Determining E₁ and E₂ values for yttrium aluminum garnet ceramics using the Duane-Hunt limit

A major challenge when performing scanning electron microscopy and X-ray analysis on many ceramic materials is their electrical insulation properties, which leads to buildup of the surface charge and reduced contrast in the secondary electron image. A new procedure was established to quantitatively determine the neutral state values, E₁ and E₂ , of yttrium aluminum garnet (YAG) ceramics using the Duane-Hunt limit (E_DHL ) of Bremsstrahlung, in order to eliminate this charge effect. Thirty-eight E_DHL values were linearly fitted with the last portion of X-ray spectra acquired under the incident energy, E₀ , from 0.35 to 5.0 kV. According to the distribution of E_DHL , two piecewise linear fitting was first employed with a breakpoint of 1.0 kV. Consequently, two intersection points of 0.54 and 2.48 kV, which correspond to E₁ and E₂ for YAG ceramics, were directly determined using a theoretical curve (E_DHL  = E₀ ). As a result, the high-resolution images of the YAG ceramic grain structure were successfully obtained using the calculated E₁ and E₂ values.