Thermal Emission of Alkali Metal Ions from Al30-Pillared Montmorillonite Studied by Mass Spectrometric Method

The thermal emission of alkali metal ions from al30-pillared montmorillonite in comparison with its natural form was studied by mass spectrometry in the temperature range 770-930 k. the measurements were carried out on a magnetic mass spectrometer mi-1201. for natural montmorillonite,the densities of the emission currents (j) decrease in the mass spectrum in the following sequence (t = 805 k,a/cm2): k+ (4.55 · 10-14),cs+ (9.72 · 10-15),rb+ (1.13 · 10-15),na+ (1.75 · 10-16),li+ (3.37 · 10-17). for al30-pillared montmorillonite,thermionic emission undergoes temperature-time changes. in the low-temperature section of the investigated range (770-805 k),the value of j increases substantially for all ions in comparison with natural montmorillonite (t = 805 k,a/cm2): cs+ (6.47 · 10-13),k+ (9.44 · 10-14),na+ (3.34 · 10-15),rb+ (1.77 · 10-15),and li+ (4.59 · 10-16). a reversible anomaly is observed in the temperature range 805-832 k: with increasing temperature,the value of j of alkaline ions falls abruptly. this effect increases with increasing ionic radius of m+. after a long heating-up period,this anomaly disappears and the lnj-1/t dependence acquires a classical linear form. the results are interpreted from the point of view of the dependence of the efficiency of thermionic emission on the phase transformations of pillars. © 2017 v. b. motalov et al.