Room Temperature X-ray Diffraction Patterns Research Articles

Thermally enhanced luminescence and photoluminescence properties of green-emitting Lu2(1-x)Tb2x(WO4)3 phosphors

A series of Lu2(1-x)Tb2x(WO4)3 (x = 0.00–1.00) white powder materials were prepared by a high-temperature solid-phase method. The crystal structure, microscopic morphology, elemental composition, bandgap energy, photoluminescence properties, and thermal stability of luminescence of the prepared materials were analyzed and studied through room and high temperature X-ray diffraction patterns, field emission scanning electron microscopy images, energy energy-dispersive spectra and X-ray photoelectron spectra, diffuse reflectance spectra, room and high temperature photoluminescence spectra. Under 260 nm excitation, the green emitting Lu2(1-x)Tb2x(WO4)3 samples exhibited an optimum Tb3+ doping concentration at x = 0.30. Calculated results illustrate that the concentration quenching was mainly caused by dipole-dipole interaction. Lu1.98Tb0.02(WO4)3 phosphor exhibited thermally enhanced luminescence at 120 °C, with a maximum luminescence intensity of 254 % of the initial room temperature intensity. Lu1.4Tb0.6(WO4)3 phosphor exhibited thermally enhanced luminescence at 150 °C, with a maximum luminescence intensity of 109 % of the initial room temperature intensity. The mechanism of the thermally enhanced luminescence phenomenon is further discussed to be the adsorbed crystal water and the negative thermal expansion of the material. Thermally enhanced luminescence is of great significance in overcoming luminescent thermal quenching phenomenon, improving the luminescence efficiency, optimizing the material design, and so forth. It has potential applications in high-temperature lighting, display technology, temperature sensing, and optical anti-counterfeiting.

Observation of weak ferromagnetism in the antiferromagnetic host and large electronic heat capacity in β-Mn-type structured Mn3Al alloy

Numerous interesting features of antiferromagnets open up the possibility of designing new antiferromagnetic materials that can be useful for spintronic device applications. Here we present the structural, magnetic, thermal and electrical transport properties of polycrystalline Mn3Al alloys prepared by arc melting. Rietveld refinement of the room temperature X-Ray diffraction patterns reveals that the arc-melted Mn3Al crystallizes in a β Mn phase (space group 213). Detailed analysis of the magnetic data suggests for a dominant antiferromagnetic ordering. However, an in-homogenous magnetic disorder is observed in the system having a weak ferromagnetic phase in the antiferromagnetic host. In spite of the strong spin fluctuations in this system, the signature of spin glass-like nature in these alloys are not observed as probed by the frequency-dependent AC-Susceptibility measurements. Furthermore, the heat capacity was insensitive to the applied field of 3 Tesla with a negligible magnetic contribution suggesting a large electronic contribution to the heat capacity in these alloys. This work provides a useful insight into the tunable physical properties of the Heusler alloys for exploring antiferromagnetic based spintronic applications.

Effects of bismuth substitution on the structural and ionizing radiation shielding properties of the novel BaSn1-xBixO3 perovskites: An experimental study

In this study, BaSn1-xBixO3(0.00 ≤ x ≤0.20) polycrystalline perovskites are synthesized using the conventional solid-state reaction method for their utilization as materials for shielding against ionizing radiation. The Rietveld refinement of the room temperature X-ray diffraction (XRD) pattern revealed that all samples exhibited a cubic structure with Pm3‾m space group. To investigate the photon shielding properties of the prepared samples, the mass attenuation coefficient (MAC) was experimentally measured, and then the findings were benchmarked with the calculated results from the XCOM database. The obtained experimental results showed a reasonable correlation with the XCOM data, with relative differences in the mass attenuation coefficient ranging from 0.57% to 7.1%. Based on the measured MAC, different radiation shielding parameters such as the linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP), transmission factor (TF), and radiation protection efficiency (RPE) were calculated for all ceramics studied. These findings suggest that BaSn1-xBixO3(0.00 ≤ x ≤0.20) ceramic samples could be beneficial for use in shielding applications against ionizing radiation.

