Effect of Ca substitution by Fe on the thermoelectric properties of Ca<Subscript>3</Subscript>Co<Subscript>4</Subscript>O<Subscript>9</Subscript> ceramics

(Ca_1-xFe_x)₃Co₄O₉ polycrystalline samples (x?=?0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1 and 0.2) have been prepared by solid state reaction and sintered by spark plasma sintering. Their thermoelectric properties have been studied between 323 and 1000 K. The substitution limit is low (< 3%). For higher iron contents, formation of Co₃O₄, Ca₂FeCoO₅ and a calcium ferrite compound occurs. Concerning electrical conductivity and power factor, an optimum value exists for x?=?0.03 substitution. This optimum power factor is circa 10% higher than the one of the unsubstituted sample. The optimum thermal diffusivity is measured for the sample with x?=?0.02 and is circa 9% lower than the one of the unsubstituted sample. Therefore, the dimensionless figure of merit ZT is finally increased by 14% for the (Ca_0.98Fe_0.02)₃Co₄O₉ and (Ca_0.97Fe_0.03)₃Co₄O₉ compositions.     

Improvement in microwave dielectric properties of Sr<Subscript>2</Subscript>TiO<Subscript>4</Subscript> ceramics through post-annealing treatment

Sr₂TiO₄ ceramics were synthesized via the conventional solid-state reaction process, and the effects of post-annealing treatment in air on the microwave dielectric properties and defect behavior of title compound were investigated systematically. The Q?×?f values could be effectively improved from 107,000 GHz to 120,300 GHz for the specimens treated at 1450 °C for 16 h. The thermally stimulated depolarization currents (TSDC) revealed two kinds of defect dipoles [\( \left({\mathrm{Ti}}_{\mathrm{Ti}}^{\hbox{'}}-{V}_{\mathrm{O}}^{\bullet \bullet}\right) \) and \( \left({V}_{\mathrm{Sr}}^{"}-{V}_{\mathrm{O}}^{\bullet \bullet}\right) \)] and oxygen vacancies \( \left({V}_{\mathrm{O}}^{\bullet \bullet}\right) \) were considered the main defects in Sr₂TiO₄. Under a post-annealing treatment in air, the concentrations of such defects in the ceramics decreased. Meanwhile, the impedance spectrum revealed the activation energy of the grain boundaries increased. These evidences could account for the improvement of Q?×?f values. Accompanied with a high ε_r of 40.4 and a large τ_f of 126 ppm/°C, the enhanced high-Q Sr₂TiO₄ ceramics can be good candidates for applications in wireless passive temperature sensing.     

Effect of transition metal substitution on elastoplastic properties of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> spinel

LiMn₂O₄ (LMO) derivatives partially substituted with transition metals (e.g., Ni) have received attention for their higher energy density achieved at higher charge voltage than pure LMO, and may be attractive cathode candidates for emerging all solid state batteries. Accurate mechanical properties of these high voltage spinels are required for prediction of electrode and electrolyte fracture that may compromise battery lifetime and performance. Here, we quantified the Young’s elastic modulus E and hardness H for LMO, LiMn_1.5Ni_0.5O₄ (LMNO), and LiMn_1.5Ni_0.42Fe_0.08O₄ (LMNFO) spinel microparticles via instrumented grid nanoindentation. Elastic modulus E and hardness H increased by more than 40% (up to 145 and 11 GPa, respectively) as a result of Ni or Ni/Fe substitution; such substitution also reduces the lattice parameter and increases the oxidization state of Mn. These results demonstrate how changes in transition metal occupancy can significantly affect the mechanical properties of LMO spinel, and provide critical parameters for designing against fracture in all solid state batteries.     

