Monodomain MgCuZn ferrite with equivalent permeability and permittivity for broad frequency band applications

In order for the miniaturization of a broadband antenna to be achieved, monodomain Mg_0.78Cu_0.2Zn_0.02Fe_1.96O_3.94 ferrites with various microstructures were prepared by conventional solid-state reaction method. The effect of microstructure on the magnetic and dielectric properties was studied. The results displayed that monodomain MgCuZn ferrite is a potential magneto-dielectric material for broad frequency band applications. In addition, grain size and porosity apparently influenced the permeability and permittivity spectra of the monodomain ferrite. Specifically, densely sintered MgCuZn ferrites with an average grain size of 1.41 µm displayed equivalent permeability and permittivity (such as μ' and ε'~13), as along with a low loss factor (such as tan δ_μ<0.02, tan δ_ε<0.005) in a fairly wide frequency range extending from 10 MHz to 100 MHz.     

Two phase Mg0.7Cd0.3Fe2O4–BaTiO3 composite ceramics with excellent magneto-dielectric properties for antennas in GHz band

Two phase-based composites comprising barium titanate (BaTiO₃) and spinel magnesium ferrite (1-x)Mg_0.7Cd_0.3Fe₂O₄ +xBaTiO₃ (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were investigated. The phase structure revealed the coexistence of the perovskite BaTiO₃ and spinel MgFe₂O₄ phases. The microstructural analysis indicated that the average crystallite size initially increased and then decreased, as the increase in x weakened magnetisation, decreased saturation magnetisation (from 47.5 to 35.9 emu/g) and coercivity (150–0 Oe) were obtained, resulting in reduced permeability at low frequency. The permittivity gradually increased owing to tuning by barium titanate, which has strong dielectric properties, promising a relatively large miniaturisation factor. Further, low magnetic loss (tan δ_μ ∼10⁻²) and dielectric loss (tan δ_ε ∼ 10⁻² to 10⁻³) guarantee high quality factor. The low losses and enhanced dielectric properties of the as-synthesised composites could be conducive to improving the behaviour of such magneto-dielectric composite systems in microwave applications.     

Influence of solid loading on densification behavior,micromorphology and dielectric properties of Ba0.67Sr0.33TiO3 ceramics fabricated by a novel DCC-HVCI method

Ba_0.67Sr_0.33TiO₃ (BST) ceramics with highly improved dielectric performance were fabricated by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method. The influence of solid loading on densification behavior, micromorphology, and dielectric performance of the samples was investigated. With the increase of solid loading from 40 to 50 vol%, the maximum densification rate of BST ceramics increased from 0.090 to 0.122 s⁻¹, and the densification temperature decreased from 1424 to 1343 °C, which indicated that high solid loading could promote the densification behavior of samples during sintering. BST ceramics fabricated by the DCC-HVCI method showed uniform grain size and microstructure, which was beneficial for the dielectric properties of BST ceramics. Samples obtained from 45 vol% suspensions possessed the lowest dielectric permittivity (ε_r ≈ 2801), and the dielectric loss (tanδ≈0.0262) was about 1/10 of that of dry-pressed samples (tanδ≈0.301), which could be attributed to the composition homogenization.     

Enhanced magnetodielectric properties of Co2Z ferrite ceramics for ultrahigh frequency applications achieved via Cr3+ ion doping

Phase formation, microstructure, magnetic properties, and dielectric properties of Ba_1.5Sr_1.5Co₂Fe₍₂₃−_x)Cr_xO₄₁ (0.0 ≤ x ≤ 1.0) ceramics, in which Fe³⁺ ions were substituted by Cr³⁺ ions, were systematically investigated. X-ray diffraction results reveal that Z-type hexagonal ferrite was formed by sintering at 1250 °C, and Cr³⁺ ions successfully enter lattice without destroying crystal structure. Analysis of the microstructure reveals that Cr³⁺ ion doping has significant effect on crystal micromorphology. Samples with x = 0.4 have the most homogeneous micromorphology and the highest sintering density of 5.12 g/cm³. In addition, under the influence of external magnetic field, all samples exhibit typical soft magnetic character and hysteresis characteristics, with saturation magnetization up to 63.86 emu/g (x = 0.6). Particularly, compared with undoped sample, Cr-doped samples have outstanding magnetic–dielectric properties. Firstly, with increasing Cr³⁺ amount, real part of the permeability (μ′) reaches the maximum value of 10.70 at x = 0.4, while cutoff frequency exceeds 2 GHz, and Snoek constant reaches ∼19.50 GHz. Furthermore, due to more homogeneous microstructure, samples with x = 0.4 have low magnetic loss and can maintain high quality factor (Q) over a broad frequency range. Moreover, real part of the permittivity (ε′) reaches the maximum value of 16.90 at x = 0.6, and dielectric loss remains lower than 0.013 for frequencies below 0.7 GHz. Consequently, magnetic–dielectric materials prepared in this work are expected to have extensive application prospects for ultrahigh-frequency devices.     

Good thermal stability,giant permittivity,and low dielectric loss for X9R-type (Ag1/4Nb3/4)0.005Ti0.995O2 ceramics

With the intense demand of the developing microelectronics market, the study of giant permittivity dielectric materials is being promoted. However, it is difficult to obtain suitable dielectric materials for such applications, especially due to high dielectric loss at low frequencies. In this work, Ag+Nb codoped TiO₂ ceramics were designed and fabricated in a conventional solid reaction by sintering at 1290-1340°C for 5-10 hours. The issue of how the microstructure and dielectric properties of (Ag_1/4Nb_3/4)_0.005Ti_0.995O₂ ceramics are affected by the sintering conditions was discussed. By optimizing sintering conditions, a dense microstructure, a high dielectric constant (ε_r ≈ 9410), and a low dielectric loss (tanδ ≈ 0.037) at 1 kHz were achieved. Most importantly, the temperature coefficient value of ε_r at different frequencies remained stable between −14.3% and 13.7% within the temperature range from −190 to 200°C, which has potential applications in X9R capacitor.     

Effect of Sn4+–Isovalent doping concentration on giant dielectric properties of SnxTa0.025Ti0.975-xO2 ceramics

The Sn_xTa_0.025Ti_0.975-xO₂ (x%Sn(TTO)) ceramics with x = 2.5–10% were prepared using a standard mixed-oxide method and sintered at 1450 °C for 3 h to achieve a dense microstructure. The effects of the isovalent–Sn⁴⁺ doping concentration on the crystal structure, microstructure, giant dielectric behavior, and electrical properties were systematically investigated. Continuously enlarged lattice parameters and bond lengths with a single rutile–TiO₂ phase were observed as x% increased. The mean grain size was slightly reduced (～17.3–14.6 μm) due to an increased oxygen vacancy and the solute drag effect. The dielectric permittivity (ε′) decreased with increasing x%, whereas the loss tangent (tanδ) was remarkably reduced. The semiconducting grain resistance of the x%Sn(TTO) ceramics remained unchanged owing to the same Ta⁵⁺ donor concentration. The insulating grain boundary (GB) resistance was extremely increased by more than two orders of magnitude when x% increased from 2.5 to 5.0%, leading to the significantly improved giant dielectric properties. The optimized low tanδ～0.02 and high ε′～10⁴ with temperature coefficient less than ±15% in the range of -60–210 °C were reasonably described by the internal barrier layer capacitor model. Improved dielectric properties can be obtained by engineering GB by varying the Sn⁴⁺–isovalent doping concentration. This study provides an important approach for improving the dielectric properties of co–doped TiO₂ without the creation of complex defect clusters inside the grains.     

Low loss and tailored high-frequency performances of BaO-doped NiZnCo magneto-dielectric ferrites

Spinel ferrite ceramics of nominal composition Ni_0.5Zn_0.3Co_0.2Fe₂O₄ (NiZnCo) with various BaO doping were successfully synthesized for applications as novel high-frequency magneto-dielectric materials. The influences of BaO doping on the crystal phase, density, microstructure, and magnetic and dielectric performances in the frequency range of 0.1 to 5 GHz were systematically studied. It is revealed that the doped Ba²⁺ ions aggregate to the grain-boundary regions and lead to the formation of BaFe₂O₄ phase that significantly restrains the growth of NiZnCo ferrite grains. Correspondingly, permeability and permittivity are effectively tailored through the varied grain size and density, which is demonstrated by the magnetic circuit model and the modified effective medium theory proposed herein. As BaO content x = 1.2-1.8 mol%, the NiZnCo ferrites reveal the excellent performance with almost equal values of μ′ and ε′, yielding a characteristic impedance to be nearly identical as that of free space over a wide frequency range of the VHF and UHF bands. Furthermore, the magnetic loss is effectively reduced at high frequencies, where the typical tan δ_μ at 0.5 GHz is decreased to ~0.043 with a reduction of up to 37% and the loss factor (tan δ_μ/μ′) is as low as ~0.006.     

