Positive and negative ions from some molten silicates coated on a Pt-Rh (10%) filament have been measured using mainly a Hitachi RM-6E single-focusing mass spectrometer. The samples used are Li2O-SiO2 (mole ratio 2: 1 and 3: 1), Na2O-Si02 (1: 1 and 2: 1), K2O-Si02 (1: 1), Cs20-Si02 (1: 1), PbO-Si02 (2: 1), Li20-Pb0-Si02 (2: 1: 1 and 1: 1: 2), and K2O-PbO-Si02 (2: 1: 3). The temperatures of samples are read with an optical pyrometer, but the readings can not be corrected for emissivity and window transmission. The apparent temperaturerange is between 800°C and 1 400°C.
The negative ions O-, O2-, SiO3-, MSi03- (M=Li, K, and Cs), Rh02-, RhO-3, and Pt02- are found for all the systems investigated, except Pb0-Si02 (2: 1) and Li2O-Pb0-Si02 (1: 1: 2). The proportions of these ions from K2O-PbO-Si02 and K20-Si02 are particularly large compared with those from the other systems.
When PbO is added to a K20-Si02 system, the lowest temperature at which the negative ions are detected is lowered. The intensities of these ions are also increased by the addition of PbO.
The positive ions M+, M2+, M20+ (M =Li, Na, K, and Cs), 0, + 02+, and Si+ are obtained from all systems, except PbO-SiO2 (2: 1). The ions Li3O+ and Li3SiO3+ are found in the mass spectra of Li20-Si02 and Li2O-PbO-Si02. The ions containing Pb, such as LiPb0+, are found in the mass spectra of Li2O-Pb0-Si02.