We find Mn surface segregation for single crystals of Mn doped Li2B4O7, nominally Li1.95Mn0.05B4O7(001), but as the temperature increases, evidence of this Mn surface segregation diminishes significantly. At room temperature, the surface photovoltaic charging is significant for this pyroelectric material but is quenched at a temperature well below that seen for the undoped Li2B4O7 samples. The suppression of surface charging in the region of 120 °C that accompanies the temperature of Mn dissolution in the bulk of Li2B4O7, i.e., the reversal of Mn surface segregation (215 °C), suggests that along the (001) direction, ionic transport must be considered as significant.
Applied Physics Letters
Dugan, C., Hengehold, R. L., McHale, S. R., Colón Santana, J. A., McClory, J. W., Adamiv, V. T., … Dowben, P. A. (2013). Reversible Mn segregation at the polar surface of lithium tetraborate. Applied Physics Letters, 102(16), 161602. https://doi.org/10.1063/1.4802760