Mechanistic study of the effect of Ca–Sn co-doping on the microwave dielectric properties and magnetic properties of YIG

To investigate the crystal structure, electrical properties, and magnetic properties of Ca–Sn co-doped Y_3-xCa_xFe_5-xSn_xO₁₂ (x = 0.00–0.25 in steps of 0.05), solid-state reaction experiments, first principles calculations, and complex crystal bonding theoretical calculations were performed. The relative permittivity (ε_r) is strongly correlated with the average bond ionicity when Ca²⁺ is added. Furthermore, appropriate Sn⁴⁺ substitution significantly lowers the dielectric loss (tanδ_ε) associated with the lattice energy. The right amount of Ca–Sn co-doping can change the saturation magnetization (4πM_S) and improve the microscopic morphology of YIG, lowering the ferromagnetic resonance linewidth (ΔH) of YIG. The optimized microwave dielectric and magnetic properties are as follows: ε_r = 14.7, tanδ_ε = 4.15 × 10^?4, 4πM_S = 1680 G, and ΔH = 53 Oe for Y_2.8Ca_0.2Fe_4.8Sn_0.2O₁₂ sintered for 6 h at 1425 °C. Based on this material, a simple 3D model of a strip-line circulator with an insertion loss of less than 0.3 dB at each port and isolation greater than 20 dB in the 10–12 GHz range was developed, indicating the potential of the material for microwave high-frequency components such as circulators.     

Effect of Zn and Ti Co-doping on structure and electrical properties of BiFeO3 ceramics

In this paper, the effect of Zn and Ti co-doping on the structure, dielectric, ferroelectric and magnetic properties of BiFeO₃ (BFO) ceramics have been studied. Co-doped BFO ceramics with different doping concentrations are prepared by using the sol-gel method. The structure, morphology and electrical properties of co-doped BFO ceramics are studied by using X-ray diffraction (XRD), scanning electron microscopy, impedance analyzer and ferroelectric test analysis system. Furthermore, the vibrating sample magnetometer (VSM) is used to investigate the magnetic properties. The structural transition from rhombohedral to tetragonal-like phase is observed with a high level of co-doping (x = 2.5%). In addition, higher content of Zn and Ti results in enhanced dielectric constant (ε) and reduced dielectric loss (tanδ). The highest remnant polarization of 0.4 μC/cm² and coercive electric field of 15.5?kV/cm is demonstrated at x = 2.5%. The enhanced dielectric and ferroelectric properties can be attributed to the formation of defect complexes due to the Zn and Ti substitution.     

Novel high dielectric constant and low loss PTFE/CNT composites

Spherical Ca_0.55Nd_0.3TiO₃ ceramic filled polytetrafluoroethylene composites (abbreviated as PTFE/CNT) with different filler volume fractions were prepared. The effects of filler volume fraction on microstructure, dielectric properties and thermal property were studied by scanning electron microscope, vector network analyzer and thermal dilatometer, respectively. The SEM results show that spherical particles are advantageous to reduce the porosity in the interphase which would increase the dielectric loss. Moreover, both the dielectric constant and dielectric loss increased with the increasing volume fraction of CNT microspheres. The high dielectric constant and low dielectric loss composite can be prepared when the ceramic volume fraction is 50?V%: ε_r =?12, tan?δ?=?8.5?×?10^?4 (at 10?GHz). Different models were used to predict the dielectric constant of composite, and the effective medium theory shows the least deviation from the experiment. The experimental coefficient of thermal expansions of composites with different volume fractions were less than theoretical data due to the change from loosely bound polymer chain to tightly bound polymer chain which would restrain the coefficient of thermal expansions of composites.     