Effect of Ca substitution on structure and dielectric properties of bismuth-based microwave ceramics

The effect of the chemical substitution of Ca cation on the microstructure and microwave dielectric properties of bismuth-based pyrochlores has been investigated. Broad ranges of solid solutions based on (Bi_3x Zn_2?3x )(Zn _x Nb_2?x )O₇ (x?=?0.56–0.64) were obtained with Ca cation substitution of Zn at A site. The XRD patterns revealed that the substitution of Ca for Zn led to the α–β pyrochlore phase transformation and pure β pyrochlore structure were obtained. The dielectric constants (? _r ) varied slightly with x increasing. The quality factor Q was significantly improved by Ca substitution. The temperature coefficient of resonant frequency (τ _f ) was negative and increased with x increasing. (Bi_3x Ca_2?3x )(Zn _x Nb_2?x )O₇(x?=?0.58) ceramic, sintered at 960 °C, exhibits the optimal microwave dielectric properties of ? _r ?～?74, Qf value ～6,457 (at 4.8 GHz), and τ _f ?～??143 ppm/°C.     

Influence of substitution on dielectric diffuseness in Ba<Subscript>(1-x)</Subscript>Bi<Subscript>(2+2x/3)</Subscript>Nb<Subscript>2</Subscript>O<Subscript>9</Subscript> ceramics prepared by chemical precursor decomposition method

Barium bismuth niobate, Ba_(1-x)Bi_(2+2x/3)Nb₂O₉ (BBN with x = 0.0, 0.1, 0.2, 0.3, 0.4) ceramic powders in the nanometer range were prepared by chemical precursor decomposition method (CPD). The single phase layered perovskite was prepared throughout the composition range studied. No intermediate phase was found during heat treatment at and above 600°C. The crystallite size and the particle size, obtained from XRD and TEM respectively, were in the range of 15–30 nm. The addition of Bi₂O₃ substantially improved the sinterability associated with high density (96%) which was otherwise difficult in the case of pure BaBi₂Nb₂O₉ (BBN x = 0.0). The sintering was done at 900°C for 4 h. The relative permittivity of BBN ceramics at both room temperature and in the vicinity of the temperature of maximum permittivity (T_m) has increased significantly with increase in bismuth content and loss is also decreased to a certain level of bismuth doping. T_m increased with increase in Bi₂O₃. The diffuseness (γ) in the phase transition was found to increase from 1.54 to 1.98 with the increase in Ba²⁺ substitution level from x = 0.0 to x = 0.3.     

Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu<Subscript>3</Subscript>Ti<Subscript>4</Subscript>O<Subscript>12</Subscript> ceramics

The stoichiometric CaCu₃Ti₄O₁₂ pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu₂O secondary phases on the unpolished CaCu₃Ti₄O₁₂ samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu₃Ti₄O₁₂ sample sintered at the lowest heating rate (1°C/min), which was explained by the increased grain conductivity due to the cation reactions. On the other hand, Cu₂O phase was found only on the unpolished CaCu₃Ti₄O₁₂ sample sintered over 1100°C and those are considered as the remains reduced from the CuO phase. The higher sintering temperature showed the increased dielectric constant and the loss tangent of the CaCu₃Ti₄O₁₂ samples, and this result could be interpreted by the impedance measurement data. The relationship between the processing condition and the dielectric properties was discussed in terms of the cation non-stoichiometry and the defect chemistry in CaCu₃Ti₄O₁₂.     

Studies of structural,dielectric and impedance properties of Bi<Subscript>9</Subscript>Fe<Subscript>5</Subscript>Ti<Subscript>3</Subscript>O<Subscript>27</Subscript> ceramics

Bi₉Fe₅Ti₃O₂₇ is an eight-layered material belonging to the family of bismuth layered structured ferroelectromagnets. The polycrystalline sample of this compound was prepared by a standard solid-state reaction technique. The formation of the compound in an orthorhombic crystal structure was confirmed by an X-ray diffraction (XRD) technique (lattice parameters: a?=?5.5045[27] Å, b?=?5.6104[27] Å, c?=?76.3727[27] Å). Detailed studies of surface morphology of the compound using scanning electron microscopy (SEM) exhibit that the compound has domains of plate shaped grains. Studies of dielectric and electric properties in a wide temperature range (30–500 °C) at different frequencies (100 Hz–1 MHz) exhibit an anomaly at 291?±?2 °C, which is related to ferroelectric to paraelectric phase transition as suggested by hysteresis loop at room temperature. The values and nature of temperature variation of dc conductivity exhibit the NTCR behavior of the compound.     

