Bismuth centred magnetic perovskite: A projected multiferroic (original) (raw)
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Structure and Magnetic Properties of BiFe0.75Mn0.25O3 Perovskite Prepared at Ambient and High Pressure
Solid solutions BiFe1-xMnxO3 (0.0 ≤ x ≤ 0.3) were prepared at ambient pressure and at 6 GPa. The ambient-pressure (AP) phases crystallize in space group R3c similar to BiFeO3. The high-pressure (HP) phases crystallize in space group R3c for x = 0.05 and in space group Pnma for 0.15 ≤ x ≤ 0.3. The structure of HP-BiFe0.75Mn0.25O3 was investigated using synchrotron X-ray powder-diffraction, electron diffraction and transmission electron microscopy. HP-BiFe0.75Mn0.25O3 has a PbZrO3-related √2ap×4ap×2√2ap (ap is the parameter of the cubic perovskite subcell) superstructure with a = 5.60125(9) Å, b = 15.6610(2) Å, c = 11.2515(2) Å similar to Bi0.82La0.18FeO3. A remarkable feature of this structure is the unconventional octahedral tilt system, with the primary a - b 0 a - tilt superimposed on pairwise clockwise and counter-clockwise rotations around the b-axis according to the oioi sequence (o stands for out-of-phase tilt and i stands for in-phase tilt). The (FeMn)O6 octahedra are distorted, with one longer metal−oxygen bond (2.22 – 2.23Å) that can be attributed to a compensation for covalent Bi-O bonding. Such bonding results in the localization of the lone electron pair on Bi3+ cations, as confirmed by electron localization function analysis. The relationship between HP-BiFe0.75Mn0.25O3 and the antiferroelectric structures of PbZrO3 and NaNbO3 is discussed. On heating in air, HP-BiFe0.75Mn0.25O3 irreversibly transforms to AP-BiFe0.75Mn0.25O3 above ~ 650 K. Both AP- and HP-phases undergo an antiferromagnetic ordering at TN ~ 480 and 530K, respectively, and develop a weak net magnetic moment at low temperatures. Additionally, AP-BiFe0.75Mn0.25O3 shows a peculiar phenomenon of magnetization reversal.
A multiferroic ceramic with perovskite structure: (La0.5Bi0.5)(Mn0.5Fe0.5)O3.09
Applied Physics Letters, 2008
ABO 3 perovskite multiferroic La 0.5 Bi 0.5 Mn 0.5 Fe 0.5 O 3.09 where the B-site cations is responsible for the magnetic properties and the A-site cation with lone pair electron is responsible for the ferroelectric properties was synthesized at normal conditions. This oxide exhibits a ferromagnetic transition around 240 K with a well defined hysteresis loop, and a significant reversible remnant polarization below 67K similar to ferroelectric behavior. The magnetic interaction is interpreted by the ferromagnetic Fe 3+-O-Mn 3+ and antiferromagnetic Fe 3+ (Mn 3+)-O-Fe 3+ (Mn 3+) interactions competed each other, whereas the ferroelectricity is predominantly due to the polar nature introduced by the 6s 2 lone pair of Bi 3+ cations.
Physica Scripta, 2012
In this paper, we report the synthesis of polycrystalline samples with nominal compositions Bi 0.6−x La x Ca 0.4 MnO 3 (0.0 x 0.6) via the solid state reaction route and our study of their structural, magnetic and electrical transport properties with the variation of doping concentration of La. Magnetic measurements of the parent Bi 0.6 Ca 0.4 MnO 3 compound reveal the presence of the robust charge-ordered antiferrromagnetic (COAFM) phase with charge-ordering temperature (T CO ) ∼289 K and antiferromagnetic Néel temperature (T N ) ∼136 K. The COAFM phase disappears when this compound is doped with La. Furthermore, the samples with x = 0.2-0.6 exhibit paramagnetic-to-ferromagnetic (PM-FM) transition and PM-FM transition temperature (T C ) decreases progressively from 270 to 203 K as x increases from 0.2 to 0.5. However, the samples with x = 0.0 and 0.1 do not show PM-FM transition. The temperature-dependent resistance measurements of samples with x = 0.0-0.4 exhibit an insulating behaviour, whereas samples with x = 0.5 and 0.6 exhibit metal-insulator transition at ∼163 and 198 K, respectively. The experimental results are discussed on the basis of the character of the Bi 3+ lone pair electron and the average A-site cation radius ( r A ).
Structural transitions and unusual magnetic behavior in Mn-doped Bi1−xLaxFeO3 perovskites
Journal of Applied Physics, 2012
Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated materials Rev. Sci. Instrum. 83, 103907 (2012) Magnetic hardness features and loop shift in nanostructured CuO J. Appl. Phys. 112, 083904 (2012) Analysis of long-range interaction effects on phase transitions in two-step spin-crossover chains by using Isingtype systems and Monte Carlo entropic sampling technique J. Appl. Phys. 112, 074906 A-site disorder driven sharp field-induced transition and collapse of charge ordering in Sm1/2Ca1/2-xSrxMnO3 J. Appl. Phys. 112, 073905 Effect of fast neutron irradiation induced defects on the metamagnetic transition In Ce(Fe0.96Ru0.04)2
Magneto-transport and magneto-dielectric effects in Bi-based perovskite manganites
Journal of Materials Chemistry, 2008
The study of the substitution of manganese by cobalt in the perovskite (LaBi)MnO 3 in view of discovering magneto-dielectric properties in manganites, has allowed the perovskite La 1.2 Bi 0.8 Mn 1.2 Co 0.8 O 6.02 to be selected. This phase is indeed ferromagnetic, like the parent phase La 1.2 Bi 0.8 Mn 2 O 6.20 , yet with a much higher T C (181 K instead of 103 K). Moreover, it is a better insulator than the other members with an activation energy of 86 meV. Importantly, it exhibits a significant magneto-dielectric effect of around 0.25% at 80 K. Finally, it is also shown to exhibit magnetoresistance (MR) properties at low temperature, with MR values up to À19% at 125 K. These properties are explained on the basis of Mn 4+ /Co 2+ ferromagnetic interactions, electronic phase separation and spin-lattice interactions.
Bulletin of Materials Science, 2005
Oxides of the type (La 2/5 Ba 2/5 Ca 1/5 )(Mn (2/5)-x Ni x Ti 3/5 )O 3 (0 £ £ x £ £ 0⋅ ⋅4) have been synthesized by the ceramic route. All the above oxides have been found to crystallize in the cubic perovskite structure. Rietveld refinement of the Ni-based oxide, (La 2/5 Ba 2/5 Ca 1/5 )(Ni 2/5 Ti 3/5 )O 3 gave rise to a composition (La 0⋅ ⋅44 Ba 0⋅ ⋅38 Ca 0⋅ ⋅18 ) (Ni 0⋅ ⋅42 Ti 0⋅ ⋅58 )O 2⋅ ⋅85(6) and the refined lattice parameter obtained was 3⋅ ⋅9411(2) Å (space group ; m 3 Pm R(F 2 ) = 0⋅ ⋅026, R p = 0⋅ ⋅074, wR p = 0⋅ ⋅087). A shift from antiferromagnetic to paramagnetic behaviour is observed with increase in nickel concentration, the Mn-rich phases showing antiferromagnetism around 5 K. There is a systematic decrease in the dielectric constant, ε ε and loss tangent with increase in Ni concentration (from ε ε = 592 for x = 0 to ε ε = 78 for x = 0⋅ ⋅4).