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Composites of barium hexaferrite (BaFe 12 O 19) and nickel zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4) have been prepared by the high-energy planetary ball mill method. The magnetic composites are characterized by employing X-ray Diffraction and High-Resolution Transmission Electron Microscopy (HRTEM) techniques. The percentage of barium hexaferrite (BaFe 12 O 19) and nickel zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4) in the composite has been obtained from the Rietveld analysis of XRD patterns. The average crystallite sizes of BHF and NZFO are found to be comparable in the composites. The magnetic properties of (1-x) BHF-(x) NZFO with x = 0 to 1 have been studied by measuring the magnetic hysteresis loop (M-H loop) for all the samples. The M-H loops are analyzed by plotting the loop width (ΔH) versus magnetization (M). The magnetic hysteresis loops for the BHF and NZFO are found to be symmetric in all the quadrants. However, symmetry breaks in M-H loops for composites. The symmetry breaking in magnetic hysteresis loops of the bi-magnetic composite suggests a new approach to analyzing the magnetic interaction between magnetic phases in the magnetic composites. [ABSTRACT FROM AUTHOR]

• Gadolinium doping in BHF results in modification of magnetic properties. • "Law of Approach to Saturation" gives the magnetocrystalline anisotropy constant. • Para-ferrimagnetic transition is observed around 700 K. • Maximum entropy change and RCP are found to be 0.72 J/kgK and 27.5 J/kg, respectively, near Curie temperature. • Possibility to use the Gd doped BHF at high temperature as a cooling agent. Gd doped barium hexaferrite (BaFe 12−x Gd x O 19 , x = 0.0–0.7) has been synthesized by the sol-gel method to explore its magnetic and MCE (magnetocaloric effect) properties. The materials crystallize to hexagonal magnetoplumbite phase. Average particle size decreases with the increase in Gd concentration in barium hexaferrite (BHF). The coercive field increases from 3.2 to 4.8 kOe, and saturation magnetization decreases from 68.21 to 54.23 emu/g with the increase in Gd concentration from x = 0.0 to x = 0.7. These large changes in magnetic parameters reveal the effect of Gd concentration in BHF. The saturation magnetization monotonously reduces with an increase in Gd concentration in BHF due to a decrease in average particle sizes. The saturation magnetization is found to be higher at a lower temperature (60 K) compared to that of room temperature (300 K). It is due to a reduction in thermal energy at low temperature which is smaller compared to the magnetic Gibbs free energy at low temperature. Hence, the magnetic spins are freezing along the applied magnetic field direction at the low temperature. Also, the magnetocrystalline anisotropy constant (obtained by the "Law of Approach to Saturation method") is found to be more at low temperature compared to that of room temperature due to an increase in the strength of spin-orbit coupling with the decrease in temperature (i.e. thermal energy). The M-T curves and M-H hysteresis loops reveal paramagnetic to ferromagnetic transition at the Curie temperature. The maximum entropy change was found to be in the range of 0.12–0.72 J/kgK in a window of the applied magnetic field of 0.5–3 T, and the corresponding RCP max was found to be 2.5–27.5 J/kg. The present study opens a window to explore the MCE on BHF based material. [ABSTRACT FROM AUTHOR]

Abstract: Aluminium substituted cobalt ferrite nanocrystalline materials with chemical formula CoFe2−x Al x O4 (x=0.0−0.4) have been synthesised by citrate precursor method. The crystal structure and phase purity were studied by powder X-ray diffraction (XRD). All the XRD patterns have been analysed by Rietveld refinement technique using the space group. The unit cell volume, average crystallite size, effective bond lengths and lattice parameters decrease with Al3+ concentration. Magnetic hysteresis loop measurements were carried out at room temperature using a vibrating sample magnetometer over a field range of ±2T. The saturation magnetisation, coercivity and Remanent magnetisation decrease with Al3+ concentration. The magnetic data in saturation have been analysed by employing the law of approach technique. The anisotropy constants are found to decrease with Al concentration. The saturation magnetisation, coercivity, remanent magnetisation and anisotropy constant increase with crystallite size. [Copyright &y& Elsevier]

