title: Photoluminescent Evolution Induced by Structural Transformation Through Thermal Treating in the Red Narrow-Band Phosphor K₂GeF₆:Mn⁴⁺.
abstract: This study explored optimal preparation conditions for K2GeF6:Mn(4+) red phosphors by using chemical coprecipitation method. The prepared hexagonal P3̅m1 K2GeF6:Mn(4+) exhibited efficient red emission, high color purity, good Mn(4+) concentration stability, and low thermal quenching. Structural evolution from hexagonal P3̅m1 to P63mc and then P63mc to cubic Fm3m occurred after thermal treatment at approximately 400 and 500 °C, respectively. Hexagonal P63mc phase showed an obvious zero phonon line peak at 621 nm, whereas cubic Fm3m phase showed no red emission. Yellowish K2GeF6:Mn(4+) with both hexagonal P3̅m1 and P63mc symmetries are promising commercial red phosphors for white light-emitting diodes.
authors.affiliation: †School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi, P.R. China.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Wei
authors.affiliation: ‡Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Chun Che
authors.initials: CC
authors.lastname: Lin
authors.affiliation: †School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi, P.R. China.
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Wang
authors.affiliation: ‡Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Mu-Huai
authors.initials: MH
authors.lastname: Fang
authors.affiliation: †School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi, P.R. China.
authors.forename: Huan
authors.initials: H
authors.lastname: Jiao
authors.affiliation: ‡Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.|§Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Ru-Shi
authors.initials: RS
authors.lastname: Liu
keywords: chemical coprecipitation method; phosphors; photoluminescent properties; structural evolution; thermal stability