Li2O Glass Research Articles

High strength YSZ/YSZ joints bonded with a matching thermal expansion coefficient sealing glass

A novel CaO–Al2O3–SiO2–Li2O (CASL) glass was developed for bonding yttria–stabilized zirconia ceramics (YSZ). The CASL glass possessed a coefficient of thermal expansion (CTE) that matched with YSZ and exhibited outstanding wettability on the surface of YSZ substrate. During the bonding process, mutual dissolution and diffusion between YSZ and CASL glass took place, which ensured good interface bonding. Furthermore, the rapid cooling speed led to a completely amorphous seam, which allowed the CTE of the seam to correspond with that of the original glass. The optimal flexural strength of YSZ/YSZ joints could reach more than 90 % of that of the YSZ.

Gamma and neutron attenuation of SiO2–B2O3–BaO–Li2O glasses doped with CeO2

Abstract The demonstrations impact of CeO2 on the radiation shielding properties of SiO2–B2O3–BaO–Li2O glasses has been investigated. The observed trend in density ρ ranged from 3.127 to 4.022 g/cm³, whereas the molar volume V m of these glasses decreased. The half-value layers (HVL), and mean free paths (MFP) of CL glasses reinforce the notion that the presence of Ce ions, particularly in CL2, enhances the ability of glasses’ to attenuate gamma rays. The effective electron density (N eff) increases with the addition of CeO2, suggesting a correlation between the enhancement of radiation shielding properties and the amount of CeO2 incorporated into the glasses.

Synthesis, physical, optical, and radiation attenuation efficiency of Bi2O3+SrF2+Li2O glass system

This research paper reports on the optical characteristics and ionizing radiation attenuation properties of newly fabricated 55B2O3+ 10Bi2O3+ 20SrF2+ (15-x)Li2O + xCuO where x = 0 (Cu0) - 8 (Cu8) in steps of 2 mol%. Density of the fabricated glasses was increased from 3.2836 g cm−3 to 3.5424 g cm−3 as CuO concentration enriched from 0 to 8 mol%. The estimated indirect Eg values were 3.04, 2.93, 2.86, 2.61 and 2.52 eV for the Cu0, Cu2, Cu4, Cu6 and Cu8 glass samples, respectively. Metallization criterion (M) has the following values 0.39, 0.38, 0.37, 0.36 and 0.35 for the Cu0, Cu2, Cu4, Cu6, and Cu8 glass samples, respectively. The nonlinear refractive index (n2) values were improved with further CuO content. Comparatively, μm follows the order: Cu0 < Cu2 < Cu4 < Cu6 < Cu8. The range of μ for Cu0 – Cu8 was 0.1076–7.5351, 0.1089–7.5721, 0.1108–7.6563, 0.1133–7.7761, 0.1163–7.9218 cm−1, correspondingly. The range of the HVL is 0.0920–6.3676, 0.0915–6.3676, 0.09053–6.254, 0.0891–6.1156, and 0.0875–5.9624 cm for Cu0 – Cu8, respectively. The partial density of B enhanced from 0.34106 to 0.3556 cm−1 as CuO mol% raised from 2 to 8 mol%. The total cross section for coherent (σcoh), incoherent (σinc), absorption (σabs), and total interaction (σtot) of thermal neutrons in the glasses grow with CuO content.

Investigation of AC conductivity and dielectric relaxation of lithium modified zinc borate semiconducting glasses for energy storage applications

Conductivity spectra of (80-x)B2O3.20ZnO.xLi2O (x = 10, 20, 30 and 40) glass series were studied in frequencies ranging from 0.1 Hz to 106 Hz and temperature ranging from 313 K to 573 K. The experimental data of ac conductivity is fitted using the Almond West model, and the parameters such as direct current conductivity (σdc), frequency exponent (s) and crossover frequency (ωH) have been extracted. Overlapping Large Polaron Tunneling is found to be applicable in studied glasses. Activation energy estimated from conductivity (0.89–1.39 eV), electric modulus (0.88–1.32 eV), and impedance (0.89–1.27 eV) analysis are in good agreement. Activation energy corresponding to ionic conduction in x = 30 and 40 mol% is found to be 1.09 and 1.10 eV respectively. Highest conductivity ∼2.5 × 10−5 Scm−1 is obtained for 40B2O3.20ZnO.40Li2O glass composition at 573 K. Impedance formalism indicates that electric conduction occurs via Li+ and electrons/polarons. It makes the studied glasses suitable for energy storage devices.

