  Li et al. (Science Advances, 29 January, p. eabe3068) claim the discovery of
two improper ferroelectrics, dabcoHClO4 and dabcoHBF4 (dabco =
1,4-diazabicyclo[2.2.2]octane), and that these materials exhibit superior
pyroelectric figures of merit. This information is misleading due to the
fundamental methodological errors and false conclusions, not to mention that
these ferroelectrics were reported over 20 years ago. They are proper
ferroelectrics, for which the spontaneous polarization is the macroscopic order
parameter. We show that the useful pyroelectric coefficients of these materials
are about 103 times lower than these reported by Li et al.
