Crystal chemistry and petrology of coexisting galaxite and jacobsite and other spinel solutions and solvi '
Galaxite (Gx:MnAlzO+) and jacobsite ("ID:MnFezO+)-rich spinels occur together in the metamorphosed manganese deposit near Bald Knob, North Carolina. They show limited mutual solubility with lz-lgVa Jb in Gx and 19-22% Gx in Jb. The implied solvus is consistent with syntheses oflshida et al. (1977) along the Gx-"ID pseudobinary. Refinement of the structure of one galaxite (Gxg5JbrcSpaGhr) reveals that Mn is located on tetrahedral sites and Al on octahedral sites and that galaxite is therefore a normal spinel. All available data suggest that jacobsite is also a normal spinel at low temperatures, and the solvus between galaxite and jacobsite does not seem to be caused by differences in normality/inverseness. Chemical and experimental data available for (Mg,Zn,Mg,Fe2*XFe3*,Al)zOa spinels suggest hat the ferrites (acobsite, franklinite, magnesioferrite and magnetite) show extensive solid solution and are separated from aluminate solid solutions (galaxite, gahnite, spinel (s.s.) and hercynite) by wide solvi at metamorphic temperatures.
層状マンガン鉱床に伴うJacobsiteの化学組成;層状マンガン鉱床に伴うJacobsiteの化学組成;Chemical Compositions of Jacobsites from the Bedded Manganese Ore Deposits
今回検討した層状マンガン鉱床に伴うjacobsiteの化学組成および共存する酸化鉱物との固溶関係をまとめると次のようになる。 1) jacobsiteは,一般に相当量のAl, Ti, Mgなどの元素を含み,広い固溶領域を有する。 2) 一般にgalaxite分子および"Mn2TiO4"分子を固溶する場合が多く,それぞれ最高25および36mol.%程度に達する。 3) 上記の"Mn2TiO4"分子は,iwakiite中にも最高44mol.%程度固溶しており,天然では普通に見られる固溶成分である。
Mechanism of Conduction in Li‐Substituted Transition Metal Oxides
A study of the effect of Li substitution on the electrical properties of the oxides MnO, CoO, NiO, and CuO has been made. It has been found that (1) the activation energy for conduction increases abruptly near the antiferromagnetic Curie point; (2) as Li is added the activation energy and resistivity initially decrease rapidly and then level off in the neighborhood of 2% substituted Li; (3) this initial decrease becomes progressively greater in going from MnO to CuO in the sequence of the periodic table. A rather complete understanding of these materials can be had by treating the conduction process as a thermally activated diffusion of positive holes which are trapped by the local strain induced by their own polarization field. The magnitude of the activation energy will be related to the work done against elastic forces necessary to reduce the local strain at a positive hole to zero.