Sodium Thiosulphate, Polymorphism, Solid ElectrolyteNa2S2C>3 crystallizes in 4 modifications. The familiar monoclinic a-form stable at ambient temperature transforms into the trigonal /3-form at 330 °C which at 388 °C converts to bcc y-Na2S203. These transformations are reversible. Unstable orthorhombic a'-Na2S2C>3(Pna 2i) is obtained by dehydration of the pentahydrate or by cooling the ß-phase.The y-phase decomposes in sealed ampoule to Na2SC>4 and NaSs; decomposition is slow below and rapid above 440 °C. Equilibrium displacement by distillation of sulphur accelerates decomposition even for /?-Na2S203, and maintaining low sulphur pressure by pumping gives Na2S03. ß-and y-Na2S2C>3 are superionic conductors; a dynamic model is presented for the /3-structure with Na+ conduction pathways originating from oscillation of the S0O3 2-tetrahedra. Structural relationships can be derived with respect to the arrangement of the thiosulphate groups.

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The paper is concerned with the controllability of fractional functional evolution equations of Sobolev type in Banach spaces. With the help of two new characteristic solution operators and their properties, such as boundedness and compactness, we present the controllability results corresponding to two admissible control sets via the well-known Schauder fixed point theorem. Finally, an example is given to illustrate our theoretical results.