Physical, optical, mechanical, and radiation shielding properties for the B2O3–Li2O glasses

After starting of using ionizing radiation in many different fields, the scientists focused on to develop protection methods as it is dangers for the human body. Besides time and distance the most important way is shielding of radiation by using effective materials. With this motivation, the present study analyzes the physical, optical, mechanical, and Radiation shielding properties for the B2O3–Li2O glasses. Four different glasses coded as G-1 to G-4 are simulated via MCNPX Monte Carlo code by varying the concentration of the B2O3 + Li2O at 0–15 MeV gamma ray energies. The obtained results reveal that Li2O has a favorable influence on the radiation shielding characteristics of the preferred glass sample. To assess the relation between Li2O concentration in glass and corresponding structural and mechanical changes in candidate glasses, Makishima–Mackenzie theory is applied and mechanical moduli are extracted. The structure and dimensionality of the preferred samples are derived based on the Bergman and Kantor model for fluid and compositions with the help of the fractal bond connectivity. In addition, the longitudinal velocity (VL), transverse velocity (VS), mean velocity (V mean), and acoustic impedance (Zi) related to the glasses are evaluated.

Optical properties of the B2O3–CdO–ZnO–Li2O glasses modified with MoO3

Using optical investigations, this report analyzes the impact of MoO3 on lithium zinc cadmium borate glasses. The authors made glasses with the formula 60B2O3–20CdO–10ZnO–(10-x)Li2O–xMoO3 (Where x = 0, 0.5, 1, 1.5 & 2) and the samples were employed to UV–Visible and Electron paramagnetic resonance (EPR) experimental instruments. In order to determine the band gap, refractive index, and Urbach energy, optical absorption spectra are used. With the MoO3 in these glasses, the band gap was lowered while the refractive index improved. High MoO3 concentrations with high refractive indices make these glasses useful for optical applications. Two resonance signals were visible in the EPR spectra, one at g = 4.2 and the other with g = 1.95. The second signal shows that Mo5+ ions have occupied the sites of octahedral coordination with a mild axial distortion and C4V symmetry.

The role of modifier oxides on red emission of Eu3+ ions in lithium antimonite glass system

In this study, role of three modifier oxides (viz., MgO, CaO and SrO) on red luminescence efficiency of Eu3+ ions in Sb2O3‒Li2O glass system was investigated. The absorption spectra of these glasses exhibited the bands due to 7F0→ 5D4,3,2,1,0,5G4,2,5L6 and 7F0, 1→7F6 transitions in the visible and NIR regions, respectively. Emission spectra recorded at λexc=394 nm exhibited the bands due to 5D0→7FJ (J = 0 to 4) transitions. Out of these, the band due to5D0→7F2 (red emission ) was found to be more intense. J-O parameters, Ω2 and Ω4 were evaluated using integral R/O ratio of emission spectra. Radiative parameters viz., AR, βR and σEP for Eu3+ions were calculated using J-O parameters, These parameters were observed to be the maximal for SrO mixed glasses. Variations of local symmetry and covalency in the vicinity of Eu3+ ions were found to be responsible for such larger values of these parameters and for intense red emission for SrO mixed glasses.

A closer look at the impacts of MnO2 on the optical, mechanical, and radiation shielding properties of the B2O3–BaF2–Li2O glass system of 40B2O3 + (40-x) BaF2 + 5MgO + 15Li2O + xMnO2

A closer look at the impacts of MnO2 on the optical, mechanical, and radiation shielding properties of the B2O3–BaF2–Li2O glass system of 40B2O3 + (40-x) BaF2 + 5MgO + 15Li2O + xMnO2

An effective heat dissipation strategy improving efficiency and thermal stability of phosphor-in-glass for high-power WLEDs

