Single-Mode Excitation Color-Changing Luminescent Upconversion Material and Preparation Method Thereof

Abstract

A single-mode excitation color-changing luminescent upconversion material, and its preparation method are provided. The molecular formula of the single-mode excitation color-changing luminescent upconversion material is A.sub.xMOCl.sub.y-1:Yb/Ln, where A is at least one of Lithium(I) ion (Li.sup.+), Sodium(I) ion (Na.sup.+), Sodium(I) ion (K.sup.+), or Cesium(I) ion (Cs.sup.+); M is at least one of Lanthanum(III) ion (La.sup.3+), Yttrium(III) ion (Y.sup.3+), Gadolinium(III) ion (Gd.sup.3+), or Lutetium(III) ion (Lu.sup.3+); Ln is at least one of Erbium(III) ion (Er.sup.3+), Holmium(III) ion (Ho.sup.3+), or Holmium(III) ion (Tm.sup.3+), with 1x4 and 4y7. The excitation wavelength range of the material is 950 nanometers (nm)-1100 nm, and the emission wavelength range is 400 nm-800 nm. Under single-mode near-infrared excitation, the material exhibits color-changing upconversion luminescence.

Claims

1. A single-mode excitation color-changing luminescent upconversion material having a composition represented by a formula A.sub.xMOCl.sub.y-1:Yb and Ln, wherein the single-mode excitation color-changing luminescent upconversion material is prepared by a following method: mixing chlorides of A, chlorides of M, a sensitizer, and an activator in a ratio of the formula A.sub.xMOCl.sub.y-1:Yb and Ln, followed by a solid-state reaction to obtain the single-mode excitation color-changing luminescent upconversion material; wherein A is at least one of Li.sup.+, Na.sup.+, K.sup.+, or Cs.sup.+; M is at least one of La.sup.3+, Y.sup.3+, Gd.sup.3+, or Lu.sup.3+; Ln is at least one of Er.sup.3+, Ho.sup.3+, or Tm.sup.3+; Yb acts as a sensitizer and occupies M sites in an amount of 1-30 mol %, and Ln acts as an activator and occupies M sites in an amount of 0.1-5 mol %; x=1, y=4; or x=2, y=5; or x=3, y=6; and in the A.sub.xMOCl.sub.y-1:Yb and Ln, O.sup.2 is a doped anion occupying Cl sites.

2. The single-mode excitation color-changing luminescent upconversion material according to claim 1, wherein an excitation wavelength of the single-mode excitation color-changing luminescent upconversion material is 950 nm-1100 nm; and an emission wavelength of the single-mode excitation color-changing luminescent upconversion material is 400 nm-800 nm.

3. The single-mode excitation color-changing luminescent upconversion material according to claim 1, wherein color changes of the single-mode excitation color-changing luminescent upconversion material comprise red to green, green to cyan, or green to blue.

4. The single-mode excitation color-changing luminescent upconversion material according to claim 1, wherein the chlorides of A are selected from one or more of LiCl, NaCl, KCl, and CsCl; the chlorides of M are selected from one or more of LaCl.sub.3, YCl.sub.3, GdCl.sub.3, and LuCl.sub.3; the sensitizer is selected from YbCl.sub.3; and the activator is selected from one or more of ErCl.sub.3, HoCl.sub.3, and TmCl.sub.3.

5. The single-mode excitation color-changing luminescent upconversion material according to claim 1, wherein a heat treatment temperature is 100 C.-500 C. and a heat treatment duration is 2-48 h in a solid-state reaction method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the content of the present disclosure more clearly understood, the following further detailed description of the present disclosure is provided based on the specific embodiments of the present disclosure and in combination with the attached drawings.

[0031] FIG. 1 shows the X-ray Diffraction (XRD) pattern of Cs.sub.2GdOCl.sub.4:Yb/Er in Embodiment 1 of the present disclosure.

[0032] FIG. 2 shows the upconversion emission spectra of the color-changing luminescent upconversion material Cs.sub.2GdOCl.sub.4:Yb/Er under 975 nanometers (nm) excitation at different times in Embodiment 1.

[0033] FIG. 3 shows the integrated intensity diagram of the emission spectra of the color-changing luminescent upconversion material Cs.sub.2GdOCl.sub.4:Yb/Er at 525 nm (Green) and 660 nm (Red) in Embodiment 1.

[0034] FIG. 4 shows the color-changing luminescence photos of the emission spectra of the color-changing luminescent upconversion material Cs.sub.2GdOCH.sub.4:Yb/Er powder within 4 seconds(s) in Embodiment 1.

[0035] FIG. 5 shows the XRD pattern of CsGdOCl.sub.3:Yb/Ho in Embodiment 2 of the present disclosure.

[0036] FIG. 6 shows the upconversion emission spectra of the color-changing luminescent upconversion material CsGdOCl.sub.3:Yb/Ho under 975 nm excitation at different times in Embodiment 2.

[0037] FIG. 7 shows the integrated intensity diagram of the emission spectra of the color-changing luminescent upconversion material CsGdOCl.sub.3:Yb/Ho at 475 nm (Blue), 530 nm (Green), 590 nm (Orange), and 650 nm (Red) in Embodiment 2.

[0038] FIG. 8 shows the color-changing luminescence photos of the emission spectra of the color-changing luminescent upconversion material CsGdOCl.sub.3:Yb/Ho powder within 4 seconds(s) in Embodiment 2.

