摘要:
A process for the preparation of high surface area mixed metal oxides by decomposition of solid solutions of carbonates possessing the calcite structure. Oxide compounds comprising mixtures of Ca, Mn, Fe, Co, Ni, Zn, Cd and Mg can be prepared by this method. For example, CaMnO.sub.3 with a surface area of 11 m.sup.2 /g useful as a battery cathode, has been prepared by the instant method, that is, by decomposition of a CaMn(CO.sub.3).sub.2 precursor.The mixed metal carbonate solid solutions which are used as precursors for the preparation of the mixed metal oxides are themselves prepared by the precipitation from solution of the appropriate metal ions by the addition of an excess of a carbonate ion source (such as (NH.sub.4).sub.2 CO.sub.3). The metal-ion ratio in this solution is adjusted so that the resulting precipitate has the same stoichiometry as the desired oxide. The intimate mixing achieved by using the carbonate precipitation technique allows calcination to metal oxide to be run at lower temperatures for shorter periods of time, thereby achieving higher surface areas.
摘要:
A novel battery is disclosed in which the cathode active material is an oxide having a perovskite or perovskite related structure and the general formula ABO.sub.3, wherein A is an element selected from Group IIA of the Periodic Table of the Elements and B is a non-noble transition metal selected from Group VIIB and VIII of the periodic Table of the Elements. The anode is a metal selected from cadmium, zinc, lead, lithium, sodium and potassium.
摘要:
A liquid solution method of preparing electrically conductive pyrochlore compounds of high surface area, having the formula:A.sub.2 [B.sub.2-x A.sub.x ]O.sub.7-yis disclosed wherein A is selected from lead, bismuth and mixtures thereof, B is selected from ruthenium, iridium and mixtures thereof, 0
摘要:
Novel lead-rich pyrochlore type compounds are described having the formula:Pb.sub.2 [M.sub.2-x Pb.sub.x ]O.sub.7-ywherein M is selected from the group consisting of Ru, Ir and mixtures thereof and wherein x is greater than 0 and less than or equal to about 1.2 and y is greater than or equal to 0 and less than or equal to about 1.0. A method of synthesizing these compounds is also described. The method involves the solid state reaction of a lead source and a ruthenium source and/or an iridium source at temperatures below about 600.degree. C in an oxygen-containing environment.
摘要:
A method for electrocatalytically reacting various oxidizable organic compounds by introducing current by means of an anode into an electrolyte of a cell containing the oxidizable organic compound. The anode comprises an electrocatalyst material which has at least one compound of the formula:A.sub.2 [B.sub.2-x B'.sub.x ]O.sub.7-ywherein A is selected from any of the pyrochlore structure metal cations in a group consisting of: Pb, Bi, and Tl, wherein B' is selected from any of the pyrochlore structure metal cations in a group consisting of Pb, Bi, Tl, and Sn; wherein B is a pyrochlore structure metal cation at least a major portion of which is selected from a group consisting of at least one of: Ru, Rh, Ir, and Os, wherein y is equal to or greater than zero and equal to or less than one; and wherein x is equal to or less than one and equal to or greater than zero.
摘要:
A liquid solution method of preparing electrically conductive pyrochlore compounds having the formula:A.sub.2 [B.sub.2-x A.sub.x ]O.sub.7-yis disclosed wherein A is selected from lead, bismuth and mixtures thereof, B is selected from ruthenium, iridium and mixtures thereof, 0.ltoreq..times..ltoreq.1.0 and 0.ltoreq.y.ltoreq.1. The method involves reacting A and B cations to yield a pyrochlore oxide by precipitation of A and B cations in a liquid medium having a pH which is equal to or greater than 4.5, but less than 13.5, in the presence of an oxygen source at a temperature below about 200.degree. C. for a time sufficient for reaction to occur. In those instances in which amorphous reaction products are obtained, these amorphous reaction products are subsequently heat treated at a temperature of about 200.degree. C. to about 600.degree. C. for a time sufficient to convert amorphous reaction products to crystalline pyrochlore(s).
