Maximum Dielectric Permittivity Research Articles

Effects of scandium oxide on domain structure, dielectric and ferroelectric properties of barium zirconate titanate ceramics

The Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ferroelectric ceramics were fabricated by the conventional solid state reaction method. The influences of Sc2O3 on their microstructure, especially domain structure, dielectric and ferroelectric properties were investigated by X-ray diffractometer, scanning electron microscope, LCR measurement system and ferroelectric tester. The Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ceramics are tetragonal perovskites with no impurity phases. The average grain size of Ba(Zr0.1Ti0.9)O3 ceramics decreases from ~40 µm to ~5 µm as the Sc2O3 content increases. Both the 90° ferroelectric domains and the 180° ones exist in the 0.2 mol% Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ceramics with an average grain size of ~26 µm. The ferroelectric -paraelectric phase transition temperature and the dielectric permittivity maximum of Ba(Zr0.1Ti0.9)O3 ceramics decrease with increasing Sc2O3 doping content, while the temperature stability of relative dielectric constant is improved effectively after Sc2O3 modification in BZT ceramics. The remnant polarization and the coercive field of BZT ceramics decrease in Sc2O3 highly doped BZT ceramics as the Sc2O3 content increases.

Comprehensive characterization of Ba1−xSrxTiO3: Correlation between structural and multifunctional properties

Considering the superior multifunctional performance and beautiful structural tunability, Ba(1−x)SrxTiO3 (0 ≤ x ≤ 1) samples were synthesized in this work by following a conventional solid state reaction technique. The structural, vibrational, optical and dielectric properties of the synthesized materials were characterized extensively throughout the work. Band gap energy of all the materials was evaluated from optical characterizations and correlated with structural properties. Study of leakage characteristics rendered fruitful explanation for electrical properties. At x = 0.4, a structural phase transition from ferroelectric to paraelectric state was observed. All the functional properties were correlated with structural properties. The Ba0.6Sr0.4TiO3 sample showed maximum room temperature dielectric permittivity (~4000 at 1 kHz) with good frequency and thermal stability. The dielectric loss tangent of this composition was reduced to ~0.0098 (at 1 kHz) which was even much lower than that of undoped BaTiO3. The detail temperature dependent dielectric and impedance characteristics of this sample were also evaluated. The activation energy, calculated from dielectric characterizations, was found to be ~1 eV suggesting the governance of doubly ionized oxygen vacancy for conduction and relaxation mechanism.

Effects of crystallization kinetics on the dielectric and electrical properties of BiFeO3films

BiFeO3 thin films were prepared using the chemical solution route on Pt/TiO2/SiO2/Si(100) substrates under different crystallization kinetics. The crystallization kinetic effects on the dielectric and electrical properties have been investigated. These properties included dielectric permittivity, electric modulus, electrical conductivity measurements as a function of the temperature (300–525 K) and frequency (102–106 Hz), and leakage current measurements electric field range ± 30 kV/cm at room temperature. The differences observed in conductivity and current density of the BiFeO3 films were discussed in terms of possible defects induced by the crystallization kinetic. An anomalous relaxor-like dielectric behavior characterized by a broad maximum in the real dielectric permittivity as a function of temperature and the low-frequency dielectric dispersion has been observed. The nonexpected peaks in the real permittivity were accompanied by increasing at least four orders in the conductivity’s magnitude at high temperatures. The origin of the relaxor-like dielectric anomalies is discussed, suggesting that the dielectric permittivity peaks are artifacts due to carrier migration correlated to the onset of the Maxwell–Wagner effect.

Structural, microstructural and dielectric characterizations of (Bi0.5Na0.5)TiO3based lead-free ferroelectric ceramics

(1–[Formula: see text][Formula: see text][Formula: see text]TiO3–[Formula: see text]BaTiO3lead-free ceramics have been obtained from the conventional solid-state reaction sintering method. The structural properties were investigated from X-ray diffraction and Raman spectroscopy techniques. Results revealed well-crystallized ceramic samples with perovskite structure. Microstructural properties, obtained from scanning electron microscopy measurements, have shown high density with very low porosity level. The dielectric response, analyzed as a function of the temperature and several frequencies, showed very broad peaks with a strong frequency dependence of the temperature for the maximum dielectric permittivity for the modified system. Results were analyzed considering the influence of the BaTiO3 content on the studied physical properties.

Energy density and storage capacity of La3+ and Sc3+ co-substituted Pb(Zr0.53Ti0.47)O3 thin films

We studied the energy density and storage capacity properties of rare-earth modified lead zirconate titanate thin films. Highly oriented thin films of (PbZr0.53Ti0.47)(1−y)(LaxSc1−x)yO3 wherein; [for y = 0 and x =0 viz PL0] and, [for y = 0.1 and x = 0.2, 0.4, 0.6 and 0.8 viz PL2, PL4, PL6 and PL8 respectively] abbreviated as PL10x have synthesized on MgO (100) substrate by the pulsed laser deposition technique. The higher proportion of lanthanum increased the broadening of dielectric permittivity and dielectric maxima that shifted to higher temperatures with increasing frequency, signifying the relaxor-type behavior of these films. The value of the relaxation parameter varies from γ = 1.69 for PL6 and 1.95 for PL8 that was estimated from the linear fit of the modified Curie-Weiss law indicating the relaxor nature satisfying Vogel-Fulcher relation. Furthermore, we achieved enhanced spontaneous polarization of the fabricated thin films. Slim loop hysteresis was observed on tuning lanthanum and scandium and the estimated recovered energy density (Ure) is 51.15 J cm−3 and 26.54 J cm−3 with efficiency (η) of 47.38% and 65.88% respectively for PL6 and PL8 thin films. The high dielectric permittivity, high breakdown strength, and enhanced energy storage density of thin films could make it promising materials for memory, power electronics, and energy storage applications.

Thermally induced transitions and depolarization of Fe2O3 doped PMnS-PZN-PZT piezoelectric ceramics

Thermally induced transitions and depolarization of Fe2O3 doped PMnS-PZN-PZT ceramics are investigated. The ceramics have a highly diffused dielectric peak, but the temperature for the maximum dielectric permittivity Tm is frequency independent, which rules out the ceramics to be classified as typical relaxors. Meanwhile, the depolarization temperature Td determined by the thermally stimulated depolarization current is found to be notably lower than Tm, which is distinct from the behaviors of normal ferroelectrics as well. An extraordinary phenomenon noted is that the Td coincides quite well with a characteristic temperature where the dielectric permittivity shows the fastest increase. This characteristic temperature, denoted as TF-R, is faint in the temperature-dependent dielectric permittivity but can be well resolved by taking the first derivative of dielectric permittivity with respect to temperature. In addition, it is found a number of features of the anomaly around TF-R that are quite similar to the ferroelectric-to-relaxor transition in typical relaxors, and therefore, the TF-R is assigned to a transition from ferroelectric state to a “relaxor-like” state, in which the correlation of ferroelectric order could be weakened. Complex impedance analysis reveals the presence of small polarizable entities at high temperature, providing further support for the high-temperature relaxor-like state. It is suggested that the depolarization of Fe2O3 doped PMnS-PZN-PZT is related to the disruption of long-range ferroelectric order into polar regions with small sizes, rather than the ferroelectric-to-paraelectric transition.

The effect of an AC electric field on the dielectric properties of Pb(Mg1/3Nb2/3)O3 ceramic

The dynamic dielectric response of Pb(Mg1/3Nb2/3 )O3 ceramic was experimentally studied as a function of the EAC amplitude field. An increase in real dielectric permittivity was obtained by increasing the applied electrical field within the investigated temperature range for frequencies below 10 kHz. The temperature of maximum dielectric permittivity and freezing temperature decreased with an increase in E AC. Nonlinear permittivity was studied and found to behave similarly to freezing temperature. A statistical model was used to fit the dielectric dispersion of real dielectric permittivity with temperature and frequency. The results are discussed in terms of different factors’ contributions to dielectric permittivity under different EAC field conditions.

