铬酸酐掺杂V2O5制备高红外反射率氧化铬绿颜料

研究了铬酸酐热分解制备高性能红外反射氧化铬绿颜料,在优化现有铬酸酐热分解工艺的基础上,详细探讨了掺杂制备红外反射氧化铬绿颜料的工艺条件和相关机理。借助UV-vis-NIR、FT-IR、SEM、XRD和CIE-L^*a^*b^*等手段发现:在铬酸酐热分解过程中,不同的热分解温度导致粒径变化,从而影响红外反射率;优化的制备工艺条件(热分解温度1250℃、热分解时间0.5 h)下,氧化铬绿的红外反射率达到90%。在掺杂过程中,V₂O₅的添加可使氧化铬绿的最高红外反射率达到98%。随着V₂O₅添加量的增加,红外反射率先增加后减少;当V/Cr摩尔比为0.004时,红外反射率、电导率、介电常数都达到极值,三者呈现一致的规律性变化。初步机理探索表明,氧化铬本征导电类型为空穴导电,掺杂V₂O₅以后导电类型发生改变,伴随着电阻率的变化,氧化铬吸收和反射光子能力改变,从而影响红外反射性能。

High infrared reflective chromic oxide green pigment prepared by thermal decomposition of CrO3 doped with V2O5

A CrO₃ thermal decomposition process was used to prepare high infrared reflective chromic oxide green pigment.On the basis of optimized conditions of thermal decomposition of CrO₃,the doping conditions and the related mechanism to prepare high infrared reflective chromic oxide green pigment were investigated.Through UV-vis-NIR,FT-IR,SEM,XRD and CIE-L^*a^*b^* analysis,key factors such as thermal decomposition temperature and dopant were studied.In the thermal decomposition step,particle size,as well as infrared reflectance of the chromic oxide green pigment was dependent on decomposition temperature.Under the optimized conditions of 1250℃ and 0.5 h,the infrared reflectivity of the obtained products could be as high as 90%.In the doping step,the maximum reflectivity of the chromic oxide green pigment could reach 98% with doping V₂O₅.As the content of the V₂O₅ dopant increased,the infrared reflectivity of the chromic oxide green pigment firstly increased and then decreased;conductivity and dielectric constant followed the same tendency.The mechanism showed that conductive type of the chromic oxide green pigment transformed with V₂O₅ addition,and change in conductivity resulted in subsequent change in absorptive and reflective capability of photon. At last,the infrared reflectance of the chromic oxide green pigment was improved.