Ionic conductivity, phase diagrams

Fig. 89. Magnetic (as determined by ilSR) and conducting phase diagram of RNiO, compoimds as a function of rare-earth ionic radius. From Torrance et al. (1992).

As P is lowered, we go from a to b on the phase diagram. The water boils. The evaporation of the water is endothermic and the water is cooled (b —> c), forming some ice. If the pump is left on, the ice will sublime until none is left. This is the basis of freeze drying. 95. If Ti02 conducts electricity as a liquid, then it is an ionic solid if not, then Ti02 is a network solid. 

The P,T) phase diagram for the system has been prepared (Fig. 6.6) using a combination of data from neutron scattering, NQR, vibrational spectroscopy and conductivity measurements (Cailleau et al. 1997). The neutral phase is paraelectric, while the ionic phase has paraelectric and ferroelectric regions. The nature and mechanism of the phase transition has been reviewed and treated, as well as a number of other physical properties (Le Cointe et al. 1996 Cailleau et al. 1997). 

The phase diagrams and ionic conductivities of anion-deficient ZrO2 compounds have been widely investigated, to probe the influence of both dopant size and concentration (e.g.. Ref. [95]). Whilst Sc" + doped systems possess the highest values of ionic conductivity, factors such as cost and long-term stability have favored the use of (Zri j,Yj,)O2 x/2 as the current "best material, in which the m t and t c transitions are observed at x 0.05 and xw0.16, respectively [96]. On increasing dopant (anion vacancy) concentration, the ionic conductivity initially increases with X, but reaches a maximum close to the lower limit of stability of the c phase and then decreases rapidly [97]. Many theoretical studies have attempted to provide an explanation for this effect, and it is generally accepted that vacancies are trapped... 

NMR measurements and conductivity study correlations with phase diagrams have clearly established that the amorphous elastomeric phase in PEO is primarily responsible for the ionic conductivity [59]. 

The stabilization and characterization of the monochlorodiphenylselenonium ion, Ph2SeO, in the form of its adducts with SbCls and SnCL, has been reported. The adducts were assigned ionic structures on the basis of i.r. and conductance data. The PCls-SeCU phase diagram has been studied, and a 1 1 compound that is stable up to 280 C was found. ... 

The very low conductance in a dilute w/o microemulsion system has been explained on the basis of migration of statistically charged droplets with charge fluctuation features [45-48]. In the ternary systems of water/ionic surfactants/alka-nol, benzyl alcohol, polypropylene glycol, etc., the compositions toward the oil corner in the ternary phase diagram (called the L-phase), show an increase in... 

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