Ferroelectric soft mode and microwave dielectric relaxation in BaTiO3−PbMg1/3Nb2/3O3 ceramics

${\mathrm{BaTiO}}_{3}$ (BT) is the best-known ferroelectric and $\mathrm{Pb}{\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}$ (PMN) is the best-known relaxor ferroelectric, but their solid solutions were so far studied only very scarcely. Here the high-density perovskite ceramic solid solutions of $(1\ensuremath{-}x){\mathrm{BaTiO}}_{3}\text{\ensuremath{-}}x\mathrm{Pb}{\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}$ (BT-100$x$%PMN, $x=0.075$, 0.10, 0.15) were studied by the infrared reflectivity, time-domain terahertz transmission and microwave spectroscopies (1 MHz--20 THz) and compared with the undoped BT and PMN ceramics. The spectra show presence of a split soft phonon at all temperatures, similar to that observed in BT and PMN. Microwave dielectric dispersion was observed both below and above temperature of the diffuse permittivity maximum. In the case of BT-7.5%PMN and BT-10%PMN, the main dispersion takes place above 1 GHz, in case of the BT-15%PMN, the dispersion covers more homogeneously the 1 MHz--1 THz range. The dielectric response up to the THz range of the BT-10%PMN and BT-15%PMN was fitted with three excitations: soft mode, central mode (lower-frequency component of the split soft phonon), and microwave relaxation, but the soft mode does not soften appreciably and only the latter two excitations contribute substantially to the dielectric permittivity maximum. Dielectric response of the BT-7.5%PMN is similar except for the presence of a second dielectric relaxation in the MHz range, also observed in BT. The relaxations show no PMN-like freezing and can be tentatively attributed to the dynamics of polar nanoregions in the paraelectric phase and to the domain/nanodomain wall dynamics and/or acoustic wave emission and piezoelectric resonances within the grains in the ferroelectric phase. In this way, the BT-100$x$%PMN ceramics cannot be considered as relaxor ferroelectrics, but rather as ferroelectrics with the diffuse phase transition. The broadband dielectric spectra of undoped BT ceramics revealed a split optical soft mode and two additional dielectric relaxations which are mainly responsible for the dielectric anomaly at the ferroelectric phase transition. It supports the phase transition in BT to be at the crossover from a displacive to an order-disorder type.

Simultaneous enhancement of polarization and breakdown strength in lead-free BaTiO3-based ceramics

Lead-free dielectric ceramic capacitors have garnered extensive attention owing to their excellent dielectric and energy storage characteristics. However, most currently reported lead-free dielectric ceramics have limitations, including an unclear local phase structure, and inverse correlation between polarization and dielectric breakdown strength. These issues can be well solved by establishing the relationship between structure and performance. Herein, we enhanced both the polarization and dielectric breakdown strength of BaTiO3-based ferroelectric ceramics by tailoring the temperature corresponding to the maximum dielectric permittivity to room temperature and decreasing the grain size. We confirmed the existence of a tetragonal phase structure in the relaxor BaTiO3-based ferroelectric ceramics. The simultaneously enhanced polarization and breakdown strength can be derived from the distortion of octahedral [TiO6] in the lattice and improved insulation performance. Finally, an ultrahigh recoverable energy density (Wrec) of 4.23 J/cm3 and efficiency (η) of 93.40% with decent stability (variation of Wrec ≤ 9.76% over 20–190 °C, Wrec ≤ 2.25% in 1–100 Hz, and Wrec ≤ 1.78% after 5000 cycles) were simultaneously achieved in the novel BaTiO3-based ceramics. This study may provide a feasible and paradigmatic approach to develop high performance dielectrics for energy storage applications.

