Novel yellow orange light-emitting phosphate glass ceramic material and preparation method thereof

Abstract

The invention provides a preparation method of novel yellow orange light-emitting phosphate glass ceramic. The general chemical formula of a glass matrix of the glass ceramic is 35P2O5-10BaO-40ZnO-15B2O3, Dy < 3 + > and Sm < 3 + > are doped in the glass matrix, BaZn2 (PO4) 2 nanocrystals are separated out in the glass matrix, the glass ceramic material has high crystallinity and transparency, the excitation spectrum is in an ultraviolet region, and the excitation spectrum is in an ultraviolet region. By changing the doping amount of Sm < 3 + >, the movement of the spectrum can be realized, so that the change of the emitting color is realized. Warm yellow oranges are particularly beneficial to human vision, strongly recommended for indoor lighting. A pleasant and safe atmosphere is created, a comfortable and relaxed space is enhanced, and the air purifier is suitable for families, offices and various other environments. The fluorescent material has good thermal stability and abundant luminescence performance, and can be used as a novel fluorescent material to be applied to the luminescence fields of illumination decoration, automobile illumination and the like.

Description

Technical Field

[0001] The invention relates to the technical field of phosphate glass ceramic composite materials, and in particular to a novel yellow-orange light emitting phosphate glass ceramic material and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, lighting technology has undergone significant changes, especially the rise of light-emitting diode (LED) lighting. LED lighting has gradually replaced traditional lighting methods and become the mainstream of the new generation of solid-state lighting due to its advantages such as energy saving, high efficiency, environmental protection and long life. However, the organic resin encapsulation technology currently used in the market, although it meets the application requirements to a certain extent, has exposed many shortcomings in actual use.

[0003] First, LEDs generate heat during operation. If the heat dissipation is poor, the lighting effect will be reduced and even the service life of the LED will be shortened. Traditional organic resin materials tend to soften or turn yellow in high temperature environments, affecting the color temperature and color reproduction of the light source, and thus affecting the user's visual experience.

[0004] Secondly, existing organic packaging materials have poor thermal and chemical stability, which can easily lead to light decay and reduced luminous efficiency. This phenomenon is particularly evident in high-power LED applications, where the operating temperature can reach 150-200°C, and the performance of organic materials at this temperature is often difficult to maintain.

[0005] In addition, traditional phosphor encapsulation technology usually relies on the refractive index matching of organic matter and phosphor, which limits the light absorption and emission efficiency of phosphor, resulting in unstable color temperature and insufficient luminous intensity. Therefore, developing a new type of luminescent material that can maintain excellent performance under high temperature and high-intensity light conditions has become a technical problem that needs to be solved in the current lighting field.

[0006] The new yellow-orange phosphate glass ceramic has the ability to adjust the color of light emission, which is particularly suitable for indoor lighting and can create a warm and comfortable environment. 3+ and Sm 3+ , achieving flexible adjustment of luminescence performance, especially by changing Sm 3+ The doping amount is adjusted to achieve the shift of the spectrum. The melt quenching method combined with heat treatment emphasizes the importance of nanocrystal precipitation, thereby ensuring high crystallinity and transparency. 3+ , Tb 3+ and Sm 3+Unlike the invention of the present invention, the present invention focuses more on improving the pleasure and safety of indoor lighting and decorative lighting, while having good thermal stability and luminous performance, and can maintain excellent performance in high temperature environments. This invention is significantly different from previous patent inventions in terms of luminous color adjustment, applicable environment and material composition, especially in the application of indoor lighting and creating atmosphere. At the same time, the innovation of the preparation method and the emphasis on material performance make it more competitive in specific application fields.