Lead-free ferroelectric materials are essential for environment-friendly solid-state cooling technology. In this respect, the electrocaloric effect of lead-free Ba0.8−xSr0.2SmxTiO3 (x = 0.01–0.05) ceramics has been investigated. The Rietveld refinement reveals that all the ceramics exhibit tetragonal symmetry and the tetragonality decreases for x > 0.03, which is the major reason behind the decrease in both isothermal entropy change and adiabatic temperature change. The degree of diffuseness parameter is enhanced by doping of Sm3+, which confirms the formation of polar nanoregion and the enhancement of the electrocaloric effect parameter by adding extra entropy. The relaxor behavior of the prepared samples is also confirmed by estimating the degree of deviation parameter (Δ T m = 77 K ) from the 1 ε r vs. T curve. So, the temperature stability of the prepared ceramics is improved in a broad temperature window. The highest isothermal entropy change (Δ S) , adiabatic temperature change (Δ T) , and electrocaloric strength ( Δ T Δ E ) are found to be 1.230 Jkg−1 K−1, 0.862 K, and 0.028 73 K cm/kV at 316 K, respectively, for Ba0.77Sr0.2Sm0.03TiO3. [ABSTRACT FROM AUTHOR]

• Sr doped LCMO double perovskite nanoparticles were synthesized using sol–gel method. • Nanoparticles were studied using XRD, TEM, FTIR, Raman, Uv–Vis and M−H curves. • Resistivity curve (R-T) suggest the semiconducting nature for the compound. • M−H and ZFC-FC curves show the interesting magnetic properties of Sr doped LCMO. A study on crystal structure and physical properties has been performed on nanoparticles of lead-free double perovskites, La 2 CoMnO 6 (LCMO) and Sr-doped La 2-x Sr x CoMnO 6 (LSMO:0 ≤ x ≤ 0.08) prepared by the sol–gel synthesis method. In preparation for the LSMO nanoparticle, the La site of the LCMO double perovskite was replaced with an increasing concentration of Sr atom. Structural investigation done by employing the X-ray Diffraction technique indicates that the crystallite size decreases as the doping concentration increases. The Rietveld refinement on the XRD pattern shows the formation of the rhombohedral phase of LCMO (S.G. no. 161). Strain in the prepared samples estimated from Williamson Hall (W-H) analysis shows that the strain decreases as crystallite size decreases. The presence of compressive strain is also evident from the blue shift obtained in the Raman spectrum of the nanoparticles. The UV–Vis spectra reveal the maximum absorption in the near UV region of the electromagnetic spectrum. The Bandgap analysis from Tauc's plot shows an increase in band gap with Sr doping in the LCMO host lattice (from 1.81 eV to 1.92 eV). This is attributed to the decrease in crystallite size and octahedral tilting with Sr doping. Resistivity versus temperature plots reveal the semiconducting nature of the compound. A linear nature graph between l n ρ and T - 1 4 indicates that the electric transport mechanism is governed by the variable range Hopping (VRH) model. The M−H curves show that the maximum magnetization decreases as a result of Sr doping due to the anti-site disorder introduced. dM/dT vs T curve shows two magnetic transitions at ∼ 215 K and at ∼ 173 K which are due to Co2+–O2--Mn4+ and Co3+–O2--Mn4+ ferromagnetic superexchange interactions, respectively. [ABSTRACT FROM AUTHOR]

