Surface charge was measured on four synthetic manganese dioxides. Charge densities on two cryptomelanes followed closely the values predicted by a theoretical model. Charge densities on two birnessites were much higher, and did not fit the model.
No takes yet. Share an insight, caveat, or question.
RM McKenzie (1981) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: