Heterobimetal lic bismuth-transition metal salicylate complexes as molecular precursors for ferroelectric materials. Synthesis and structure of Bi2M2(sal)(4)(Hsal)(4)(OR) (4) (M = Nb, Ta; R = CH2CH3, CH(CH3)(2)), Bi2Ti3(sal)(8)(Hsal)(2), and Bi2Ti4((

摘要

The reactions between triphenylbismuth, salicylic acid, and the metal alkoxides M(OCH2CH3)(5) (M = Nb, Ta) or Ti{OCH(CH3)(2)}(4) have been investigated under different reaction conditions and in different stoichiometries. Six novel heterobimetallic bismuth alkoxy-carboxylate complexes have been synthesized in good yield as crystalline solids. These include Bi2M2(sal)(4)(Hsal)(4)(OR)(4) (M = Nb, Ta; R = CH2CH3, CH(CH3)(2)), Bi2Ti3(sal)(6)(Hsal)(2), and Bi2Ti4(OiPr)(sal)(10)(Hsal) (sal = O2CC6H4-2-O; Hsal = O2CC6H4-2-OH). The complexes have been characterized spectroscopically and by single-crystal X-ray diffraction. Compounds of the group V transition metals contain metal ratios appropriate for precursors of ferroelectric materials. The molecules exhibit excellent solubility in common organic solvents and good stability against unwanted hydrolysis. The nature of the thermal decomposition of the complexes has been explored by thermogravimetric analysis and powder X-ray diffraction. We have shown that the complexes are converted to the corresponding oxide by heating in an oxygen atmosphere at 500 C. The mass loss of the complexes, as indicated by thermogravimetric analysis, and the resulting unit cell parameters of the oxides are consistent with the formation of the desired heterobimetallic oxide. The complexes decomposed to form the bismuth-rich phases Bi4Ti3O12 and Bi5Nb3O15 as well as the expected oxides BiMO4 (M = Nb, Ta) and Bi2T4O11. [References: 41]