Resistivity dependent dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles

Abstract

High resistivity in nanostructured Pb͑Fe 0.012 Ti 0.988 ͒O 3 system prepared by using polyvinyl alcohol ͑PVA͒ in chemical route is observed. The PVA acts as a surfactant to limit the particle size. The Fe substitution for Ti controls the chemical stoichiometry and reduces the lattice distortion, i.e., c / a ratio, and hence the transition temperature reduces with Fe content. The phase structure, morphology, particle size, dc resistivity, and dielectric and magnetic properties of Pb͑Fe 0.012 Ti 0.988 ͒O 3 nanoparticles have been characterized by x-ray diffraction, transmission/ scanning electron microscopy, source meter, LCR meter, and vibrating sample magnetometer. The results indicate that the nanosize particles have high resistivity, which improves the dielectric constant at high-frequency region and increases magnetization of the specimens. The observed variable-range-hopping conduction mechanism indicates that Fe doping leads to the occurrence of local defect states in the PbTiO 3 lattice. The dispersionless dielectric properties with low loss are observed up to 15 MHz. The dielectric properties are improved than those obtained by the conventional process. The initial permeability values do not exhibit much variation up to ferromagnetic transition temperature after which it falls sharply. The large value of saturation magnetization is observed at room temperature.

Improved Room‐Temperature Ferromagnetism in Self‐Assembled Disk‐Like Superstructures of Fe‐Doped PbTiO3 Nanocrystals

“…Both of the S‐type hysteresis loops of Samples‐K and ‐N show obviously ferromagnetic at room temperature. The saturation magnetization ( M s ) of Sample‐K is 7.54 × 10 −2 emu/g, with a coercive field of about 50O e, and is much larger than the saturation magnetization of Sample‐N, almost 27 times stronger than that of the Fe(1%)‐doped PbTiO 3 sample in the paper we reported previously ( M s ≈2.8 × 10 −3 ), and even larger than that reported by Verma et al 10,11 . ( M s =41.6 × 10 −3 emu/g, H c ≈125 Oe for Fe (1.2 mol%)‐doped PbTiO 3 ).…”

“…7,8 In previous works, we reported Fe-doped PbTiO 3 nanocrystals showing room-temperature ferromagnetism (M s 5 0.8 Â 10 À3 ), where oriented-aggregation of the nanocrystals gave rise to the enhancement of ferromagnetism. 9 Verma et al [10][11][12] obtained significantly improved room-temperature ferromagnetism in Fe-doped PbTiO 3 (M s 5 41.6 Â 10 À3 emu/g) nanocrystals and Pb 0.7 Sr 0.3 (Fe 0.012 Ti 0.988 )O 3 (60 Â 10 À3 emu/g) thin film, which have been attributed to the reduction of crystal size corresponding to the increase of surface area. On the basis of previous studies, large surface and increased interfaces of the doped ferroelectric nanocrystals are essential to improve room-temperature ferromagnetism.…”

Room temperature ferroic orders in Zr and (Zr, Ni) doped SrTiO$_3$

“…revealed soft FM nature of the as-synthesized STO sample. The origin of FM behaviour can be attributed to the presence oxygen vacancies V 2− O induced as a result of charge imbalance due to loss of Sr 2+ at high sintering temperature [68][69][70][71][72][73]. Moreover the variable oxidation state of Ti (Ti 4+ ⇔ Ti 3+ ) in STO can also facilitate oxygen vacancy to maintain charge equilibrium.…”

Multifunctional behaviour of nanostructured Pb0.7Sr0.3(Fe0.012Ti0.988)O3thin film

“…For example, multiferroic Pb(Fe 0.66 W 0.33 ) 0.80 Ti 0.20 O 3 thin film has single-phase electric dipole and magnetic spin order near room temperature, so that the ferroelectric/dielectric properties may strongly affect the magnetic spin order [4][5][6]. This is why the most studied multiferroic systems of Pb(Fe, Ti)O 3 (PFT) in both bulk and thin film forms are famous for room temperature ferromagnetism and ferroelectricity coexistence and also magnetoelectric (ME) coupling at a low phase transition temperature [7,8]. However, when the PFT system contains nanograins, the researcher can think more seriously about their resulting parameters.…”