Solid-state Route Method Research Articles

Probing the effect of LaFeO3 on the structural, electrical, and dielectric properties of Sr0.8Sn0.2Bi2Nb2O9 processed through solid state route method

SrBi2Nb2O9 belongs to the class of Aurivillius layered ferroelectric oxide materials and this article offers a suitable method for understanding the structural and electrical properties of this class material for industrial application. With this aim we have synthesized LaFeO3 (LFO) doped Sr0.8Sn0.2Bi2Nb2O9 (SBN) novel ceramic by solid state route using ball milling in an ethanol medium for 20 h with 200 rpm, followed by single-step microwave sintering. For better phase formation, the obtained powders are compressed into cylindrical pellets and fired at 1000 °C for 5 h. The sample was critically analyzed using powder X-ray diffraction data confirming the distorted perovskite structure. The dielectric properties were studied in a frequency range of 10 Hz to 2 MHz at different temperatures revealing many exciting results. Further analyzing the impedance spectroscopy gives an idea about the contribution of different electrically dynamic regions in different conduction processes.

Influence of Na/Mg Co-Doping in Tuning Microstructure, Transport, Optical, and Magnetic Properties of TiO2 Compounds for Spintronics Applications

In recent years, researchers have been making a persistent effort to discover innovative and appropriate oxide materials that can be exploited in optoelectronics devices. The primary objective of this research is to study the effect of Na/Mg co-doping on microstructure, transport (dielectric and Hall Effect), optical and magnetic properties of Ti0.94-yNa0.06MgyO2 (y = 0–0.08) compounds that were synthesized using a solid-state route method. All the compounds have been crystallized to a single rutile phase, as reported by the XRD study. The elemental color mapping reveals that there is a consistent distribution of all of the elements across the compound. The XPS study suggests that Ti mostly resided in the Ti4+ oxidation state. The enhancement of the Mg co-doping concentration led to a decrease in the dielectric value as well as the AC conductivity of the material. In addition to this, it has been noted that these compounds have a low dielectric loss. The analyses of Nyquist plots reveal that the increase of Mg co-doping concentration led to a rise in the amount of relaxation that is non-Debye sort. This, in turn, caused a reduction in the amount of resistance exhibited by grains and grain boundaries. The Maxwell–Wagner model was used to conduct an analysis of the dielectric data, and the results indicated that the hopping of charge carriers is most likely to be responsible for the transport of electrical charges. From the optical properties’ measurement and analyses, it was noticed that the band gap had been slightly changed, but the transmittance value had increased from 81% for Ti0.94Na0.06O2 to 84% with an increase in Mg co-doping concentration. The Hall Effect analysis unequivocally pointed to the presence of p-type conductivity as well as an increased carrier density concentration. The room temperature magnetization versus field measurement indicates the ferromagnetic nature of the samples. Thus, the co-doping of Mg with Na in TiO2 leads to a narrowing of the band gap of TiO2 while tweaking the optical and transport properties. The studied materials can be utilized for spintronics and optoelectronics applications.

Catalytic behavior of Pr1-xBa1+xCo2O6-δ in alkaline medium

In this work, a series of double perovskite oxide materials Pr1-xBa1+xCo2O6-δ (x = 0.05, 0.10, 0.15, and 0.20) was synthesized using the solid-state route method. Their catalytic activity and stability in 1 M KOH alkaline medium were investigated. The phase formation and structure of the prepared oxides were determined by Powder X-ray diffraction. The morphology of prepared catalysts was confirmed by SEM analysis. The catalytic performance of the prepared catalyst in alkaline solution was investigated using electrochemical measurements for both oxygen evolution reaction (OER) and oxygen reduction reactions (ORR). This series of double perovskite oxide materials exhibit catalytic activity for both OER and ORR. Pr0.90Ba1.10Co2O6-δ shows wonderful OER activity among all the catalysts with a specific capacitance of 598.40 F/g and double-layer capacitance of 38.94 mF/cm2. Power low gives a hint of oxide-ion intercalation pseudocapacitance in the Pr0.90Ba1·10Co2O6-δ. On the other hand, Pr0.95Ba1·10Co2O6-δ exhibits potential behavior for ORR. Overall, our findings highlight the combined effects of incorporating Ba into double perovskite PrBaCo2O6-δ in its behavior for OER and ORR.

