Magnetodielectric Coupling Research Articles

Multiferrocity in spin chain based polycrystalline Sm2BaCoO5

Sm2BaCoO5, a spin chain based polycrystalline compound which crystallize in orthorhombic structure (space group, Immm), is known to order antiferromagnetically close to 38 K. As motivated by 1) its Tb analogues [1] which show giant magneto-dielectric coupling and a new type-II multiferroic and 2) recently discovered multiferroicity in Sm2BaMO5 (M=Ni and Cu) compounds [2,3], detailed dielectric, ferroelectric and magneto-electric measurements have been carried out for Sm2BaCoO5. Magnetic and heat capacity measurements confirm the antiferromagnetic ordering at around 38 K. Interestingly ferroelectric transition also occurs around 38 K as revealed by frequency independent dielectric data as well as pyro-current measurements in various protocols. Therefore, the presented experimental results show that spin chain oxide Sm2BaCoO5 is new type-II multiferroic and we have identified R2BaCoO5 (R=Tb, Sm)- spin chain based cobaltates, is the new multiferroic series, so far unexplored.

Magnetic properties and linear negative magnetocapacitance in rutile like LiFe2SbO6

Abstract We report the high-temperature magnetic ordering and the observation of linear negative magnetocapacitance mediated by a low-temperature magnetic phase crossover in the compound LiFe2SbO6. The combined observations of the absence of a second harmonic generation (SHG) signal, and Rietveld refinements of X-ray and neutron powder diffraction (NPD) patterns of the sample confirm that LiFe2SbO6 crystalizes in a centrosymmetric Pnnm structure. The DC magnetization measurements reveal that an antiferromagnetic ordering sets in at high temperature (TN= 850). The magnetic anomaly in the DC magnetization at a lower temperature T = 13 K, is corroborated by AC susceptibility and the specific heat measurements. We observe a linear negative magnetocapacitance below T = 13 K, demonstrating an indirect magneto-dielectric coupling. Further, the neutron powder diffraction study reveals a collinear antiferromagnetic ordering with a wavevector k = (0, 0, 0).

Settlement stability, electrical properties, and magnetoelectric properties of Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 multiferroic fluids modulating by particle sizes

Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 (MZFO-PZT) multiferroic fluids with different MZFO particle sizes were prepared, and magnetoelectric coupling effects were observed to be enhanced at room temperature. The X-ray diffraction analysis (XRD) indicates that the MZFO and PZT particles are in the pure phases. Scanning electron microscopy (SEM) images illustrate a decrease in MZFO particle size with increased ball milling time. As the MZFO particle sizes decrease, the settlement stability of multiferroic fluids becomes worse. The dielectric constant displays a nonlinear variation, exhibiting a maximum value of 4.52 at 140 Hz when the MZFO particle size is 0.55 μm. The residual polarization strength decreases and increases as particle size decreases, while the saturation polarization strength decreases gradually. The application of magnetic field results in a notable enhancement of the dielectric characteristics and ferroelectric properties, which indicates the presence of magnetodielectric and magnetoelectric coupling effects. The magnetoelectric coupling coefficient (αME) is 15.14 V/(cm·Oe) when the MZFO particle size is 0.61 μm. By modifying the strength of the applied magnetic field, the αME attains a maximum value of 114.43 V/(cm·Oe). This approach offers an effective strategy for optimizing the magnetoelectric coupling effect of multiferroic materials. Therefore, it is expected to be used in new magnetoelectric devices such as magnetoelectric random memories and magnetic field sensors.

Modulated magnetostriction and multiferroic properties in the PVDF-based cobalt ferrite particulate composites