The composites (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 are prepared by solid‐state reaction method using microwave double‐step sintering. Ba0.8Sr0.2TiO3 crystallizes to tetragonal crystal symmetry with P4mm space group and CoFe2O4 crystallizes to cubic crystal symmetry with Fd3¯m space group. Electron microscopy techniques are used to understand the microstructure, elemental composition, and morphology of the composites. The dielectric properties are measured in the 1 Hz–1 MHz frequency range and 40–400 °C temperature range. Composite with x = 0.1 (ε′ ≈ 170, tan δ = 0.08 at 1 kHz) and 0.2 (ε′ ≈ 390, tan δ = 0.07 at 1 kHz) has better dielectric properties than the parent Ba0.8Sr0.2TiO3 ferroelectric (ε′ ≈ 125, tan δ = 0.16 at 1 kHz) and CoFe2O4 ferrimagnetic phases (ε′ ≈ 375, tan δ = 0.72 at 1 kHz), respectively. Composite with 10% cobalt ferrite has the highest saturation polarization (2.1 μC cm−2), the highest remanent polarization (0.9 μC cm−2), and coercive field (23.9 kV cm−1) compared to ferroelectric phase followed by x = 0.2 composite (PS = 1.6 μC cm−2, Pr = 0.8 μC cm−2, and EC = 19.2 kV cm−1). Composite with x = 0.2 shows the highest magnetic coercive field of 1.96 kOe. Hence, this article advocates that 20% ferrite in the composites is the optimized composition for multiferroic applications. The present study will help to explore piezoelectric, magnetostrictive, and magnetoelectric properties of (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 for the technological application. [ABSTRACT FROM AUTHOR]

Multiferroic composites are the current research interest due to their multi-functional behavior with promising electrical and magnetic properties compared to single crystallographic phase multiferroic materials. Hence, multiferroic composites of (1−x)Bi0.85La0.15FeO3-(x)NiFe2O4 (x = 0 to 0.50) have been investigated by considering Bi0.85La0.15FeO3 as a ferroelectric phase and NiFe2O4 as a magnetic phase. The crystal structure was examined by analyzing the X-ray diffraction (XRD) patterns. Different crystal structure parameters were obtained from the Rietveld refinement of XRD patterns. An increase in the lattice parameters of both Bi0.85La0.15FeO3 (BLFO) and NiFe2O4 (NFO) phases has been observed with the increase in the percentage of NiFe2O4 in the composites. Absorption peaks in Raman spectra shift toward lower frequencies with the increase in the percentage of NFO in the composite. Variation of lattice parameters and shifting of the Raman modes suggest the lattice strain at the interfaces of BLFO and NFO. Theoretical magnetizations were calculated for all composites by using the sum rule (using the magnetization of individual phases) and compared with experimentally observed magnetization. Interestingly, the experimental values of magnetizations of the composites are more than the theoretically calculated ones. It could be due to the lattice strain, which was observed from the XRD and Raman analysis. [ABSTRACT FROM AUTHOR]

An attempt has been made here to synthesized ceria (CeO2) and Ce0.80Zr0.20−xAxO2 (A = Fe, Co; x = 0–0.20) powders via novel sol–gel technique using metal nitrate hydrates as precursors and distilled water and ethanol as solvents. The resulting gel was dried at 130 °C for 24 h and calcined successively at 850 and 950 °C for 3 h each. Ceria is shown to exhibit a fluorite-type cubic structure with a slightly higher lattice parameter a = 5.428 Å, Z = 4, space group Fm 3 ¯ m , some Ce3+ ions and oxygen vacancies. 20% zirconium substitution of cerium causes decrease of ‘a’ to 5.395 Å owing to a lower ionic radius of Zr4+ vis-à-vis Ce4+. However, the lattice parameter first increases and then decreases with partial/ full replacement of Zr4+ by cobalt or iron ions. Evidence is found for existence disorder/strain, mismatch of ionic radii and oxidation states of cations, and appropriate oxygen vacancies to ensure charge neutrality of systems. The photoluminescence (PL) spectra reveal peaks at ~ 371, 402, and 432–445 nm, which are attributed to Ce 4f0 → 4f1 direct transition, Ce 4f0 → 4f1 electron transfer via oxygen F++ state, and oxygen vacancies (excited oxygen F+* → F+ transition), respectively. Their Raman spectra display a peak at ~ 462 cm−1 due to F2g symmetric vibrations of a cubic CeO8 sub-cell with some variation in position and sharpness with/without a signal in the range 150–170 cm−1 by introduction of different cations leading to distortion and formation of anion vacancies. [ABSTRACT FROM AUTHOR]

• Overall magnetic properties depend on phase evolution. • Average particle size increased with increasing annealing temperature. • Transition from single-domain to multi-domain configuration with annealing. • Incoherent magnetization reversal mechanism in single domain Ba 1-x Sr x Fe 12 O 19. The correlation of phase evolution (annealing at different temperatures) with magnetic properties like magnetization reversal, coercivity mechanism, and energy product in M-type hexaferrite by substituting Sr in place of Ba has been reported in the present article. The Ba 1-x Sr x Fe 12 O 19 (x = 0.0, 0.5, & 1.0) have been prepared by the sol–gel auto-combustion method followed by annealing at different temperatures from 800 °C to 1200 °C. The structural and magnetic properties have been characterized by X-ray diffraction, Field emission scanning electron microscopy, Raman spectroscopy, and Vibrating sample magnetometer. The Rietveld refinement confirms contraction in unit cell parameters by replacing Sr in place of Ba and lattice expansion with increasing annealing temperature. There is no significant effect of substitution on magnetic properties found rather heat treatment affects greatly. The transition from a single domain to multidomain particles and their contribution to initial magnetization curves are analyzed. The differential susceptibility (dM/dH) calculated from room temperature magnetization confirms the existence of a pinning effect during magnetization reversal for samples heat treated below 1200 °C. Secondary phases or grain boundaries are believed to act like pinning centers. This work opens insight into the domain wall motion by microstructure engineering. The coercivity is tuned to 6.09 kOe by controlling the annealing temperature for the Ba 1-x Sr x Fe 12 O 19 (x = 1.0) sample. The maximum energy product (BH) max in the range of 0.94–1.27 MGOe has been achieved. [ABSTRACT FROM AUTHOR]

Structural, optical, temperature dependent magnetic and electrical properties have been investigated for the nanocrystalline NiFe 1.97 RE 0.03 O 4 (RE = La3+ and Sm3+) compound. Without any signs of a secondary REFeO 3 phase, the Rietveld refinement reveals a single-phase spinel structure possessing cubic symmetry for current samples. The decrease in lattice constant has been observed as a result of RE ions substitution. The TEM micrographs reveal nanosized particles with an average size of 35 ± 3 nm and 32 ± 3 nm for La3+ and Sm3+ substituted samples. EDX spectra of both samples show good compositional homogeneity. HRTEM micrographs of both samples show well resolved lattice fringes and their inter-planar spacing matches with that obtained from the Rietveld analysis of the XRD patterns. The concentration of Fe2+ and Fe3+ ions has been estimated from the XPS spectra analysis and it is found to be ∼ 22% and 78% for NiFe 1.97 La 0.03 O 4 and, 20% and 80% for NiFe 1.97 Sm 0.03 O 4 compound. The optical energy band gap for rare earth substituted samples is found to be more than that of pure nickel ferrite. The value of saturation magnetization (M s) and magneto-crystalline anisotropy constant (K 1) estimated from the "Law of Approach to Saturation" equation for rare earth substituted samples are found to be less than that of pure nickel ferrite. However, an enhanced value of coercivity has been observed with RE substitution. ZFC (zero field cooling) and FC (field cooling) DC magnetization curves measured at 100 Oe in the temperature range of 60–400 K reveal a combination of weak and intermediate forms of magnetic interaction between the particles for both samples. Temperature dependent analysis of saturation magnetization and coercivity employing modified Bloch's law and Kneller's relation supports the nanomagnetic behavior of both samples. Under an AC magnetic field of 14.92 kA/m and frequency 337 kHz, the SAR and ILP values have been found to be ∼ 331 W/g and 4.22 nHm2/kg for NiFe 1.97 La 0.03 O 4 and, ∼ 241 W/g and 3.21 nHm2/kg for NiFe 1.97 Sm 0.03 O 4. The dielectric relaxation data have been analyzed at various temperatures ranging from 40 to 300 0C over the frequency range 100 Hz-1 MHz using electrical impedance spectroscopy. The dielectric constant for rare earth substituted samples is found to be more and their AC conductivity is observed to be less than that of pure nickel ferrite. The analysis of temperature dependent AC conductivity employing Jonscher's power law suggests that the charge carrier's conduction mechanism of both samples follows the small polaron hopping mechanism below 200 0C, thereafter; it follows the correlated barrier hopping mechanism. The activation energy estimated by imaginary impedance spectra is found to be 0.411 eV and 0.398 eV for NiFe 1.97 La 0.03 O 4 and NiFe 1.97 Sm 0.03 O 4 which is more than that of pure nickel ferrite. The Cole-Cole plots at different temperatures suggest the presence of non-Debye-type relaxation. The modeling of Cole-Cole plots with equivalent circuits for both samples confirms the contribution of both grain and grain boundary in electrical conduction. The estimated stretching exponential factor by fitting the modified KWW (Kohlrausch-Williams-Watts) equation to the imaginary modulus curve reveals relatively more dipole-dipole interaction in NiFe 1.97 Sm 0.03 O 4 than that of the La3+ substituted sample. [Display omitted] • Samples crystallized to single phase cubic spinel structure with F d 3 − m space group. • ZFC-FC analysis reveals intermediate type magnetic interaction between particles. • SAR is estimated by initial slope, Box-Lucas and modified Newton cooling approach. • Nyquist plots reveal non-Debye type dielectric relaxation and NTCR type behavior. • Presence of considerable induced dipole-dipole interaction in current samples. [ABSTRACT FROM AUTHOR]