Effect of holmium (Ho) partial substitution in structure and ferroelectric properties of bismuth ferrites (BFO)

Multiferroic holmium doped bismuth ferrite samples, prepared by solid-state route method are analyzed in this study to understand the effect of Ho3+ in the crystal structure, thermal properties, dielectric behavior, ferroelectricity, and AC conductivity of bismuth ferrites. Preliminary structural analysis using XRD and refinement characterize to see the distortion in the rhombohedral type of structure with doping. Effect of holmium on morphology, using FESEM and compositional analysis using EDAX show more uniform and dense distribution of well-developed grains as well as a better phase formation with lesser secondary phase, for 80% holmium doped sample. Dielectric, AC conductivity, and impedance parameters variation with frequency and temperature are studied to investigate the electrical behavior of Ho-BFO. Emphasis on the effect of holmium doping on the ferroelectric nature of the doped BFO is further analyzed in terms of P-E loops. The temperature effect on the dielectric properties exhibits an anomaly corresponding to magneto-electric coupling in the samples; all these results are discussed here in detail.

Multifunctional characterization of Ca-modified new double perovskite for energy harvesting devices

The conventional solid-state route method was adopted for the synthesis of the double perovskite Ba1.5Ca0.5FeVO6. The well define spikes that appear in the XRD profile of the investigated sample suggested the formation of a single-phase new compound. The structural refinement carried out through POWD and MAUD software suggested the material crystallize in the monoclinic phase having a space group of P21/m. The morphological investigation of the sample was carried out by field emission scanning electron micrograph (FESEM). The involvement of different vibrational modes such as stretching, bending, etc. as well as functional groups associated with the compounds was studied through Raman and Fourier transform infrared (FTIR) spectroscopic techniques. The electronic configuration and chemical valence state of the involved elements were investigated by incorporating X-ray photoelectron spectroscopy. The optical sensitivity and bandgap of the material were studied through UV–Visible spectroscopy. The dielectric properties of the material were investigated by monitoring the variation of dielectric parameters (dielectric constant and loss tangent) with frequency while non-destructive impedance and modulus techniques were adopted for electrical characterization. Besides, the AC and DC conductivity spectra were studied for a detailed investigation of electrical properties and the type of charge carriers in the material. The identification of ferromagnetism in the material at room temperature was done by M-H loop.

Solid-State Synthesized BiFeO3 Perovskite-Based Fast-Response White-Light Photodetector

This letter reports an indium doped tin oxide (ITO)/ZnO nanoparticles (NPs)/ BiFeO3 ferroelectric perovskite /poly (3, 4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS)/Ag heterostructure based white-light photodetector. ZnO nanoparticles are synthesized using the sol-gel process, whereas solid-state route method is used for synthesizing BiFeO3. The X-ray diffraction (XRD) of ZnO nanoparticles and BiFeO3 thin film confirms the formation of the wurtzite hexagonal structure of ZnO NPs and the rhombohedral structure of BiFeO3 perovskite. The high-resolution scanning electron microscopy (HR-SEM) of the films confirm the highly dense and uniform growth of ZnO nanoparticles and BiFeO3. The measured responsivity characteristics over 400-750 nm show the maximum responsivity of ~34 mA/W over the wavelength of 450 to 650 nm at an applied bias voltage of 2 V. The photodetector exhibits a reasonably fast light response with the rise time of 7.21 s and fall time of 6.23 s.

Compositional effect on oxygen reduction reaction in Pr excess double perovskite Pr1+xBa1-xCo2O6-δ cathode materials

The kinetics of oxygen reduction reaction (ORR), being a prime requisite for electrode materials after the higher conductivity. Further, electrodes are observed to dissolute on reaction at triple phase boundary. However, the compositional effect on ORR is least understood. In order to inspect the ORR mechanism with substitution, a series of (1 + x) PrCoO3 − (1 − x) BaCoO3 (x = 0.2 to 1.0 with step of 0.2) compositions are prepared using conventional solid-state route method. The Rietveld refinement of X-ray diffractograms and specific heat curves confirms the formation of double phase comprising orthorhombic Pmmm phase corresponding to PrBaCo2O6-δ and Pnma phase corresponding to PrCoO3 for x = 0.2 to 0.8 with well connected and porous microstructure. The triple phase boundary reactions suggest the formation of Co(OH)3 along with H2 gas on reaction of these composite electrodes with H2O during electrochemical dissolution. However, chronoamperometric studies prove the suitability of x = 0.6 sample with higher ORR and liberation of H2 gas at room temperature.

