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Calcium copper titanate (CCTO) ceramic is prepared by conventional solid-state reaction (SSR) technique. Sintering of manufactured CCTO ceramic is completed at 1050 °C for 4 h. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) are used to know the crystallinity and microstructural properties of CCTO ceramic. The space group (Im3) of CCTO crystal structure is confirmed by XRD analysis. FE-SEM image discloses that the grains have distinguishable grain boundaries. Grains are highly compact and porosity is very low. The dielectric properties and electrical properties are investigated in the temperature and frequency range of (30–130 °C) and (100 Hz–1 MHz), respectively. At 100 Hz and 30 °C, CCTO exhibits a giant dielectric constant ~ 7685. Impedance analysis confirms the relaxation, depends on temperature in CCTO ceramic. Existence of relaxation named non-Debye in CCTO ceramic is confirmed by Modulus study. Activation energy calculated by linear fitting of dc-conductivity is 0.14 eV. This material is a suitable candidate for capacitor application due to giant dielectric constant. [ABSTRACT FROM AUTHOR]

Single phase NaNb 1 − x Mn x O 3 (NMn) with x = 0.00−0.06 ceramics were synthesized using solid state reaction technique at 1150 °C sintering temperature. The Rietveld refinement of XRD patterns of NMn ceramics confirms the orthorhombic phase symmetry with P b m a space group. The field emission scanning electron microscopy (FE-SEM) reveals that grains become denser and larger with doping. The dielectric constant (ϵ ′) and tangent loss (tan δ) study has been done at room temperature to 500 °C over a wide frequency in both cooling and heating mode. The anomaly at high temperature region in temperature dependent dielectric constant (ϵ ′) plot in both thermal cycle attributes to the P(AFE)-R(AFE) polymorphic phase transition. The relaxor nature of the studied samples strongly depends on dopant concentration and applied field. The impedance analysis reveals negative temperature coefficient of resistance (NTCR) behaviour of material. The Nyquist study suggests the non-Debye characteristic of the dielectric relaxation in NMn ceramics. • Rietveld refinement confirms the single phase formation of NMn samples. • Anomaly in ɛ vs. T plot suggests the P-R polymorphic phase transition. • High value of ɛ and low value of tan δ obtained for Mn modified NN samples. • Non-Debye type relaxation and NTCR nature confirmed from impedance study. [ABSTRACT FROM AUTHOR]

Sodium niobate ( N a N b O 3 ) ceramics is prepared by conventional solid state reaction method at sintering temperature 1150  °C for 4 h. The structural information of the material has been investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FE-SEM). The XRD analysis of N a N b O 3 ceramics shows an orthorhombic structure. The FE-SEM micrograph of N a N b O 3 ceramics exhibit grains with grain sizes ranging between 1 µm to 5 µm. The surface coverage and average grain size of N a N b O 3 ceramics are found to be 97.6 % and 2.5 µm, respectively. Frequency dependent electrical properties of N a N b O 3 is investigated from room temperature to 500  °C in wide frequency range (100 Hz–5 MHz). Dielectric constant, ac–conductivity, impedance, modulus and Nyquist analysis are performed. The observed dielectric constant (1 kHz) at transition temperature (400 °C) are 975. From conductivity analysis, the estimated activation energy of N a N b O 3 ceramics is 0.58 eV at 10 kHz. The result of Nyquist plot shows that the electrical behavior of N a N b O 3 ceramics is contributed by grain and grain boundary responses. The impedance and modulus spectrum asserts that the negative temperature coefficient of resistance (NTCR) behavior and non-Debye type relaxation in N a N b O 3 . [ABSTRACT FROM AUTHOR]