[0007] In this context, phosphate glass ceramic materials have gradually attracted the attention of researchers due to their excellent thermal stability, chemical stability and luminescence performance. Through the heat treatment of glass materials with controlled crystallization, not only can excellent light transmittance and luminescence performance be achieved, but also environmental pollution and health risks can be effectively reduced. Therefore, the development of a new type of yellow-orange phosphate glass ceramic material with excellent optical properties and thermal stability will provide a new solution for the further improvement of LED lighting technology. Summary of the invention

[0008] The purpose of the present invention is to provide a new type of yellow-orange phosphate glass ceramic and a preparation method thereof in view of the deficiencies of the prior art. The method is completed by raw material preparation, melting and quenching, annealing, tableting and heat treatment steps, and adopts a P2O5-BaO-ZnO-B2O3 glass matrix, wherein P2O5 and B2O3 provide a rigid structure, so that the glass ceramic material has the advantages of high hardness and good mechanical properties, and at the same time creates nucleation and boundary conditions for the glass crystallization process; the role of introducing ZnO and BaO is to provide the necessary constituent elements for the precipitation of nanocrystalline BaZn2(PO4)2. The glass ceramic material obtained by the method of the present invention has good thermal stability, achieves excellent light transmittance, can effectively transmit light, and becomes an ideal luminescent material. The preparation method is simple and efficient.

[0009] The invention discloses a novel yellow-orange phosphate glass ceramic material, wherein the glass matrix of the glass ceramic material is composed of BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, and B2O3 13-15%, and Dy is doped in the form of a compound. 3+ , Sm 3+ The doped dysprosium compound Dy2O3 and samarium compound Sm2O3 account for 0.5% and 0.1-1% of the total mass of other raw materials respectively, and BaZn2(PO4)2 nanocrystals are precipitated in the glass matrix. The specific operation is carried out according to the following steps:

[0010] Raw materials preparation:

[0011] a. Weigh glass matrix raw materials BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, B2O3 13-15% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.1-1%, mix them in an agate mortar, grind for 3-4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0012] Melting and quenching:

[0013] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1200-1300° C. and calcined for 2-4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0014] annealing:

[0015] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0016] Tableting:

[0017] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0018] Heat Treatment:

[0019] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 fluorescent glass-ceramic materials.

[0020] A method for preparing a novel yellow-orange luminescent phosphate glass ceramic material is carried out according to the following steps:

[0021] Raw materials preparation:

[0022] a. Weigh glass matrix raw materials BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, B2O3 13-15% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.1-1%, mix them in an agate mortar, grind for 3-4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0023] Melting and quenching:

[0024] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1200-1300° C. and calcined for 2-4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0025] annealing:

[0026] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0027] Tableting:

[0028] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0029] Heat Treatment:

[0030] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 fluorescent glass-ceramic materials.

[0031] The novel yellow-orange phosphate glass ceramic and its preparation method described in the present invention have a matrix glass with good forming ability and thermal stability, low phonon energy and good transparency, and are a good matrix for rare earth ions, with low molding temperature and low raw material cost. 2+ The radius and doping Dy 3+ 、Sm 3+ The radius of the doped Dy 3+ 、Sm 3+ It is easier to embed into nanocrystalline BaZn2(PO4)2. A large number of rare earth luminescent ions are embedded in a low phonon energy environment, which is beneficial to reduce the probability of non-radiative transition and improve the luminescence efficiency.

[0032] Compared with the prior art, the present invention has the following technical effects:

[0033] 1. The present invention first obtains glass by melt quenching method, and then partially crystallizes it by heat treatment to obtain a glass ceramic material rich in BaZn2(PO4)2 nanocrystals, which provides a low phonon energy environment for rare earth luminescent ions. A large number of rare earth luminescent ions Dy 3+ 、Sm 3+It can be embedded in a low phonon energy environment, which is beneficial to increase its luminescence intensity, reduce the probability of non-radiative transitions, and improve luminescence efficiency.

