GB/T 24981.2-2020Test methods of rare earth long afterglow phosphors—Part 2: Determination of afterglow brightness (English PDF)

3.1 Saturating excitation

The excitation light source is 5 500 K ~ 6 500 K light source (xenon lamp, fluorescent lamp, LED lamp). Extend the excitation time, and the afterglow brightness of the phosphor changes within 5%.

4.1 Illumination test device

The illumination test device shall meet the following conditions:

a) The measurement range is 10 lx ~ 1 x 10^5 lx; the accuracy shall meet the requirements of the national grade-1 illuminometer. […]

6.2 Illumination correction

Turn on the light source and stabilize for 10 min ~ 30 min according to the requirements of the instrument. Place the photometric probe of the illumination test device on the sample to be excited; adjust the light source; ensure that the average illumination illuminating the tested sample is stable at 1 000 lx ± 5 lx or 25 lx ± 0.5 lx.

6.3 Afterglow brightness test

6.3.1 Load the sample into the sample pan; compact and make the surface flat.

6.3.2 Place the sample pan at the place to be excited, so that the sample is irradiated by the light source to reach a saturated excitation state; the excitation illumination on the test surface of the sample shall meet the requirements of 4.1c).

6.3.3 Turn off the light source; immediately use the afterglow brightness test device to test the afterglow brightness of the sample; record the afterglow brightness values of 10 min, 30 min, and 60 min. If the buyer has special requirements, the supplier and the buyer shall negotiate and determine.

6.3.4 Do 3 parallel tests; take the arithmetic average. The relative deviation of the test results shall not exceed 5%.

7.1 Repeatability

For the measured values of the afterglow brightness of two independent tests that are obtained under repeatability conditions, within the average range given below, the absolute difference between these two test results does not exceed the repeatability limit (r); the case of exceeding the repeatability limit (r) is not more than 5%; the repeatability limit (r) is obtained by linear interpolation according to the data in Table 1. […]