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Samples of the system SrCe1−xGdxO3 (x = 0.0, 0.02, 0.04, 0.06 and 0.10) were prepared using a conventional ceramic route. The phase and structural properties of samples were investigated using X-ray diffraction. Rietveld refinement of the XRD data supported the crystallization of samples in an orthorhombic structure under space group Pnma . FTIR and TGA measurements indicated the presence of SrCO3 in all the samples. The incorporation of Gd into the lattice was shown to reduce the direct optical bandgap and average grain size. The DC conductivity of the cylindrical pellets of samples was investigated using AC impedance measurements at temperatures ranging from 300 to 600 °C. The highest conductivity was observed for the composition SrCe0.98Gd0.02O3 such as 1.54 × 10−3 Scm−1 at 600 °C. This compound has the potential to be work as mixed ionic and electronic conductor for SOFCs. The XPS spectra of Ce 3d and O 1 s confirmed the presence of Ce in both Ce3+ and Ce4+ states and oxygen vacancies. The oxygen vacancies in the samples were analyzed using Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Powders of a few compositions of the system Sr2Ce1-xNaxO4 (x = 0, 0.02, 0.04, 0.06, and 0.10) have been prepared by the conventional solid-state reaction method. Analysis of the XRD patterns has shown a preference of dopant Na+ for the Sr2+ sites with increasing content of dopant (x). Rietveld refinement of the XRD patterns confirmed that each sample crystallized in orthorhombic structure with space group Pbam. The purity of the synthesized samples was further examined using Raman Fourier Transform Infrared (FTIR) spectroscopy techniques. Raman spectroscopy has further indicated the risk of decomposition of Sr2CeO4 phase with increasing doping concentration. Optical band gap energy computed using UV–visible absorption data (Tauc's plot) falls between 2.91 and 3.10 eV, decreasing with increasing x. The shape of the excitation and emission spectra remains unchanged with increasing Na+ concentration. Two excitation peaks located around 290 nm and 350 nm are seen in photoluminescence (PL) excitation spectra. All Na-doped samples display an intense blue emission at 472 nm similar to undoped Sr2CeO4. SEM images of fractured surfaces of the sintered pellets have shown a significant role of Na doping on the morphology and grain size of the Sr2CeO4. [ABSTRACT FROM AUTHOR]

The samples of Sr2‐xNdxSnO4 with x = 0, 0.01, 0.02, 0.04, 0.06, and 0.10 were synthesized by a high‐temperature solid‐state ceramic route. Rietveld refining of X‐ray diffraction results showed that all the synthesized compositions are single phase under tetragonal crystal structure. The presence of functional group and local structure has been studied using FTIR and Raman spectroscopy, respectively. XPS study of samples showed the presence of oxygen vacancy and interstitial oxygen in the sample. Optical band gap of samples analyzed by UV‐Vis spectra gradually increases with dopant concentration, and Photoluminescence (PL) spectroscopy study showed most intense emission around 1064 nm. Room‐temperature magnetic hysteresis curve in sample SSN2 showed ferromagnetism, slowly decreasing with Nd and becoming antiferromagnetic for higher compositions. Utilizing the absorption state observed in PL as metastable state makes it promising candidate for laser and IR detector application and the ferromagnetic/antiferromagnetic nature of sample makes it suitable candidate for spintronics device applications. [ABSTRACT FROM AUTHOR]