[0034] 2. The glass ceramics of the present invention change the doping Sm 3+ The value can be adjustedBaZn2(PO4)2:Dy 3+ / Sm 3+ The luminescent color of glass ceramics is mild and colorful, and they have good thermal stability and luminescence stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 XRD spectra of the glass ceramics in Examples 1, 2, 3, 4, and 5 of the present invention;

[0036] Figure 2 This is a surface SEM image of the glass ceramic in Example 3 of the present invention;

[0037] Figure 3 This is an EDS element mapping image of the Ba element in the glass ceramic in Example 3 of the present invention;

[0038] Figure 4 This is an EDS element mapping image of the Zn element of the glass ceramic in Example 3 of the present invention;

[0039] Figure 5 This is an EDS element mapping image of the Sm element of the glass ceramic in Example 3 of the present invention;

[0040] Figure 6 This is an EDS element mapping image of the P element of the glass ceramic in Example 3 of the present invention;

[0041] Figure 7 This is an EDS element mapping image of the O element of the glass ceramic in Example 3 of the present invention;

[0042] Figure 8 This is an EDS element mapping image of the Dy element of the glass ceramic in Example 3 of the present invention;

[0043] Fig. 9 is the emission spectrum of the glass ceramics in Examples 1, 2, 3, and 4 of the present invention;

[0044] Fig.10 are the emission spectrum color coordinates of the glass ceramics in Examples 1, 2, 3, 4, and 5 of the present invention;

[0045] Fig.11 is the emission spectrum of the glass ceramic in Example 5 of the present invention;

[0046] Fig.12 This is the temperature-dependent emission spectrum of the glass ceramic in Example 3 of the present invention. DETAILED DESCRIPTION

[0047] Example 1

[0048] Raw materials preparation:

[0049] a. Weigh glass matrix raw materials BaCO3 10%, ZnO 20%, NH4H2PO4 55%, B2O3 15% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.1%, mix them in an agate mortar, grind for 3 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0050] Melting and quenching:

[0051] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1200° C. and calcined for 2 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0052] annealing:

[0053] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0054] Tableting:

[0055] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0056] Heat Treatment:

[0057] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600°C for 2 hours, and finally cool to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

[0058] The obtained BaZn2(PO4)2 glass ceramics XRD is as follows Figure 1 As shown in Figure 1, both the crystalline peak and the amorphous peak exist, and the peak position and intensity of the crystalline peak correspond to the PDF card of BaZn2(PO4)2, indicating the existence of the corresponding crystalline phase; under the excitation of 361nm light source, the measured emission spectrum is shown in Figure 1. Fig. 9 (Example 1), showing Dy 3+ / Sm 3+ Characteristic emission peak position of doped BaZn2(PO4)2 phosphate glass ceramics; color coordinates are (0.4314, 0.4284), see Fig.10At the indicated position, the color temperature is 5443K, which is warm yellow light emission.

[0059] Example 2

[0060] Raw materials preparation:

[0061] a. Weigh glass matrix raw materials BaCO3 18%, ZnO 17%, NH4H2PO4 52%, B2O3 13% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.5%, mix them in an agate mortar, grind for 4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0062] Melting and quenching:

[0063] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1250° C. and calcined for 3 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0064] annealing:

[0065] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0066] Tableting:

[0067] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0068] Heat Treatment:

[0069] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

[0070] The obtained BaZn2(PO4)2 glass ceramics were excited by 361nm light source, and the emission spectrum was shown in Fig. 9 (Example 2), showing Dy 3+ / Sm 3+ Characteristic emission peak position of BaZn2(PO4)2 doped phosphate glass ceramics; color coordinates are (0.4463, 0.4234), see Fig.10 At the indicated position, the color temperature is 3284K, which is warm yellow light emission.