Phosphor-in-glass (PiG) is one of the most important spectral converters to overcome thermal effect in high-power white light-emitting diodes (LEDs). The Al2O3–SiO2–B2O3–ZnO–Na2O–Li2O glass was designed and sintered with Y3Al5O12:Ce3+ (YAG: Ce) phosphors at the low temperature of 650 °C to obtain YAG: Ce-PiG. The optimized YAG: Ce-PiG shows the white light of the luminous efficiency (LE), correlated color temperature (CCT) and chromaticity coordinate (CIE) of 177.5 lm/W, 6410 K and (0.31,0.34), respectively. The white LEDs (WLED) were fabricated by coupling the YAG: Ce-PiG with a blue light emitting chip, and the correlation between the luminescence properties, the thickness of PiG and the ratio of phosphors was investigated. More importantly, the WLEDs of a maximum luminous efficiency can reach up to 199.5 lm/W with the thickness of 0.35 mm. In addition, a structure with vacuum packaging technique based on the WLEDs lighting combined with sapphire as substrate was fabricated, which can effectively reduce the heat accumulation during the working process of WLEDs. Compared with normal non-vacuum packaging, the working temperature of WLEDs was reduced by about 35%, from 359.2 to 232.2 °C, with the novel vacuum packaging technique under 30W high-power chip and the luminous performance can still be maintained at 94.7%. In a word, the prepared YAG: Ce-PiG exhibits a great potential for application in high-power solid-state WLEDs.

A significant role of MoO3 on the optical, thermal, and radiation shielding characteristics of B2O3–P2O5–Li2O glasses

The glass system 42.5P2O5–42.5B2O3–(\(15-x\)) Li2O–\(x\) MoO3 \(x\) = \((0, 2.5,5.10 \;{\text{and}}\;15\)), was fabricated using a melt-quenching technique. Optical features are examined depending on measuring the absorption and transmission of the prepared glasses. The energy gap (\(E_{{{\text{opt}}}}\)), increases from 2.23 to 2.49 e.V. Urbach (\(E_{u}\)), decreases from 0.513 to 0.5 e.V. Basicity, polarizability, electronegativity, and some physical constants are determined. The temperature of the glass transition Tg, increases from 493 to 532 °C, the temperature of onset glass crystallization Tc increases from 493 to 532 °C and the temperature of the crystallization Tp increases from 606 to 636 °C. Radiation shielding properties have been examined by Phy-X / PSD. The impact of adding MoO3 to the glasses on their shielding ability was investigated. The lower value of the (MFP) sample has been detected at a higher MoO3 concentration and it is good radiation attenuation glasses. For radiation protection applications, the investigational glasses had superior characteristics.

Influence of modifiers on the physical, structural, elastic and radiation shielding competence of Dy3+ ions doped Alkali boro-tellurite glasses

Highly efficient gamma ray shielding glasses with chemical composition 39.5H3BO3–25TeO2−15MO−10Na2CO3–10K2CO3−0.5Dy2O3 (M = BaO, CaO, SrO, Li2O, ZnO) were synthesized by traditional melt-quenching technique. Physical, structural and elastic features of the glass systems were examined to prove the formation of bridging oxygens. The attributes such as optical basicity and ionic nature (Ic) clarifies that the glasses are inclined in the direction of ionicity rather than covalency. The γ-ray shielding parameters of the investigated glasses were calculated in an important range in radiation protection (0.015–15 MeV). At 0.02 and 0.03 MeV, the SrO containing glass (BTNKD-Sr) shows the highest μ/ρ values which is substituted by the BaO glass (BTNKD-Ba) thereafter. It signifies that BTNKD-Sr is the most effective material in shielding lower energy photons (up to 0.0374 MeV), while BTNKD-Ba indicates better shielding against photons in a wide energy region (0.0374–15 MeV). The half value layer (HVL) values of the prepared glasses range from 0.0163 cm for Li2O glass (BTNKD-Li) to 0.0073 cm for ZnO glass (BTNKD-Zn) at 0.015 MeV, while the corresponding values range from 9.62 cm (BTNKD-Li) to 6.68 cm (BTNKD-Zn) at 15 MeV. The effective atomic numbers (Zeff) of the glasses are rapidly decreased at 0.3 MeV.

UV–Vis absorption spectroscopic analysis of [formula omitted] ion doped oxyhalide glasses

The glass networks are exciting with a result of their bonding like bridging and non-bridging over oxygens ions. In these networks the B2O3 and Li2O glass network is added with Bi3+ and Er3+ ions. we calculated some optical properties of oxyhalide glass system 60B2O3+30Li2O+xEr2O3+10-xBiCl3. With x changing from 0.1 to 0.5 mol % utilizing UV–Vis absorption spectra and the band gap was calculated utilizing Tauc plot relation. In these networks carry out direct and indirect permitted optical band gap energies (Eg). These outcomes show that, Eg decreases with the addition of Er3+ ions oxyhalide glasses content. Several proposed relationships for the refractive index and band gap energy for various compositions are discussed. Utilizing distinctive theoretical models, a suitable relationship is identified for the composition studied in this work.

