The energy of crystallographic shear plane formation in reduced tungsten trioxide

The free energy of crystallographic shear (CS) planes in reduced tungsten trioxide has been considered in a semiquantitative fashion. The CS planes are treated as chemical defects in the tungsten trioxide structure and the energy to create such defects is considered to be largely due to enthalpy contributions due to chemical bond breaking. An assessment of this enthalpy term for the various CS plane types known in the tungsten oxide based CS phases is made and the results are then used to explain the experimentally observed CS plane microstructures in binary and ternary tungsten oxide CS phases.