  A calculation of the expected signal due to Primakov coherent conversion of
solar axions into photons via Bragg scattering in several solid--state
detectors is presented and compared with present and future experimental
sensitivities. The axion window m_a>~0.03 eV (not accessible at present by
other techniques) could be explored in the foreseeable future with crystal
detectors to constrain the axion--photon coupling constant below the latest
bounds coming from helioseismology. On the contrary a positive signal in the
sensitivity region of such devices would imply revisiting other more stringent
astrophysical limits derived for the same range of the axion mass.
