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Journal of Materials Science

, Volume 30, Issue 14, pp 3720–3729 | Cite as

The optical properties and a.c. conductivity of magnesium phosphate glasses

  • S. K. J. Al-Ani
  • I. H. O. Al-Hassany
  • Z. T. Al-Dahan
Papers

Abstract

Magnesium phosphate [X MgO-(100−X) P2O5] glasses in the composition range [X=20, 25, 30, 40, 45, 50 mol %] have been made. The optical properties and a.c. conductivities were measured and their amorphous nature confirmed by X-ray diffraction technique. The variation of relative density with x was anomalous. In the ultraviolet/visible regions it was found that the fundamental absorption edge is a function of glass compositions and lower absorption coefficients, α(Ω) follow the so-called Urbach edge. At lower absorption levels (1<α<104cm−1), the width of the tail of localized states in the band gap, Eg, did not vary significantly with glass composition and lay in the range (0.26–0.343) eV. In the high absorption region (α(Ω)>104 cm−1), the behaviour of α(Ω) suggests that there are two different transition energies for electrons in k-space, namely direct allowed transitions and non-direct transitions. In the infrared region at wavelengths λ=2.5–30 Μm, the transmission spectrum has four absorption bands. Using the Kramers-Kronig theory, the optical constants (refractive index n and extinction coefficient k) have been determined from the transmission spectrum. The a.c. conductivity, σ(Ω), real and imaginary dielectric constants, ε1, ε2, and loss factor, tan δ, have been determined at room temperature in the frequency region, Ω = 2×104−106 Hz. It has previously been established theoretically that σ(Ω)∼Ωs and s was found to be in the range 0.64–0.73, depending on glass composition.

Keywords

Refractive Index Dielectric Constant Relative Density Transmission Spectrum Loss Factor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1995

Authors and Affiliations

  • S. K. J. Al-Ani
    • 1
  • I. H. O. Al-Hassany
    • 1
  • Z. T. Al-Dahan
    • 1
  1. 1.Department of PhysicsCollege of Education for Women, University of Baghdad, JadiryaBaghdadIraq

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