Microwave Dielectric Properties of CuO-V<Subscript>2</Subscript>O<Subscript>5</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-Doped ZnNb<Subscript>2</Subscript>O<Subscript>6</Subscript> Ceramics with Low Sintering Temperature

Microwave dielectric properties of low temperature sintering ZnNb₂O₆ ceramics doped with CuO-V₂O₅-Bi₂O₃ additions were investigated systematically. The co-doping of CuO, V₂O₅ and Bi₂O₃ can significantly lower the sintering temperature of ZnNb₂O₆ ceramics from 1150 to 870C. The secondary phase containing Cu, V, Bi and Zn was observed at grain boundary junctions, and the amount of secondary phase increased with increasing CuO-V₂O₅-Bi₂O₃ content. The dielectric properties at microwave frequencies (7–9 GHz) in this system exhibited a significant dependence on the relative density, content of additives and microstructure of the ceramics. The dielectric constant ( _r) of ZnNb₂O₆ ceramics increased from 21.95 to 24.18 with increasing CuO-V₂O₅-Bi₂O₃ additions from 1.5 to 4.0 wt%. The quality factors (Q× f) of this system decreased with increasing CuO-V₂O₅-Bi₂O₃ content and ranged from 36118 to 67100 GHz for sintered ceramics, furthermore, all Q× f values of samples with CuO-V₂O₅-Bi₂O₃ additions are lower than that of un-doped ZnNb₂O₆ ceramics sintered at 1150C for 2 h. The temperature coefficient of resonant frequency ( _f) changed from –33.16 to –25.96 ppm/C with increasing CuO-V₂O₅-Bi₂O₃ from 1.5 to 4.0 wt%     

Structure and properties of Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> doped Bi(Mg<Subscript>1/2</Subscript>Ti<Subscript>1/2</Subscript>)O<Subscript>3</Subscript>-0.38PbTiO<Subscript>3</Subscript> ceramics with MPB composition

0.62Bi(Mg_1/2Ti_1/2)O₃-0.38PbTiO₃-xwt%Bi₂O₃ (BMT-0.38PT-xBi₂O₃) ceramics were prepared by conventional powder-processing method. It indicated that the morphotropic phase boundary (MPB) region located in 0.0?≤?x?≤?0.3. For x?=?0.3, it exhibited good piezoelectric properties, d₃₃ ~245pC/N and k_p ~40 %. With the increase of Bi₂O₃ content, the Curie temperature (T_c) was found to increase, and the dielectric loss was found to decrease above 200 °C compared with BMT-0.38PT sample. Finally, it can be found that depolarization temperature was around 350 °C by thermal depoling method.     

Phase compositions and microwave dielectric properties of MgTiO<Subscript>3</Subscript>-based ceramics obtained by reaction-sintering method

MgTiO₃-based microwave dielectric ceramics were prepared successfully by reaction sintering method. The X-ray diffraction patterns of the sintered samples revealed a major phase of MgTiO₃-based and CaTiO₃ phases, accompanied with Mg₂TiO₄ or MgTi₂O₅ determined by the sintering temperature and time. The microwave dielectric properties had a strong dependence of sintering condition due to the different phase compositions and the microstructure characteristics. The ceramics sintered at 1360 °C for 4 h exhibited good microwave dielectric properties: a dielectric constant of 20.3, a high quality factor of 48,723 GHz (at 9GHz), and a temperature coefficient of resonant frequency of ?1.8 ppm/^oC. The obtained results demonstrated that the reaction-sintering process is a simple and effective method to prepare the MgTiO₃-based ceramics for microwave applications.     

Influence of fillers on the re-crystallization and dielectric properties of 60ZnO-30B<Subscript>2</Subscript>O<Subscript>3</Subscript>-10SiO<Subscript>2</Subscript> glass

This paper reports re-crystallization behaviour of 60ZnO-30B₂O₃-10SiO₂ pure glass. Influence of different fillers on the re-crystallization is also highlighted. Irrespective of the nature of the filler, glass transition temperature (T_g) remains the same as that of the pure glass at 570 °C. The onset crystallization temperature is enhanced by 15 to 25 °C owing to filler addition. The peak crystallization temperature corresponding to Zn₃B₂O₆, ZnB₂O₄ and willemite occurs at 735, 810 and 851 °C for the pure glass. In the presence of alumina, gahnite emerges first at 700 °C followed by ZnB₂O₄ phase. With mullite as filler, initially ZnB₂O₄ and willemite formed at 700 °C and gahnite phase emerged only at 750 °C and peaks at 787 °C. In the presence of fused silica only ZnB₂O₄ and willemite phases were observed. The dielectric properties of the pure glass and that of the glass + fillers are also reported. Re-crystallization of various low K phases ensures good dielectric porpertis with reduced glass content after sintenring.     

