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This investigation involves the synthesis and study of dielectric, structural and impedance properties of polycrystalline Bi(Ni 2/5 Ti 2/5 Fe 1/5)O 3 (symbolized as BNTF) nano-ceramic. The BNTF polycrystalline sample was fabricated through the use of a conventional solid-state reaction route. X-ray structural examination reveals that the parent compound (i.e., BiFeO 3) crystallizes in the rhombohedral structure (space group-R3c) while that the BNTF compound crystallizes in orthorhombic symmetry. The substitution of NiTiO 3 into BiFeO 3 enhances various properties and reduces electrical leakage current. The average crystallite size is calculated to be 29 nm. The room temperature textures and surface morphologies of the specimen were verified by field-emission scanning electron microscope, and show uniform grains distribution on sample surfaces. Dielectric parameters (constant and tangent-loss) and impedance spectroscopy parameters of NiTiO 3 modified BiFeO 3 compound were investigated over a wide temperature range (25–500 °C) at different frequency (25 kHz-500 kHz), which offers several interesting features of BNTF material suitable for further device applications. [ABSTRACT FROM AUTHOR]

A lead free multiferroic material, Bi(Co 0.45 Ti 0.45 Fe 0.10 )O 3 (BCTF45/10) was synthesized by a solid-state reaction route at high temperatures. BCTF45/10 powder was prepared using appropriate raw maretials in oxide powders with methanol medium. As-prepared circular shaped pellets were sintered at 1053 K for 6 h to produce a compact form. Preliminary structural properties and elemental analysis were determined using X-ray diffraction and energy-dispersive X-ray spectroscopy techniques respectively at room temperature. The microstructure or surface morphology of the sintered sample was carried out by using field emission scanning electron microscope (FE-SEM). The XRD analysis shows that the compound exhibits the single-phase of orthorhombic symmetry. The average crystallite size estimated using the Scherrer's technique was found to be 30 nm. The influence of Co and Ti substitution (at Bi and Ti sites of BiFeO 3 ) on some physical and electrical properties of BiFeO 3 was examined by using phase sensitive multimeter in a wide frequency and temperature ranges. The magnetic nature of the sample was studied using vibrating sample magnetometer. Study of room temperature magnetic hysteresis loop exhibits the enhanced ferromagnetic characteristic with saturation magnetization of 5.091 emu/g and coercive field of 0.213 kOe respectively. The enhanced magnetic properties highlight various potential applications of Co/Ti doped BCTF45/10 materials. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO 3 ), one of the most prominent members of multiferroics, has multiple promising characteristics useful for multifunctional applications. Multi-doped (Cd, Ti) complex bismuth ferrite [i.e., Bi(Cd 1/4 Ti 1/4 Fe 1/2 )O 3 ] ceramic was synthesized through a mixed-oxide route. X-ray structural analysis of the prepared material provides its basic crystal data of a single-phase orthorhombic system. The scattered crystallite size and lattice strain of the material were estimated using Scherrer and Williamson–Hall approaches respectively using X-ray diffraction peaks. Analysis of the micrograph of field emission scanning electron microscope shows uniform and densely packed grains on the surfaces of the pellet sample suggesting the formation of good quality and high-density sample. A significant effect of substitution of multiple elements at the Fe-site on dielectric constant and tangent loss of BiFeO 3 has been observed. Detailed studies of temperature (25–500 °C) and frequency (1–1000 kHz) dependence of impedance and ac-conductivity have provided the effect of grains and grain boundaries on the conduction mechanism and dielectric relaxation of the material. Based on the magnetic measurements, it is concluded that (Cd, Ti) modified bismuth ferrite has provided saturation magnetisation (M s ) and coercivity (H c ) of 2.66 emu g −1 and 653.75 Oe respectively which are consistent with those of many compounds of similar type. [ABSTRACT FROM AUTHOR]

Structural and electrical properties of Bi(Fe0.85Gd0.15)O3 ceramics, synthesized via standard solid state reaction technique is reported in this communication. Powder X-ray diffraction analysis reveals the phase transition from rhombohedral to orthorhombic symmetry. The structural study shows the formation of a dense compact high quality sample. The average crystallite size was found to be 38 nm. High dielectric permittivity value is observed with an increasing temperature. Impedance spectroscopy analysis suggests a semiconductor nature and conductivity study confirms the presence of correlated barrier hopping mechanism. The P-E loop study shows an enhancement in remnant polarization. Furthermore, several other interesting features are also reported in this work. [ABSTRACT FROM AUTHOR]

The yttrium (Y)-modified bismuth ferrite (BFO) ceramic compound (i.e. Bi(Fe0.85Y0.15)O3, abbreviated as BFYO15) has been synthesized through a standard solid state reaction technique. The results of its various properties, such as structural, dielectric and electrical features of Y-modified BFO were thoroughly investigated. The analysis of X-ray diffraction data confirms the phase formation of the compound, and shows the structural change from the rhombohedral to orthorhombic crystal system. The calculated average crystallite size of the sample was found to be 42 nm. The detailed studies of the dielectric parameters, impedance and ac-conductivity were performed in a wide frequency range (1–1000 kHz) at different temperatures (25–350°C). All the studies clearly show the significant change in dielectric and other electrical parameters on Y-substitution at the Fe site. Further, some of the results and electrical characteristics of the material may be used to select the material for potential device applications. [ABSTRACT FROM AUTHOR]

