Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as ...Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as pigments or under-layers has been reported in past,reports on metal oxide or doped metal oxide pigments with high NIR reflectance is scarce.We report for the first time a blue colored cobalt aluminate type pigment prepared through doping of cerium,praseodymium or neodymium.CIELAB color measurements and calculation ofDE indicated that the Nd doped sample had crystal size of(36±1)nm,bandgap value of(2.4±0.2)eV and color coordinates similar to that of cobalt aluminate.The molar ratio as estimated by EDX was found to be Al:Cu:Co:Ce:Nd:O=2:0.06:0.06:0.012:0.00012:6.18.The pigment was found to have potential applications as a cool blue colorant,owing to changes in optical properties arising out of crystal chemistry changes.Incorporation of rare earth metal ions was found to enhance the NIR reflectance by 10%,when compared to a conventional cobalt aluminate pigment.The oxide has been well characterized and its performance as a pigment evaluated.We have proposed that changes in crystal lattice when neodymium enters into Ce4+sites enhance the NIR reflectance by about 9%as against the entry of praseodymium.展开更多
基金One of the authors(SPR)thanks the Department of Science and Technology,Government of India for the funding received under the WOS-A programFinancial assistance of the CSIR New Delhi under the XII Plan project is also acknowledged.
文摘Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as pigments or under-layers has been reported in past,reports on metal oxide or doped metal oxide pigments with high NIR reflectance is scarce.We report for the first time a blue colored cobalt aluminate type pigment prepared through doping of cerium,praseodymium or neodymium.CIELAB color measurements and calculation ofDE indicated that the Nd doped sample had crystal size of(36±1)nm,bandgap value of(2.4±0.2)eV and color coordinates similar to that of cobalt aluminate.The molar ratio as estimated by EDX was found to be Al:Cu:Co:Ce:Nd:O=2:0.06:0.06:0.012:0.00012:6.18.The pigment was found to have potential applications as a cool blue colorant,owing to changes in optical properties arising out of crystal chemistry changes.Incorporation of rare earth metal ions was found to enhance the NIR reflectance by 10%,when compared to a conventional cobalt aluminate pigment.The oxide has been well characterized and its performance as a pigment evaluated.We have proposed that changes in crystal lattice when neodymium enters into Ce4+sites enhance the NIR reflectance by about 9%as against the entry of praseodymium.