Synthesis of (Ba<Subscript>1−x</Subscript>Sr<Subscript>x</Subscript>)(Ti<Subscript>0.5</Subscript>Zr<Subscript>0.5</Subscript>)O<Subscript>3</Subscript> ceramics and effect of Sr content on room temperature dielectric properties

The compositions in the system (Ba_1−x Sr _x )(Ti_0.5Zr_0.5)O₃ with different Sr (x) content, were synthesized through solid oxide reaction route. The phase formation behaviors in the system were investigated by XRD. The room temperature dielectric properties of the compositions were investigated in the frequency range 10 Hz to 13 MHz. The solid solution system Ba_1−x Sr _x Ti_0.5Zr_0.5O₃ remains as cubic perovskite up to x < 0.6 and transforms into the tetragonal structure above x > 0.6. Composition with x = 0.6 contains a mixture of cubic and tetragonal phases with broadened diffraction pattern. It is observed that the increasing of Sr substitution results in the decreasing of bulk density, average grain size and dielectric constants etc. in the composition system. The AC dielectric conductivity of the ceramics also decreases with the increase in Sr-substitution due to decrease in loss as well as grain size with that substitution.     

Optimization of the thermoelectric properties of Bi<Subscript>2</Subscript>O<Subscript>2</Subscript>Se ceramics by altering the temperature of spark plasma sintering

The n-type polycrystalline Bi₂O₂Se ceramics were fabricated by solid state reaction and SPSed at different temperatures (873–973 K). The grains of the sample grow up gradually and the grain size enlarges from about 200 nm to micrometer level with the increase of sintering temperature. The highest electrical conductivity of 6.23 S/cm is obtained for the sample sintered at 898 K which benefits from grain orientation along (00l) plane and the highest measured density. The electrical transport properties tend to decline with further increase of the sintering temperature due to the decrease of density and the orientation degree. The maximum power factor of 78.39 μWK^?2m^?1 is obtained at 773 K. The thermal conductivity is intrinsically suppressed owing to the layered crystal structure of Bi₂O₂Se and fine grains within the nanometer size. The ZT value reaches 0.09 at 773 K for the sample SPSed at 898 K and the optimal temperature during the SPS process has been determined.     

The Similar Defect Chemistry of Highly-Doped SrBi<Subscript>2</Subscript>Ta<Subscript>2</Subscript>O<Subscript>9</Subscript> and SrBi<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>9</Subscript>

The equilibrium electrical conductivities of undoped SrBi₂Ta₂O₉ (SBT) and SrBi₂Nb₂O₉ (SBN) have been shown to behave quite differently. SBT has the behavior expected for a 1% acceptor-doped oxide, while SBN behaves like a 1% donor-doped oxide. This difference has been related to the substantial cation place exchange that occurs between the Bi^{+ 3} and Sr^{+ 2} ions in the alternating layers of the structure. It was proposed that this place exchange is not entirely self-compensating, as would be expected for a simple, isotropic oxide, but that there is some local compensation within each layer by lattice and/or electronic defects. It is now shown that the equilibrium conductivity of 3% donor-doped SBT is similar to that of undoped SBN, while the equilibrium conductivity of 3% acceptor-doped SBN resembles that of undoped SBT. Thus the defect chemistrys of the two compounds are quite similar, but the equilibrium conductivities are displaced along a doping axis.     