The Ni- and Ti-modified BiFeO3 nanoceramic (i.e., Bi(Ni0.45Ti0.45Fe0.10)O3) with various effective ball milling times (i.e., 10 h, 20 h and 30 h) were blended by planetary (high energy) ball milling method in conjunction with a traditional solid-state reaction route. The outcome of milling time on various properties, such as structural, electrical and ferroelectric features of Ni/Ti modified BiFeO3, was investigated thoroughly. These properties were interpreted using distinct characterization tools, such as powder X-ray diffraction, scanning electron microscope, transmission electron microscope, dielectrics and ferroelectric measurements. The particle size of as-synthesized compounds and the intensity of diffraction peaks decline obviously as the milling time rises due to the compression stress, shear friction and other mechanical forces, which are created inside ball mill jars. Investigation of dielectric properties (frequency dependent) displayed the boosted tendency of dielectric constant with increased co-doping concentration. Elaborated analysis of impedance data at selected sets of frequency/temperature estimates the grains influence and boundaries in the capacitive and resistive parameters of the synthesized samples. An elaborated investigation of the impedance spectroscopy spectrum evidently exhibited the size dependence impedance/dielectric relaxation features of the synthesized compounds. The frequency and/temperature dependence of conductivity (alternating current) confirmed the universal power law of Jonscher. The observed ferroelectric hysteresis loop trend reveals that the nanoceramic holds good ferroelectric properties. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, much attention is paid for the development of lead-free complex or mixed metal oxides, which can be utilized for multi-functional devices. This communication provides the information on synthesis (by mixed oxide route) and physical properties (structural, electrical and ferroelectric) of the polycrystalline sample of Bi(Fe 0.9 La 0.1)O 3 Analysis of the phase formation and basic crystal data of the material using X-ray diffraction (XRD) technique shows an orthorhombic symmetry with well-defined cell parameters. It has been shown that a small amount (10%) of La substitution at the Fe site of BiFeO 3 suppresses the impurity phase usually observed during phase formation of BiFeO 3. The average crystallite size, calculated through applying Scherrer's technique, was found to be 68 nm. For the study of surface morphology (grain size and distribution) of the compound, the scanning electron microscope (SEM) was used. The grains of different dimension were found homogeneously distributed at the entire surface of the sample. The La substitution strongly affects the capacitive (dielectric) and resistive (electrical) characteristics of bismuth ferrite in a wide range of frequency and temperature. The contributions of grains and grain boundaries in the capacitive as well as in the resistive properties of the material at different temperatures and frequencies were studied by means of the impedance spectroscopy technique. This study has provided numerous useful and interesting data which may find potential industrial applications. [ABSTRACT FROM AUTHOR]

This communication mainly discusses the effect of Fe-site substitution of gadolinium (Gd) and yttrium (Y) on structural, dielectric, electrical and ferroelectric properties of bismuth ferrite (BiFeO 3). The Gd and Y modified bismuth ferrite of chemical compositions, Bi(Fe 0.9 Gd 0.1)O 3 (referred as BFGO10) and Bi(Fe 0.9 Y 0.1)O 3 (referred as BFYO10) has been prepared through a high-temperature solid-state-reaction method. Preliminary structural analysis has been performed by using X-ray diffraction data and pattern of BFGO10 and BFYO10, which show the structural transformation from the rhombohedral to orthorhombic symmetry. Structural analysis confirms a little suppression of impurity phases in the bismuth ferrite, which has been eliminated by the substitution (small amount 10%) of Gd and Y at its Fe-site. The average crystallite size of Gd and Y-modified BFO, evaluated with the help of Scherrer's relation, is found to be 45 nm and 42 nm respectively. The field emission scanning electron microscopy (FESEM) image reveals the formation of good quality samples along with proper and uniform distribution of grains. Detailed analysis of the impedance analyzer (LCR Meter) data, collected in a frequency range of (1–1000 kHz) at different temperatures (25–500 °C), exhibits the significant change in the dielectric, resistivity and capacitive features of the materials. The remnant polarization and coercivity are obtained through the polarization vs electric field (P-E loop) studies. The numerous other interesting information and important data obtained in this work may be utilized for device applications. • XRD data confirms crystal symmetry changes from rhombohedral to orthorhombic phase. • Higher dielectric permittivity (ϵ r) with small dielectric loss (tanδ) was achieved. • The dielectric relaxation process is non-Debye type. • Enhancement in the remnant polarization (P r) is observed. [ABSTRACT FROM AUTHOR]

Low electric and magnetic moment features are the main drawbacks that restrict the practical utilities of bismuth ferrite. Successfully, we have substituted Li+ and W6+ in Sb3+ and Fe3+ sites to eliminate further confinements of bismuth ferrite (referred as BFO/BiFeO 3). A new lead-free perovskite compound of (SbLi) 1/2 (Fe 2/3 W 1/3)O 3 (symbolized as SLFWO) has been produced through ceramic processing (high temperature) route. The calcination temperature of said compound is confirmed from the thermogravimetric analysis. The structural, microstructural, magnetic and electrical (dielectric constant/loss, impedance, modulus, conductivity) features of the said material have been studied over an extensive range of frequency (100 Hz-1 MHz) and temperature (RT-400 °C). The finding of reflection indices and crystal parameters approve the development of polycrystalline nature with orthorhombic symmetry of the compound. The impedance analysis confirms the existence of non-Debye type relaxation trend. The frequency-temperature dependence of ac-conductivity studies proves the nature and conduction mechanism in the compound. At specific peak frequency, the modulus spectrum movements of the charge carrier vary from wide array to narrow array. The peak frequencies increase with temperature signifying the thermally activated relaxation process. The value of leakage current rises with the temperature that established the NTCR trend of the compound. The observed values of remanent magnetization, saturation magnetization and coercivity of SLFWO are 0.5647 emu/g, 0.04953 emu/g, and 104.242 Oe respectively. • The material is quite new considering its application point of view. • The structural, thermal, impedance and magnetic properties with in-depth understanding are explained well in this manuscript. • The material has an excellent electrical and magnetic property. [ABSTRACT FROM AUTHOR]