Reversible upconversion luminescence modification based on photochromism has received considerable interest due to its potential applications in optical storage and high‐sensitivity optical switches. However, stimulation‐induced bleaching by an external thermal field is generally used for photochromism‐induced reversible upconversion luminescence modification, which limits its practical application. In this work, a gray BaMgSiO4:Yb3+,Tb3+ ceramic is prepared, exhibiting the photochromism from gray to pink color when stimulated by 254 nm light. Interestingly, the pink BaMgSiO4:Yb3+,Tb3+ ceramic can be bleached by either a 473 nm laser or thermal stimulation. The reversible change between gray and pink color exhibits excellent reproducibility over several cycles by alternating between 254 and 473 nm (or thermal) light stimulation. The influence of the reversible photochromism of the BaMgSiO4:Yb3+,Tb3+ ceramic on its upconversion luminescence is investigated. Reversible modification of the upconversion luminescence is demonstrated by alternating between 254 and 473 nm (or thermal) light stimulation. For reversible modulation of the upconversion luminescence, excellent reproducibility is realized after several cycles. As an example, the application of the BaMgSiO4:Yb3+,Tb3+ photochromic ceramic as an anti‐counterfeiting agent is described.
Reversible luminescence modulation of upconversion phosphors has the potential applications as photoswitches and optical memory and data storage devices. Previously, the photochromic reaction was extensively used for the realization of reversible luminescence modulation. It is very necessary to develop other approaches such as thermomchromic reaction to obtain the reversible upconversion luminescence modulation. In this work, the WO:Yb,Er phosphors with various colors were prepared at various temperatures, exhibiting tunable upconversion luminescence attributed to the formation of oxygen vacancies in the host. Upon heat treatment in the reducing atmosphere or air, the WO:Yb,Er phosphors show a reversible thermomchromic property. The reversible upconversion luminescence modulation of WO:Yb,Er phosphors was observed based on thermomchromic reaction. Additionally, the upconversion luminescence modulation is maintained after several cycles, indicating its excellent stability. The WO:Yb,Er phosphors with reversible upconversion luminescence and excellent reproducibility have potential applications as the photoswitches and optical memory and data storage devices.
Reversible modulation
of upconversion luminescence induced by the
external field stimuli exhibits potential applications in various
fields, such as photoswitches, optical sensing, and optical memory
devices. Herein, a new MoO3:Yb3+,Er3+ thermochromic phosphor was synthesized via a high-temperature solid-state
method, and the reversible color modification of the MoO3:Yb3+,Er3+ phosphor was obtained by alternating
the sintering conditions either in a reducing atmosphere or in air.
The color of the MoO3:Yb3+,Er3+ phosphor
changed from light-yellow to blue under sintering in the reducing
atmosphere and returned back after sintering again in air. The influence
of reversible thermochromism on the upconversion luminescence of MoO3:Yb3+,Er3+ phosphor was investigated.
The MoO3:Yb3+,Er3+ phosphor prepared
in air exhibited visible upconversion luminescence, while the MoO3:Yb3+,Er3+ phosphor has no upconversion
luminescence after sintering in the reducing atmosphere. This up-conversion
luminescence modulation shows excellent reproducibility after several
cycles. The thermochromic MoO3:Yb3+,Er3+ phosphor with reversible modulated upconversion luminescence shows
great potential for practical applications in optical switches and
optoelectronic multifunctional devices.
The upconverting luminescence properties of phosphors are dependent on the hosts. In this work, the WO:Yb, Er phosphor was prepared, and the reversible phase transformation from the WO to the WO was obtained by alternating the sintering in a reducing atmosphere or in air. The influence of reversible phase transformation on the upconversion luminescence was investigated first. The WO:Yb, Er phosphor exhibits the visible upconversion luminescence, while no upconversion luminescence was observed in the WO:Yb, Er phosphor. The reversible modulation of upconversion luminescence of the WO:Yb, Er phosphor retains the excellent reproducibility, exhibiting the potential applications in data storage and optical switches.
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