Sol-gel synthesis and Opto-electrical properties study of double perovskite oxide Dy2NiMnO6 thin film

Thin film of double perovskite oxide Dy2NiMnO6 (DNMO) has been synthesised by the simple and cost-effective chemical solution deposition technique. The room temperature X-ray diffraction pattern and Raman spectroscopy confirm the monoclinic (space group - P21/n) crystal structure of polycrystalline DNMO thin film. The optical and electrical properties of DNMO thin film are investigated to study the detailed photo physical properties of DNMO thin film. The direct band gap and temperature dependant impedance spectroscopy confirm its semiconductor behaviour. Impedance spectroscopy also shows two types of dielectric relaxation behaviour and the nature of conductivity reveals the electron hopping conduction mechanism. Moreover, the chemical solution deposited DNMO film shows promising photo response under white light.

Substantial enhancement in magnetic and magnetodielectric properties of 0.7(Bi2Fe4O9)-0.3(La0.67Sr0.33MnO3) composite

In pursuit of room-temperature magnetoelectric materials for numerous technological applications various materials are vigorously explored. Such is the motivation behind the synthesis of 0.7(Bi2Fe4O9)-0.3(La0.67Sr0.33MnO3) composite. The phase purity and structural analysis are examined through Rietveld refinement of room temperature X-ray diffraction (XRD) pattern, which shows that the composite has ‘Pbam + Pbnm’ phases. X-ray photoelectron spectroscopy confirmed the presence of mixed valence state of magnetic ions i.e. Fe2+ (41%), Fe3+ (45%), Fe4+ (14%) and Mn2+ (88%), Mn3+ (12%) favouring superexchange and double exchange interactions contributing to enhanced magnetizations. The presence of weak ferromagnetism in the composite is confirmed by large irreversibility in ZFC-FC data, isothermal magnetization curves and Arrott plots throughout the wide temperature range (10–300 K). High value of coercivity (Hc) is observed with an increase in temperature which indicates magnetic anisotropy in the system. Along with that, a plausible magnetodielectric (MD) coupling is evidenced in temperature dependent dielectric (ε′) and tan loss. Later, it is verified through intrinsic MD results carried out at higher frequency. At room temperature, the MD effect is found to be ∼2%. A contrasting behaviour in magnetic field variation of MD% is at 10 K and 300 K. However, a butterfly-shaped MD curve is evidenced where MD% ∼0.21% at 10 K. Lastly, Landau free energy expression confirmed that MD effect emerges from the coupling term ‘γP2M2′ where γ is ∼1.6 × 10−2 (emu/g)−2 and ∼1.1 × 10−2 (emu/g)−2 at 10 K and 300 K respectively. Thus, the above findings highlight the significance of the composite as a potential room temperature magnetoelectric material for device applications.

Experimental and theoretical investigation of FeCrVAl and related compounds

We have carried out a combined theoretical and experimental investigation of FeCrVAl, and the effect of Mn and Co doping on its structural, magnetic, and electronic band properties. Our first principles calculations indicate that FeCrVAl, FeCr0.5Mn0.5VAl, and FeCr0.5Co0.5VAl exhibit nearly perfect spin polarization, which may be further enhanced by mechanical strain. At the same time, FeCrV0.5Mn0.5Al and FeCrV0.5Co0.5Al exhibit a relatively small value of spin polarization, making them less attractive for practical applications. Using arc melting and high vacuum annealing, we synthesized three compounds FeCrVAl, FeCr0.5Mn0.5VAl, and FeCr0.5Co0.5VAl, which are predicted to exhibit high spin polarization. The room temperature x-ray diffraction patterns of all samples are fitted with full B2 type disorder with a small amount of FeO2 secondary phase. All samples show very small saturation magnetizations at room temperature. The thermomagnetic curves M(T) of FeCrVAl and FeCr0.5Co0.5VAl are similar to that of a paramagnetic material, whereas that of FeCr0.5Mn0.5VAl indicates ferrimagnetic behavior with the Curie temperature of 135 K. Our findings may be of interest for researchers working on Heusler compounds for spin-based electronic applications.

