The Crystal Structure of Tetragonal Lead Monoxide

Abstract

The maximum temperature at which molybdenum trioxide can be safely ignited without fear of appreciable loss by volatilization has been established as approximately 600°.Conditions and apparatus for accurately and conveniently converting molybdenum trisulfide to trioxide have been described.The use of oxidizing agents to aid the conversion of the sulfide to oxide is unnecessary.

On the crystal structure of tetragonal (red) PbO

“…From the last column of Table 2 it becomes apparent, that the neutron diffraction data disagree with jF 2 values calculated for Levi & Natta's structure. A better agreement between jF 2 values, in particular for well resolved peaks, as compared to the structure model with O atoms in 2(b) shows, that the structure of tetragonal PbO as proposed by Dickinson & Friauf (1924) is supported also by a neutron diffraction study.…”

“…The discrepancy factor is 0-092 for atomic sites, as proposed by Dickinson & Friauf (1924) and 0-11 for O placed in 2(b). For the former structure a systematic variation of the lead-atom parameter Zpb gives the best agreement between observed and calculated intensities for zpb = 0.237 ± 0.002.…”

“…Subsequently Levi & Natta (1926) was a distorted NaCl structure with every lead atom surrounded by six oxygens at distances 2.5-2.8 A. Dickinson & Friauf's (1924) conclusions were supported later by Moore & Pauling (1941) using powder data and by Bystrom (1945) using a single-crystal. The results of the X-ray investigations are summarized in Table I.…”

“…Dickinson & Friauf (1924) have found the tetragonal unit cell to contain two Pb atoms a6 ¼,¼, z and ~,~,E, and two oxygen atoms at ~, ¼, 0 and ¼, ~, O, the space group DY~a-P4/nmm being assigned as the most probable. An interesting coordination arrangement was discovered: each Pb atom was bound to four oxygen atoms forming a square pyramid with a lead atom at the apex.…”

Polymorphic Transition of PbO, Initiated by Curing Conditions of Mesocomposites Under Action of Constant Physical Fields

“…Вступ У ХІХ ст. було встановлено для α-PbO параметри тетрагональної гратки, кількість молекул, що її утворюють, просторову групу симетрії [1]. Ці результати спонукали продовжувати вивчати поліморфізм не лише для PbO, але і для оксидів важких металів SnO, PtO [2,3].…”