Subjects: Materials Science >> Materials Science (General) submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to investigate the magnetoelectric coupling performance of BaFe10.2Sc1.8O19 samples at room temperature,
BaFe10.2Sc1.8O19 samples were prepared by solid phase method and sol-gel method. The phase structure was determined by
X-ray diffraction, the prepared samples are all single-phase polycrystals with a space group of P63/mmc. The surface morphology
was observed by field emission scanning electron microscopy, the samples prepared by solid phase method show that
there is not uniform in composition and a "scandium-rich phase". The morphology analysis of the sample prepared by sol-gel
method shows that the grains of BaFe10.2Sc1.8O19 exhibit uniform distribution with hexagonal platelet-shaped structure, and
the grain size is about 3-5 μm. The magnetic results of the samples prepared by the sol-gel method and the solid state reaction
show that the solid state reaction sample undergoes phase transition at about 250 K, and the hysteresis line does not exhibit
magnetoelectric coupling behavior at room temperature; Temperature and magnetic field dependence of magnetization
for the sample prepared by sol-gel method show that BaFe10.2Sc1.8O19 exhibits ferrimagnetic to conical spin structures phase
transition near 330 K. Magnetic field dependence of magnetocapacitance is similar to the behavior in magnetization, which
indicate that the systems exist ferroelectric polarization induced by the conical spin structures. It can be understood by the
inverse Dzyaloshinskii-Moriya model.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract：
In order to study the magnetic phase transition and dielectric relaxation of TbCrO3 at low temperature, TbCrO3
samples were prepared by the sol-gel self-propagating combustion synthesis method, and its magnetic and electrical properties
were analyzed. The crystal structue and physical properties of TbCrO3 were characterized by X-ray diffractometer, field
emission scanning electron microscope and physical property measurement system, respectively. X-ray diffraction results
show that the synthesized TbCrO3 is single with Pbnm space group. The DC magnetization curve shows that the Neel temperature
of the material is TN=162 K, the theoretical value of the effective magnetic moment of the molecule is consistent
with the experimental value obtained by extrapolation of the high-temperature paramagnetic section of the magnetization
curve, indicating that the magnetic properties of the sample follow Curie's law, the Weiss constant is negative (-32.2 K),
indicating the antiferromagnetic coupling characteristics inside the sample. In the dielectric measurement, at low frequency
and high temperature, the sample has dielectric dispersion and giant dielectric constant, which is attributed to space charge
polarization. The sample shows dielectric relaxation near 200 K, and the loss peak moves to high temperature with increasing
frequency. The fitted activation energy is 0.358 eV, which is close to the activation energy of other samples in the
RCrO3 system. According to the relationship between the imaginary part of the dielectric constant and the frequency, the relaxation
is the Maxwell-Wagner relaxation. From impedance spectroscopy analysis, relaxation is caused by the interaction of
grain boundaries and grains. TbCrO3 has a paramagnetic-antiferromagnetic phase transition at low temperature, and dielectric
relaxation shows thermal activation behavior.
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