Multiferroic materials (MFM) have drawn substantial attention for developing smart magnetodielectric devices. Herein, cobalt ferrite CoFe2O4 (CFO) was synthesized by a glycine–nitrate sol-gel auto-combustion route and, PVDF-based particulate composite films embedded with CFO have been developed. A comprehensive investigation evaluated the effects of magnetostriction, initiated from the embedded CFO phase, on magnetodielectric characteristics of composite films. The structural, electrical, magnetostrictive and magnetodielectric properties were investigated. The embedded CFO particulate endows PVDF matrix at a higher β–phase forming ability, which enhances the ferroelectricity with a polarisation (Pmax∼1.09 μC/cm2@ 850 kV/cm), a higher dielectric constant (εr∼12.33) and lower dielectric loss. The typical magnetic hysteresis loop was obtained with saturation magnetization (MS∼4.96 emu/g) and coercivity (HC∼1.49 kOe), revealing the ferromagnetic ordering in composite films. The response of the magnetodielectric (MD) is observed at room temperature, that is, a large negative MD coefficient ∼2.1 % @ Hcr∼5.0 kOe is achieved for Co0.9Fe2.1O4/PVDF composite films, while MD∼0.65 %@ Hcr∼1.0 kOe is obtained for Co1.1Fe1.9O4/PVDF films, accompanied by a maximum MD∼4.35 % at resonance frequency. The variation in the MD performance reveals a close correlation to the modulated magnetostriction, such as the magnetocrystalline anisotropy, field-induced coefficient and magnetostrictive susceptibility, indicating the strain-mediated coupling MD effect. The multiferroic properties in CoxFe3–xO4/PVDF composites have potential for magneto-dielectric sensing applications. Furthermore, this work would be exploited to understand MD coupling mechanism and develop MFM for multifunctional devices.

Enhanced magnetic property and magnetodielectric coupling effect in multiferroic Gd2BaCuO5 via Zn2+ doping

The multiferroics with remarkable magnetoelectric (ME) coupling and technological application have drawn significant attention. Here, we report a chemical doping tunable effect on the magnetic, ferroelectric, and dielectric properties in type-II multiferroic Gd2BaCuO5. The magnetic measurement results show that a long-range antiferromagnetic ordering forms at the Néel temperature (TN1) of ∼12.1 K, and a second magnetization anomaly occurs at a lock-in transition temperature (TN2) of ∼6.4 K. Sharp peaks in the pyroelectric and dielectric curves are observed at the magnetic transition temperatures, indicating intrinsic coupling between magnetic and ferroelectric orderings. The doping of Zn2+ results in a gradual enhancement of magnetization due to the increase of uncompensated spins, and large magnetodielectric (MD) coupling parameter up to ∼7.65 % is obtained in Gd2BaCu0.7Zn0.3O5 because of strong spin-phonon coupling. The ferroelectric property is weakened in Zn2+ doped samples, suggesting the critical role of the 4f-3d magnetic interactions in determining the ME coupling effect. Moreover, an effective manipulation of electric field on magnetization is observed in Gd2BaCuO5. This work helps understand the importance of 4f-3d magnetic interactions in inducing ferroelectricity and explore the ME and MD coupling effects with multiple magnetic orderings.

Tunable magnetoelectronic properties in Bi3+ substituted YCrO3

A detailed structural, magnetic as well as dielectric dynamics study is carried out to investigate the influence of Bi3+ on YCrO3. All the samples crystalize in orthorhombic structure with Pnma symmetry and the grains are mostly stretched with Bi. A coexisting tunable fraction of both antiferromagnetic (AFM) and weak ferromagnetic (WFM) phases is acquired by the system down to Low-T. An abnormal negative magnetization in zero field is correlated to the competition among AFM and WFM phases. Maximum magnetization decreases while the coercivity first increases and then decreases with Bi is correlated to the competing effect between the local deformation and Cr–O–Cr exchange interaction. The magnetodielectric coupling with improved permittivity might be associated with the 6s2 lone pair electron of Bi3+. Furthermore, ac-conductivity increases with a decrease in activation energy (0.27–0.11 eV), is explained in the framework of structural model and charge carrier hopping between Cr3+ and Cr4+ ions.

Correction: Room temperature magneto-dielectric coupling in the CaMnO3 modified NBT lead-free ceramics

Correction: Room temperature magneto-dielectric coupling in the CaMnO3 modified NBT lead-free ceramics

Recapitulation of the magnetic and magnetodielectric properties of (1-x)LiNbO3 - (x)La0.9Na0.1MnO3 (x = 0.1, 0.2, 0.3) composites