Possibility of relaxor-type ferroelectricity in delafossite CuCrO2 near room temperature

Ceramic sample of CuCrO2 was synthesized via a solid-state reaction method. XANES, dielectric, ferroelectric, pyroelectric, synchrotron x-ray diffraction (SXRD), transmission electron microscope (TEM) and Raman measurements were performed on the prepared sample. Ferroelectric hysteresis loop, PUND, and pyroelectric current measurements indicate the presence of ferroelectricity in the prepared sample. The appearance of a broad maximum in dielectric permittivity and its frequency dispersion indicates the possibility of relaxor-type ferroelectricity in the system. Furthermore, TEM measurements revealed the presence of nano regions that are speculated to be polar and hence are giving rise to relaxor-type ferroelectricity. Careful analysis of XRD data indicates that the distorted CrO6 octahedra is giving rise to strain in the sample. This strain might be responsible for the observed nano regions, which might be polar, in the otherwise non-polar matrix. It is proposed that these polar regions are responsible for the presence of relaxor-type ferroelectricity in the sample.

On the Effect of Water-Induced Degradation of Thin-Film Piezoelectric Microelectromechanical Systems

Lifetime and reliability in realistic operating conditions are important parameters for the application of thin-film piezoelectric microelectromechanical systems (piezoMEMS) based on lead zirconate titanate (PZT). Humidity can induce time-dependent dielectric breakdown at a higher rate compared to dry conditions, and significantly alter the dynamic behavior of piezoMEMS-devices. Here we assess the lifetime and reliability of PZT-based micromirrors with and without humidity barriers operated at 23°C in an ambient of 0 and 95 % relative humidity. The correlation of the dynamic response, as well as the ferroelectric, dielectric, and leakage properties, with degradation time was investigated. In humid conditions, the median timeto-failure was increased from 2.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> [1.9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> -4.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ] s to 1.1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> [0.9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> -1.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> ] s at 20 VAC continuous unipolar actuation, by using a 40 nm thick Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> humidity barrier. However, the initial maximum angular deflection, polarization, and dielectric permittivity decreased by about 6, 11, and 12 %, respectively, for Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> capped devices. For both bare and encapsulated devices, the onset of electrothermal breakdown-events was the dominant cause of degradation. Severe distortions in the device's dynamic behavior, together with failure from loss of angular deflection, preceded time-dependent dielectric breakdown in 95% relative humidity. Moreover, due to the film-substrate stress transfer sensitivity of thin-film devices, water-induced degradation affects the reliability of thin-film piezoMEMS differently than bulk piezoMEMS.

Dielectric response of Rb2ZnCl4 within porous aluminum oxide

The dielectric properties of a composite material obtained by embedding of the Rb2ZnCl4 salt into a matrix of porous Al2O3 film with an average pore diameter of about 300 nm were studied within the temperature range 110–350 K. A wide temperature hysteresis of dielectric permittivity exceeding the range of experimental temperatures was revealed. A broad maximum of dielectric permittivity was found, the position of which varies within 230–330 K, depending on the thermal prehistory of the sample. It is supposed that this maximum is associated with a ferroelectric phase transition in the Rb2ZnCl4 inclusions.

Temperature-dependent dielectric properties of metal-doped ZnO nanofiller reinforced PVDF nanocomposites

Here, we report on the successful fabrication of organic-inorganic composite films with poly (vinylidene fluoride) (PVDF) polymer and calcium doped zinc oxide (CaZ) and cadmium doped zinc oxide (CdZ) as two different nanofillers. The incorporation of these nanofillers resulted in increased crystalline and piezoelectric β-phase content of PVDF composites. The comparison of temperature-dependent dielectric studies showed enhanced dielectric properties of CaZ-loaded PVDF composites compared to CdZ-based PVDF composites. At 1 kHz, a maximum dielectric permittivity of 26.13 with a dielectric loss of 0.477 was obtained for 10 wt% CaZ-loaded PVDF composite film (10 CaZ-P) at 100 °C. The relaxation time of as-prepared composites showed Arrhenius behavior and lower activation energy for 10 CaZ-P composites (66.24 kJ/mol). For the 10 CaZ-P composite films, the AFM topography analysis showed higher roughness value (16.54 nm) and confirmed the lower activation energy of the same.

