X-ray diffractional and electrochemical studies of the reduction of a spinet-related manganese dioxide, Li0.27(2~Mn204:MnO19~, were carried out in lithium nonaqueous cells. The reduction of this oxide proceeded topotactically in three steps; a reduction in two phases [cubic: ac = 8.045(6)A and ac = 8.142( 2)A] was characterized by a constant opencircuit voltage (OCV~ of 4.110(5)V for 0.27(2)

X‐ray diffractional (XRD) studies were carried out for the electrochemical reduction of heat‐treated electrolytic MnO2 (250° and 400°C for 7 days). A series of XRD examinations indicated that the reaction proceeded without the destruction of the core structure of electrolytic manganese dioxide (EMD). The structural changes during the electrochemical reductions of both EMDs were described, assuming a tetragonal sublattice. Both heat‐treated electrolytic MnO2normals (HEMDs) behaved similarly in the tetragonal sublattice parameter vs. the reduction degree plots. During the first half of the reduction, HEMD phase having a tetragonal sublattice ( a=4.39–4.40Å , c=2.86–2.90Å ) was converted into a new LixMnO2 phase having an expanded tetragonal sublattice ( a=4.9–5.0Å , c=2.82–2.86Å ), i.e., in a two‐phase reaction. In the 30–90% reduction, the a‐axis increased continuously as a function of reduction degree, i.e., in a homogeneous phase reaction. The possible crystal structure of the deep discharge product LixMnO2 false(x>0.8false) is discussed, assuming a tetragonal unit cell ( a=normalca.5Å , c=normalca.2.85Å ) having the normalNiAs‐normaltype structure by analogy with LixRuO2 , and an orthorhombic unit cell, i.e., a=2×normalbÅ , b=normalca.5Å , c=normalca.2.85Å . From these, assuming an orthorhombic unit cell having a=10.2true7_Å , b=4.9true3_Å , and c=2.8true5_Å , all diffraction lines from the reduction products of HEMD were indexed.

X-ray diffractional and electrochemical characterization of deep discharge products (Li=MnO2s) of heat-treated electrolytic MnO2s (HEMDs) from 200 ~ to 450~ at 50~ intervals were carried out. XRD examinations of the discharged Li=MnO2s indicate the core structures were the same regardless of startingoHEMDs used. All LixMnO2 XRD patterns were indexed and explained using an orthorhombic unit cell having a = ca. 10A, b = ca. 5A, and c = ca. 2.85A. Possible structures having such a unit cell were discussed based on models which consisted of [1 • 1]-, [1 z 2]-, and [1 • 3]-tunnel structures. Electrochemical tests of discharge products indicated the Li=MnO2s were rechargeable in lithium nonaqueous cell, i.e., 150-180 mAh -g-1 of rechargeable capacity. The reaction mechanism of LixMnO~ in the rechargeable region was also examined and shown to be a homogeneous-phase reaction in a Li=MnO2 matrix, which anisotropically shrank and expanded within ca. 10% in unit cell volume during the oxidation and reduction, respectively. These XRD and electrochemi-) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.15.241.167 Downloaded on 2015-03-08 to IP ABSTRACTThe hot corrosion of preoxidized 99% and 99.99% pure Ni covered with a thin Na2SO4 film in a SO2-O2 gas atmosphere was investigated at 900~ by an electrochemical method using a sodium sensor and an oxygen probe. The preoxidation conditions were varied in order to affect the sulfidation of Ni, which resulted in an increase in salt basicity and thereafter catastrophic corrosion. The basicity gradient generated across the thin salt film supported a self-sustaining basic fluxing and reprecipitation of the protective NiO scale.

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ChemInform Abstract The XRD data obtained during the electrochemical reduction of heat-treated (250 rc C and 400 rc C, 7 d) electrolytic MnO2 cathodes in a lithium nonaqueous cell indicate that the reaction occurs via electron injection and Li+ insertion to form a LixMnO2 phase without destruction of the core structure. The structural changes occurring during reduction are described in detail assuming a tetragonal sublattice.