Potassium niobate

Perovskites and related compounds Barium titanate Lead titanate Potassium niobate Potassium tantalate niobate Lithium niobate Lithium tantalate Barium titanium niobate Ba-Na niobate ( Bananas )... 

Simple ABO compounds in addition to BaTiO are cadmium titanate [12014-14-17, CdTiO lead titanate [12060-00-3] PbTiO potassium niobate [12030-85-2] KNbO sodium niobate [12034-09-2], NaNbO silver niobate [12309-96-5], AgNbO potassium iodate [7758-05-6], KIO bismuth ferrate [12010-42-3], BiFeO sodium tantalate, NaTaO and lead zirconate [12060-01 -4], PbZrO. The perovskite stmcture is also tolerant of a very wide range of multiple cation substitution on both A and B sites. Thus many more complex compounds have been found (16,17), eg, (K 2 i/2) 3 ... 

Only certain types of crystalline materials can exhibit second harmonic generation (61). Because of symmetry considerations, the coefficient must be identically equal to zero in any material having a center of symmetry. Thus the only candidates for second harmonic generation are materials that lack a center of symmetry. Some common materials which are used in nonlinear optics include barium sodium niobate [12323-03-4] Ba2NaNb O lithium niobate [12031 -63-9] LiNbO potassium titanyl phosphate [12690-20-9], KTiOPO beta-barium borate [13701 -59-2], p-BaB204 and lithium triborate... 

Sodium niobate(7 6) [12201 -59-17, 7Na20 6Nb20 3IH2O or Naj4Nbj2 037-31H2 0, forms a crystalline precipitate when a hot solution of a soluble niobium compound is added to a hot concentrated sodium hydroxide solution. It is insoluble in the presence of excess sodium hydroxide but is sparingly soluble in pure water. It also can be formed by addition of sodium hydroxide or chloride to a solution of the 4 3 potassium niobate. 

Potassium iodide, 20 634 Potassium ions, 20 597, 598, 641 in soap-water system, 22 727 Potassium isotopes, 20 598 Potassium magnesium sulfate, 20 626 Potassium manganate(V), 15 592 Potassium manganate(VI), 15 594-596 Potassium metal, 20 604 production of, 20 600 reducing power of, 20 599 Potassium muds, 9 4 Potassium niobate, 17 152-153 Potassium nitrate, 20 609, 634-636 solubility of, 20 636t uses of, 20 636... 

Bulk potassium niobate (KNbOs) is well suited to our needs, beeause birefringent type-I non-critical phasematehing (NCPM) can be exploited for highly efficient SHG of 850 nm at room temperature . This NCPM avoids any spatial waUc-off between the fundamental and second harmonic beams, as well as maximizing the angular acceptance of the phasematching process. 

L.E. Busse, L. Goldberg, M.R. Surette, and G. Mizell, Absorption Losses in MgO-doped and undoped potassium niobate, JoMfno/ of Applied Physics 75(2), 1102-1110 (1994). 

Tantalum can be separated from niobium by recrystallization of the double potassium fluorides. In the commercial process the ore is fused with caustic soda. The insoluble sodium niobate, sodium tantalate, and... 

Zirconium can be removed from the mixed precipitated acids by fusing them with potassium carbonate and extracting the melt with cold water. The niobium and tantalum pass into solution as niobate and tantalate of potassium respectively, while the zirconium remains undissolved as the dioxide, Zr02.4 The method is more suited for the removal of zirconium from niobates than from tantalates.3... 

Addition of excess of potassium thiocyanate to an alkaline solution of a niobate, followed by zinc and concentrated hydrochloric acid, produces a golden-brown colour which may be almost red in the presence of larger quantities of niobium. It is stated that ndther tantalum nor titanium gives any coloration under the same conditions.3 Addition of... 

The monoxide has been variously described, according to the method of preparation, as a black powder, or glistening crystals, or beautiful black cubes. Its density varies from 6 3 to 6-7, and it is a good conductor of electricity. On being heated in air it oxidises readily to the pentoxide with considerable evolution of heat. It dissolves in hydrofluoric acid and hydrochloric acid with evolution of hydrogen, and a pentavalent niobium salt is formed in solution. It is also dissolved by boiling potassium hydroxide to form potassium niobate. This behaviour of niobium monoxide towards acids and alkali indicates that divalent salts of niobium are too unstable to exist. A divalent chloride of tantalum has, however, recently been isolated (see p. 192). 

After being strongly ignited, niobium pentoxide becomes insoluble in all acids other than hydrofluoric acid, but is dissolved by molten potassium hydrogen sulphate, ammonium hydrogen sulphate, and borax. It is also insoluble in solutions of alkalis, but is converted into the alkali niobates by fusion with alkali hydroxides and carbonates. 

The alkali niobates are most conveniently prepared by the action of caustic alkalis on niobic acid or on solutions of niobium oxytri-fluoride. Other compounds of niobic acid and bases are generally prepared by fusing niobic add with the oxide, hydroxide, carbonate, or other salt of the metal. Occasionally double decomposition of a soluble alkali niobate and a soluble salt of the metal has been employed. Larsson s method1 consists in predpitating a solution of potassium niobate with a salt of a metal the dried predpitate is fused for thirty-six hours at a high temperature with boric acid, and the melt is boiled with water to which hydrochloric acid has been added. The residue consists of crystals of the insoluble niobate of the metal, usually the metaniobate. 

Niobates are usually insoluble in water even many of the alkali niobates are insoluble. Insoluble alkali niobates are formed when niobium pentoxide is fused with only small proportions of alkali carbonate. 7 6 Sodium niobate, 7Na20.6Nb205. H20, is insoluble in solutions of high sodium-ion concentration, and is therefore precipitated. by the addition of sodium salts to solutions of potassium niobate. Ammonium niobates are unknown when excess of an ammonium salt is added to a solution of an alkali niobate, a voluminous precipitate is thrown down which is rapidly decomposed by water to yield niobic 1 Larsson, Zeitsck. anorg. Ch m., 1896,12,197. 

Cadmium Metaniobate.—The anhydrous salt, Cd0.Nb205, is obtained by fusing potassium niobate with cadmium chloride. It forms yellowish-brown, glistening crystals, the density of which is 5-93.4 The hydrated salt Cd0.Nb20s.3 H20 is thrown down as a pale yellow precipitate on adding a solution of a cadmium salt to sodium metaniobate.8... 

Calcium Pyroniobate, 2Ca0.Nb205, is prepared by fusing with calcium chloride either niobium pentoxide or the precipitate obtained by the action of calcium chloride on potassium niobate solution the melt is extracted with water containing hydrochloric add,10 when the salt remains in small, colourless, glistening, prismatic crystals.11 Density at 17° C. 4-484. 

Lithium Niobate, 7Li2O.6Nb2O6.20H2O, is a crystalline substance which results from the action of lithium nitrate on a concentrated solution of potassium niobate, K20.3Nb205.5H20.8... 

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