Narrow band red-emitting A₂GeF₆:Mn⁴⁺ (A = Na, K, Rb, Cs) phosphors were prepared through a two-step precipitation–cation exchange route using a K₂MnF₆ precursor as the Mn⁴⁺ source. The phase purity, morphology, and constituent were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), and electron paramagnetic resonance (EPR) examination. Optical properties were investigated by photoluminescence spectra (PL and PLE) and high-resolution PL. A temperature-dependent PL examination was performed to investigate the electron–phonon coupling emission mechanism of Mn⁴⁺ in these alkali fluorogermanates. The PL data show that both ordered distribution and appropriate distance between Mn⁴⁺ ions are propitious for enhancement of the emission intensity. A resonance emission enhancement (REE) mechanism has been proposed to explain the intensity increment among these products. These phosphors present bright red emission under blue light (467 nm) illumination, among which Cs₂GeF₆:0.03Mn⁴⁺ exhibits the most excellent optical properties with a quantum yield (QY) of 93%. A WLED (white light-emitting diode) fabricated with blend of commercial YAG:Ce³⁺ and this phosphor emits intense warm white light with low color temperature (CCT = 3385 K) and high color rendering index (Ra = 90.5), implying its potential application as red phosphor in WLEDs.

中文翻译：

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通过沉淀-阳离子交换途径合成的荧光粉窄带发红的A ₂ GeF ₆：Mn ⁴⁺（A = Na，K，Rb，Cs）荧光粉的共振发射增强（REE）。

使用K ₂ MnF ₆前驱体作为Mn ⁴⁺源，通过两步沉淀-阳离子交换途径制备了发射红光的窄带A ₂ GeF ₆：Mn ⁴⁺（A = Na，K，Rb，Cs）荧光粉。。通过X射线衍射（XRD），扫描电子显微镜（SEM），X射线光电光谱（XPS）和电子顺磁共振（EPR）检查来表征相纯度，形态和组成。通过光致发光光谱（PL和PLE）和高分辨率PL对光学性质进行了研究。进行了随温度变化的PL检查，以研究Mn ⁴⁺的电子-声子耦合发射机理在这些碱性氟锗酸盐中。PL数据显示，有序分布和Mn ⁴⁺离子之间的适当距离都有利于增强发射强度。已经提出了共振发射增强（REE）机制来解释这些产品之间的强度增加。这些磷光体在蓝光（467 nm）照射下呈现亮红色发射，其中Cs ₂ GeF ₆：0.03Mn ⁴⁺表现出最优异的光学性能，量子产率（QY）为93％。由商用YAG：Ce ³⁺掺混制成的WLED（白色发光​​二极管） 该磷光体发出强烈的暖白光，具有较低的色温（CCT = 3385 K）和较高的显色指数（Ra = 90.5），这意味着它有可能在WLED中用作红色磷光体。