Modifying magnetic properties of MnBi with carbon: an experimental and theoretical study

MnBi and MnBi-based materials have been investigated as prospective rare-earth-free permanent magnets with moderate energy product. One of the main issues with MnBi synthesis is the presence of residual Bi in the sample which reduces the net magnetization. We have found that MnBi synthesized in the presence of carbon substantially reduces the amount of residual Bi, improving its saturation magnetization. We have synthesized Mn55Bi45 and Mn55Bi45C x samples using arc melting and high-vacuum annealing. The room temperature x-ray diffraction patterns indicate that both Mn55Bi45 and Mn55Bi45C x crystallize in the hexagonal NiAs-type structure. The Rietveld analysis of the x-ray patterns shows that the amount of residual Bi reduces from 16 wt.% for Mn55Bi45 to 5 wt.% for Mn55Bi45Cx. The high-field (3 T) magnetizations measured at room temperature are 61 emu g−1 and 66 emu g−1 for Mn55Bi45 and Mn55Bi45C x , respectively. To understand the role of C in enhancing the magnetization of MnBi, we carried out the first-principles calculations of both stoichiometric and nonstoichiometric MnBi alloys, which suggests that the increase of magnetization in Mn55Bi45C x may be due to the coating of MnBi grains with C.

Electronic band structure and magnetism of CoFeV0.5Mn0.5Si

Half-metallic Heusler alloys have attracted significant attention due to their potential application in spin-transport-based devices. We have synthesized one such alloy, CoFeV0.5Mn0.5Si, using arc melting and high-vacuum annealing at 600 °C for 24 hours. First principles calculation indicates that CoFeV0.5Mn0.5Si shows a nearly half-metallic band structure with a degree of spin polarization of about 93%. In addition, this value can be enhanced by the application of tensile strain. The room temperature x-ray diffraction patterns are indexed with the cubic crystal structure without secondary phases. The annealed sample shows ferromagnetic order with the Curie temperature well above room temperature (Tc = 657 K) and a saturation magnetization of about 92 emu/g. Our results indicate that CoFeV0.5Mn0.5Si has a potential for room temperature spin-transport-based devices.

Transformation of a ceramic precursor to a biomedical (metallic) alloy: Part I – sinterability of Ta2O5 and TiO2 mixed oxides

Mixed Ta2O5 – TiO2 binary system was studied by a combination of differential thermal analysis (DTA), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and in situ high temperature X-ray diffraction (HT-XRD) techniques. Different compositions of the mixed oxide powders were fabricated by ball–milling the powdered compositions, pelletizing the homogenized composite powders, and heating the green pellets in air at different temperatures for fixed time intervals. The sintered pellets were evaluated and characterized with respect to porosity, morphology, and phase distribution. DTA runs of the un-sintered powders indicated the onset temperatures for both exothermic and endothermic changes in the binary system. Significant amount of sintering was observed to take place at temperatures higher than 900 °C. Both room and high temperature X-ray diffraction patterns exhibited consistency in phase formation. A ternary compound (TaTiO4) and a ternary solid solution (Ti0.33Ta0.67O2) were observed to form in both room and high temperatures in addition to the respective binary phases (Ta2O5 and TiO2). A sintering temperature in the range 900–1000 °C was observed to be adequate to achieve the requisite mechanical strength and optimum internal porosity (40–48%) for subsequent electrochemical polarization experiments.

