Key Points of article about Dielectric and spectroscopic property of glass

As per study, Adding Bi2O3 up to 12.5 mol% decreases the thermal stability and increases the crystallization behavior of prepared non-crystalline solids.

Kubelka-Munk function is used to measure the optical band gap of glasses.

where R∞ is the relative remittance (R∞=Rsample / Rstandard) , 

S is the sample’s scattering coefficient, 

K is the absorption coefficient, and 

F(R∞) is the K-M function or the remission function.

Tauc equation has been used to calculate band gap energy.

By increasing the Bi2O3 content, the band gap energy slightly increases.

Here Non-bridging oxygen (Connected to only one P atom, associated with a metal ion (P-O-M)) ions decrease, a development of bridging oxygens occurs and the dense glass structure is created.)

The refractive index decreases with increase in Bi2O3. It was calculated for the glass using the Dimitrov and Sakka equation.

The trivalent cations(Bi3+)  improves the strength of phosphate glass due to the relative ability of the glass matrix which leads to the creation of the M3+–O–P bond.

With the addition of Bi2O3 content in the glasses, Metallization criterion(M) values increased. refractive index and optical band gap of the material

have an impact on  M values.

The replacement of the P2O5 by 2.5 mol% of Bi2O3 leads to a decrease in ac-conductivity values, and then the conductivity rises with more replacement of the P2O5 content to 10 mol%. The main reason for the conduction is the presence of Li+ions.

For an Oxygen/Phosphorus ratio < 3, and in spite of the high concentration of Bi3+ ions, the O–P bond becomes longer, which results in decreasing the polarizability and hence, the conductivity of the glass.

At low frequencies, tangent loss (dissipation of energy) is high and reduces as the frequency goes to high due to the presence of Maxwell-Wagner-Sillars polarization. (It occurs at regions with different electrical properties e.g. conductivity or permittivity. It describes the accumulation of charge at interfaces between different phases or regions when an alternating electric field is applied.)

M'(electric modulus) has low values at low frequency, then increases with rising frequency until it attains a constant value at f > 6 kHz due to the increase in the movement of the charges under a high-frequency electric field.

Source: https://link.springer.com/article/10.1007/s00339-024-08103-4