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GB/T 24981.2-2020 PDF in English


GB/T 24981.2-2020 (GB/T24981.2-2020, GBT 24981.2-2020, GBT24981.2-2020)
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GB/T 24981.2-2020: PDF in English (GBT 24981.2-2020)

GB/T 24981.2-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S 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’s 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
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.