Durability and Ionic conductivity Flashcards

1
Q

Why is Na+ diffusivity in a silicate glass significantly greater than in NaCl?

A

~ in NaCl, Na+ diffusion needs the adjacent Na+ site be vacant and that Cl- ions move out of the way
~ an open glass network facilitates easy motion of Na+
~ higher conc of Na2O PUSHES NETWORK OPEN, facilitating Na+ migration

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2
Q

How do alkali containing glasses become electrically conductive at high temp?

A

~ mobile Na+ ions, not e-
~ more Na2O dialates network, more Na+ mobility

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3
Q

What trend is shown between alkali silicate glasses and high ionic conductivity?

A

~ Rb+<K+<Li+<Na+
~ ionic conductivity increases with decreasing cation size (smaller cations move with less displacement of surrounding ions)

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