The present study provides structural, ferroelectric, magnetic, magnetodielectric and the optical properties of the composite (1-x)LiNbO3-(x)La 0.9Na 0.1MnO3 with different values of x (where x = 0.1, 0.2 and 0.3) at room temperature. Ferroelectric phase LiNbO3(LNB) and magnetic phase La 0.9Na 0.1MnO3(LNMO) were synthesized by conventional solid state reaction method. Rietveld X-ray diffraction pattern reveals the structural purity of the synthesized samples. The ferroic and antiferroic nature of the composites were investigated from M-H hysteresis loop, at x = 0.3 shows highest value of saturation magnetization. The reduced ferroelectric nature of the prepared samples was revealed through P-E hysteresis loop measurement with sample x = 0.1 shows highest value of remnant polarization room temperature. Magnetoelectric coupling nature of the composite sample was confirmed through magnetodielectric measurement. Among the studied composites highest value of magnetodielectric percentage (MD%) at 1 kHz is obtained for sample with x = 0.3. Enhanced magnetodielectric coupling coefficient value of 5.5 is achieved for the sample with x = 0.3. Optical properties were examined from UV absorbance analysis technique. On increasing LNMO content, there was a slight decrease in the band gap energy. The enhanced magnetoelectric coupling property of the present synthesized composite paves the way for more room temperature multifunctional materials.

Synthesis, structural, optical, dielectric, magnetic and magneto-dielectric properties of CoFe2O4 and Graphene Quantum Dots (GQDs) decorated CoFe2O4 hybrid nanocomposite

A sol-gel synthesis method was used for the synthesis of pure CoFe2O4 (CFO) as well as Graphene Quantum Dots (GQDs) decorated CoFe2O4 Hybrid Nanocomposite (GCHN). From X-ray diffraction (XRD) data it was analyzed that both these samples have a cubic structure with Fd-3m space group. Using Debye-Scherer's equation, the average sizes were determined to be 24.48 and 13.74 nm, respectively. FTIR spectra revealed details about vibration bands and functional groups present. Raman spectra confirmed existence of GQDs in GCHN with an ID/IG ratio of ∼0.8. The results of Field emission scanning electron microscopy (FESEM) analysis exhibited microstructural morphological details having shapes of grains to be non-uniform in shape. UV–visible data was used to calculate band gap (Eg) energy by using Tauc plot method and found to be 2.52 eV and 2.99 eV respectively for CFO and GCHN. Urbach energy (EU) was found to be 1.03 and 1.19 eV for CFO and GCHN respectively. The dielectric properties of GCHN were analyzed for dependence on frequency and temperature and explained by Maxwell-Wagner-type polarization. The frequency-dependent ac conductivity (σac) followed Jonscher's power law and investigated dynamics of ion hopping. Impedance spectroscopy was used to further evaluate Nyquist plots with respect to temperature as well as magnetic fields to estimate grain and grain boundary contributions. This was further used to evaluate electrical characteristics such as relaxation time (τ). Activation energies (Ea) calculated using relaxation times were found to be 0.48 eV for CFO while 0.22 and 0.92 eV for GCHN respectively. At room temperature, CFO and GCHN exhibited a strong magneto-dielectric coupling (MD) and showed negative magneto-dielectric properties in low-frequency regions. At room temperature (RT), magnetization values of CFO and GCHN displayed were 38.48 and 7.52 emu/g respectively. The lower magnetization value was possibly due to shielding by GQDs in GCHN. These properties enable it to be used as a potential application in microelectronic systems, spintronics, optical and optoelectronic devices, magnetic resonance imaging (MRI) and memory devices.

Spin-phonon coupling driven magnetodielectric effect in low-dimensional complex magnetic BaGdFeO4 system

In this report, we have investigated the detailed magnetodielectric properties associated with spin-phonon coupling in the BaGdFeO4 polycrystalline compound, X-ray diffraction study confirms the orthorhombic crystal structure with a space group of Pnma. The DC magnetization measurements indicate the complex magnetic behavior with multiple magnetic transitions at TN1 = 62 K and TN2 = 31 K. In the field-dependent magnetization study, field-induced metamagnetic transitions and their temperature dependence have been attributed to the competing magnetic interactions of two magnetic sub-lattices with rare-earth (Gd3+) and Fe3+ magnetic spins. Dielectric measurements have revealed the correlation of observed dielectric anomalies with the magnetic transitions. The frequency-independent and magnetic field-dependent dielectric anomalies, along with the corresponding magnetic transitions, thus corroborate the subtle magnetodielectric coupling studied by temperature-dependent magnetodielectric measurements. We discuss possible origins for the magnetodielectric behavior in terms of weak spin-phonon interactions, as confirmed by the temperature-dependent Raman spectra measurements.