摘要翻译:公开了一种制备具有下式的导电烧绿石化合物的液体溶液方法:其中A选自铅,铋及其混合物,B选自钌,铱及其混合物, /=x=1.0和0 = y = 1。 该方法包括使A和B阳离子反应,通过在pH为等于或大于4.5但小于13.5的液体介质中,在氧源的存在下,在A 温度低于约200℃,持续足以产生反应的时间。 在获得无定形反应产物的情况下,随后将这些无定形反应产物在约200℃至约600℃的温度下热处理足以将无定形反应产物转化为结晶烧绿石的时间。
摘要:
A method of preparing electrically conductive pyrochlore compounds having the formula:A.sub.2 [B.sub.2-x A.sub.x ]0.sub.7-yis disclosed wherein A is selected from lead, bismuth and mixtures thereof, B is selected from ruthenium, iridium and mixtures thereof, O.ltoreq.x.ltoreq.1.0 and 0.ltoreq.y.ltoreq.1. The method involves reacting A and B cations using at least one solid reactant source of these cations in a liquid alkaline medium having a pH of at least about 13.5 in the presence of an oxygen source at a temperature below about 200.degree. C. for a sufficient time for reaction to occur.
摘要翻译:公开了一种制备具有下式的导电烧绿石化合物的方法:其中A选自铅,铋及其混合物,B选自钌,铱及其混合物, x <= 1.0和0 = y = 1。 该方法包括使用这些阳离子的至少一种固体反应物源在pH为至少约13.5的液态碱性介质中在氧源存在下在低于约200℃的温度下使A和B阳离子反应足够的 反应发生的时间。
摘要:
Novel bismuth-rich pyrochlore-type compounds are described having the formula:Bi.sub.2 [M.sub.2-x Bi.sub.x ]O.sub.7-ywherein M is selected from the group consisting of Ru, Ir and mixtures thereof and wherein x is greater than zero and less than or equal to about 1.0 and y is greater than or equal to zero and less than or equal to about 1.0. Electrochemical devices containing these compounds as electrocatalyst materials for oxygen electrodes are also described.
摘要:
An electrochemical device is described which has an oxygen electrode which contains a pyrochlore type electrocatalyst material. This electrocatalyst material is one or more electrically conductive pyrochlore compounds selected from the compounds of the following formula:A.sub.2 B.sub.2 O.sub.7-y (1)wherein A is any of the known pyrochlore structure metal cations, B is a pyrochlore structure metal cation at least a major portion of which is selected from the group consisting of one or more of Ru, Rh, Ir, Os, Pt, Ru-Pb mixtures and Ir-Pb mixtures, and wherein O.ltoreq.y.ltoreq.1.0. Desirably, A is a pyrochlore structure metal cation at least a major portion of which is selected from the group consisting of one or more of Pb, Bi and T1. A preferred group of pyrochlore compounds which are included in the above formula are those having the following formula:Pb.sub.2 [M.sub.2-x Pb.sub.x ]O.sub.7-y (2)wherein M is selected from the group consisting of Ru and Ir, wherein O.ltoreq.X.ltoreq.1.2 and O.ltoreq.y.ltoreq.1.0.
摘要:
A new low temperature layered manganese compound of the formula Ca.sub.2 Mn.sub.3 O.sub.8 has unexpectedly been synthesized in pure form. The unit cell dimensions of this new compound have been determined by X-ray diffraction and reveal that the compound is monoclinic with lattice parameters of a=11.02 A, b=5.85 A, c=4.94 A, .alpha.=90.degree., .beta.=109.80.degree., .gamma.=90.degree.. The structure consists of pseudohexagonal Mn.sup.4+ sheets with similar oxygen sheets on either side, giving a distorted octahedral coordination to the Mn.sup.4+. Every fourth Mn.sup.4+ is missing in these layers, so their composition is Mn.sub.3 O.sub.8 with chains of coordination octahedra linked by common edges (rutile type arrangement). The Ca ions are situated between the Mn.sub.3 O.sub.8 layers.This new Ca.sub.2 Mn.sub.3 O.sub.8 compound is prepared in pure form by means of the solid solution precursor technique whereby solid solution, mixed metal carbonates of the desired metals (Ca and Mn) having the calcite structure are precipitated from mixtures of the solutions of the salts of calcium and manganese, said salts being selected from the group consisting of carbonates, nitrates, sulfates, oxalates, acetates, precipitation being the result of the addition of a source of carbonate ions, such as ammonium carbonate, sodium carbonate, potassium carbonate of CO.sub.2, so as to achieve mixing on the atomic scale. The resulting solid solution mixed metal carbonate is subsequently calcined, preferably at a temperature of from between 600.degree.-875.degree.C to the mixed metal oxide in the pure form possessing high surface area (on the order of 20-50 m.sup.2 /g). This new material has uses as a battery cathode.