Summary: Nanocrystalline powders of co‐doped ceria oxides Ce0.85La0.10Sr0.05O2‐δ (CLSO) and Ce0.85Gda0.10Sr0.05O2‐δ (CGSO) have been synthesized by auto combustion method at 100°C using sucrose as fuel. Thermal analysis (TGA/DSC) of as‐prepared powders indicated calcination above 400°C to remove organic residue. The average grain size of the pellets sintered at 1200°C for 4 hours is 436 and 683 nm for CLSO and CGSO, respectively. The electrical conductivity of the sintered samples was determined by impedance measurements in the temperature range 300°C to 600°C and the frequency range 20 Hz to 2 MHz. At 600°C, the total electrical conductivity (σt) of CGSO is 6.78 × 10−3 S cm−1, 2.5 times higher than 2.72 × 10−3 S cm−1 of CLSO. Further, it is found that the value of grain boundaries blocking factor (αgb) of CGSO is 0.47 which is 30% lesser than 0.68 of CLSO at 600°C. The higher value of electrical conductivity of CGSO as compared to CLSO is attributed to the lesser blocking effect of grain boundaries, smaller lattice distortion and denser microstructure of CGSO as compared to CLSO. The electrical conductivity of synthesized samples has been compared with the electrical conductivity of similar compositions of co‐doped CeO2 oxides. Our study indicated that the sintering temperature, and hence, the morphology of sintered samples has a significant role in determining the electrical conductivity. The presence of oxygen vacancies in the synthesized samples is experimentally supported by using UV‐visible spectroscopy, Raman spectroscopy, and thermal analysis techniques. [ABSTRACT FROM AUTHOR]

The reaction mechanism for the formation of Sr2SnO4 by solid-state reaction between SrCO3 and SnO2 has been investigated using thermal analysis (TG and DSC) combined with X-ray diffraction (XRD) techniques. It is observed that the formation of single-phase Sr2SnO4 takes place by reaction between SrO and SrSnO3 at temperatures ≥ 900 °C. Based on these studies, a few compositions of the system Sr2−xLaxSnO4 (x = 0.01, 0.02, 0.04, 0.06 and 0.10) have been synthesized by calcination at 1000 °C for 8 h. Rietveld refinement of the XRD data confirmed that all the synthesized samples have tetragonal structure, space group (I4/mmm) and symmetry group D4h17. The crystallite size and induced lattice strain has been calculated using size strain plot (SSP), varies from 30 to 50 nm and from (3.00 to 6.27) × 10−3, respectively. Raman and Fourier transformed infrared (FTIR) spectroscopy techniques have been utilized to ponder local changes in the structure of Sr2SnO4 with La incorporation. The optical properties of the samples have been studied using UV-Vis spectroscopy. The systematic shift in the position of the absorption edge (toward the higher wavelength) indicates the incorporation of La in the lattice of Sr2SnO4. The direct and indirect band gap of the samples calculated through Tauc's plot. The variation in the value of direct band gap is attributed to changes in the charge compensation mechanism or/reduction in particle size. [ABSTRACT FROM AUTHOR]

A few compositions of (Ba 1-x La x) 2 SnO 4 with 0 ≤ x ≤ 0.10 have prepared via solid-state ceramic route followed by calcination at 1000 °C for 8 h. The preliminary phase of samples has analyzed using XRD and found to be crystallized into tetragonal structure up to 4 atoms %. The solubility limit of La at Ba-site has reconfirmed using FTIR and Raman analysis. The AC conductivity spectra of single-phase samples follow universal Jonscher's power law σ a c = σ d c (1 + (f f h) n). Further, the thermal dependence of dc conductivity (σ d c) and hopping frequency (f h), indicating the presence of Arrhenius type charge transport in the samples. Ghosh scaling applied to σ a c of all temperatures found to superimpose on a single master curve, indicates the invariance of conduction mechanism. The impedance spectroscopy studies reflect the major contribution of grain in the conduction and relaxation process of all sample. Based on present study, the present material can be potentially used in semiconductor devices, UV-detector, and mixed ionic and electronic conductor (MIECs) by utilizing absorption states and thermo-curves as metastable state. • Single phase samples of Ba 2-x La x SnO 4 (0 = x ≤ 0.10) are synthesized at 1000 °C. • The solubility limit of La is analyzed by XRD, Raman, and UV–Vis. study. • The AC conductivity of single-phase samples follow universal Jonscher's power law. • AC conduction mechanism is explained using OLPT model. • Contribution of grain/grain boundaries is analyzed by Impedance spectroscopy. [ABSTRACT FROM AUTHOR]