Magnetic and dielectric properties of the Co-defective Ca3Co2-xO6 compounds

The Ca3Co2-xO6 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) samples were prepared by reducing the stoichiometric ratio of Co atoms. Their structure, magnetic properties, dielectric and magnetodielectric properties were investigated. XRD results show that the presence of a small number of vacancies does not change the crystalline structure. The positive Curie-Weiss temperature θ and interchain exchange constants J indicate that ferromagnetic interactions are stronger than the antiferromagnetic interactions in Co-defective Ca3Co2-xO6. The Co-vacancies could weaken the Co-Co exchange interactions, it has an obvious dilution effect on the ferromagnetic interactions within the chain. The magnetization steps move to low field accompanying the defects increase. Simultaneously, Co defects could also release part of the magnetic frustration. The competition of the released magnetic frustration and the dilution effect of the vacancies to the ferromagnetic chains and low doping concentration make the Co-defective Ca3Co2-xO6 present similar magnetic property with the parent Ca3Co2O6. At the positions of magnetic phase transition and the critical magnetic field of magnetization steps, clear dielectric anomalies can be detected. This result suggests the strong magnetodielectric coupling effect in Ca3Co2-xO6 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) samples.

Synthesis, dielectric, and magneto – dielectric properties of carbon quantum dots/ZnFe2O4 hybrid nanocomposite

Carbon quantum dots doped ZnFe2O4 Spinel Ferrite, that is, CQD-ZSF hybrid nanocomposite was thrivingly synthesised exploiting sol-gel based synthesis technique. Structural assessment supports Fd-3m space group with cubic spinel structure with mean size of 10.33 nm as obtained from Scherrer formula. Raman spectra confirmed the existence of CQD in ZSF. The samples contained a variety of vibration bands, according to the FT-IR analysis. The dielectric permittivity (ε) and tangent losses (tan δ) was conducted with frequency from 100 Hz to 1 MHz range at different temperatures ranging from 300 to 773 K. It was found that ε as well as tan δ receded monotonously with extending frequency. This information reveals a space or interfacial dipolar relaxation phenomenon. The electrical properties and the ion hopping dynamics were probed with the assistance of an AC-electrical conductivity (σac) analysis. Frequency-dependent σac heeded Jonscher’s law of power. The advent of arcs semicircular by nature in cole-cole plot indicates cloud of electronic process occurring within sample. At 300 K, by applying an external magnetic field varying till 1.5 Tesla magnetic field, the magneto-dielectric effects of the sample were measured by obtaining ε and tan δ versus frequency values displaying negative ML% (magneto-loss) and MD% (magneto-dielectric) coupling of −32.57% and −58.13%, respectively.

Magnetoelectric coupling optimization in lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 and Ni0.5Zn0.5Fe2O4 nanocomposites for magneto-mechano-electric generator

Magneto-mechano-electric (MME) generators efficiently harness ubiquitous stray magnetic fields and convert them into electricity, capturing significant attention for powering innumerable wireless sensors. In this study, lead-free 0-3 particulate magnetoelectric (ME) nano-composite ceramics, specifically x(Ba0.85Ca0.15Zr0.1Ti0.9O3)-(1-x)Ni0.5Zn0.5Fe2O4 [x(BCT-BZT)–(1-x)NZFO], were synthesized using the sol-gel method. Subsequently, a flexible MME generator was designed, incorporating the optimized ME composite. Structural parameter calculations indicated higher tetragonal distortion of 0.4% in 0.4(BCT-BZT)-0.6NZFO, possibly due to uniform particulate distribution. The ME composites displayed uniform dual-phase microstructures, with 0.4(BCT-BZT)-0.6NZFO showing a higher NZFO concentration. The maximum values of the magnetodielectric (MD) and ME coupling coefficients have been determined to be -3.6% and 2.55 mV cm -1 Oe-1, respectively, for an x = 0.4 composite. The MME generator is designed using an optimized 0.4(BCT-BZT)-0.6NZFO ME composite with film thickness of 34 μm. This MME generator harvests a sinusoidal wave with a maximum output peak-to-peak voltage of 4.1 V when exposed to a weak AC magnetic field of 10 Oe at a frequency of 50 Hz. Additionally, the device demonstrates an exceptional optimal DC power density of 3.89 μW cm-3. The lead-free 0-3 particulate ME composite enables effective magnetic energy harnessing. As a result, it holds great promise as an efficient autonomous power supply for various Internet of Things based applications.

