Elastic constants of orthorhombic KNbO3by X-ray diffuse scattering

All nine elastic constants of orthorhombic potassium niobate (space group Bmm2) have been determined at room temperature from a diffractometric study of 006, 040 and 600 diffuse reflexions. The values of the elastic constants in units of 1012 dynes.cm−2 are: C11 = 0.354, C22 = 0.516, C33= 0.632, C44 = 3.558, C55 = 3.651, C66 = 2.069, C12 = −1.058, C23 = −1.914, C13 = −2.027. Equiscattering contours and K surfaces have been calculated using these values of the elastic constants.