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GB/T 24981.2-2020 English PDF (GBT24981.2-2020)

GB/T 24981.2-2020 English PDF (GBT24981.2-2020)

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GB/T 24981.2-2020: Test methods of rare earth long afterglow phosphors - Part 2: Determination of afterglow brightness

This Part of GB/T 24981 specifies the determination method of afterglow brightness of rare earth long afterglow phosphors. This Part applies to the determination of the afterglow brightness of rare earth long afterglow phosphors.
GB/T 24981.2-2020
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.120.99
H 14
Replacing GB/T 24981.2-2010
Test methods of rare earth long afterglow phosphors -
Part 2: Determination of afterglow brightness
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: OCTOBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Method principle ... 5
3 Terms and definitions ... 5
4 Instruments and devices ... 5
5 Sample preparation ... 6
6 Test procedures ... 6
7 Precision ... 7
Test methods of rare earth long afterglow phosphors -
Part 2: Determination of afterglow brightness
1 Scope
This Part of GB/T 24981 specifies the determination method of afterglow brightness of rare earth long afterglow phosphors.
This Part applies to the determination of the afterglow brightness of rare earth long afterglow phosphors.
2 Method principle
Use a light source of a color temperature of 5 500 K ~ 6 500 K as the excitation light source; use the specified illuminance to directly illuminate the sample. When the sample is excited and saturated, turn off the excitation light source; use a luminance meter to measure it; record the brightness value of the afterglow fluorescence of the sample at the specified time interval, to get the afterglow brightness of the sample.
3 Terms and definitions
The following terms and definitions are applicable to this document.
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 Instruments and devices
4.1 Illumination test device
The illumination test device shall meet the following conditions:
a) The measurement range is 10 lx ~ 1??105 lx; the accuracy shall meet the requirements of the national grade-1 illuminometer.
6.1.3 During the measurement process, except for the illumination of the excitation light source within the specified excitation time, stray light interference such as visible light or ultraviolet light is not allowed. 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 Precision
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.
Table 1 ?€? Afterglow brightness and repeatability limits of the long
afterglow products

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