Abstract: Zn2+ ion substituted nanocrystalline cobalt ferrite materials with the chemical formula CoZn x Fe2− x O4 for x =0.0, 0.1, 0.15, 0.2, 0.25 and 0.3 have been synthesised by standard citrate precursor method. The crystal structure and phase purity have been studied by powder X-ray diffraction (XRD) method by employing Rietveld refinement technique. The cation distribution between the tetrahedral site (A-site) and octahedral site (B-site) has been determined by Rietveld analysis. The distribution of cations changes with the Zn2+ concentration. Average crystallite size and lattice constant increase with the annealing temperature. The lattice constants decrease with the increasing Zn concentration. The vibrational modes of the octahedral and tetrahedral metal complex in the sample have been carried out using Fourier transform infrared spectroscopy (FT-IR). The FT-IR spectra of the sample have been studied in the wave number range of 380–800cm−1 and it shows the presence of absorption bands which are assigned to tetrahedral and octahedral metal complexes. The elemental analysis has been carried out using energy dispersive spectroscopy (EDS) with the help of Field Emission Scanning Electron Microscope (FE-SEM) and the results reveal that the elements are as per the stoichiometric ratio in all the samples. The Magnetic hysteresis loop measurements were carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±2T. Annealing at 200°C, superparamagnetic nature has been observed for compositions x =0.15–0.3. The magnetic data in saturation have been analysed by employing the law of approach (LA) technique. The saturation magnetisation increases with the Zn for x ⩽0.15 and then decreases. The coercivity decreases with the increasing Zn concentration for 600°C annealed samples. The magnetocrystalline anisotropy constants are found to increase for x ⩽0.15 and then decrease with the Zn concentration. [Copyright &y& Elsevier]