The Structure of Gd3+-Doped Li2O and K2O Containing Aluminosilicate Glasses from Molecular Dynamics Simulations

Understanding the atomic structure of glasses is critical for developing new generations of materials with important technical applications. In particular, the local environment of rare-earth ions and their distribution and clustering is of great relevance for applications of rare earth-containing glasses in photonic devices. In this work, the structure of Gd2O3 doped lithium and potassium aluminosilicate glasses is investigated as a function of their network modifier oxide (NMO–Li2O, K2O) to aluminum oxide ratio using molecular dynamics simulations. The applied simulation procedure yields a set of configurations, the so-called inherent structures, of the liquid state slightly above the glass transition temperature. The generation of a large set of inherent structures allows a statistical sampling of the medium-range order of the Gd3+ ions with less computational effort compared to other simulation methods. The resulting medium-range atomic structures of network former and modifier ions are in good agreement with experimental results and simulations of similar glasses. It was found that increasing NMO/Al ratio increases the network modifier coordination number with non-bridging oxygen sites and reduces the overall stability of the network structure. The fraction of non-bridging oxygen sites in the vicinity of Gd3+ ions increases considerably with decreasing field strength and increasing concentration of the network modifier ions. These correlations could be confirmed even if the simulation results of alkaline earth aluminosilicate glasses are added to the analysis. In addition, the structure predictions generally indicate a low driving force for the clustering of Gd3+. Here, network modifier ions of large ionic radii reduce the probability of Gd–O–Gd contacts.

Synthesis and structural, optical, physical properties of Gadolinium (III) oxide reinforced TeO2–B2O3–(20-x)Li2O-xGd2O3 glass system

This study aimed to investigate different types of glasses based on 50TeO2–30B2O3–(20-x)Li2O-xGd2O3 (x = 0, 5, 10, 15, 20 mol.%) system in terms of their structural, optical, physical properties. Accordingly, five different samples were fabricated using melting-annealing method. Density calculations of the synthesized glasses were performed by using Archiemedes principle. Structural, optical, physical and radiation interaction properties were characterized through the XRD analyses, Raman spectra along with optical band gap, refractive index and Urbach energy and advanced simulation methods. Increasing Gd2O3 reinforcement from 0% to 20% mole increased glass density from 4.065 gcm−3 to 5.430 gcm−3. Optical transmittance as well as absorption parameters varied almost monotonically with increasing ratios of Gd2O3 indicating the ability to estimate and control these properties using Gd2O3 additive. Substitution of Li2O with Gd2O3 within the structure increased the optical band gap significantly. The results showed that TBLG20 sample with the highest Gd2O3 additive has the highest gamma-ray and charged particle attenuation properties. It can be concluded inserting of high concentration Gd2O3 to TeO2–B2O3–Li2O glass system is useful synergetic tool of combining structural, optical, and radiation characteristics.

Structural and nuclear shielding qualities of B2O3–PbO–Li2O glass system with different Ag2O substitution ratios

Structural and gamma-ray/neutron radiation protection characteristics of (50-x)B2O3 +40PbO+10Li2O + xAg2O (x = 0, 2.5, 5, 7.5, 10 wt fraction (wt) %) glass system encoded BPLA glasses have been extensively surveyed. The structure of the prepared glasses has been investigated over X-Ray Diffraction (XRD) patterns. With the addition of Ag2O, the glasses' amorphous structures have not deteriorated, and the density and molar volumes of BPLA glasses inversely varied. Mass attenuation coefficients (MAC) for BPLA glasses have been generated enjoying Monte Carlo N-Particle- Extended (MCNPX) simulation code for the broad gamma-ray energy range of 0.015–15 MeV. It has been observed that the MAC values of the BPLA10 glass are higher than the others at all energy levels. Furthermore, while Ag2O concentration in the glass has increased, Half Value Layer (HVLs) Energy Absorption and Exposure Buildup Factors (EABFs, and EBFs) have dropped off for photon energies which are important for shielding applications. It has been noticed from these results that owning higher equivalent atomic number (Zeq) values, BPLA10 can be employed effectively for gamma-ray attenuation. Lastly, the results found for fast neutron removal cross-sections (∑R) have shown that the Ag2O additive grew the density and ∑R values of the glasses. As with photon shielding, it is observed that BPLA10 glass can be more preferable in terms of neutron retention according to other glasses. One can conclude that Ag2O enhances the shielding capacity of the glass system studied and BPLA10 glass can be considered as a good material for gamma-rays/fast neutrons shielding.

