Mass Spectrometric Study on Phosphorus in Molten Carbon-saturated Iron

Thermodynamic Measurement of Di-calcium Phosphate

“…The double Knudsen cells allow the measurement of ion currents of evaporated species from two specimens under identical conditions in a single experiment: One is an experimental specimen and the other taken as a reference. Details of the equipment for double Knudsen cell mass spectrometry are described elsewhere, [9,20,[22][23][24][25] and therefore, they are explained only briefly here. A chamber was vacuumed by rotary pumps (RPs) and turbo molecular pumps (TMPs), and residual gas pressure in this chamber was kept below 1 9 10 -4 Pa. A cell holder in the chamber held two Knudsen cells.…”

Thermodynamic Measurement of Calcium Phosphates by Double Knudsen Cell Mass Spectrometry

“…The Gibbs energy changes of Reactions [3] and [5] were determined with the pressure of PO obtained by measurements and that of P 2 , which was calculated based on Eq. [7].…”

“…Double Knudsen cell mass spectrometry was developed as a means of directly measuring thermodynamic data of metals, alloys, and intermetallic compounds. [1][2][3][4][5][6] However, this method often has not been employed to determine the thermodynamic properties of oxide systems, since it is difficult to interpret fragment ions yielded during a measurement and to control oxygen potential in an experimental system even though this potential is one of the most important factors in such a measurement. [1,7,8] It is anticipated that use of double Knudsen cell mass spectrometry will provide more accurate data on thermodynamics and experimental conditions of oxide systems than can be learned by currently established methods.…”

“…[3,5] B. Preparation of Calcium Phosphates Calcium phosphates were prepared by mixing calcium carbonate and phosphoric acid to yield mole ratios of Ca/P = 3/2 or 2/1.…”

“…[3] and [5] could be estimated by PO pressures in equilibrium with the mixtures charged to the Knudsen cell with Cu-P alloy.…”