The studies carried out in this paper are directed towards preparation of nanocomposite films of PVA (polyvinyl alcohol)-GO (graphene oxide) with variable wt% of GO by simple solution mixing technique and exploration of spectroscopic, surface morphological, structural, optical, electrical, and mechanical properties. In this article, the detailed molecular structure of PVA-GO polymer nanocomposites (PNCs) was optimized by using the Gaussian code (B.01 version). Experimentally, the structural information was gathered by using the X-ray diffractometer and determined the crystalline size (varying from 12. 82 nm to 24.62 nm for 1–5 wt% of GO in PVA/GO PNCs) and micro-strain (varying between 7.21 × 10−3 and 42.12 × 10−3) produced in the samples through Williamson-hall plot. The existence of the functional groups with their role in the nanocomposites was also examined with the help of FTIR technique. In order to identify the Raman bands (availability of D and G bands at ~1340 and 1595 cm−1, respectively, while the 2D band at ~2910 cm−1) and corresponding structural changes were studied by Raman spectrometer (with the usage of 532 nm laser). The study of surface morphology was performed by utilizing the AFM and FESEM (with EDAX) techniques and effect of GO on the surface roughness of the nanocomposite film was studied. The r.m.s. roughness of the films were set up to be 90.375 nm, 96.449 nm, 98.120 nm, 99.006 nm and 99.891 nm for GO of 1–5 wt%, respectively. The optical properties were determined using UV–Vis-NIR spectrophotometer and tuning of optical bandgap (varied from 3.56 eV to 2.45 eV with 1–4 GO wt%) was investigated. The resulting variation due to GO concentration was also confirmed with structural information. The electrical characteristics (capacitance, dissipation factor and electrical conductivity) were also investigated. The DMA analysis of the nanocomposites was performed to measure the mechanical property (Young's Modulus varying from 2 GPa to 16 GPa for 1–5 GO wt%) and found that the nanofillers (GO) plays an important role to enhance the various abovementioned properties. [Display omitted] • Reparation of PVA-GO nanocomposites and understanding role of GO in the composite via their characterizations • Determining the crystallized phase of GO dominating over the PVA giving modification in crystallite size and presence of micro-strain. • Confirmation of functional groups and their role in the nanocomposite and study of Raman bands and corresponding structural changes in the composites • Study of tunability of the optical bandgap on incorporation of GO. This tuning in band gap has also been supported by XRD and computational results. • Study of capacitance, dissipation factor, electrical conductivity and observation of significant enhancement of mechanical properties of the prepared nanocomposites [ABSTRACT FROM AUTHOR]

• The samples have been synthesized using Sol-Gel combustion route at 60 °C. • All samples are crystallized into cubic spinel group under space group (Fd 3 ¯ m). • Positive zeta potential reflects stability of nano-powders in conducting liquid. • Optical band gap of samples reflects inorganic semiconducting nature. • Temperature-dependent resistivity shows Arrhenius type conduction in samples. The Ni modified samples ZnFe 2-x Ni x O 4 with x = 0, 0.05, and 0.10 were synthesized using the sol-gel combustion method at 60 °C. The phase of obtained samples was determined using X-ray powder diffraction and found that it crystallized into a cubic spinel group. The lattice parameter of samples was decreased with increasing Ni concentration. However, the local symmetry of samples was explored using Raman spectroscopy. The presence of Raman band at 655 cm−1 was assigned to the vibration of Fe-O; found to be shifted towards higher wavenumber reconfirm the incorporation of Ni. The optical bandgap of the samples was determined using the Tauc plot and found to be in the range of 2.50 to 2.95 eV, which reflects the inorganic semiconducting nature of samples. Dielectric properties of samples were studied as a function of frequency and temperature show the presence of interfacial and orientational polarization in the sample. The resistivity of samples has been studied using Arrhenius model, and found three different regions of conduction within investigated temperature range. The first region assigned to the hopping of electron, while the second region to the hopping of polaron via the orientation of dipole (2 Ni Fe ' - 2 h.) , or (2 Ni Fe ' - V o..) , and the third region assigned to migration of V o.. or e ' / h.. The conductivity of samples found in range of (0.85–8.95) S-cm−1 higher than conventional electrolytes used in IT-SOFCs. Based on these studies, the present materials can be used as a potential candidate for semiconductor devices and electrolytes in IT-SOFCs applications. [ABSTRACT FROM AUTHOR]