Multiferroic La0.2Pb0.7Fe12O19 ceramics: Ferroelectricity, ferromagnetism and colossal magneto-capacitance effect

The mutual control of the electric and magnetic properties of a multiferroic solid is of fundamental and great technological importance. In this article, the synthesis procedure of La0.2Pb0.7Fe12O19 ceramics was briefly described and the data acquired for the materials characterization is presented. This data article is related to the research article-Acta Mater. 2016, 121, 144 (j.actamat.2016.08.083). Electric polarization hysteresis loop and I-V curve, which help to confirm the ferroelectricity of La0.2Pb0.7Fe12O19 ceramics, were presented. Strong magnetic polarization data was also presented. The great variation of the dielectric constants along with the magnetic field has been presented which helped to demonstrat the giant magnetocapacitance of La0.2Pb0.7Fe12O19. All the datasets were collected at room temperature. Large ferroelectricity, strong magnetism and colossal magneto-capacitance effect have been all realized in one single phase La0.2Pb0.7Fe12O19 at room temperature.


Subject area
Physics More specific subject area Materials physics, functional materials.
Type of data figures How data was acquired Instruments used-Bruker D8 Advance for XRD measurement, ZT-IA ferroelectric measurement system, Quantum Design physical property measurement system (PPMS), Wayne Kerr 6500B LCR station.

Data format
Raw, analyzed, etc Experimental factors The ceramics were heat treated in oxygen atmosphere at 700°C for three times and then both surface sides were coated with silver electrode for ferroelectric measurement and magnetic field-dependent capacitance measurement. The powders for magnetic characterization measurement have also been annealed in O 2 for three times.

Experimental features
The magnetocapacitance data was measured by placing the specimen in a space between two magnets. The magnetic field was adjusted by voltage and current of the coils of the magnets. The measurement was performed under different frequencies at room temperature.

Data source location
Wuhan University of Technology, Wuhan, China,

Data accessibility
Data is supplied with in this article.
Value of the data

Data
The data given in this data article is in the form of three figures. It describes briefly the preparation process of the La 0.2 Pb 0.7 Fe 12 O 19 ceramics, the electric and magnetic characterization of the La 0.2 Pb 0.7 Fe 12 O 19 ceramics as well as its magnetoelectric coupling phenomenon. The data article includes ferroelectric and I-V datasets giving the information of the electric polarization and two current peaks upon applied field, ferromagnetic datasets and variable magnetic field dependentcapacitance datasets.

Experimental design, materials and methods
The single-phase La 0.2 Pb 0.7 Fe 12 O 19 powders were prepared by a polymer precursor method, certain amount of power was pressed into a pellet which was sintered into ceramic. After sintering, the ceramic has subsequently experienced heat-treatment in O 2 at 700°C three times to remove the oxygen vacancies and transform Fe 2 þ into Fe 3 þ in the La 0.2 Pb 0.7 Fe 12 O 19 ceramic. for P-E hysteresis loop measurement, both sides of the ceramic surfaces were coated with silver paste as electrode which was sintered at 820°C for 15 min. Then the ferroelectric hysteresis loop was measured upon the polycrystalline La 0.2 Pb 0.7 Fe 12 O 19 pellet with electrodes by using an instrument referred as ZT-IA ferroelectric measurement system. Magnetization measurement was carried out on a Quantum Design Physical Property Measurement System (PPMS). The magnetocapacitance parameters of the La 0.2 Pb 0.7 Fe 12 O 19 ceramics were measured using a Wayne Kerr 6500B LCR station or an IM 3533-01 LCR meter by applying a variable magnetic field on the specimen.     compound. The origin of the ferroelectricity of M-type lead hexaferrite has been discussed in detail in the previous literatures [1,2].

Giant magnetocapacitance effect
In order to check out the magnetoelectric coupling effect of La 0.2 Pb 0.7 Fe 12 O 19 ceramics, we then measured the capacitance of the specimens at different frequencies upon a applied magnetic field. The specimen was coated with silver electrodes on both surfaces and then put in a space between two magnets, the frequency-dependent capacity data was measured by a IM3533-1 LCR Meter (Hioki Company, Japan) without and with applying a magnetic field at B ¼150 mT. Fig. 4b shows the great response of capacity (or dielectric constant) to the magnetic field as a function of frequencies for La 0.2 Pb 0.7 Fe 12 O 19 ceramics. We found that there was a giant response of the capacitance (dielectric constant) to the magnetic field at low frequency region. There is big difference between the dielectric constants without (Fig. 4a) and with (Fig. 4b) external magnetic field. Upon the applied magnetic field (B ¼150 mT), the dielectric constant (ε(B)) could oscillate along with ε(0) in a great amplitude, varying from 204065.6 to À 229257.9. The dielectric constant (ε(B ¼150 mT)) was determined to be 68184 at the frequency of 50 Hz and 42951 at 100 Hz, respectively (Fig. 4b); while the corresponding dielectric constants at B ¼0 (ε(0)) equal to 921.4 at 50 Hz and 731.6 at 100 Hz, respectively. The maximum value of the magnetocapacitance ratio exceeds 2.18 Â 10 4 % (ΔεðBÞ ¼ ðεðBÞÀεð0ÞÞ=εð0Þ, B ¼150 mT and f¼ 50 Hz). These values match well with that being measured by a Wayne Kerr 6500B LCR station [3]. The agreement between two sets of capacitance data (B ¼150 mT) being measured from two different LCR meters indicates the reliability and repetitiveness of the B-field dependent dielectric constants.