Band Gap Engineering in Zinc Doped Sodium Hexa-titanate

Objectives: In this article Zinc doped Sodium Hexa-titanate ceramic materials were prepared for investigating of optical behaviors. Methods and Analysis: Pure and Zinc doped Sodium Hexa-titanate (Na2 Ti6 O13) ceramic materials have been synthesized using solid state route method, by adding sodium carbonate and titanium dioxide in a proper ratio and passes through different process. Structure and phase of all synthesized ceramic materials were analyzed using X-ray diffraction, and found single phase and monoclinic structure of pure and zinc doped samples. Morphology of all synthesized materials has been studied using scanning electron microscopy. Absorption spectra of these Hexa-titanate samples have also been recorded. Findings: The Crystalline size of synthesized samples was calculated with Debye-Scherrer equation, as well as the energy band gaps have been calculated using Tauc relation with respect to absorption wavelength. Application: The energy band gap has been reduced by doping ZnO from 3.780eV to 2.779eV. These narrower band gaps can be used in different infrared and thermoelectric sensors. Keywords: Energy Band Gap, Monoclinic, Scanning Electron Microscopy, Sodium Hexa-titanate, Tauc Relation

Study of Microstructural, Electrical and Dielectric Properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 Ceramics

The present work studies the microstructural and electrical properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 ceramics synthesized by solid-state route method. Microstructure and elemental analysis of both samples were carried out by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) method, respectively. Phase analysis by X-ray diffraction (XRD) indicated formation of single phase distorted structure. The XRD data were further analyzed by Rietveld refinement technique. Raman analysis reveals that Y atom substitutes La site into the LPMO with shifting of phonon modes. The temperature variation of resistivity of undoped and Y-doped La0.9Pb0.1MnO3 samples have been investigated. The electrical resistivity as a function of temperature showed that all samples undergo an metal-insulator (M-I) transition having a peak at transition temperature TMI. Y-doping increases the resistivity and the metal-insulator transition temperature (TMI) shifts to lower temperature. The temperature-dependent resistivity for temperatures less than metal-insulator transition is explained in terms the quadratic temperature dependence and for T > TMI, thermally activated conduction (TAC) is appropriate. Variation of frequency dispersion in permittivity and loss pattern due to La-site substitution in LPMO was observed in the dielectric response curve.

Structural and Optical properties of poly-crystalline BaTiO3 and SrTiO3 prepared via solid state route

Polycrystalline BaTiO3 (BTO) and SrTiO3 (STO) were synthesized by solid state route method and properties of made polycrystalline were characterized by X-Ray diffraction (XRD), Raman Spectroscopy & FTIR Spectroscopy. XRD analysis shows that samples are crystalline in nature. In Raman Spectroscopy measurement, the experiment has been done with the help of JOBIN-YOVN HORIBA LABRAM HR800 single monochromator, which is coupled with a “peltier cooled” charge coupled device (CCD). Raman Spectroscopy at low temperature measurement shows the phase transition above & below the curie temperature in samples. Fourier transform Infrared spectroscopy was used to determine the Ti-O bond length position.

Microwave synthesis of hydroxyapatite bioceramic and tribological studies of its composites with SrCO3 and ZrO2

Hydroxyapatite (HAp) powders were prepared successfully using microwave-assisted co-precipitation method. HAp powder was characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy for structural confirmation of the prepared material. Further, six composites of HAp with SrCO3 and ZrO2 were synthesized to study the morphological and tribological behaviour. Three composites of HAp with three varying 2, 4, 6 wt% of SrCO3 and similarly other three with ZrO2 were prepared using solid-state route method. Scanning electron microscopy (SEM) analysis confirmed that the presence of SrCO3 and ZrO2 among HAp particles helps in grain growth during the sintering processes. The tribological study reveald that the inclusion of SrCO3 and ZrO2 in pure HAp enhanced the resistance to wear and specific wear rate. The average grain size of HAp–ZrO2 was observed more in comparision to the average grain size of the HAp–SrCO3. The values of the specific wear rate and wear of HAp–SrCO3 and HAp–ZrO2 composite ceramics lies in the range from 4.13,239 × 10−5 to 5.44517 × 10−5 mm3/Nm and 4.68693 × 10−5 to 6.10099 × 10−5 mm3/Nm, respectively.