Microwave dielectric properties of Na<Superscript>+</Superscript> and M<Superscript>3+</Superscript>-doped Ba(Mg<Subscript>0.5</Subscript>W<Subscript>0.5</Subscript>)O<Subscript>3</Subscript> ceramics

In this study, phase evolution, microstructure, and microwave dielectric properties of (Ba_0.98Na_0.02)(Mg_0.48M³⁺_0.02W_0.5)O₃ (M³⁺?=?Al, Ga, Sc, In, Yb, Y, Dy, Gd, and Sm) ceramics sintered at 1700 °C for 1 h were investigated. All the compounds exhibited an ordered cubic perovskite structure. Regardless of the ionic radius of the doped M³⁺ ions, BaWO₄ was detected as the secondary phase in all the compounds. The field emission scanning electron microscopy (FE-SEM) images revealed a dense microstructure in all the compounds, except in the Al-doped compound, which exhibited an insufficient grain growth. The large and irregularly shaped grains indicated that the liquid phase sintering occurred. Splitting of the A_1g(O) mode was observed in the Raman spectra of large M³⁺ ion-doped compounds. Splitting of the F_2g modes did not occur and the bands were sharp, indicating that the cubic symmetry was retained. As the ionic radius of the doped M³⁺ ions increased, the dielectric constant (ε_r) increased slightly. The compounds doped with M³⁺?=?Sc, In, Yb, and Y exhibited a very high quality factor (Q?×?f₀) in the range of 250,000 ~ 280,000 GHz. In the case of the compounds doped with M³⁺?=?Al, Ga, Sc, In, Yb, Y, and Dy, the value of the temperature coefficient of resonant frequency (τ_f) was in the range of ?24 ~ ?19 ppm/°C, while the Gd and Sm-doped compounds exhibited positive values of 2.8 and 31.2 ppm/°C, respectively. The dielectric constant, quality factor, and temperature coefficient of resonant frequency of the In-doped compound, i.e., (Ba_0.98Na_0.02)(Mg_0.48In_0.02W_0.5)O₃, were 18.7, 286,557 GHz, and???24.4 ppm/°C, respectively.     

Excellent dielectric constants observed in heterogeneous conduction Ba(Zr<Subscript>0.25</Subscript>Ti<Subscript>0.75</Subscript>)O<Subscript>3</Subscript> ceramics doped with Sr(Fe<Subscript>0.5</Subscript>Nb<Subscript>0.5</Subscript>)O<Subscript>3</Subscript>

The (1-x)Ba(Zr_0.25Ti_0.75)O₃-xSr(Fe_0.5Nb_0.5)O₃ or (1-x)BZT-xSFN ceramics have been fabricated via a solid-state reaction technique. All ceramics exhibit a pure phase perovskite with cubic symmetry. The addition of a small amount of SFN (x?=?0.1) produces an obvious change in dielectric behavior. Very high dielectric constants (ε_r?>?164,000 at 1 kHz and temperature?>?150°C) are observed and the value is obviously higher than dielectric constants for Ba(Zr_0.25Ti_0.75)O₃ and Sr(Fe_0.5Nb_0.5)O₃ ceramics. The ferroelectric measurement data suggests that the unmodified sample exhibited a ferroelectric behavior. However, a transformation from a ferroelectric to a relaxor-like behavior is noted with increasing x concentration. Impedance Spectroscopy (IS) analysis indicates that the presence of excellent dielectric constants is due to the heterogeneous conduction in the ceramics after adding SFN, which can be explained in terms of the Maxwell-Wagner polarization mechanism.     

Structural,dielectric and magnetic properties of particulate composites of relaxor (BaTi<Subscript>0.85</Subscript>Sn<Subscript>0.15</Subscript>O<Subscript>3</Subscript>) and ferrite (NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript>) synthesized by gel-combustion method

Particulate composites of (1-x) BaTi_0.85Sn_0.15O₃ – x NiFe₂O₄ (with x?=?5, 10,15 and 20 wt%) were synthesized using the solid-state reaction method by sintering at 1350 °C for 4 h. Formation of the diphase composites was confirmed by X-ray diffraction (XRD) and Fourier Transform Infra-red (FTIR) techniques. Temperature (RT-200 °C) and frequency (20 Hz- 1 MHz) dependent of AC conductivity, dielectric constant and dissipation have been studied. The dielectric constant exhibits strong frequency dispersion in the range 20 Hz-1 kHz which is attributed to Maxwell-Wagner interfacial polarization occurring at grain-grain-boundaries interface/interface of grains of BTS-NF. The M-H curve of all the composites exhibited a hysteresis loops typical charcateistic of a ferromagnetic material. The ferromagnetic ordering in the composites on account of NiFe₂O₄ as a constituent is explained using bound magnetic polarons (BMPs) model. The experimental magnetic data have been fitted to BMP model. Value of M_s is smaller, whereas of H_c and M_r are higher of the composites compared to value for NiFe₂O₄. The temperature at which divergence in the M vs. T plot in ZFC and FC starts is higher for the composites than for NiFe₂O₄.     

