Transmission electron microscopic study of early stage gamma(1) (Ag(2)Hg(3)) and beta(1) (Ag-Hg) phases: technical note.

Incomplete reaction, residual free mercury, and high volatility of mercury are often major causes of the discrepancy in chemical composition of gamma(1) measured by different methods. The high mercury volatility also proves to be a major difficulty in transmission electron microscopy (TEM) study of high mercury materials. Provided in this report is a preparation method for TEM thin foils that can largely eliminate the mercury loss problem. The results show that the lattice constant of early stage gamma(1) crystals is 10.05 Delta with a chemical composition of Ag(41.08)Hg(58.92) (or Ag(2)Hg(2.87)). The chemical composition data shows that little or no mercury is lost during specimen preparation. The lattice parameters, a and c, of beta(1) crystals are 3.01 and 4.88 Delta, respectively with a chemical composition of Ag(1.1)Hg(0.94). It seems that the present specimen preparation method allows for accurate TEM microanalysis of high mercury amalgam phases such as gamma(1) and beta(1), which has been extremely difficult to do in the past.