Critical behavior studies in Ti-substituted lanthanum bismuth perovskite manganites

Perovskite manganite La0.4Bi0.6Mn1−xTixO3 (x = 0.05 and 0.1) synthesized using conventional solid state route method give rise to critical phenomenon in their magnetic interactions due to the substitution of non magnetic Ti ions. The critical behavior is observed near paramagnetic–ferromagnetic transition and is studied by magnetization measurements. Various techniques like Modified Arrott plot, Kouvel–Fisher method, scaling equation of state analysis and the critical magnetization isotherm were used to analyze the magnetization data on magnetic phase transition. The values of critical exponents β and γ obtained using different techniques are in good agreement. The obtained critical exponents are found to follow scaling equation with the magnetization data scaled into two different curves below and above the transition temperature, TC. This confirms that the critical exponents and TC are reasonably accurate. The obtained critical exponents for both the samples deviates from mean-field model and do not completely follow the static long range ferromagnetic ordering. This behavior is consistent with non magnetic nature of Ti substituted at Mn site and can be associated with Griffiths phase like phenomenon.

Magnetic and electrical properties of Ti-substituted lanthanum bismuth manganites

We are reporting the influence of non-magnetic Ti ions on magnetic, electrical, magneto-transport, and dielectric responses in polycrystalline ferromagnetic insulating samples $$ {\text{La}}_{ 0. 4} {\text{Bi}}_{ 0. 6} {\text{Mn}}_{{ 1 { - }x}} {\text{Ti}}_{x} {\text{O}}_{ 3} $$ (x = 0.05 and 0.10) synthesized by solid-state route method. Powder X-ray diffraction analysis reveals that the samples crystallize in tetragonal structure indexed to I4/mcm space group. Scanning electron micrographs suggest that the increase in Ti substitution inhibits grain growth process leading to decrease in grain size. The characteristic magnetic dilution with increase in x is evident due to the non-magnetic nature of the Ti ions. Also, in magnetization curve, the observed glassy behavior restricts the long-range magnetic spin interactions in the broader temperatures range. The electrical resistivity measurements exhibited semiconducting nature throughout the measured temperature range (110–300 K) without metal-semiconductor phase transition. The magneto-transport behavior in the paramagnetic region (for T > 150 K) follows $$ \left[ {{\text{MR}}\sim \frac{\Delta \rho }{{\rho \left( {0T} \right)}}} \right] \propto H^{n} $$ relation, giving possible correlation between electrical and magnetic properties. Resistivity data at low temperature region suggest that the conduction is due to the hopping of charge carrier, satisfying SE-VRH mechanism. However, the resistivity data at high-temperature regime suggest the localization of small polarons. The large dielectric responses achieved with multiple relaxations are understood due to extrinsic and intrinsic properties. Complex impedance spectrums have been analyzed using equivalent circuits to determine different contributions responsible for the relaxation process with Ti substitution.

Granular Responses of GdBa2Cu3O7-δ Using ac Magnetic Susceptibility Measurement under ac and dc Magnetic Fields

Abstract Granularity of bulk materials has a great impact on the characterization of superconductors as well as its path towards room temperature applications. Bulk GdBCO that has crystal formation and Tc close to YBCO were fabricated using the conventional solid state route method. AC magnetic susceptibility measurement is done on the sample to observe the granular responses brought about by small magnetic field values that is superimposed with DC magnetic field. Results show that compared to YBCO, GdBCO show more sensitive behaviour with the addition of DC magnetic field. It is shown in the results that abrupt response in the AC loss peaks observed in χ” is more prominent in GdBCO even at lower applied magnetic fields.

Dielectric Properties of Y2O3 and Nb2O5 Co-Doped Barium Titanate Ceramics

Conventional solid-state route method was used to prepare barium titanate ceramics doped with Y2O3 and Nb2O5, Ba(Y0.5Nb0.5)xTi(1-x)O3 (x = 0.02, 0.04, 0.06, 0.08). The X-ray diffraction results confirmed that Y3+ and Nb5+ both substitute for Ti4+ at the B-site of ABO3 perovskite type structure, and second phase appeared for x = 0.04 and 0.06. With the increases of Y3+ and Nb5+ concentrations, peak of dielectric constant of Ba(Y0.5Nb0.5)xTi(1-x)O3 ceramics shifts to lower temperature more rapidly than that of BaZrxTi1-xO3 ceramics as the same x content. It was found that Ba(Y0.5Nb0.5)0.06Ti0.94O3 ceramics has compact structure, better temperature stability of dielectric constant, larger dielectric tunability under DC electric field. The results showed that, the Y2O3 and Nb2O5 doping improved the figure of merit for the BaTiO3 ceramics.

