General Situation of Rare Earth Phosphor Standard System in China

A batch of lamp powder standards was promulgated and implemented to meet the needs of the development of China's rare earth phosphor industry. A standard system for rare earth phosphors was established. The system includes product standards, analytical test method standards, and standard samples to establish advanced and perfect The internationally accepted rare earth standard system has laid a good foundation. In the revision of the standard system, the standard drafting unit fully investigates the domestic and international production and trade situation, investigates and collects relevant data, collects domestic and foreign standard materials and technical reports, technical agreements and order contracts, etc., to the actual production of China's rare earth phosphor industry. Based on the situation, fully taking into account the advanced nature, scientificity, rationality, applicability and principles of international standards, the standards basically meet the needs of the industry.

At present, only China has a relatively complete standard system for rare earth phosphors. In other countries, there are no national standards and industry standards for rare earth phosphors. There are only some enterprise standards for rare earths in foreign countries. Experts confirmed by the standard validation meeting, most of the standards in this series of lamp powder standards have reached the international advanced level, such as "Rare Earth Yellow Phosphor for White LED Lights", "Rare Earth Trichromatic Phosphors for Lamps", "Rare Earth Long Afterglow" The three product standards such as Phosphor Powder and the related eight test method standards have reached the international advanced standards, and the other standards have reached the international general level.

1. Rare earth trichromatic phosphor for lamp and test method thereof

In 1993, China established national standards and revised them in 2002. This revision has adjusted the relative brightness, emission spectrum and chromaticity performance, thermal stability, density, specific surface area and other indicators of the standard red powder, blue powder and green powder respectively. At the same time, the chroma performance of the mixed powder was evaluated. Center particle size. It is worth mentioning that the relative brightness and specific surface area of ​​the revised standard are determined by using the national standard samples that have been issued to make the relative brightness measurement more comparable, and the specific surface area is improved. Accuracy, and increased assessment of thermal quenching, pH and conductivity. Compared with GB/T 14633-2002, this standard mainly has the following changes:

The normative reference documents have been added to the reference standard GB/T 5838 "phosphor terminology" and GB/T20170.1 "Rare earth metal and its physical properties test method for the determination of the particle size distribution of rare earth compounds";

Delete the definition of “granularity distribution” and “correlated color temperature”; increase the definition of “thermal annihilation”; adjust the symbolic representation of relative brightness and chromaticity coordinates in “thermal stability”;

The center value (xm, ym) of the red fluorescent pink product coordinates, the center value (ym) of the blue fluorescent pink product coordinates, and the particle characteristics (including the center particle diameter) in the original Table 1, Table 2, Table 3, and Table 4. The assessment of the specific surface area is adjusted from the assessment center value and the deviation value to only the deviation value. The central value is determined by the supplier and the buyer.

Delete the assessment of the particle size distribution in the original table 1, table 2, and table 3;

Delete the original table 1 and table 2 for the evaluation of thermal stability, the original table 3 thermal stability assessment temperature is adjusted from 550 ° C to 600 ° C;

Combine the original table 1, table 2, and table 3.

Each grade increases the evaluation index for heat annihilation, pH and conductivity;

The original table 4 is checked for the relative brightness and the correlated color temperature; the deviation of the chromaticity coordinates and the indicator of the color rendering index are adjusted.

The main technical indicators of rare earth trichromatic phosphors for lamps are as follows:

1. Determination of relative brightness

The test method of this standard is relatively mature. Since the standard sample of rare earth phosphor has been developed, it is of great significance to accurately test the product and ensure the quality of the product. In this test, samples from a number of manufacturers were used to test multiple samples with standard phosphors. In order to make the test data more comparable, the relative brightness and specific surface area of ​​the rare earth trichromatic phosphors for lamps are required to be determined by the national standard sample “Rare Earth Tricolor Standard for Lamps (GSB04-1649~1653-2003)”. The test data is accurate.

2. Determination of emission spectrum and chromaticity performance

Whether the performance of the calibration lamp is stable and accurate is directly related to the accuracy of the measuring instrument. Therefore, the calibration lamp is changed from 100h every two years or two years to 50h every other year or year, and the radiation is 253.7nm. The intensity stability is better than 0.5% and the radiation intensity stability of 253.7nm is better than 0.2%/10min. As the measurement accuracy of the instrument increases, the standard deviation of the wavelength uncertainty is not more than 1 nm, and the standard deviation is adjusted to be no more than 0.5 nm; the standard deviation of the wavelength uncertainty is adjusted to be less than 0.5 nm and the standard deviation is not more than 0.2 nm. At the same time, the standard reproducibility of the chromaticity coordinates u and v is better than 0.0002, and the standard reproducibility of the chromaticity coordinates u and v is better than 0.0003.

3. Determination of thermal stability

After the phosphor is heated to a room temperature by heating at a certain temperature (generally air condition), the brightness of the light is measured and compared with the brightness of the light when it is not heated. Since the heating causes damage to the valence state or the like of the activator of the phosphor, the luminance of the emitted light is lowered. For the stability of the heat treatment of the phosphor (when the tube is baked), it is mainly considered that the activator is equivalent to the phosphor which is easily oxidized, such as blue powder. This standard is to improve the thermal stability test requirements. The initial recommended holding time is 1h. However, considering the lamp making process and saving power, it is considered that 0.5h is enough to analyze the thermal stability of rare earth trichromatic phosphors, so the supplementary experiment is 600 °C. /0.5h of data. In addition, during the test, the test results of the different test units were quite different. The main reason for the analysis was that the furnace temperature was not controlled properly. The experimental area must be a constant temperature zone. If the furnace temperature is well controlled, the experimental data will be stable.

4. Determination of density

Since the previously used density bottles are currently circulated on the market, they are not easily available. In order to facilitate the use of each unit, the previously used density bottle was changed to a standard size pycnometer; the pycnometer has two specifications of 25mL and 50mL. From the viewpoint of saving the amount of the penetrating agent and the sample to be tested, a 25 mL-type pycnometer is selected as the measuring container. From the data of the verification results, the power intensity and duration of the ultrasound, the magnitude and duration of the vacuum, and the quality of the powder have no significant deviation from the obtained density result data. This is because the surface tension of anhydrous ethanol is small and saturated. Goodness, plus appropriate ultrasonic and vacuum processing steps, so the deviation is small. Therefore, the experimental steps are still: ultrasonic power 50W, ultrasonic time 5min, vacuum degree 0.9kPa, vacuum time 10min.