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TSC and dc conductivity for cesium iron phosphate glasses

The thermally stimulated current (TSC) and dc conductivity have been measured for iron phosphate glasses containing up to 20 mol% of Cs2O. Thermally stimulated depolarisation current (TSDC) measurements from 120 to 400 K show two current peaks, P1 attributed to the polarisation caused by dipolar defects and P2 due to an interaction between the caesium ions and nonbridging oxygen ions. The dc conductivity and activation energy were constant and independent of Cs2O content. With increasing caesium concentration in caesium iron phosphate glasses the slowly moving casium ions are more tightly bound to the nonbridging oxygen ions and make no measurable contribution to dc conductivity. The dc conduction in these glasses is totally electronic, controlled by electron hopping between iron ions. The ionic conduction is immeasurably small because of the low mobility of the casium ions. Raman spectroscopy indicated that the structure of these glasses was composed of predominantly pyrophosphate (P2O7) groups, but the metaphosphate chains (PO3) also existed.

TSC ; DC conductivity ; cesium iron phosphate glass ; Raman spectroscopy

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