Dielectric properties of pure and Mn-doped CaCu<Subscript>3</Subscript>Ti<Subscript>4</Subscript>O<Subscript>12</Subscript> ceramics over a wide temperature range

The effect of manganese doping on the dielectric properties of CaCu₃Ti_4-xMn_xO₁₂ (x?=?0, 0.02, 0.04) were investigated over a broad temperature range (93–723 K) in the frequency range from 100 Hz to 10 MHz. Two dielectric relaxations and two dielectric anomalies were observed. The low-temperature relaxation appearing in the temperature range below 200 K is the characteristic relaxation for CaCu₃Ti₄O₁₂. This relaxation was attributed to the polaron relaxation due to electron hopping between Ti³⁺ and Ti⁴⁺ states. Due to the negative factors of notable decreases in the Ti³⁺/Ti⁴⁺ and Cu³⁺/Cu²⁺ ratios and the concentration of oxygen vacancies as revealed by X-ray photoemission spectroscopy, Mn-doping was found to gradually destroy rather than move this relaxation to a higher temperature. The high-temperature relaxation occurring around room temperature was found to be a Maxwell-Wagner relaxation caused by grain boundaries. Our results confirm that the colossal dielectric behavior in the tested samples results from both polaron and Maxwell-Wagner relaxations, but is predominated by the latter relaxation. The low-temperature anomaly behaves as a phase-transition-like behavior. It was argued to be created by oxygen vacancies transition from static disorder to dynamic disorder. The high-temperature anomaly is an artificial effect caused by negative capacitance.     

Crystallization,microstructures and properties of low temperature co-fired CaO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript> glass-ceramic

CaO-Al₂O₃-SiO₂ glass-ceramic were prepared by melt quenching technique. The crystallization behavior and properties were studied by means of a non-isothermal, thermal analysis technique, X-ray diffraction and scanning electron microscopy. The influence of sintering temperature on phase formation, microstructure, bending strength, dielectric and thermal properties were determined. The activation energy of crystallization and the Avrami parameter were also discussed. The X-ray diffraction results show that SiO₂ phase could be found in all samples and CaSiO₃ and anorthite phases could only be observed in the samples sintered at above 875°C. The densification of glass-ceramic starts at 730°C after the liquid glass is formed and stops at 803°C. Complete densification was achieved at 875°C and the highest mechanical strength was obtained at 850°C, but density significantly decreased at higher temperatures. The coefficient of thermal expansion and the dielectric constant increase with the increasing sintering temperature. The value of the Avrami parameter (n) is ~1.6 and the apparent activation energy (E) is 298 kJ/mol.     

Mechanical and electrical properties of Bi<Subscript>1.5-x</Subscript>La<Subscript>x</Subscript>Zn<Subscript>0.92</Subscript>Nb<Subscript>1.5</Subscript>O<Subscript>6.92</Subscript> pyrochlore ceramics

BiFeO₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (BF-PMN-PT) ternary ceramics with pure perovskite phase were prepared through a two-step solid reaction method. Based on structural analysis, the ternary phase diagram of BF-PMN-PT solid solution at room temperature has been established. The Curie temperature T_C, remnant polarization P_r and piezoelectric constant d₃₃ vary in the range of 138 to 225 °C, 15.12 to 23.65 μC/cm² and 129 to 276 pC/N, respectively. The coercive field Ec increases gradually from 5.77 to 29.56 kV/cm upon PT content increasing. The magnetic study suggests that the magnetism turns from diamagnetism for PMN-PT to paramagnetism for BF-PMN-PT by adding BiFeO₃ into PMN-PT and adding more content of BF does not change the paramagnetism further.