Uranobite, also known as beta, contains 26.6% uranium trioxide, 34.80% niobium pentoxide and 18.30% titanium dioxide. Isometric crystal system, a= 10.32a, symmetrical m3m. Crystal octahedron, diamond dodecahedron. Color brown to black, stripe brown, hardness 4 ~ 5, relative density 3.75 ~ 4.82. Occurs in granite pegmatite. The varieties of beta include: rare earth beta, tantalum beta, lead beta aluminum beta, thorium beta and lead beta;
Brown, light green brown, black. Mineral surfaces often have a thin film of light gray or yellow. The stripes are brown. Grease luster, waxy luster to glass luster or semi-metallic luster. Translucent to opaque. No cleavage. Shell fracture, staggered fracture. Crispy. Hardness 3-5.5, specific gravity 3.75-4.82, heating can increase to 5.08. In tianheshi granite-pegmatite, niobite is symbiotic with microplagioclase, biotite, calcite and thorium. The granite pegmatites in the aegirinization are symbiotic with pyroxene, hornblende, biotite, magnetite, ilmenite and zircon. In addition, the symbiosis of beta with beryl, thorium and uranite and monazite has been found in hydrothermal veins. The world's famous producing areas include the democratic republic of Madagascar (Ambotofotsy,Madagascar) and the kingdom of Norway.
Potassium niobate is a new type of functional material widely used at present because of its special layered structure, unique photochemical properties, semiconductor properties, catalytic activity and other properties.
There are many reports on the preparation methods of potassium niobate titanate and potassium tantalate titanate. The earliest preparation method is solid-phase sintering method, which has the characteristics of short synthesis time, less pollution and simple process and has been the main direction of research in various countries. However, the solid-phase sintering method requires high temperature, and the product is difficult to achieve the molecular level mixing, high energy consumption, easy to introduce impurities, its purity, uniformity is poor, and the reaction is difficult to control. Later, some people adopted the sol-gel method. However, this method is difficult to be widely used due to its tedious preparation process, high cost of raw materials and harsh requirements of experimental conditions. In recent years, the inflow heat method has attracted extensive attention, but the pressure required for the synthesis of potassium niobate powder in supercritical and subcritical water is high and the equipment investment is large.
