T. Thara, P. Rao, Athira K. V. Raj
Sep 15, 2019
Citations
1
Influential Citations
14
Citations
Journal
Solar Energy Materials and Solar Cells
Abstract
Abstract New series of brilliant yellow colorants with high NIR reflectance in rare earth doped scheelite type oxides, [(LiRE)0.125Bi0.75][W0·25V0.75]O4 (RE = La–Yb) and [(LiLa)x/2Bi1-x][WxV1-x]O4 (x = 0–0.3) were developed by the ceramic route. Different advanced techniques were used to examine the structural, morphological and optical properties of the synthesized colorants. The pigment series [(LiLa)x/2Bi1-x][WxV1-x]O4 undergoes a structural transformation from a monoclinic to a tetragonal scheelite phase and the second pigment series with various rare earth substitutions crystallize with a tetragonal phase. Strong absorption in the ultraviolet and blue region is observed for all the samples leading to brilliant yellow colorants with high solar reflectance. The band gap variation associated with the introduction of different energy levels between valance band and conduction band defines the various yellow shades of the pigments. Classically [(LiGd)0.125Bi0.75][W0·25V0.75]O4 pigment showed intense yellow color (b* 84.62) having NIR reflectance of 94% that has improved values than the commercially available Sicopal yellow. The probable applicability studies of [(LiLa)0·125Bi0.75][W0·25V0.75]O4 pigment as cool pigment was also exemplified on a concrete cement block and on a metal sheet. Chemical resistance tests are a sign of their permanence in the severe weathering conditions. These pigments are found to be promising ones for exterior coating energy saving applications.