Chemical pressure enlarged camouflage color zone in Mn(IV)-activated yellow-green pigments

Abstract

Environment-friendly and cost-effective versatile yellow-green inorganic pigments are technically significant for natural camouflage but rare. Here, we adopt site-selective parent-doping of Mn–Li into the octahedral Ca-site (CaB) of Ca3TeO6 to deliver vivid greenish pigments by the unprecedented yellow-green Mn4+O6 chromophore, yielding tunable pigments resemble to seasonal leaves. The camouflage color zone of these pigments are remarkably enlarged by chemical pressure via Mg2+/Sr2+-substitution for the A-site Ca (CaA). The locally anisotropic and positive chemical pressure on chromophore group is scaled to be around +14.4/+23.3 GPa, as estimated from the accompanied geometric evolution of Mn4+O6. The achieved pigments also demonstrate excellent chemical and thermodynamic stability and high (60–80%) near infrared reflectivity in 1500–2500 nm, showing potential applications for natural camouflage and yellow-green “cool pigments”. These findings built a bridge between chemical and equivalently physical pressure, and nominated a way to estimate the overall and local strain/pressure by optical descriptor.