Statistical design for the optimization of the red to orange ratio in YBO₃:Eu³⁺ phosphors

In this study, response surface methodology (RSM) is applied for the optimization of red/orange ratio of YBO₃:Eu³⁺ phosphors synthesized via hydrothermal process. The influence of various process parameters namely borate/yittrium ratio (1, 2, 3), Eu³⁺ concentration (5%, 10%, 15%), and ethanol concentration (20%, 40%, 60%) were taken into consideration. A total of 15 experimental runs were carried out based on Box-Behnken design. Response surface plots were used to determine the interaction effects of the process parameters and optimum conditions of hydrothermal process. Regression analysis shows good fitting of the experimental data to the quadratic polynomial model with P-value of 0.025, F-value of 6.73 and coefficient of determination of 0.924. The optimum experimental conditions were as follows: borate/yittrium ratio at 1.928, Eu³⁺ concentration at 15%, ethanol concentration at 20%. The predicted R/O ratio under the optimum conditions is in good agreement with the R/O ratio obtained from the experiment under the same optimum conditions. The results indicate Box-Behnken design can help for the searching of optimum factors and improve R/O ratio. Moreover, the quadratic model from the Box-Behnken design can quantitatively describe the inherent relationships between the process factors and R/O ratio of YBO₃:Eu³⁺ phosphors.