Induced slim ferroelectric hysteresis loops and enhanced energy-storage properties of Mn-doped (Pb0·93La0.07)(Zr0·82Ti0.18)O3 anti-ferroelectric thick films by aerosol deposition

In this study, the high ferroelectric hysteresis loss of (Pb_0·93La_0.07)(Zr_0·82Ti_0.18)O₃ (PLZT 7/82/18) antiferroelectric (AFE) ceramics was reduced by employing a combinatorial approach of Mn acceptor doping followed by thick film fabrication via an aerosol deposition (AD) process. The grains of the as-deposited PLZT 7/82/18 AFE AD thick films were grown by thermal annealing at 550 °C to enhance their electrical properties. Investigation of the electrical properties revealed that Mn-doping results in improved dielectric and ferroelectric properties, increased dielectric breakdown strength (DBS), and energy-storage properties. The Mn-doped PLZT AFE AD films possess a frequency-independent high dielectric constant (ε_r ≈ 660) with low dielectric loss (tan δ ≈ 0.0146), making them suitable candidates for storage capacitor applications. The bipolar and unipolar polarization vs. electric field (P-E) hysteresis loops of PLZT 7/82/18 AFE AD thick films were found to be slimmer than those of their bulk form (double hysteresis) with significantly reduced ferroelectric hysteresis loss, which is attributed to the AD-induced mixed grain structure. The Mn-doped PLZT 7/82/18 AFE AD thick films exhibited a low remnant polarization (P_r ≈ 9.22 μC/cm²) at a high applied electric field (~2750 kV/cm). The energy-storage density and energy efficiency of the Mn-doped PLZT AFE AD thick films were calculated from unipolar P-E hysteresis loops and found to be ~38.33 J/cm³ and ~74%, respectively.     

Ferrite ceramic filled poly-dimethylsiloxane composite with enhanced magnetic-dielectric properties as substrate material for flexible electronics

Improving magnetic-dielectric properties of polymer materials, through filler of functional ceramics, provides feasibility to develop high-frequency flexible electronics. Poly-dimethylsiloxane (PDMS), an inert silicone with low elasticity modulus and high transparency, has been considered a promising candidate for flexible electronics. Current PDMS matrix used in high-frequency devices suffers from unsatisfactory properties due to very low dielectric constant. In this study, using ultrasonic stirring and vacuum-pumping process, we prepare a series of xCo₂Z/PDMS (x = 2; 4; 6; 8; 10) composite films, which are consisted of PDMS matrix and different quantity of micro-sized ferrite particles. XRD pattern indicates that the obtained ferrite particles include Co₂Z main phase and BaM second phase. We demonstrate that 4Co₂Z/PDMS film has improved magnetic-dielectric properties at 800 MHz (μ' = 1.49; ε' = 4.54 tanδ_μ = 0.058; tanδ_ε = 0.008). Also, the film has high saturation magnetization (σ_s = 17.51 emu/g). Furthermore, SEM micrographs show that using ultrasonic stirring and fast curing, the micro-sized ferrite particles are well dispersed in PDMS matrix. Our study, which provides a simple method to improve high-frequency magnetic and dielectric properties of PDMS matrix, could pave the way for development of high-frequency flexible electronics.     

High-temperature dielectric and energy storage properties of Bi0.5Na0.5TiO3-based ceramics modified by Sr0.8Na0.4Nb2O6

Sr_0.8Na_0.4Nb₂O₆ with a tungsten bronze structure is introduced into perovskite-structured 0.94(Bi_0.5Na_0.5)TiO₃-0.06BaTiO₃ composition (abbreviated as BNT-BT-xSNN, x = 0-0.04). The temperature stability of dielectric properties and energy storage performance is found to be effectively enhanced by Sr_0.8Na_0.4Nb₂O₆ dopant. When x is 0.03, the temperature ranges covering |ε'-ε'_150°C|/ε'_150°C ≤15% and tanδ ≤ 0.02 are 43°C-404°C and 90°C-422°C, respectively. More importantly, ε′ can be retained as high as 3304 at 150°C. Besides, the variances of energy storage density and its efficiency are 6.4% and 5.3%, respectively, in the temperature range from room temperature (RT) to 180°C. Therefore, this work provides a new method of compositional modification in BNT-based materials to improve their temperature stability of dielectric and energy storage properties.     

