The diffusion of sodium ions in analcite as a function of water content

Abstract

The conductivity of analcite has been measured as a function of temperature and water content. The self-diffusion of sodium ions in analcite ma20 . A1203 .4siO2.2H20) has been studied using 22Na, and the results are shown to be in agreement with the conductivity data for analcite containing more than 25 % of water (2 mole of water per formula = 100 %). Values of AH*, AS* and AG* at 400" K are quoted. The data are interpreted in terms of a rate-controlling process involving the energy barrier for migration of a water molecule.The migration of monovalent cations in anhydrous analcite (M20 . Al2O3. 4Si02) has been studied by Beattie 1 using a conductance technique. The conductivity of zeolites as a function of their water content has been examined by Rabinowitsch and Wood.2 Their experiments indicated that the conductivity of chabazite (CaO . A1203 . 4 SiO;? . 6 H20) increased with increasing water content. This suggests that under certain conditions zeolitic water may be partially ionized, which is unlikely. Similar results were obtained using ammonia as the sorbed gas.The water molecule has an effective radius of approximately 1.3r8, so that it can readily migrate through zeolites such as analcite. Tiselius3 studied the diffusion of water into analcite by an optical method and concluded that the diffusion coefficient was concentration dependent. Beattie 4 has recently shown that conduction in analcite containing two cations is governed by the slowermoving ion, except at low concentrations of this ion. If the energy barrier for the migration of a water molecule were greater than that for sodium ion migration it might be expected that in a hydrous analcite the former would represent the rate-controlling process. In this way measurement of the conductivity of hydrated analcite would give a temperature dependence related to the energy barrier for the diffusion of the uncharged water molecule. The work to be described relates the migration of sodium ions in analcite to the water content.

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

“…The activation energy of conduction decreases with increasing surface coverage in certain oxides [107,133,163], clay materials [163,164], zeolites [154,160,163], layered zirconium phosphonates [140], amine-intercalated titanium(IV)-phosphate [139] and proteins [117,161]. It increases (or stays almost constant) in collagene [159] and in zeolite [169] and silica/ alumina catalyst systems [155], and it changes as a maximum function in certain textiles [116] and Vycor-glass [172]. The 6.…”

Excessive Perinatal Mortality in a Small Town Associated with Evidence of Toxoplasmosis

“…It will be seen from Table X that the distribution of dye-test titres in the control group does not differ greatly from what would be expected in a rural community on the basis of Professor Beattie's survey of blood donors in Lincolnshire (Beattie, 1957(Beattie, , 1959. The slight excess of positive reactors as compared with that expected in an urban community is in keeping with the theory that there may have been an epidemic of toxoplasmosis in Barton-on-Humber during the three years 1956-8.…”

“…Serial dye test estimations on women who have borne affected children, cases of active toxoplasmosis, and women found to have high titres during an antenatal survey have been recorded by Holmdahl (1953), Feldman andMiller (1956), Makstcnieks and Verlinde(1957), Beverley and Beattie (1958), Beattie (1958Beattie ( , 1960, and others. From these it is apparent that after infection titres rise over a period of a few months to very high levels of the order of 1/10,000remain there for a short time and then fall.…”

“…Investigation of this disease was therefore deemed worth while. ToSxoplasmosis had been shown by Beattie (1957) to be prevalent in Lincolnshire. His survey of blood donors in small towns and rural areas of Lincolnshire showed that in Brigg, where the stillbirth rate was 9.0, only 10% of blood donors had positive dye tests at a titre of 1/16, whereas 27% of blood donors from Brigg Rural District ,Mad positive dye tests.…”

Dielectric properties of some synthetic minerals

“…Ducros and Rimsky (176) claim that the Ca++ ions in hydrated natural chabazite are situated near the centres of the hexagonal prisms at the top and bottom of each cage, They were unable to place the This is probably due to the additional loss contribution from the increased number of water molecules, to the lowering of the energy barrier to cation migration and to a wider distribution of relaxation times. It is (160,161,165,168) …”