Observation of room-temperature ferroelectricity in spark-plasma sintered GdCrO3

A spark-plasma sintered ${\mathrm{GdCrO}}_{3}$ (SPS-GCO) is found to stabilize in its ferroelectric phase beyond room temperature. The intrinsic nature of this room-temperature ferroelectricity is established using ferroelectric positive-up--negative-down measurements and supported through piezoresponce force microscopy measurements. The SPS-GCO undergoes antiferromagnetic ordering at much lower temperatures, only below $\ensuremath{\approx}170\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Thus, any role of magnetism to the observed room temperature ferroelectricity in SPS-GCO can be ruled out. This is contrast to the concomitant antiferromagnetic and ferroelectric ordering observed below $\ensuremath{\approx}170\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ in ${\mathrm{GdCrO}}_{3}$ (GCO) (prepared using standard solid-state synthesis technique). Using detailed Rietveld refinements of room-temperature x-ray diffraction patterns, SPS-GCO is found to stabilize in the noncentrosymmetric orthorhombic $Pna{2}_{1}$ space group (the reported low-temperature ferroelectric phase in GCO), while GCO stabilizes in the centrosymmetric $Pbnm$ space group at room temperature. Using first-principles calculations, we investigated the relative energies among various possible structures of ${\mathrm{GdCrO}}_{3}$ and found that the orthorhombic $Pna{2}_{1}$ and $Pbnm$ space groups are the most stable structures. The ferroelectric $Pna{2}_{1}$ phase of SPS-GCO (stabilized at room temperature using the high-pressure and high-temperature spark-plasma sintering process) undergoes transition to the paraelectric centrosymmetric phase upon heating beyond $\ensuremath{\approx}450\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ (as confirmed using dielectric and calorimetric measurements), which on subsequent cooling to room temperature does not undergo a transition back to the ferroelectric phase and remains in the centrosymmetric $Pbnm$ phase.

Structural, thermal and dielectric behaviour of exfoliated graphite nanoplatelets (xGnP) filled EVA/EOC blend composites

Nano-composites of xGnP filled ethylene vinyl acetate (EVA)/ethylene-octene copolymer (EOC) (80–20) blend with 0, 1, 3, 5, 9, 11 wt % of xGnP were fabricated by solution casting followed by compression moulding. The room temperature X-ray diffraction (XRD) pattern and field emission scanning electron microscope (FESEM) of the investigated samples reflect distribution of exfoliated graphite nanoplatelets (xGnP) in the EVA/EOC matrix. The thermo-physical properties of the composites were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC analysis shows that with increase in xGnP contents, crystallisation temperature increase and act as a nucleating agent. TGA analysis data validates the stability of composites with increase in xGnP wt % in the composites. The dielectric and conducting behaviours of the studied samples were investigated by computer controlled impedance analyser within the frequency range of 100 Hz to 5 MHz. The room temperature relative permittivity (εr) value increases with rise in wt % of xGnP loading and achieved maximum at 9 wt % and then it falls. Similar behaviour also noticed in ac conductivity study. The nature of charge carriers in the composites were investigated by utilising non-destructive impedance spectroscopy technique. The theoretical fitting of experimental data of Nyquist plot reveals all the compounds perform the bulk behaviour. Additionally, ac conductivity study validates Johnsher’s universal power law which confirms motions of the charges are translational one. I ∼ V characteristics of the studied samples were carried out by using Keithly electrometer which confirms that conduction behaviour was non-Ohmic at lower wt % xGnP loading but Ohmic conduction was achieved at higher wt % xGnP loading. From both impedance and I ∼ V study we have also confirmed the increases in conductance with increase in wt % of xGnP loading and shows similar phenomena as observed in dielectric study.

First principles study of phase stability in Ba-based tantalate complex double perovskites

Despite the practical importance of Ba-based perovskite dielectrics in microwave applications, the literature does not consistently agree which structural phases form. To provide insight, we use density functional methods to calculate Gibbs energies of structural polymorphs of 1:1 ordered Ba-based perovskites. Ba(In1/2Ta1/2)O3 has a ground state Fm3¯m cubic phase at 0 K, while Ba(Y1/2Ta1/2)O3, Ba(Gd1/2Ta1/2)O3, and Ba(Nd1/2Ta1/2)O3 form lower symmetry ground state phases. With increasing temperature, the structural phases change from monoclinic I2/m to trigonal R3¯ and finally to cubic Fm3¯m. For the zero and higher temperature conditions, the energy differences between the ground state and next higher energetic polymorphs are below 50 meV/atom and arise predominantly from changes in the octahedral tilts. The resulting coexistence of two or more polymorphs at room temperature and similar x-ray diffraction patterns may explain why so many papers report different phases for the same compound.