Effect of oxygen vacancies and cationic valence state on multiferroicity and magnetodielectric coupling in (1-x)BaTiO3.(x)LaFeO3 solid solution

A solid solution of (1-x)BaTiO3–(x)LaFeO3 (x = 0, 0.007, 0.015, 0.031, 0.062) has been investigated for room temperature multiferroicity and magnetodielectric effect. The incorporation of La and Fe ions in ferroelectric BaTiO3 leads to increased lattice disorder and generation of oxygen vacancies that induces magnetism. A detailed correlated study using XRD, XPS and Raman spectroscopy is being reported. A typical ferromagnetic and ferroelectric nature of each sample are confirmed by M−H and P–E hysteresis loops, respectively at room temperature. Temperature dependent dielectric studies reveal the decrease of transition temperature from 137 0C for undoped to room temperature for increasing substitution. The changes in the dielectric property with applied magnetic field shows the indications of magnetodielectric effect. For x = 0.015, existence of both proper ferroelectric without lossy properties and ferromagnetic properties in a single tetragonal phase makes it a perfect room temperature multiferroic material. For this sample, the magnetodielectric coupling is the strongest with Magnetocapacitance of ∼2.7% and Magneto loss of ∼0.8% at 10 kHz and 1 T. The multiferroicity and the magnetodielectric effect exhibited by this material has been correlated to the structural properties, electric and magnetic properties, changes in valence states, and oxygen vacancy (Ov).

Effect of Al3+ substitution on the magnetodielectric properties of the one-dimensional frustrated Ca3Co2O6

Ca3Co2-xAlxO6 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) were prepared via the conventional sol-gel method. The structure, magnetic, dielectric and magnetodielectric properties were investigated. The Rietveld structural refinement confirms the rhombohedral structure of the samples. The positive Curie-Weiss temperature θ and magnetic coupling exchange constants J indicate the dominant intrachain ferromagnetic interactions in the spin chains. The obvious inhibition effect to equally spaced magnetization steps demonstrates that Al3+ could release the magnetic frustration. With Al3+ substitution, both the magnetization intensity and the critical field of the ferrimagnetism to ferromagnetism transition decrease. The samples present obvious dielectric anomalies around the Curie temperature Tc and the freezing temperature Tf. Meanwhile, the magnetic field dependence of dielectric permittivity decreases suddenly at critical magnetic fields. These results reveal strong magnetodielectric coupling effect in Ca3Co2-xAlxO6. The same sign of Δεr and Δtanδ suggests that the magnetodielectric coupling effect is intrinsic.

Detailed investigation on structural, optical, dielectric and magneto-dielectric properties with enhanced magneto-impedance characteristic of NdFeO3 nanoparticles

NdFeO3 (NFO) was synthesized using sol-gel citrate method and subsequent calcination at 1023 K. Utilizing Rietveld refinement analysis of the XRD pattern, it has been verified that NFO exhibits an orthorhombic crystal structure, with space group Pbnm. NFO grains were seen to be strongly agglomerated in a SEM image, despite their irregular shapes. The analysis of optical properties revealed a transmittance range of ∼20%–∼50% and an optical band gap of 2.15 eV for the NFO material. The dielectric properties of NFO were analyzed with respect to their dependence on frequency and temperature, while the ac electrical conductivity was studied in terms of its frequency variation. The dielectric dispersion behavior of NFO is explained by Maxwell Wagner-type polarization. A negative magneto-dielectric (MD) coupling of −19% and −35% was measured for ε and tanδ at 1 kHz for NFO. Magneto-impedance measurements on NFO showed positive magneto-resistance and both positive and negative magneto-capacitance, suggesting that the grain effect had a substantial role in the material's magnetic properties. These results suggest that NFO is an excellent choice for memory-based electronic devices with an appropriate band gap for optoelectronic applications having a large MD effect.

Photocurable Hybrid Materials with High Magnetodielectric Coupling

Photocurable Hybrid Materials with High Magnetodielectric Coupling

Structure driven magnetic properties and magnetodielectric coupling in a mixed metal oxide NdCr0.5Co0.5O3

Mixed-metal oxides provide a vast playground to enhance and tune their functional properties, as compared to the respective parent oxides. In this context, we report the magnetic, thermal, dielectric, and magnetodielectric properties of NdCr0.5Co0.5O3. Three magnetic transitions, T N1 –antiferromagnetic ordering of Cr3+ cations from paramagnetic state, T N2—spin reorientation of these Cr3+ cations, and T N3—due to Nd ordering induced by the Cr sub-lattice; have been observed due to a reduction in orthorhombic distortion. Modification of magnetic interactions is also noted because of the presence of Co cations in NdCrO3 matrix. The reduction in Nd3+-Cr3+ interactions is further concluded from the Schottky anomaly in the heat capacity, which arises due to Zeeman splitting of the ground state Kramer’s doublet of Nd3+ cations. The presence of significant magnetodielectric coupling (∼4%) below T N2 has been observed. Additionally, double relaxor-like behaviour around 176 and 230 K, with activation energy ∼0.24 and 0.32 eV, is observed due to charge carrier hopping at Cr/Co-site. Our studies indicate that structure-driven modifications of Cr3+-Cr3+ and Nd3+-Cr3+ interactions are responsible for enhanced value of magnetic transitions and magnetodielectric coupling in NdCr0.5Co0.5O3, as compared to its respective parent compounds.

Enhanced magnetic, magnetodielectric, and field-dependent magnetoimpedance correlation in the Bi5Ti3FeO15/Bi2Fe4O9 composites

The physical properties of the Aurivillius Bi5Ti3FeO15 compound are enhanced by adding the magnetic BFO compound. The magnetic, magnetodielectric (MD), and magnetoimpedance (MI) properties of Bi5Ti3FeO15/Bi2Fe4O9 composites are investigated. The samples are prepared by the sol–gel-modified method, and the Rietveld refinement verifies the diphasic nature of the composites. The Raman spectra demonstrate the shifting of the vibrational modes due to adding the BFO phase, which is associated with the BO6 (B = Fe/Ti) octahedral. The maximum shift in Raman modes and bond length of Fe-O is noticed for the x = 0.2 composite. Room temperature magnetization data reveals the highest value of Ms and Mr is found for x = 0.2 composite, which is caused by the interaction among the AFM/FM magnetic ordering. The frequency-dependent MD shows the maximum MD% strength of ∼0.55 % for x = 0.1 and minimum magnetoloss (ML)% of ∼0.08 % for x = 0.3 composites. Field variation of MD data shows ∼30 times enhancement of MD% and ∼7 times reduction of the ML% for x = 0.2 sample as compared to the pure sample. The enhanced MD effect is due to the non-collinear ordering of Fe spins in the BFO sample, which results in the possible inverse Dzyalonskii-Moriya interaction in the composites. Additionally, the Ginzburg-Landau approach confirms that the maximum coupling coefficient γ (6.79 emu−2. g2) is observed for x = 0.4 of the BFO sample. The field-dependent capacitive MI and Cole-Cole plot analysis reveals the capacitive origin behind the MD effect. The non-linear variance of magnetoconductance in the pure sample (x = 0.0) is attributed to the maximum ML%. Hence, the enhanced MD coupling with capacitive MI properties is a great advantage for designing magnetic sensors and storage devices.

Unconventional multiferroicity induced by structural distortion and magnetostriction effect in the layered spin-1/2 ferrimagnet Bi2Cu5B4O14

Complex systems with strongly entangled microscopic degrees of freedom often host a plethora of exotic properties. Herein, we report the unconventional and interesting multiferroic behavior of a layered noncentrosymmetric ferrimagnetic spin-1/2 system, ${\mathrm{Bi}}_{2}{\mathrm{Cu}}_{5}{\mathrm{B}}_{4}{\mathrm{O}}_{14}$. Neutron powder-diffraction study deciphers a robust ferrimagnetic ($\ensuremath{\uparrow}\ensuremath{\downarrow}\ensuremath{\downarrow}\ensuremath{\downarrow}\ensuremath{\downarrow}$) ordering below a temperature ${T}_{C}=25\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, which remains unaltered even under a high magnetic field of $H=10\phantom{\rule{0.16em}{0ex}}\mathrm{T}$. Interestingly, two successive ferroelectric transitions are observed, one of which is triggered by the magnetostriction effect and emerges concomitantly with the ferrimagnetic ordering at ${T}_{C}={T}_{E2}=25\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. This is accompanied by a pronounced dielectric peak and a prominent magnetodielectric coupling at ${T}_{C}$. By contrast, other ferroelectric transition commences in the paramagnetic state at ${T}_{E1}=32\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, which is solely caused by a prominent structural distortion. This strong structural distortion is revealed by the synchrotron x-ray-diffraction study, which is further supported by a concurrent, sharp, anomalous phonon softening observed in the Raman spectra.