Abstract: Single phase materials of PbZr1− x Ti x O3 (x =1.00, 0.65 and 0.35) were prepared by following the solid state route. All the materials were prepared in nanocrystalline form as well as microcrystalline form. Evolution of crystallization was studied by characterizing the samples annealed at different temperatures. XRD patterns were analyzed with the help of Fullprof program by employing Rietveld refinement technique. The patterns for x =1.00 and 0.65 could be refined using P4mm space group in tetragonal symmetry. However, the samples for x =0.35 could be refined using R3c space group in rhombohedral symmetry. It has been found that crystallite size increases with the annealing temperature for all the samples. The scanning electron microscope (SEM) and energy dispersive X-ray spectroscope (EDS) analysis reveals that the materials are uniform and their composition is as per the chemical formulae. All the samples exhibit ferroelectric to paraelectric transition. [Copyright &y& Elsevier]

In this report, a detail analysis of the impact of annealing temperature on the structural, elastic, morphological, optical, and magnetic behavior of NiFe 2 O 4 nanoparticles prepared by the citrate sol-gel method is presented. Analyzing the XRD patterns by the Rietveld method confirms that all the annealed samples have been crystallized to cubic spinel structure belonging to F d 3 − m space group with a single phase. Rietveld analysis demonstrates the change in structural and microstructural parameters and movement of cations from tetrahedral to octahedral sites and vice-versa upon annealing. The quantitative estimation of Ni2+ & Ni3+ and Fe2+ & Fe3+ has been carried out using XPS analysis. Decreases in peak broadening and shift of five Raman active peaks towards higher frequency upon annealing have been analyzed using the phonon confinement model. The variation in elastic parameters with annealing temperature has been assessed by FTIR analysis. The UV analysis reveals the increase of the optical energy band gap and the decrease of Urbach energy with annealing temperature enhancement. A noticeable sharp absorption band at 748 nm in UV spectra is attributed to A 3 2 g (3 F) → T 3 1 g (3 F) electronic transition. Room temperature magnetic hysteresis loops exhibit an increase of saturation magnetization upon annealing which is discussed with reference to finite size effects and disorderly surface spins. The estimated value of magnetocrystalline anisotropy constant by Law of Approach to saturation (LAS) theory as well as coercivity value elucidates the annealing effect in changing the magnetic single domain state of the particle to a multidomain state. Analysis of ZFC and FC magnetization curve measured at 100 Oe in the temperature range 400 K–60 K reveals the significant impact of annealing temperature on magnetic anisotropy, inter-particle interaction, and blocking temperature. Exploring the magnetic hysteresis loop measured in the temperature range 60–400 K over field strength of ± 3 T demonstrates the significant role of annealing on magnetic exchange interaction. Temperature dependent behavior of saturation magnetization and coercivity has been analyzed using modified Bloch's law and Kneller's relation. The magnetic heating efficiency examined by the induction heating system reveals that the sample has enough potential for hyperthermia application. • Microstructural parameters and Fourier electron density are estimated by Rietveld. • Elastic parameters changes with annealing temperature. • Increase of energy band gap and decrease of Urbach energy occur upon annealing. • ZFC-FC analysis provided information on inter-particle interaction. • SAR is estimated by initial slope, Box-Lucas and modified Newton cooling approach. [ABSTRACT FROM AUTHOR]

Barium hexaferrite (BHF) is a promising material for technological applications. Hence, the large production of BHF for industrial application needs attention. Therefore, the effect of annealing temperature on the crystal structure, morphology, and magnetic properties of barium hexaferrite has been explored in this article. The BaFe12O19 (BHF) was prepared by the sol–gel method and annealed at different temperatures (800 °C, 900 °C, 1000 °C, and 1100 °C). The crystal structure of BHF is investigated by the Rietveld refinement of XRD patterns using Fullprof suit software. Bond lengths and bond angles have been calculated using the Rietveld refined crystal structure parameters. The FESEM micrograph reveals the cylindrical shape of BHF particles for the samples annealed above 900 °C. Large average grain size has been observed for 1100 °C annealed BHF sample. The average crystallite size (obtained from XRD analysis) and particle size (obtained from FESEM) increase with an increase in annealing temperature of BHF. It is observed that the magnetic properties of BHF depend on bond angles and bond lengths between Fe and O atoms at different crystallographic sites. The saturation magnetization and coercivity are found to increase with the increase in average crystallite or particle size, but the variation is very small. [ABSTRACT FROM AUTHOR]