An unusual frequency dispersion of the dielectric permittivity maxima at temperatures around the tetragonal–cubic phase transition of methylammonium lead iodide

We report studies on the unusual frequency dispersion of the dielectric permittivity maxima of methylammonium lead iodide pellets at temperatures around the tetragonal–cubic phase transition. The origin of this observed permittivity response was studied in terms of grains and grain boundaries’ contributions in impedance, electric modulus, dielectric permittivity, and electrical conductivity. From theoretical fits of impedance and electric modulus measurements at different temperatures over a frequency range of 103–10 Hz, the reconstructed contributions of the grain boundary and grain permittivities show peaks around 339 K and 384 K, respectively. The origin of the grain boundary permittivity peak is discussed in terms of heterogenic ionic conduction associated with I− and MA+ ions in MAPbI3, while the peak in grain permittivity at high temperature is in terms of ionization of intrinsic carriers. The high value of the grain dielectric permittivity (εg=1193), compared to the reconstructed grain boundary permittivity (εgb=53), suggests a possible relaxor ferroelectric behavior with a diffuse phase transition for methylammonium lead iodide. The difficulties in confirming the ferroelectric nature of this halide perovskite based on impedance and electrical module data are also discussed.

Polymorphic and morphotropic phase transitions in Pb(Mg1/3Nb2/3)O3–PbTiO3 solid solutions

Study of evolution of ferroelectric correlations in a system which intrinsically exhibits short range polar order in the form of polar-nano regions (PNRs), is the goal of the present work. For this purpose, well-known Relaxor ferroelectric i.e. PbMg1/3Nb2/3O3(PMN) and its solid solutions with PbTiO3(PT) has been systemically synthesized by varying composition, precursors and synthesis parameters. Dynamics associated with the PNRs and structural phase transitions of various polymorphs have been traced through temperature and frequency dependent dielectric permittivity profile. Formation of solid solutions with PT generates ferroelectric correlations associated with the tetragonal polymorphs, suppresses thermal fluctuations, overcomes diffused character of phase transition, effects polarization switching, stabilizes ferroelectric hysteresis characteristics and shifts dielectric permittivity maxima toward higher temperatures. Addition of PT led to relaxation dynamics associated with the multiple polymorphic phase transitions for T < 500 K, where system exhibits intrinsic character. Polymorphs with low symmetries lies below freezing temperature, where structural phase transition generates polar order. Diffusivity and activation energy of phase transitions, and freezing temperatures of polar regions of various processes have been quantified and compared as a function of PT. Excellent ferroelectric response of the compositions lying in the vicinity of the Morphotropic phase boundary composition has been observed.

The influence of sintering temperature on structural and electrical properties of x (Ca0.28Ba0.72)Nb2O6-(1-x) (Sr0.61Ba0.39)Nb2O6 ceramics

The novel tetragonal tungsten bronze x(Ca0.28Ba0.72)Nb2O6-(1-x)(Sr0.61Ba0.39)Nb2O6 solid solution ceramics were successfully synthesized by a conventional solid-state reaction method. The structural, dielectric, and ferroelectric properties of the ceramics were studied in detail. The result indicates that the sintering temperature has a significate influence on the microstructure, phase transition, dielectric, and ferroelectric properties of the prepared ceramics. The fluid phase participating during the sintering processing is common for the system. The Curie temperature T0 increases for all compositions, but the temperature of the maximum dielectric permittivity Tm decreases for the composition with the high content of Sr because of the ordering-disordering effect.

Electrical properties of, Na1−0.315K0.315Nb1−yTayO3 (0 ≤ y ≤ 0.05) system

Na0.685K0.315Nb1−yTay O3 (where y = 0, 0.01, 0.02, 0.03, 0.04, 0.05) based ceramics were synthesized by the conventional solid-state reaction process. The effects of (Ta) – doping on the phase structure and electrical properties of (NKNTaO3) were observed. The cell parameters were refined by High Score Plus software, using Rietveld method, The monoclinic Pm(6) space group was chosen in these refinements. X-ray diffraction analysis shows that the crystal structure of the ceramics, without and with Ta-doping possessed monoclinic symmetry. Among the prepared compositions, a break in the XRD peaks shifting tendency was observed at y = 0.03, and also maximum dielectric permittivity, loss tangent and electrical conductivity observed at the composition with y = 0.03.

