Syntheses And Characterization Of Novel Phosphate Fluorides

Inorganic phosphates have been attracting great interest in recent years owing to their potential applications in nonlinear optics,Li-ion batteries,artificial bones,LED,catalysts,and so on.At the same time,the fluorine has an great effect on synthesis,structure and performance of phosphates.In this thesis,we have synthesized several phosphate fluorides in phosphothermal route and reported some of their performances.1.By introducing the B-O group into phosphate,this thesis improved the low second-harmonic generation(SHG)effect and birefringence of the phosphate materials in nonlinear optics(NLO),synthesized a non-centrosymmetric fluorinated borophosphate KB(PO4)F(KBPF)featuring a cut-off wavelength of less than 200 nm,a moderate birefringence and a large SHG effect comparable to KBe2BO3F2(KBBF)..These properties together with its simple formula consisting of common elements make KB(PO4)F a very promising deep-UV NLO crystal.The larger SHG effect of[BO3F]included by KB(PO4)F break the limit of[BO3],which show another way to search new nonlinear optical materials.2.Because of the excellent optical properties,the cerium tetravalent oxide have been widely used in daily life as UV filter material.However,for all of natural rare earth phosphates reported in recent years,the valence of cerium is trivalent,leading to the selective absorption in the ultraviolet,which affects its applications.The tetravalent cerium phosphate has good UV absorption,low refractive index,high chemical inertness and low photocatalytic activity,which make it to be an excellent UV filter.But the synthesis of the tetravalent cerium phosphate is difficult.In this thesis,three kinds of tetravalent cerium phosphate and a cerium fluoride(KCe2(PO4)3,KCe(P207)F,KCe(PO4)F2 and K7Ce6F3i)were synthesized at high fluoride concentration system by phosphothermal method.It has been found that the regulation of the structure and composition of tetravalent cerium phosphate can be achieved by adjusting the ratio of boric acid to phosphoric acid.The results show that the UV absorbance of the three kinds of tetravalent cerium phosphates are better than that of the existing inorganic UV filters and have great prospects.