Al-substituted strontium hexaferrite (SrFe 12-x Al x O 19) has been synthesized by the sol-gel auto-combustion method, followed by microwave sintering at 1100 °C. The Rietveld refinement of XRD patterns reveals the hexagonal crystal symmetry with P6 3 /mmc space group. Lattice contraction has been observed with the increasing Al3+ concentration in SrFe 12-x Al x O 19. The anisotropy field is found to be ∼25 kOe for SrFe 11·5 Al 0·5 O 19. The (BH) max (maximum energy product) of 1.20 MGOe is obtained for x = 0.0 whereas there is a 63.66% enhancement of coercivity for SrFe 11·5 Al 0·5 O 19 at 300 K. However, the highest (BH) max of 1.84 MGOe has been achieved at 60 K for SrFe 11·5 Al 0·5 O 19. The criterion for a permanent magnet is satisfied by analyzing the hardness parameter. All the samples are found to be magnetically hard with (BH) max in the range (1.00–1.20) MGOe at 300 K. • Lattice contraction in SrFe12-xAlxO19 (0≤x≤0.5) • All the synthesized samples are magnetically hard • Enhancement of anisotropy field up to 25 kOe • Uniform magnetic interaction confirmed by ΔH vs M plot • Highest (BH)max of 1.84 MGOe achieved for SrFe11.5Al0.5O19 at 60 K [ABSTRACT FROM AUTHOR]

Ba(Fe0.5Nb0.5)O3 [BFN] nanomaterial sample was prepared by the solid-state reaction method. The various structural parameters have been calculated by the Rietveld refinement method using cubic crystal symmetry with Pm m space group. The microstructural analysis has been carried out by the Field Emission Scanning Electron Microscopy (FESEM).The complex impedance spectroscopy of the BFN nanomaterial has been analyzed in a wide range of temperature (40 °C–400 °C) and frequency(1 kHz–1 MHz).The correlation between microstructure with electrical transport properties of Barium Iron Niobate (BFN) nanomaterial has been reported. [ABSTRACT FROM AUTHOR]

• Barium hexaferrite (BHF) film on Si substrate deposited by pulse laser depositions. • BHF film has very less coercive field compared BHF nanoparticle. • Magnetic parameters are directional dependent. • Magnetic bifurcation is observed in the film as well as powder due to magnetic frustration. The thin film of BaFe 12 O 19 (BHF) on a silicon substrate has been prepared by the pulse laser deposition method. The crystal structure, morphology, elemental analysis, and magnetic properties have been investigated by using X-Ray Diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy, elemental dispersive x-ray analysis, and vibrating sample magnetometry, respectively. The Rietveld refinement of XRD patterns of BHF powder has been performed to study the crystal structure and lattice parameters. Peak shifting in XRD pattern and Raman spectra for the thin film have been observed compared to that of powder sample. It could be due to the existence of stress at the interface of film and substrate. The magnetic hysteresis loops (M-H loops) of BHF thin film and powder were traced at 60 K and 300 K. The M-H loops of BHF suggest the hard and soft magnetic nature of powder and thin film, respectively. There is a large difference has been observed between saturation magnetization measured by applying a magnetic field parallel and perpendicular directions of the thin film. The bifurcation in zero field cooling (ZFC) and field cooling (FC) magnetization curves reveals the magnetic frustration in the thin films. [ABSTRACT FROM AUTHOR]