Evaluation of optical features and ionizing radiation shielding competences of TeO2–Li2O (TL) glasses via Geant4 simulation code and Phy-X/PSD program

Abstract Via this article, the optical features and ionizing radiation shielding competences of xTeO2 − (100 − x)Li2O, where x = 70 to 95 in steps of 5 mol% glasses to be used in nuclear shielding areas were evaluated. These glasses were coded as TL05-TL30 according to x value. Refractive index (noptical), molar (refractivity (Rmolar) and polarizability (αmolar)), reflection loss (Rloss), Optical transmission factor (Toptical), dielectric constants (estatic and eoptical), and metallization criterion (Mcriterion) of TL-glasses have been investigated. The mass (MAC) and linear (LAC) attenuation coefficients were examined via Geant4 toolkit simulation code and verified via Phy-X/PSD. Results revealed that the (noptical) was increased from 2.24 to 2.30. The Rmolar varied from 17.432 to 19.122 (cm3/mol), the αmolar increased from 6.917 to 7.588 (×10−24 cm3), and the (estatic) varied from 5.022 to 5.308. The TL30 glasses possess the lowest values, while TL05 found to possess the maximum MAC values. The MAC values were in the order of (MAC)TL05 > (MAC)TL10 > (MAC)TL15 > (MAC)TL20 > (MAC)TL25 > (MAC)TL30 which highlights the role of Te addition to the glass matrix to enhance the shielding capacity of theses glasses. The HVL of these TL-glasses can be arranged in reverse order with MAC, where (HVL)TL30 > (HVL)TL25 > (HVL)TL20 > (HVL)TL15 > (HVL)TL10 > (HVL)TL05. The highest Zeff values are found at the low photon energy and ranged from 48.91 to 49.47 at 0.015 MeV for TL30 and TL05, respectively. While at 15 MeV, Zeff values are found 28.42 and 32.97 for TL30 and TL05, respectively. The TL05 glass with the highest TeO2 ratio has the largest Zeq values. The TL05 glass owns very low values of energy absorption buildup factor (EABF) and exposure buildup factor (EBF). This indicates that the TL05 sample was more effective than other samples in absorbing gamma radiation. One can conclude that the investigated TL-glasses have high ability to attenuate gamma-ray, especially TL05 glass sample. Therefore, these glasses can be applied in the field of nuclear protection.

Comparative evaluation of nuclear radiation shielding properties of xTeO2 + (100–x)Li2O glass system

In the present investigation, nuclear radiation shielding parameters of xTeO2 + (100–x)Li2O (where x = 95, 90, 85, 80, 75, and 70 mol%) glass system have been examined. Gamma shielding parameters such as mass attenuation coefficients (MAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), effective atomic number (Zeff), effective electron density (Neff) were calculated. Moreover, neutron effective cross sections (∑R) are determined. The calculations for present materials have been performed in different photon energy ranges (0.01–20 MeV) and using Monte Carlo N-Particle eXtended (MCNPX) simulation code and theoretical results were also obtained with WinXcom program. The results obtained from the MCNPX and WinXcom program were found to be in well harmony. Moreover, for the assessment of radiation shielding success of tellurite glasses, the mass stopping power (MSP) and projected range (PR) were computed for proton and alpha particles using stopping and range of ions in matter (SRIM) code. When the results obtained from the study are examined, it is seen that 95TeLi glass has the lowest HVL, TVL, MFP, TF and the highest (∑R) values. Therefore, the 95TeLi glass has the most perfect radiation shielding achievement than other investigated glasses.