Effect of cation distributions on structural and magnetic properties of Ni1-xCoxFe2O4 spinel ferrites

Single-phase polycrystalline samples of Ni1-xCoxFe2O4 (x = 0 – 0.50) were prepared by sol gel method and their structural and magnetic properties were studied. Room temperature X-ray diffraction patterns and Rietveld refinement confirm cubic crystal structure (Fd3-m). The lattice constant, saturation magnetization, magnetic anisotropy constant and coercivity of the samples are found to increase with Co concentration. An analytical quantum mechanical method was used to estimate the cation distributions in the prepared samples with the help of measured magnetic moment at T = 5 K. Even though, most of the doped Co ions occupy the octahedral site, considerable distribution of Co2+ ions at tetrahedral site is noticed. The observed magnetization is explained based on cation distribution worked out from quantum mechanical method. The red shifting of Raman active mode A1g and ESR results further confirm the presence of divalent cations in the tetrahedral sites.

Effect of Fe and Co doping on structural and electrical properties of La0.5Sr1.5MnO4 layered-structure and the corresponding La0.5Sr0.5MnO3 perovskite

In this study, structural and electrical properties of La0.5Sr1.5Mn0.5T0.5O4 (T = Mn, Fe, and Co) manganites, with K2NiF4 structure, have been investigated and compared with those of La0.5Sr0.5Mn0.5T0.5O3 perovskite manganites. The room temperature X-ray diffraction patterns of the synthesized La0.5Sr1.5Mn0.5T0.5O4 layered-structures and La0.5Sr0.5Mn0.5T0.5O3 perovskites were indexed with tetragonal and orthorhombic structures, respectively. The FE-SEM images revealed that the average size of La0.5Sr1.5Mn0.5T0.5O4 particles prepared by solid state reaction method using La0.5Sr0.5Mn0.5T0.5O3, as the starting materials, is larger compared with that of La0.5Sr0.5Mn0.5T0.5O3 synthesized by the modified sol-gel route. The SEM micrographs of the sintered ceramics indicated that the average grain size of La0.5Sr1.5Mn0.5T0.5O4 layered-structures is larger than that of the corresponding La0.5Sr0.5Mn0.5T0.5O3 perovskites, which is supported by FE-SEM images. The electrical conductivity measurements, in the range of room temperature to 800 °C, indicated that these oxides have semiconducting behavior, and their transport properties can be described by small polaron conduction mechanism. Results showed that La0.5Sr1.5Mn0.5T0.5O4 layered-structures have lower electrical conductivity in comparing to the corresponding La0.5Sr0.5Mn0.5T0.5O3 perovskites, since the perovskite structure provides three-dimensional (Mn/T)3+–O–(Mn/T)4+ interaction, whereas it is two-dimensional interaction in the layered-structure. The reduction in conductivity with Fe doping could be due to the presence of Fe3+ ions, which causes a decrease in Mn3+/Mn4+ ratio and the number of electrons involved in hopping mechanism. The electrical conductivity enhancement of La0.5Sr1.5MnO4 by doping Co can be associated with reducing Mn/Co‒O bond length and the increase in the overlap between O 2p and Mn/Co 3d orbitals.

Structural, magnetic, dielectric and hyperfine interaction studies of titanium (Ti4+)-substituted nickel ferrite (Ni1+xTixFe2−2xO4) nanoparticles

