperature(T_(c))of this system was in the range 154-165℃with the dielectric constant peak of 6000 for y=0.5 at 100 kHz.Well-saturated piezoresponse hysteresis loops were observed for all compositions indicating room temperature ferroelectricity.With increasing Ba content(up to 0.3 wt%)the remanent magnetization M,increased and the coercive magnetic field decreased.

Study the structural and magnetic properties of rare-earth ions(La and Gd)doped Ba_(0.9575)Ca_(0.0025)Ti_(0.80685)Mn_(0.002475)Nb_(0.002475)Zr_(0.1782)O_(3)(BCTMNZ)ceramics

In this paper,we investigated the influence of rare earth(RE=La and Gd)doped Ba_(0.9575)RE_(0.04)Ca_(0.0025)Ti_(0.80685)Mn_(0.002475)Nb_(0.002475)Zr_(0.1782)O_(3)(BCTMNZ)ceramics were fabricated by using a conventional solid state reaction method.The doping effects of La and Gd on the structural and magnetic properties were studied.The structural pattern of the ceramic samples were investigated by X-ray diffraction and the results indicated that both samples shows an orthorhombic structure with pure phase.Strain and crystalline size values for Gd and La doped were 0.31-0.33%and 0.154-0.181μm,respectively.The room temperature hysteresis loops were obtained by using a vibrating sample magnetometer.La doped ceramic showed the higher value of mag-netization i.e.,0.369μB/f.u.as compared to Gd doped BLTMNZ ceramics.