Carbonation reaction of (Ca, Mg)O protective layer on plasma display panel

Abstract

We have been applying a low discharge voltage (Ca, Mg)O protective layer to plasma display panels to reduce their power consumption. However, (Ca, Mg)O is highly reactive with CO2, and the resulting carbonate formation during high‐temperature panel sealing in air impairs the low discharge voltage characteristic. We investigated the mechanism of the carbonation reaction that occurs on a (Ca, Mg)O surface during annealing in air at 450°C and found that the CO2 diffuses through the formed CaCO3 layer and that a (Ca, Mg)O + CO2 → CaCO3 + MgO reaction then occurs. This carbonation reaction evidently stops when the growing MgO finally forms a layer at all boundaries between the CaCO3 and (Ca, Mg)O regions.

Annealing process for recovery of carbonated (Mg,Ca)O protective layer for plasma discharge device

“…The analysis of the depth profiles of photoelectron signals from carbon has revealed that the depth of the presence of carbon from the surface is related to the discharge voltage for a (Ca,Mg)O protective layer with different CaO concentrations. 42) We have directly demonstrated that no carbonation of the (Mg,Ca)O protective layer in the panels occurs at Mg sites, but that it occurs predominantly at Ca sites; the carbonation ratio is clearly related to discharge voltage, even at the same CaO concentration.…”

“…The material with the highest potential as a higher-γ protective layer is (Mg,Ca)O. [25][26][27][28][29][30] (Mg,Ca)O is relatively stable compared with the other materials described above because it is MgO-based. Many groups report that low discharge voltages are obtained relative stably with a (Mg,Ca)O protective layer.…”