Conductivity and dielectric relaxation in sodium borosulfate glasses

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• 作者：Inder Pal ; Ashish Agarwal ; Sujata Sanghi ; Anshu Sheoran ; Neetu Ahlawat
• 关键词：Oxide materials ; Electrical transport ; Ionic conduction ; Electrochemical impedance spectroscopy
• 刊名：Journal of Alloys and Compounds
• 出版年：2009
• 出版时间：20 March 2009
• 年：2009
• 卷：472
• 期：1-2
• 页码：40-45
• 全文大小：651 K

文摘

Sodium borosulfate glasses having composition xNa₂SO₄·(30−x)Na₂O·70B₂O₃ (1.5 ≤ x ≤ 9.0 mol % ) were prepared by melt-quenching technique. The influence of Na₂SO₄ on physical and thermal properties has been interpreted using density, molar volume and DSC data. The decrease in glass transition temperature (T_g) with increase in Na₂SO₄ content indicates that the average chain length of the host glass matrix decreases. The temperature-dependent conductivity data of the above glass samples have been obtained using impedance measurement in the temperature range 523–593 K and the frequency range 20 Hz to 1 MHz. The dc electrical conductivity (σ_dc) follows Arrehenius relationship and activation energy is 0.83 ± 0.03 eV for ionic migration. The dc conductivity (at 553 K) of the glass with x = 1.5 mol % is 2.08 × 10⁻⁴ Ω⁻¹ m⁻¹ and it is 6.16 × 10⁻⁴ Ω⁻¹ m⁻¹ for x = 9 mol % . The ac conductivity obeys Almond-West type power law behaviour: σ(ω) = σ_dc + σ_ac(ω) = σ_dc + Aω^s. The behaviour of the complex permittivity, dielectric loss and dielectric modulus as a function of frequency was also investigated. An excellent time–temperature superposition in the imaginary part of dielectric modulus (M″) confirms that the dynamical processes are temperature independent and is also an indicative of a common ion transport mechanism.