[0039] FIG. 9 shows the XRD pattern of K.sub.3YOCl.sub.5:Yb/Tm in Embodiment 3 of the present disclosure.

[0040] FIG. 10 shows the upconversion emission spectra of the color-changing luminescent upconversion material K.sub.3YOCl.sub.5:Yb/Tm under 975 nm excitation at different times in Embodiment 3.

[0041] FIG. 11 shows the color-changing luminescence photos of the emission spectra of the color-changing luminescent upconversion material K.sub.3YOCl.sub.5:Yb/Tm powder within 6 s in Embodiment 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following describes the disclosure in detail with reference to specific embodiments and accompanying drawings to enable those skilled in the art to better understand and implement the disclosure. However, the embodiments provided are not intended to limit the disclosure.

Embodiment 1 (Cs.SUB.2.GdOCl.SUB.4.:Yb/Er)

[0043] This embodiment provides a preparation method for a single-mode excitation color-changing luminescent upconversion material (Cs.sub.2GdOCl.sub.4:Yb/Er), the steps are as follows:

[0044] weighing 2 millimoles (mmol) of CsCl, 0.78 mmol of GdCl.sub.3, 0.2 mmol of YbCl.sub.3, and 0.02 mmol of ErCl.sub.3, mixing uniformly in a mortar, and calcining the mixture in a tube furnace at 450 degrees Celsius ( C.) for 24 hours (h) to obtain Cs.sub.2GdOCl.sub.4:Yb/Er. Its XRD pattern is shown in FIG. 1.

[0045] Under 975 nanometers (nm) excitation, the emission spectra of the obtained Cs.sub.2GdOCH.sub.4:Yb/Er are captured continuously. From the emission spectra and integrated intensity of the emission at different times (FIG. 2 and FIG. 3), it may be seen that the initial red emission band (660 nm) intensity is higher than the green emission band (525 nm), showing red emission. As excitation time increases, the red emission weakens while the green emission intensifies, eventually showing green emission. FIG. 4 demonstrates that Cs.sub.2GdOCH.sub.4:Yb/Er exhibits red-to-green color-changing luminescence within 4 seconds(s) under 975 nm excitation.

Embodiment 2 (CsGdOCl.SUB.3.:Yb/Ho)

[0046] This embodiment provides a preparation method for a single-mode excitation color-changing luminescent upconversion material (CsGdOCl.sub.3:Yb/Ho), the steps are as follows:

[0047] weighing 1 mmol of CsCl, 0.78 mmol of GdCl.sub.3, 0.2 mmol of YbCl.sub.3, and 0.02 mmol of HoCl.sub.3, mixing uniformly in a mortar, and calcining the mixture in a muffle furnace at 300 C. for 2 h to obtain CsGdOCl.sub.3:Yb/Ho. Its XRD pattern is shown in FIG. 5.

[0048] Under 975 nm excitation, the emission spectra of the obtained CsGdOCl.sub.3:Yb/Ho are measured at different times. The emission bands in the spectra are integrated, and the results are shown in FIG. 6 and FIG. 7. It may be seen from FIG. 6 that at the initial stage of 975 nm excitation, the green emission intensity (540 nm) of the sample is dominant, and its red emission intensity (660 nm) is relatively weak, so the sample emits green light at the initial stage; with the prolongation of excitation time, the blue light emission intensity (475 nm) of the sample gradually increases, and its intensity exceeds that of green light and red light in the later stage (shown in FIG. 7). As may be seen from FIG. 8, CsGdOCl.sub.3:Yb/Ho exhibits green-to-cyan color-changing luminescence within 4 s under 975 nm excitation.

Embodiment 3 (K.SUB.3.YOCl.SUB.5.:Yb/Tm)

[0049] This embodiment provides a preparation method for a single-mode excitation color-changing luminescent upconversion material (K.sub.3YOCl.sub.5:Yb/Tm), the steps are as follows:

[0050] weighing 3 mmol of KCl, 0.79 mmol of YCl.sub.3, 0.2 mmol of YbCl.sub.3, and 0.01 mmol of TmCl3, mixing uniformly in a mortar, and heat-treating the mixture in an oven at 120 C. for 48 h to obtain K.sub.3YOCl.sub.5:Yb/Tm. Its XRD pattern is shown in FIG. 9.

[0051] Under continuous 975 nm excitation, the emission spectra of the obtained K.sub.3 YOCl.sub.5:Yb/Tm are obtained at different times (FIG. 10). The emission spectrum initially shows a strong green emission peak at 525 nm and a weaker blue emission peak at 475 nm, resulting in green luminescence during the early excitation stage. As excitation time increases, while the green emission band intensifies, the blue emission band exhibits more significant enhancement, ultimately leading to blue-dominated luminescence in the later stage. The time-resolved luminescence photographs of the solid powder visually confirm this single-wavelength-excited color-changing (green to blue) upconversion phenomenon (FIG. 11).

[0052] It is evident that the above-described embodiments are merely illustrative embodiments provided for clarity, and are not intended to limit the scope of implementation. Those skilled in the art may make various modifications or adaptations based on the foregoing description without departing from the essence of the present disclosure. It is neither necessary nor possible to enumerate all possible implementations herein. Nevertheless, any obvious variations or modifications derived therefrom shall remain within the protective scope of the present disclosure.