Cobalt aluminate spinel-mullite composites synthesized by sol-gel method

Blue pigments based on CoxZn1−xAl2O4 spinels synthesized by the polymeric precursor method

“…On the other hand, Stangar et al [20] considered that the bands whose wavelengths are below 520 nm are due to electronic transitions of Co 3þ in octahedral sites. Sales et al [23] observed a band at 480 nm, but they did not show its attribution.…”

“…Zayat and Levy [22] also working with a Co-deficient CoAl 2 O 4 samples, but in this case powders displaying the Co 0.75 Al 2.25 O 4 stoichiometry, reported the absorbance bands at 543 nm, 580 nm and 630 nm. Sales et al [23] investigating powders with the composition 3(Al 1.95 Co 0.025-Ti 0.025 O 3 )$2SiO 2 , heat treated at 995 C for 1 h, found peaks at 510 nm, 575 nm and 618 nm. The position of the bands I, II and III in the present paper, 550, 580 and 620 nm, generally agrees with the values disclosed in the literature [22,24].…”

Lattice strain estimation for CoAl2O4 nano particles using Williamson-Hall analysis

“…Preparation of CoAl 2 O 4 [12][13][14][15][16][17][18] was developed using different methods that can provide many advantages such as ability to control homogeneity, purity of the sample, relatively low temperature proseccing, size and shape controle as well as distribution of ceramic particles which overcoming traditional methods.…”

“…The synthesis of CoAl 2 O 4 has been reported in different routes, such as sol-gel [12,13], heat induced collapse [14], solid-solid reaction [15,16], hydrothermal, and thermal decomposition [18]. Moreover, the simple and straightforward method or metal complex method was used to prepare Mg-Al-TEA complex directly from the Al(OH) 3 , MgO compounds and triethanolamine (TEA, N(CH 2 CH 2 OH) 3 ), as a precursor for MgAl 2 O 4 [19].…”

CoAl2O4–mullite composites prepared by sol–gel processes

“…Trivalent cations with ionic radii close to that of Al 3+ can readily be incorporated in mullite structure. As shown recently [3][4][5] cations (Me) with larger ionic radii rather react with alumina forming MeAl 2 O 4 than enter to mullite structure. Spinels containing transition metal ions can act as efficient catalysts in various heterogeneous chemical processes, or selective oxidation and reduction agents of several organic molecules.…”