Frequency, temperature and In dependent electrical conduction in NiFe2O4 powder

A series of polycrystalline spinel ferrites with the composition NiIn_xFe_2-xO₄ (0 ≤ x ≤ 0.3) were prepared by the solid state reaction to study the effect of In³⁺ ions substitution on their dc electrical resistivity and dielectric properties. The dc resistivity has been investigated as a function of temperature and composition. The indium ion increases the dc resistivity and activation energy of the system. A study of the dielectric properties of these mixed ferrites, as a function of composition, frequency and temperature, has been undertaken. The dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tanδ) all decreases with frequency as well as with the composition. The dielectric constant (ε′) and dielectric loss tangent (tanδ) were increases with increasing temperature. AC conductivity increases with increase in applied frequency. The dielectric behavior of the present samples is attributed to the Maxwell-Wagner type interfacial polarization. The conduction mechanism in these ferrites is due to electron hopping between Fe²⁺ and Fe³⁺ ions on adjacent octahedral sites.     

Effect of the CoFe2O4 initial particle size when sintered by microwave on the microstructural,dielectric, and magnetic properties

The particle size of CoFe₂O₄ powders (average particle size of 350 nm) was reduced to 50 nm by high-energy milling. In this paper, special attention was given for analyzing the densification and grain growth of both particle sizes (350 and 50 nm) subject to ultrafast sintering assays using microwave sintering and their effect on the magnetic and electric properties. The results indicated that the grain growth was 10 times higher for the nanoparticle system, reaching similar sizes of ~1 μm in both cases after sintering. The relative density values were higher (95%) in the nanoparticle system due to the wide distribution of particle sizes generated in the grinding process. Qualitatively inferred microscopy analysis showed high sinterability of fine particles with a narrow distribution of grain size when subjected to ultrafast firing processes. Magnetization measurements at room temperature clearly show the reduction of Hc with increasing grain size. Electric resistivity, dielectric constant (ε′), and dielectric loss tangent (tan δ) were measured as a function of frequency at room temperature. The low values of dielectric constant (ε′) and dielectric loss (tan δ) in the low frequency range, shown for all samples sintered by microwave, prove the excellent uniformity in the microstructure.     

Ultra-stable X9R type CaCu3-xZnxTi4.1O12 ceramics

CaCu_3-xZn_xTi_4.1O₁₂ (x?=?0.00, 0.05 and 0.10) precursor powders were prepared by the polymer pyrolysis (PP) solution method. Ultra-stable X9R type capacitor with very low loss tangent (tanδ) ~0.017 varied within a value of less than 0.05 in a wide temperature range of ?60 to 150?°C and high dielectric constants (ε^′) ~9200 with Δε′ ≤?±?15% in a wide temperature range of ?60 to 210?°C was achieved in CaCu_2.95Zn_0.05Ti_4.1O₁₂ (Zn05-1) ceramic obtained by sintering the precursor powder (x?=?0.05) at 1060?°C for 8?h. A major role for the validity of ε^′ and tanδ in these wider temperature ranges was suggested to originated from the very high grain boundary resistance (R_gb ~413,190?Ω?cm), resulting from the effect of Zn²⁺ doping and TiO₂-rich at grain boundary. With the excellent dielectric properties of (Zn05-1) ceramic, it was suggested to be applied for X8R and X9R capacitors. Interestingly, improvements of nonlinear properties with very high nonlinear coefficient (α ~ 25.94) and breakdown field (E_b~ 3146.25?V.cm^?1) values were achieved in (Zn05-1) ceramic, as well.     

Magnetodielectric response of composites based on a natural garnet and spinel ferrites for sub-GHz wireless applications

A natural garnet with excellent dielectric properties was mixed with different weight percentages of two spinel ferrites, Ni_0.5Zn_0.5Fe₂O₄ (NZO) and LiFe₅O₈ (LFO) to tailor its magnetodilectric properties. 3 wt% B₂O₃ was added to enhance the density of the composites. X-ray diffraction study revealed the decomposition of the mineral into hematite and cordierite and vibrational spectroscopic analysis confirmed the non-reactivity of decomposed mineral with spinel ferrites. Microstructural analysis shows well densified and almost tightly packed grains for garnet-Ni_0.5Zn_0.5Fe₂O₄ (G-N) and garnet-LiFe₅O₈ (G-L) composites. The optimised dielectric and magnetic properties of 0.5 G-0.5 NZO are ε_r = 4.1, μ_r = 1.8, tan δ_ε = 0.02, tan δ_μ = 0.49, whereas that of 0.5 G–0.5 LFO are ε_r = 4.4, μ_r = 1.4, tan δ_ε = 0.001, tan δ_μ = 0.05 at 1 GHz. Due to the moderate permittivity of garnet, a better impedance matching compared to magnetodielectric composites based on high-permittivity dielectric counterparts is observed. Hence, the present study indicates that G-N and G-L composites are potential candidates for sub-gigahertz wireless applications.     

