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0.8BaTiO₃–0.2Bi_0.5K_0.5TiO₃ (BT–BKT20) lead-free ceramics were prepared by conventional solid state reaction method followed by high energy ball milling. The formation of a single phase tetragonal structure in the material was confirmed by X-ray diffraction. Frequency and temperature-dependent dielectric studies show relaxor behavior in the BT–BKT20 which was found to obey modified Curie–Weiss law with degree of diffuseness 1.573. Complex impedance and electric modulus spectroscopy studies reveal temperature-dependent relaxation process in the material. The Cole–Cole plots were measured at high temperatures at which grain effect was observed. Impedance and electric modulus spectroscopy studies show non-Debye kind of conductivity relaxation process in the present material. Activation energies were calculated from impedance and electric modulus spectroscopy and the values of activation energy indicated that the conduction is ionic in nature. AC and DC conductivity have been measured and studied at different temperatures.

In the present study, pure and ${}_{\mathrm{\text{L}}}$-cystine (LC) doped zinc thiourea sulphate (ZTS) crystals have been grown by slow evaporation solution technique at ambient temperature. The powder X-ray diffraction (XRD) analysis has been carried out to identify the shifts in peak positions and structural parameters of grown crystals. The incorporation of LC in ZTS crystal has been qualitatively analyzed by means of Fourier transform infrared (FTIR) spectroscopic study. In UV-visible studies, the influence of LC on optical transparency, bandgap and various optical constants of ZTS crystal have been investigated to explore various optical applications. The thermal stability of LC doped ZTS crystal has been determined by means of differential scanning calorimetry (DSC) analysis. The hardness behavior and hardness number of grown crystals have been comparatively evaluated by employing the Vicker’s microhardness test. The dielectric study of pure and LC doped ZTS crystal has been carried out at different temperature. In Kurtz–Perry powder technique, the second harmonic generation (SHG) efficiency of LC doped ZTS crystal is found to be 1.16 times that of ZTS crystal.

Dielectric measurements were made over the temperature range 80–300 K at different frequencies (10 kHz, 50 kHz, 100 kHz, 500 kHz and 1 MHz). The degree of relaxor behavior and diffuseness of phase transition were correlated to the cationic disorder at lattice site B. Non-Debye dielectric behavior was observed in the present samples and a modified Arrhenius relation proposed by Chen et al. was found to best describe the frequency dependent dielectric maxima temperature.

L-Leucine Magnesium Nitrate HexaHydrate ($\mathrm{\text{LL}}+\mathrm{\text{MNHH}}$) crystal is a nonlinear optical (NLO) material of semiorganic type. It has grown using a slow evaporation solution growth (SEST) technique at elevated temperature (40^∘C) by dissolving LL+MNHH in double distilled water. It was crystalized and recrystalized from a supersaturated solution by stirring it for several hours to get high optical perfection. The X-ray diffraction studies confirmed the presence of the intermixed compound in the $\mathrm{\text{LL}}+\mathrm{\text{MNHH}}$ crystal and possess monoclinic structure. Fourier transform infrared spectroscopy (FTIR) spectrum identified the functional groups of the grown crystal. The crystal has very good optical absorption and transparency in the UV–Vis region. The thermal analysis revealed the thermal stability of the crystal. The dielectric study shows that dielectric constant and dielectric loss decrease at higher frequencies. The crystal showed nonlinear property by second-harmonic generation (SHG) study. This type of material with fair nonlinearity is useful in optoelectronics application devices.

The scope of the present work is in enhancing the particle size, and dielectric properties of Mg-substituted Cobalt ferrites nanoparticles prepared by sol–gel auto combustion method. The different ratios of Mg-substituted Co Ferrites (Co${}_{1-x}$Mg_xFe₂O₄($x=0.00$, 0.05, 0.10, 0.15, 0.20 and 0.30)) are calcinated at 850${}^{\circ }$C. The synthesized nanoparticles were characterized by powder XRD, FTIR, FE-SEM, EDX techniques and dielectric behavior. The structural parameters were confirmed from powder XRD and the average particle size is obtained from 39 to 67 nm due to the substitution of Mg${}^{2+}$ which was calculated by Debye Scherrer’s formula. FE-SEM showed the surface morphology of the different ratio of the sample. The dielectric loss has measured the frequency range of 50Hz–5MHz. From electrical modulus, conductivity relaxation and thermal activation of charge carriers has been discussed.

Polycrystalline Ni–Zn–Cr ferrite nanoparticles with composition Ni_0.5Zn_0.5Cr_xFe_2-xO₄ (for x in the range of 0.00–0.25 insteps of 0.05) were prepared through the nitrate-citrate gel autocombustion method. The as-obtained powders were ground and annealed at 1000°C for 4 h and characterized for spinel phase using X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). X-ray diffraction revealed the existence of single phase spinel while the TEM micrographs showed the presence of nearly spherical particles with soft agglomeration. Pelleted and toroidal samples of the same ferrite compound were sintered at 1000°C for 4 h. The dielectric constant and the dielectric loss tangent decreased with frequency in the range of 1 kHz–13 MHz while the initial permeability remained almost constant at lower measuring frequencies and thereafter increased with frequency for all samples. The observed variations have been discussed in the light of existing understanding.

In recent years rare earth compounds especially their fluorides have drawn particular attention as electrochemical gas sensors. Lanthanum and cerium fluoride based sensors have been investigated for sensing the fluorine, oxygen, and carbon monoxide because of their high chemical stability and high ionic conductivity. The fast response and good sensitivity of these sensors rely on the ion conduction properties of these thin films. In the present work Cerium Fluoride thin film has been prepared by vacuum thermal evaporation method. The electrical characterization is carried out using the Impedance spectroscopy method in the frequency range of 50 Hz to 5 MHz. The temperature dependence of ionic conductivity obeys the Arrhenius behavior and the activation energy E_a is found to be 0.3eV. The modulus and the dielectric spectra analysis reveal the non – Debye nature and the distribution of relaxation time due to the presence of grain and grain boundaries in the film. The relaxation energy E_d has been calculated from the dielectric spectra. The similar value of activation and relaxation energies suggests that the charge carriers that are responsible for bulk conductivity and relaxation process are the same. The optical measurement done in the wavelength range of 400-2500 nm confirms that the CeF₃ thin film is highly transparent and the band gap energy is found to be 3.5 eV.