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Developing Intense Blue and Magenta Colors in α‐LiZnBO 3 : The Role of 3d‐Metal Substitution and Coordination
Author(s) -
Tamilarasan S.,
Reddy M. L. P.,
Natarajan S.,
Gopalakrishnan J.
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201601124
Subject(s) - magenta , crystallography , metal , chemistry , pigment , chromophore , crystal structure , transition metal , absorption (acoustics) , materials science , photochemistry , organic chemistry , inkwell , composite material , catalysis
We describe the synthesis, crystal structures, and optical absorption spectra/colors of 3d‐transition‐metal‐substituted α‐LiZnBO 3 derivatives: α‐LiZn 1− x M II x BO 3 (M II =Co II (0< x <0.50), Ni II (0< x ≤0.05), Cu II (0< x ≤0.10)) and α‐Li 1+ x Zn 1−2 x M III x BO 3 (M III =Mn III (0< x ≤0.10), Fe III (0< x ≤0.25)). The crystal structure of the host α‐LiZnBO 3 , which is both disordered and distorted with respect to Li and Zn occupancies and coordination geometries, is largely retained in the derivatives, which gives rise to unique colors (blue for Co II , magenta for Ni II , violet for Cu II ) that could be of significance for the development of new, inexpensive, and environmentally friendly pigment materials, particularly in the case of the blue pigments. Accordingly, this work identifies distorted tetrahedral MO 4 (M=Co, Ni, Cu) structural units, with a long M−O bond that results in trigonal bipyramidal geometry, as new chromophores for blue, magenta, and violet colors in a α‐LiZnBO 3 host. From the L*a*b* color coordinates, we found that Co‐substituted compounds have an intense blue color that is stronger than that of CoAl 2 O 4 and YIn 0.90 Mn 0.10 O 3 . The near‐infrared (NIR) reflectance spectral studies indicate that these compounds exhibit a moderate IR reflectivity that could be significant for applications as “cool pigments”.