Lateral cracks during sliding indentation on various optical materials

AbstractA series of static and sliding indentation (ie, scratching) was performed and characterized on a wide range of optical workpiece materials [single crystals of Al2O3 (sapphire), SiC, Y3Al5O12 (YAG), CaF2, and LiB3O5 (LBO); a SiO2–Al2O3–P2O5–Li2O glass ceramic (Zerodur); and glasses of SiO2:TiO2 (ULE), SiO2 (fused silica), and P2O5–Al2O3–K2O–BaO (Phosphate)] at various applied loads using various indenters (Vickers, 10 µm conical, and 200 µm conical). Despite having different load dependencies, the lateral crack depth formed during sliding indentation quantitatively scales with that formed during static indentation, explaining why static indentation has been historically effective in describing various grinding parameters. Depending on the indenter geometry, the amount of residual trench damage (plastic deformation and local fracturing) during sliding indentation was often enhanced by more than an order of magnitude compared with static indentation. A simple ploughing scratch model, which considers both tangential and normal stresses (where the tangential stress is amplified by relatively small tangential contact area), explains this enhancement and other observed trends. Accounting for the high correlation between residual trench depth and volumetric fracturing, the model is extended to estimate the amount of fracture damage as a function of the material properties of the workpiece, indenter geometry, and applied load. Such a model has utility in the design of optimized grinding processes, particularly the abrasive geometry. Finally, at higher loads (&gt;1 N), lateral cracks were often observed to preferentially propagate in the forward scratching direction, as opposed to perpendicular to the scratch as typically observed. High‐speed imaging of the scratch process confirms that these cracks propagate ahead of the sliding indenter during the scratching event. Finite element stress analysis suggests the ploughing frictional forces increase the mode I tensile stresses at the leading edge of the sliding indenter explaining the direction of crack propagation of such cracks.

Synthesis, microstructure and characterization of ultra-low permittivity CuO–ZnO–B2O3–Li2O glass/Al2O3 composites for ULTCC application

In view of lead-free low-softening CuO–ZnO–B2O3–Li2O glass, novel glass/Al2O3 ceramic composites were prepared by solid-state reaction route for ultra-low temperature co-fired ceramic (ULTCC) applications. The phase evolution and compositions, microstructure and microwave dielectric properties of the composites were studied by XRD, SEM and dielectric property measurement. Four phases including Cu2Al6B4O17, Li2CuB4O8, CuB2O4 and Al2O3 coexist in the glass/Al2O3 ceramic composites sintered in the range of 640–660 °C. However, the contents and types of the phases depend on the composition of the composites and firing temperature. The optimum properties with a permittivity εr = 3.79, a quality factor Q × f = 38557 GHz (at 16.64 GHz) and a temperature coefficient of resonance frequency τf≈0 ppm/oC as well as a heat conductivity λ = 1.46W(mK)−1can be achieved for the glass/ceramic composite containing 10 wt% Al2O3 sintered at 640 °C. Moreover, the composite can be co-fired compatible with Ag and Al electrodes.The as-prepared glass/Al2O3ceramic composites are promising candidate for ULTCC application.

Synthesis and study of electrical properties of Li2O modified P2O5-ZnO-Na2O glasses

The transparent glasses of composition 40P2O5-20ZnO-(40-x)Na2O-xLi2O have been prepared using conventional melt quenching technique (where 0 ≤ x ≤ 25 Li2O mol. %). The amorphous nature of the prepared glass samples is confirmed by x-ray powder diffraction (XRD). By increasing the Li2O content, the density and oxygen packing density increase while the molar volume decreases which indicates that the structure is more compact. The differential thermal analysis (DTA) studies showes that 15 mol.% Li2O glass sample has the highest thermal stability and the glass transition temperature (Tg) decreases as the content of Li2O increases till 25 mol.% Li2O . The ac and dc electrical conductivities and dielectric constants of the prepared glass samples have been investigated. It is found that the dc conductivity increases with the concentration of Li2O mol.% and the temperature dependence of the dc conductivity at low temperature (303 – 383 K) and at high temperature (403 – 473 K) obey the Arrhenius law. The activation energies ΔEdc1 (at high temperatures) and ΔEdc2 (at low temperatures) were determined. The values of σdc can be obtained also from the impedance study at different temperatures and different concentrations using Cole-Cole plot. To determine the conduction mechanism, the ac conductivity and its frequency exponent (s) have been analyzed by correlated barrier hoping model (CBH). It is found that s has values between 0.89-0.996; consequently. The correlated barrier hopping (CBH) seems to be the most interesting model related to the obtained results. Real and imaginary parts of dielectric constant (e' and e'') have been found to decrease with increasing frequency and temperature and this result would be discussed by means of dielectric polarization mechanism of material. The maximum value of the maximum barrier height Wm obtained from Guitini equation was found to increase with increasing of Li2O mol. %.