With procedures for electron diffraction structure analysis established in Moscow, intensity data, mainly from oblique texture patterns, were often used for quantitative crystal structure analyses of inorganic compounds, in addition to the organic materials discussed in Chapter 6. While favorable results might be expected for light-atom structures such as boric acid (Cowley, 1953a), ammonium sulfate (Udalova and Pinsker, 1964), and ammonium chloride (Kuwabara, 1969), as originally claimed, it might be more difficult to accept the validity of heavier-atom structures described in the books of Pinsker (1953), and Zvyagin (1967), and the recent chapter by Vainshtein, Avilov, and Zvyagin (1992). However, a typical analysis could be cited, that of the semiconductor AgT1Se2, for which Imamov and Pinsker (1965) collected 200 independent oblique texture intensities. Agreement of the final model to the observed data was R ≈ 0.20, and it was decided that the bonds are covalent. Difficulties experienced in determining the structures of basic lead carbonate (Cowley, 1956) and the A-phase of alumina (Cowley, 1953b) from single-crystal patterns, on the other hand, lead one to appreciate why Cowley and Moodie (1957) would have been motivated to develop a more accurate, multiple-beam model for dynamical electron diffraction. It was obvious that the Blackman two-beam model accepted by other laboratories did not adequately account for the measured deviations from the kinematical theory, especially when selected area diffraction intensities from single crystals were used for structure analysis.
KeywordsBoric Acid Atomic Position Kind Permission Electron Diffraction Data Inorganic Structure
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