Jg. Fagan et Vrw. Amarakoon, SOL-GEL COATING OF YBA2CU3O7-X WITH TIO2 FOR ENHANCED ANISOTROPIC GRAIN-GROWTH, Journal of materials research, 8(7), 1993, pp. 1501-1509
This investigation focused on the effects of TiO2 additions (2.5-5 mol
%) incorporated via sol-gel coating of powders on sintering behavior,
microstructure development, electrical resistivity, and magnetic susc
eptibility of YBa2Cu3O7-x. Specimens were sintered at less-than-or-equ
al-to 960-degrees-C for 6 h in all cases. TEM analysis indicated the s
ol-gel coating to be uniformly distributed around each particle and of
thickness approximately 20 to 40 nm. The addition Of TiO2 was seen to
reduce the sintering temperature by up to approximately 200-degrees-C
, indicating the formation of a liquidus phase below that normally rep
orted for YBa2Cu3O7-x. Grain growth and grain anisotropy behavior were
influenced by TiO2 addition. A maximum in density, grain size, and an
isotropy was achieved with 2.5 mol % addition sintered at 930-degrees-
C. TiO2 addition was shown to result in the formation of greater amoun
ts of secondary phases such as Y2BaCuO5 and BaCuO2, particularly at hi
gher TiO2 levels and sintering temperatures. The use of TiO2 additions
also altered the magnetic susceptibility with the optimum response oc
curring for samples with 2.5 mol % TiO2 addition when sintered at 930-
degrees-C.