Rubidium niobates

Rubidium Niobates.—When niobium pentoxide is fused with rubidium carbonate and the melt is extracted with water, fine, silky needles of composition 3Rb20.4Nb205.9 Ha0 are left behind. Concentration of the filtrate yields monoclinic crystals of 4Rb20.3Nba0B. 14H20, which are isomorphous with the corresponding tantalum salt and with the corresponding caesium niobate and tantalate. a b c= 0-8815 1 1-0491 j3=95° 53. It slowly loses some of its water on exposure to- air.3... 

Rubidium Pemiobate, Rb3Nb08, is obtained as a white, crystalline powder by the action of rubidium carbonate and excess of hydrogen peroxide on 4 3 rubidium niobate. 

Ccesium Niobates.—Fusion of niobium pentoxide and caesium carbonate and extraction of the melt with water yields monoclinic crystals which have the composition 4Cs20.3Nb205.14H20, and which are iso-morphous with the rubidium salt. Addition of alcohol to the aqueous solution furnishes crystals of 7Cs2O.6Nb2O5.80H2O. ... 

Oxalo-niobates or niobo-oxalates correspond to the vanado-oxalates, and contain both oxalic acid and niobic add radicals in the complex anion. The only known series possesses the general formula 3R aO. Nb 205.6C203.a H20, where R stands for an alkali metal. The sodium, potassium and rubidium salts are prepared by fusing one molecular proportion of niobium pentoxide with three molecular proportions of the alkali carbonate in a platinum crucible. The aqueous extract of the melt jjs poured into hot oxalic add solution concentration and cooling, or addition of alcohol or acetone, then brings about precipitation of the complex salt. Comparison of the dectrical conductivity measurements of solutions of the alkali oxalo-niobates with those of the alkali hydrogen oxalates determined under the same conditions indicates that the oxalo-niobates are hydrolysed in aqueous solution, and that their anions contain a complex oxalo-niobic acid radical.6... 

Rubidium Oxalo-niobate, 3Rb20.Nb205.6C203.4H20, is obtained in small needles by precipitation from its aqueous solutions with alcohol. It forms supersaturated solutions very readily. 

Potassium dihydrogen phosphate Rubidium dihydrogen arsenate Rubidium dihydrogen phosphate Strontium barium niobate Strontium barium niobate Tellurium oxide Rutile... 

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