Structure of Na43+ in Sodium Zeolite Y

Abstract

The growing interest in the inclusion compounds of the alkali metals in zeolites stems from their potential use as basic catalysts1 and increasingly from a rich variety of observations relating to their electronic, magnetic and optical A considerable volume of electron spin resonance (ESR) investigations has demonstrated the existence of a range of brightly colored paramagnetic centers-&'"-"+ and N+"'-')+ (m = 3,4; n = 3-6)-in zeolites X, Y, and A?-'5 Structures of zeolites containing cesium, rubidium, potassium, and sodium clusters have been reported by Seff and co-workers16-19 and by Armstrong et al.?n-22 but the location of the single-electron ionic cluster Na3+ continues to be the subject of debate.'n.11.23.24The incorporation of larger amounts of alkali metal results in dark solids with single-line ESR spectra, widely attributed to the formation of metallic clusters within the zeolite pores?s More recent work has cast doubt on this interpretation?5 and it has been proposed that in sodium-loaded sodium zeolite Y (Nd Na-Y), for example, the ESR line results from the interaction ' Rutherford Appleton Laboratory. Current Address: School of Chem+University of Birmingham.

Structure and Electronic Properties of Potassium-Loaded Zeolite L

“…Again the jump from ∼ 1% for u < 5 to ∼3% for u ≥ 5 would seem to indicate a relatively abrupt change in the measured properties of the samples at this composition. Much higher observed spin fractions have been reported , in zeolites containing the sodalite cage structural unit, which is known to be the site of stable paramagnetic clusters such as Na 4 3+ and K 4 3+ . , In many cases the presence of such species, which consist of a single unpaired electron delocalized over four cations, is confirmed by the observation of a characteristic ESR hyperfine splitting pattern, but in no case at any temperature was any evidence of hyperfine splitting detected in K u /K 9 -L.…”

Dissolving alkali metals in zeolites: genesis of the perfect cluster crystal

“…This conclusion is confirmed by the preliminary results of neutron diffraction studies on this compound. 29 Remaining electrons released from the ionization of sodium atoms entering the zeolite, over and above the eight located in Na43 + traps within the sodalite cages, apparently do not contribute significantly to the paramagnetism of the sample. This finding may be compared to the results of Ursenbach et al , 11 who also note a strong tendency towards spin pairing in clusters formed in the supercages after the filling of the sodalite cages is complete.…”

Localisation assisted by the lattice relaxation and the optical absorption of extra-framework electrons in 12CaO·Al2O3

“…Unusual properties of these materials [3] can be useful in a variety of technological applications including chemical catalysis, electron emitting devices and functional materials. However, all known organic electrides (see for example [1 -3] and references therein) become unstable at temperatures higher than À 40 -C. A search for new types of electrides has resulted in materials formed by zeolite frameworks heavily doped with alkali atoms such as Na [4] and Cs [5][6][7]. A novel type of an electride has been recently reported in [8].…”