GASEOUS METABORATES. 3. THE BERYLLIUM OXIDE-BORON OXIDE SYSTEM. RESEARCH ON THERMODYNAMICS OF THE AL-B-O, BE-B-O AND AL-BE-O SYSTEMS
Abstract
Gaseous beryllium metaborate, Be(BO2)2, was identified mass spectrometrically in the vapor above the berylliumboron-oxygen system. A study of this system by differential thermal analysis and Knudsen effusion using a vacuum balance and mass spectrometer, showed solid Be3B2O6 to be the only condensed mixed oxide phase present with a melting point of 1495 = 5C. The following thermodynamic values were obtained for the formation of gaseous beryllium metaborate from beryllium oxide and gaseous boron oxide: BeO(c) + B2O3(g) = Be(BO2)2(g); enthalpy at 1500C = 22 = 5 kcal/mole; entropy at 1500C = 6 = 1 eu/mole. For the formation of solid Be3B2O6 from the condensed oxides: 3BeO(c) + B2O3(l) = Be3B2O6(c); enthalpy = -23 = 5 kcal/mole; entropy = -13 = 2 eu/mole. The metal-anion bond strengths in the gaseous lithium and beryllium metaborates show the same relation to each other as the bond strengths in the corresponding chlorides, thus further confirming the pseudohalide character of the gaseous metaborates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1965
- Accession Number
- AD0613660
Entities
People
- Alfred Buchler
- Paul E. Blackburn
Organizations
- Arthur D. Little