Estimation of relaxor behavior in Sr2+ doped Na0.5Bi0.5TiO3 ceramics

An attempt has been made to study the relaxation mechanism of nanoscopic polar regions (PNRs) in Sr2+ doped Na0.5Bi0.5TiO3 relaxors; in particular, the compositions (0.90Na0.5Bi0.5TiO3–0.10SrTiO3, 0.80Na0.5Bi0.5TiO3–0.20SrTiO3, 0.70Na0.5Bi0.5TiO3–0.30SrTiO3) with temperature stable dielectric permittivity > 4500 over a broad range of working temperatures are chosen for this work. The temperature and frequency dependent growth and dynamics of these PNRs are investigated around the three crucial temperatures-$$T_{\text{B}}$$ (Burn’s Temperature), $$T_{\text{m}}$$ (temperature of maximum dielectric permittivity) and $$T_{\text{f}}$$ (freezing temperature) employing some empirical models and IS technique. Careful examination of combined plots of normalized $$M^{\prime\prime}\left( f \right)$$ and $$Z^{\prime\prime}\left( f \right)$$ spectra suggest a transition from long range ordering to short range dipolar relaxation as samples are cooled from above $$T_{\text{B}}$$ to below $$T_{\text{f}}$$. Activation energies derived from the Arrhenius fit of $$f_{\hbox{max} }$$ (from $$M^{\prime\prime}\left( f \right)$$ plot) reveal different relaxation mechanisms of the PNRs in three separate temperature domains around $$T_{\text{B}}$$, $$T_{\text{m}}$$ and $$T_{\text{f}}$$. This is also advocated by the analysis of stretched exponent $$\beta$$ obtained from Gaussian and KWW fit. Further, a scaling study made on the $$M^{\prime\prime}\left( f \right)$$ spectra predicts temperature sensitive dipolar relaxation. The present study may add a new dimension to the establishment of NBT-ST relaxor ceramics as potential material for capacitor applications at a higher temperature.

Suppression of Dielectric Loss at High Temperature in (Bi1/2Na1/2)TiO3 Ceramic by Controlling A-site Cation Deficiency and Heat Treatment

Dielectric capacitors are integral components in electronic devices that protect the electric circuit by providing modulated steady voltage. Explosive growth of the electric automobile market has resulted in an increasing demand for dielectric capacitors that can operate at temperatures as high as 400 ℃. To surpass the operation temperature limit of currently available commercial capacitors that operate in temperatures up to 125 ℃, Bi1/2Na1/2TiO3 (BNT), which has a large temperature-insensitive dielectric response with a maximum dielectric permittivity temperature of 300 ℃, was selected. By introducing an intentional A-site cation deficiency and post-heat treatment, we successfully manage to control the dielectric properties of BNT to use it for high-temperature applications. The key feature of this new BNT is remarkable reduction in dielectric loss (0.36 to 0.018) at high temperature (300 ℃). Structural, dielectric, and electrical properties of this newly developed BNT were systematically investigated to understand the underlying mechanism.

Tuning the permittivity of tellurium dioxide by Ti substitution

Structure with the asymmetric environment of cation has a large effect on the polarization mechanism and dielectric response. In this study d0 cation, Ti4+ is introduced into asymmetric α-TeO2 to prepare TixTe(1-x)O2 (x = 0 to 0.25) by conventional solid-state method. In all the samples, it is found that the dielectric response increases relative to the parent α-TeO2. Sample with x = 0.25 forms cubic TiTe3O8 phase and shows maximum dielectric permittivity of 77. The remaining samples show biphasic nature comprising cubic (TiTe3O8) and tetragonal (α-TeO2) phase and their dielectric behaviour follows the Lichtenecker logarithmic mixing rule of composites. Structural analysis reveals that the cubic TiTe3O8 phase consists of TeO4 and TeO6 framework structure with locally strained TeO4 units compared to α-TeO2 and the Raman study complements this observation. The local strain enhances the dipolar polarizability of TeO4 unit; additionally, ionic polarizability of TiO6 unit also contributes to high dielectric permittivity in TiTe3O8.