We review the pyroelectric properties and electronic structure of Li2B4O7(110) and Li2B4O7(100) surfaces. There is evidence for a pyroelectric current along the  direction of stoichiometric Li2B4O7 so that the pyroelectric coefficient is nonzero but roughly 103 smaller than along the  direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the  direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected. The time dependent surface photovoltaic charging suggests that surface charging is dependent on crystal orientation and doping, as well as temperature.
Adamiv, V. T., et al. (2010). The Electronic Structure and Secondary Pyroelectric Properties of Lithium Tetraborate. Materials, 3(9), 4550–4579. https://doi.org/10.3390/ma3094550