Effective dielectric loss (tan δ) reduction of CaCu3Ti4O12 (CCTO) via various addition of glasses

Addition of various glasses has successfully reduced tan δ of CCTO-based ceramics. Less amounts (0-1.0 wt%) of glasses (BaO-SrO-Nb₂O₅-B₂O₃-SiO₂ [BSNBS] and SrO-B₂O₃-SiO₂ [SBS], respectively) were added into pure CCTO and sintered at 1040°C for 10 hours. The phase formation and microstructure of each sample were characterized using X-ray diffraction and scanning electron microscopy, respectively. The dielectric behavior of the samples was measured at 1 MHz. The addition of BSNBS and SBS glasses (≤0.5 wt%) successfully reduced tan δ of CCTO from 0.5 until 0.4 and 0.39, respectively, and simultaneously increased ε_r. Smaller tan δ and ɛ_r were further obtained when the added glasses were more than 0.5 wt%. These behaviors were due to segregation of glasses together with precipitation of CuO which decreased the grain size, and caused the presence of pores at grain boundaries. Therefore, small amount of various additions of glasses could modify the CCTO dielectric properties.     

Thermal stability improvement of dielectric properties and non-ohmic characteristic of CaCu3+xTi4O12 ceramics via a Cu-nonstoichiometric approach

In this work, the effects of Cu composition on the thermal stability of the dielectric and nonlinear properties of CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.2) ceramics obtained via a polymer-pyrolysis chemical process were studied. The mean grain sizes of Cu-stoichiometric (x = 0), Cu-deficient (x < 0) and Cu-excess (x > 0) CaCu_3+xTi₄O₁₂ ceramics were found to be ~3.2, ~3.4 and ~3.7 μm, respectively. Interestingly, very good dielectric properties (0.020 ≤ tanδ ≤ 0.038 and 4000 ≤ ε′ ≤ 7065) were attained in CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.1, excluding x = 0.2) ceramics. Moreover, the variation of dielectric constant (ε′) within a limit of ±15% (Δε′_{± 15%}) over a wide temperature range (T_R) of ?70 – 220 °C with low tanδ < 0.05 (tanδ_<0.05) over a T_R of ?70 to 80 °C were achieved in a CaCu_2.8Ti₄O₁₂ ceramic. These results suggest that this ceramic could be applicable for X9R capacitors and energy storage devices that require high thermal stability. Additionally, the nonlinear properties of Cu-nonstoichiometric ceramics could be improved when compared with those of the Cu-stoichiometric material. The incremental changes of dielectric and nonlinear properties of CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.2) ceramics revealed the significant role of Cu composition on grain boundary resistance (R_gb), which was confirmed by impedance spectroscopy analysis. In addition, XANES results revealed the proper ratios of Cu⁺:Cu²⁺ and Ti³⁺:Ti⁴⁺ found in these ceramics, indicating the semiconducting behavior of these grains.     

Influence of cobalt and sintering temperature on structure and electrical properties of BaZr0.05Ti0.95O3 ceramics

Pure and Co-modified BaZr_0.05Ti_0.95O₃ ceramics were fabricated by the traditional solid state reaction technique. The influence of cobalt and sintering temperature on structure, dielectric, ferroelectric properties and diffuse phase transition of BZT ceramics were investigated systematically. 1300 °C was the optimal sintering temperature for BZT ceramics. The solid solubility limit of Co ions in BZT matrix was determined to be 0.4 mol%. The introduction of a moderate amount of Co ions was believed to benefit the microstructure development and make the grain size more uniform. Compared with undoped counterparts, 0.4 mol% Co-modified ceramics showed equivalent ferroelectric properties with a high remnant polarization (P_r=9.6 μC/cm²) and a low coercive field (E_c=0.21 kV/mm). Besides these, a relative high dielectric coefficient (ε_r=2030) and a low dielectric loss (tan δ=1.85%) were also obtained on this composition. The degree of diffuse phase transition was enhanced by the addition of Co ions. The related mechanism of the diffused phase transition behavior was discussed.