Tetravalent titanium (Ti4+)-substituted nickel ferrite nanoparticles with varying composition were prepared by standard sol–gel auto-combustion method. The phase identification and nanocrystalline nature were studied through X-ray diffraction (XRD) technique. The room temperature X-ray diffraction pattern show only those planes which belong to cubic spinel structure. No extra peak other than cubic spinel structure appeared in the XRD pattern suggesting that the prepared nanoparticles possess single-phase cubic spinel structure except x = 0.4, 0.5 and 0.6. The plane (311) observed in the XRD pattern showed maximum intensity and is used to calculate the crystallite size (t). The Debye–Scherrer’s formula was used to calculate the crystallite size which was found to vary between 19 and 23 nm for varying Ti composition x. The lattice constant (a) and other structural parameters were obtained from XRD data. The lattice constant is found to be decreasesing with increase in Ti substitution. The FE-SEM images of typical samples confirmed the spherical shape morphology. The magnetic properties were studied by means of vibrating sample magnetometer and Mossbauer spectroscopy technique. All the samples exhibit a good magnetic property which decreases with Ti substitution. The saturation magnetization goes on decreasing from 43.14 (for x = 0.0) to 12.86 (for x = 0.5) which may be attributed to the decreasing A–B interaction. The Mossbauer spectrum of typical samples show sextet pattern. The Moosabauer parameters like isomer shift, quadrupole splitting, Line width etc. were obtained. The dielectric parameters such as dielectric constant, dielectric loss and dielectric loss tangent etc. were recorded using vector network analyzer.

Structural and Electrochemical Properties of Lanthanum Silicate Apatites La10Si6−x−0.2AlxZn0.2O27−δ for Solid Oxide Fuel Cells (SOFCs)

An excellent oxide ion conductivity with high oxygen transportation of lanthanum silicate apatite at the solid oxide fuel cell (SOFC) can be achieved through the solid-state reaction method. The doped La10Si6−x−0.2AlxZn0.2O27−δ (x = 0.2 and 0.4) materials sintered at 1600°C accomplished crystallinity and crystal structure of apatite-type. The structural and electrochemical characterizations of La10Si6−x−0.2AlxZn0.2O27−δ (x = 0.2 and 0.4) were executed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and electrochemical impedance spectroscopy (EIS) measurements. The total oxide ion conductivities of La10Si6−x−0.2AlxZn0.2O27−δ (x = 0.2 and 0.4) were measured from low to intermediate operating temperature range (450 to 800°C) using electrochemical impedance spectroscopy. Room temperature XRD patterns of La10Si6−x−0.2AlxZn0.2O27−δ (x = 0.2 and 0.4) exhibited La10Si6O27 apatite phase with space group P63/m as the main phase with the minor appearance of La2SiO5 as an impurity phase. The highest total oxide ion conductivity of 3.24 × 10−3 Scm−1 and corresponding activation energy of 0.30 eV at 800°C were obtained for La10Si5.6Al0.2Zn0.2O26.7 which contains a low concentration of Al3+ dopant.

Low temperature synthesis and investigations of magnetic properties of cobalt ferrite nanoparticles

In the present study we report the synthesis of cobalt ferrite nanoparticles using one of the well-known wet chemical method i.e. sol-gel auto combustion technique. The synthesis was carried out at sufficiently low temperature of 100°C. Citric acid was used as a fuel in the synthesis process. The obtained nanoparticles were sintered at 550°C for 4 h and then used for structural and magnetic investigations. The phase pure nature and nano crystalline nature was investigated through X-ray diffraction technique. Room temperature X-ray diffraction pattern show well defined reflections oriented at different Bragg’s angle corresponding to Miller indices (220), (311), (222), (400), (422), (511) and (440). All this reflections belongs to cubic spinel structure. Thus, XRD analysis confirms the formation of single phase compound. The particle size was obtained through Scherrer’s equation and found to be 21 nm, indicating the nanocrystalline nature. The magnetic properties were investigated using pulse field hysteresis loop tracer at room temperature. The saturation magnetization show increased values as compared to the bulk cobalt ferrite. The coercivity found to be less which exhibits the superparamagnetic behaviour. The obtained structural and magnetic parameters are useful in biomedical applications.