The large electrocaloric effect associated with the ferroelectric-relaxor and ferroelectric-paraelectric phase transition, and various temperature dependent scaling behaviours on A-site modified BaTiO 3 (Ba 1-x Sr x TiO 3 , x = 0.00, 0.10, 0.20, and 0.25) have been reported in this article. The compositionally induced relaxor behaviour with diffuse phase transition has been reported. The Rietveld refinement of XRD patterns reveals that all the samples crystallize to the P4mm space group. Raman spectra analysis at room temperature supports the XRD patterns analysis. The diffuse phase transition behaviour of the prepared sample has been confirmed by estimating the diffuse phase parameter (γ = 1.444 ± 0.003) from the temperature variation dielectric plot. A large adiabatic temperature change (Δ T) of 0.278 K and isothermal entropy change (Δ S) of 0.494 J/kgK have been observed for the sample x = 0.20 (Ba 0.8 Sr 0.2 TiO 3) at 338 K. The temperature dependent scaling relation for remnant polarization (P r), coercive field (E c), and hysteresis area < A > are found to be P r ∝ T − 1.009 , E c ∝ T − 1.890 and < A > ∝ T − 1.169 , respectively. The present comprehensive studies on A-site modified BaTiO 3 illustrate the electrocaloric cooling efficiency of this material. • Significant adiabatic temperature change (Δ T) of 0.278 K on Ba 0.8 Sr 0.2 TiO 3. • Significant isothermal entropy change (Δ S) of 0.494 J/kg K on Ba 0.8 Sr 0.2 TiO 3. • Polar-nano region (Relaxor ferroelectric signature) near the room temperature. • Diffuse phase parameter (γ =1.444) reveals the diffuse phase transition behaviour of Ba 0.8 Sr 0.2 TiO 3. • The scaling relations are P r ∝ T − 1.009 , E c ∝ T − 1.890 , and < A > ∝ T − 1.169 . [ABSTRACT FROM AUTHOR]

The composite of BaFe 12 O 19 (BHF) and CoFe 1·75 Zn 0·25 O 4 (CZF) with different weight percentages have been synthesized by using the high energy planetary ball mill technique. The obtained powders have been characterized by employing the X-ray diffraction, Field Emission Scanning Electron Microscope, and Energy Dispersive X-ray analysis techniques. The lattice parameters and phase percentage have been obtained by the Rietveld refinement analysis of XRD peaks. The crystallite sizes of BHF are greater than the CZF. The magnetic hysteresis loops have been recorded by using the Vibrating Sample Magnetometer (VSM) for all samples. The magnetic interaction between BHF and CZF in the composite has been investigated by plotting the loop width (ΔH) versus magnetization (M). The shape of these curves between loop width versus magnetization is changed with a different weight percentage of BHF and CZF. The saturation magnetization increases with an increase in the concentration of CZF in the composites. Vegard's law is used for comparing the theoretical and experimental magnetic parameters. The squeezing in hysteresis loop at H = 0 vanishes for (55)% BHF + (45)%CZF sample below 150 K and interesting magnetic interaction between two phases has been observed. Image 1 • Structural analysis has been carried out by the Rietveld refinement analysis. • Increase in Mr , Ms and decrease in H c with increase in weight percentage of CZF in BHF and CZF nano composites. • Vegard's law has been used to calculate the theoretical magnetization and coerecivity. • The squeezes at H = 0 in M-H loops are vanished at lower temperature. [ABSTRACT FROM AUTHOR]

The Rietveld refinement of XRD patterns reveals the crystallization of all the materials (BaFe 12-x Zn x O 19 for x = 0.0, 0.2, 0.4, and 0.6) to hexagonal symmetry with space group P6 3 /mmc. The lattice strain created in the crystal due to the ionic size mismatch of Zn and Fe. The Law of Approach (LA) to saturation method is employed to obtain the saturation magnetization (M s) and magnetocrystalline anisotropy constant (K 1) from M − H hysteresis loop. The maximum saturation Magnetization (M s) and minimum coercivity are found to be for BaFe 11·8 Zn 0·2 O 19 (i.e., x = 0.2). The magnetocrystalline anisotropy constant (K 1) reduces with the increase in temperature. The magnetic properties and magnetic crystalline anisotropy in Zn modified barium hexaferrite have been explained by considering the strain in the lattice site and superexchange interaction. [ABSTRACT FROM AUTHOR]