Non-magnetic impurity induced magnetism in rutile TiO2:K compounds

Recent ab initio studies have theoretically predicted room temperature ferromagnetism in several oxide materials of the type AO2 in which the cation A4+ is substituted by a non-magnetic element of the 1 A column. Our purpose is to address experimentally the possibility of magnetism in Ti1−xKxO2 compounds. The samples have been synthesized via the solid state route method at equilibrium. Our study has shown that Ti1−xKxO2 is thermodynamically unstable and leads to a phase separation, in contradiction with the hypothesis of ab initio calculations. In particular, the crystalline TiO2 grains appear to be surrounded by K-based phase. The oxidization state of the Ti ion is found to be in Ti4+ as confirmed from the x-ray photoelectron spectra measurement. Nevertheless, K:TiO2 compounds exhibit weak paramagnetism with the highest magnetic moment of ∼0.5 μB K−1 but no long-range ferromagnetic order. The observed moment in these compounds remains much smaller than the predicted moment of 3 μB by ab initio calculation. The apparent contradictions between our experiments and first-principles studies are discussed.

Effect of A site and B site doping on structural, thermal, and dielectric properties of BiFeO 3 ceramics

Polycrystalline Bi 1− x Ba x Fe 1− y M y O 3 (M = Co and Mn; x = 0.1, y = 0.1) were synthesized by solid-state route method to study the compositional driven structural transformations in multiferroics. Room temperature X-ray diffraction patterns confirmed the formation of perovskite structure. Rietveld-refined crystal structure parameters revealed the existence of rhombohedral R3 c symmetry for both the samples. The samples were found to be nearly free from any other secondary phases. Raman analysis reveals that Ba atom substitutes Bi site and Mn and Co atom substitutes Fe site into the BiFeO 3 with the shifting of phonon modes. The red shift is attributed to Co or Mn doping where as blue shift occurs from Ba doping. The differential scanning calorimetry reveals the corresponding Neel temperature 370 °C and 326 °C for Co and Mn doped samples. Ba and Co substitution with x = 0.1 and y = 0.1 has not affected the Neel temperature of the parent BiFeO 3 as well of Ba and Mn substitution. The variation of frequency dispersion in permittivity and loss pattern due to A-site and B-site substitution in BiFeO 3 was observed in the dielectric response curve.

Electrical transport of Ce doped La–Ca–Mn–O system

We report here the low temperature (below transition temperature T P) resistivity behavior of Ce doped La 0.7Ca 0.3MnO 3. Polycrystalline samples of compositions La 0.7Ca 0.3MnO 3 (sample 1), La 0.7Ca 0.25Ce 0.05MnO 3 (sample 2) and La 0.65Ce 0.05Ca 0.3MnO 3 (sample 3) were prepared by solid state route method. From the XRD studies, it is revealed that all the samples exhibit the single phase with orthorhombic structure (Space group Pnma). From the resistivity data, it is found that all the samples show metal to insulator transition and with the Ce doping the transition temperature ( T P) decreases. The resistivity data in the metallic region from 55 K to 190 K show T 2 dependence for all the samples, consistent with the electron–electron scattering. In the temperature range above 190 K, the two-magnon and electron–phonon processes contribute to scattering of carriers. It is also found that the value of resistivity increases with the doping of Ce on Ca site but decreases with the doping of Ce on La site.

A new layer perovskites Pb 2Ga 2Nb 2O 10 and RbPb 2Nb 2O 7: An efficient visible light driven photocatalysts to hydrogen generation

We report here the novel approach to synthesis of layer perovskite photocatalysts, Pb 2Ga 2Nb 2O 10 and RbPb 2Nb 2O 7 using solid state route (SSR) and molten salt synthesis (MSS) method. The reported modified MSS method has advantage over conventional SSR method for uniform particle size, well-defined crystal structure, controlled morphology and stoichiometry vis-à-vis photocatalysis. The structural study was performed using X-ray difractometry (XRD) and computation based on density functional theory (DFT). The simulation study showed that both the compounds belong to the Ruddlesden-Popper phase (A′ 2A n−1 B n O 3 n+1 ; n = 2 or 3). The surface morphology of the materials was studied using field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The average particles size of perovskites Pb 2Ga 2Nb 2O 10 and RbPb 2Nb 2O 7 was in the range 20–40 and 70–90 nm respectively. The efficacy of these materials was studied to particle size and morphology as a visible light driven photocatalyst for the hydrogen generation from H 2S. Electronic band structure with DOS has also been performed for both the materials. Being a stable single-phase ternary-layered oxide perovskites and band gap (2.75 eV) in visible domain, they may have potential applications in electronic devices as well.