Magnetic Properties of Nickel Ferrite Magnetic Nanoparticles Prepared via Glycine Assisted Sol-Gel Auto Combustion Route

The present research paper deals on the synthesis of nickel ferrite (NiFe2O4) nanoparticles using sol-gel auto combustion technique in which glycine was used a chelating agent. The prepared nanoparticles were annealed at 500°C for 4 h. and then used for structural, magnetic and other investigations. The X-ray diffraction technique was used for phase purity and structural determination. Room temperature X-ray diffraction pattern of NiFe2O4 nanoparticles shows all the reflections belonging to cubic spinel structure. The reflections are intense and slightly broader. No extra peak other than cubic spinel structure was observed in the XRD pattern. This indicates the single phase formations of the nickel ferrite nanoparticle. The refinement of XRD data has been carried out by using full proof programmer. The lattice constant was calculated using XRD data as well as Cohen’s least square method, the obtained lattice constant matches with the reported value. The other structural parameters like lattice strain, X-ray density etc. structural parameters were also calculated using standard relations. The crystallite size was determined using Scherrer’s formula in which the most intense peak (311) was considered. The crystallite size was found to be 24 nm which indicates the nanocrystalline nature of the prepared nickel ferrite nanoparticles. The magnetic properties of were investigated using the pulse field hysteresis loop (PFHL) technique at room temperature. The saturation magnetization, coercivity and remanence magnetization shows enhanced values. All the structural and magnetic properties results were compared with the reported data in which other chelating agent like citric acid etc.

Structural, dielectric, and electrical characteristics of selenium-modified BiFeO3–(BaSr)TiO3 ceramics

The selenium (Se)-modified 0.5BiFeO3–0.5(BaSr)TiO3 was synthesized employing a high-temperature solid-state technique. Structural analysis (through Rietveld refinement) of the room-temperature X-ray diffraction pattern and data of the material confirms the tetragonal (P4mm) symmetry of the compound. Studies of scanning electron micrograph (SEM) and energy dispersive X-ray spectroscopy (EDS) data reveal the nature and characteristics (i.e., size, shape and distribution of grains, grain boundaries, voids and presence of elements, etc.,) of surface morphology and structure of the compound. Detailed analysis of temperature and frequency dependence of dielectric and impedance data exhibits the relaxor type of ferroelectric behavior and semiconductor (negative temperature coefficient of resistance) nature of the material. The material is found to have high resistivity and low dielectric (tangent) loss. Study of the temperature dependence of leakage current characteristics (i.e., electric field dependent current density) shows the leaky behavior of the material. The Se-modified 0.5BiFeO3–0.5(BaSr)TiO3 (BFBST), compared to its components (BFBST and pure BiFeO3), material possesses different types of conduction process, like space charge limited (SCLC), Ohmic, Hopping type. Poole–Frenkel emission (PFE) and Schottky emission (SE) fitted data give an evidence/idea about the bulk-limited and interface-limited conduction mechanism present in the system. The energy gap values (Eg) of Se substituted BFBST and BiFeO3 are found to be 0.55 eV and 0.78 eV, respectively, in the low-temperature range.

Strongly enhanced polarization and dielectric breakdown strength of PZT95/5 by doping of Ce4+ and Nb5+

In this report, we investigate ferroic properties of Nb5+ and Ce4+ co-doped bZr0.95Ti0.05O3 (PZT95/5) ceramics, prepared via conventional solid state reaction route. Room temperature X-ray diffraction pattern suggests that synthesized samples crystallize with rhombohedral crystal symmetry (space group—R3c), equivalent to Zr rich PZT materials. Dielectric constant (er) exhibits anomaly in the vicinity of transition temperature. To unveil, the effect of co-doping on nature of evolved phase, we follow diffusion coefficient, $$\gamma$$ , obtained from modified Curie-Wiess law. Value of $$\gamma$$ is found to be ~ 1.24 and ~ 1.20 for 2% and 3% Ce4+ doped material, respectively, and $$\gamma >1$$ for diffused type ferroelectric (FE) systems. Saturated P-E loop profile evidences that co-doping of Nb5+ and Ce4+ causes strong enhancement in technologically appealing ferroic properties, e.g., spontaneous polarization, remnant polarization and breakdown strength. Such advances in ferroic properties are highly appreciated in field of various ferroelectric-based technology.