New blue pigments based on Col plus and Las plus doped hibonite for NIR-reflective coatings

New blue pigments based on Ca,=-iaxAl iota 2_CoxU iota g (x = 0-0.5) were obtained by the combustion method, avoiding the expensive annealing step. The obtained pigments have a speci.ic surface area between 3 and 5 m2jg. The c ystallite size of Ca iota-xLaxAl iota 2-xCox01g pigments decreases from 44 to 26 nm, as the substitution degree, x, increases from 0 to 0.5 apfu. Despite the low Co2 content (<4% mass), the pigments show intense blue shades and high total solar reflectance. CIE C/a /b. parameters show that, with the increase of chromophore content from 0.1 apfu (73.3/-2.6/-34.1) to 0.5 apfu (60.5/2.6/-47.0) the blue color of the pigments intensifies, whilst the total solar reflectance decreases from 70.7% (x = 0.1) to 59.6% (x = 0.5). The tests performed contirmed the possibility of using Ca iota_x1axAl12_xCo,,O iota gpigments in making cool, NIR-reflective coatings.(R) 2023 Elsevier Ltd. All rights reserved.

Automated summary

New blue pigments based on Ca,=-iaxAl iotas2_CoxU iotasg (x = 0-0.5) were obtained by the combustion method, without annealing. The obtained pigments have specific surface areas between 3 and 5 m2/g. As the substitution degree, x, increases from 0 to 0.5 apfu, the crystallite size of Ca iota-xLaxAl iotas2-xCoxO1g pigments decreases from 44 to 26 nm. Despite the low Co2 content (<4% mass), the pigments exhibit intense blue shades and high total solar reflectance. CIE C/a /b parameters indicate that as the chromophore content increases from 0.1 apfu (73.3/-2.6/-34.1) to 0.5 apfu (60.5/2.6/-47.0), the blue color of the pigments intensifies while the total solar reflectance decreases from 70.7% (x = 0.1) to 59.6% (x = 0.5). The tests confirmed the potential use of Ca iota-x1axAl iotas2-xCoO iotag pigments in producing cool, NIR-reflective coatings.