[0071] Example 3

[0072] Raw materials preparation:

[0073] a. Weigh glass matrix raw materials BaCO3 15%, ZnO 18%, NH4H2PO4 54%, B2O3 13% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.8%, mix them in an agate mortar, grind for 3.5 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0074] Melting and quenching:

[0075] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1280° C. and calcined for 4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0076] annealing:

[0077] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0078] Tableting:

[0079] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0080] Heat Treatment:

[0081] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

[0082] The temperature-dependent emission spectrum color coordinates of the obtained BaZn2(PO4)2 glass ceramics are as follows: Fig.12 As shown in Figure 2, with the increase of temperature, the color coordinates of the emission spectrum hardly shift, indicating that the material has good thermal stability; under the excitation of a 361nm light source, the measured emission spectrum is shown in Figure 2. Fig. 9 (Example 3), showing Dy 3+ / Sm 3+ Characteristic emission peak position of BaZn2(PO4)2 doped phosphate glass ceramics; color coordinates are (0.4555, 0.4090), see Fig.10 At the indicated position, the color temperature is 3003K, which is warm yellow light emission.

[0083] Example 4

[0084] Raw materials preparation:

[0085] a. Weigh glass matrix raw materials BaCO3 12%, ZnO 19%, NH4H2PO4 55%, B2O3 15% by mass, weigh doping Dy2O3 0.5% and Sm2O3 1%, mix them in an agate mortar, grind for 3 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0086] Melting and quenching:

[0087] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1300° C. and calcined for 4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0088] annealing:

[0089] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0090] Tableting:

[0091] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0092] Heat Treatment:

[0093] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

[0094] The obtained BaZn2(PO4)2 glass ceramics were excited by 361nm light source, and the emission spectrum was shown in Fig. 9 (Example 4), showing Dy 3+ / Sm 3+ Characteristic emission peak position of doped BaZn2(PO4)2 phosphate glass ceramics; color coordinates are (0.4611, 0.3956), see Fig.10 At the indicated position, the color temperature is 2742K, which is warm yellow light emission.

[0095] Example 5

[0096] Raw materials preparation:

[0097] a. Weigh glass matrix raw materials BaCO3 14%, ZnO 20%, NH4H2PO4 52%, B2O3 14% by mass, weigh doping Dy2O3 0.5% and Sm2O3 0.2%, mix them in an agate mortar, grind for 4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible;

[0098] Melting and quenching:

[0099] b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1300° C. and calcined for 4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained;

[0100] annealing:

[0101] c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder;

[0102] Tableting:

[0103] d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds.

[0104] Heat Treatment:

[0105] e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

[0106] The obtained BaZn2(PO4)2 glass ceramics were optically tested under 402nm light source excitation. Fig.11 Display Dy 3+ / Sm 3+ Characteristic emission peak position of BaZn2(PO4)2 doped phosphate glass ceramics; color coordinates are (0.4824, 0.4144), see Fig.10 At the indicated position, the color temperature is 2439K, which is orange light emission.

Claims

1. A new type of yellow-orange luminescent phosphate glass ceramic material, characterized in that: The glass matrix of the glass ceramic material is composed of BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, and B2O3 13-15% by mass percentage. Dy is doped in the glass matrix in the form of a compound. 3+ , Sm 3+ The doped dysprosium compound Dy2O3 and samarium compound Sm2O3 account for 0.5% and 0.1-1% of the total mass of other raw materials respectively. BaZn2(PO4)2 nanocrystals are precipitated in the glass matrix. The specific operation is carried out according to the following steps: Raw materials preparation: a. Weigh glass matrix raw materials BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, B2O3 13-15% by mass, weigh doped Dy2O3 0.5% and Sm2O3 0.1-1%, mix them in an agate mortar, grind for 3-4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible; Melting and quenching: b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1200-1300° C. and calcined for 2-4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained; annealing: c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder; Tableting: d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds. Heat Treatment: e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

2. A method for preparing a novel yellow-orange luminescent phosphate glass ceramic material, characterized in that: Follow these steps: Raw materials preparation: a. Weigh glass matrix raw materials BaCO3 10-18%, ZnO 17-20%, NH4H2PO4 52-55%, B2O3 13-15% by mass, weigh doped Dy2O3 0.5% and Sm2O3 0.1-1%, mix them in an agate mortar, grind for 3-4 hours to obtain a uniformly mixed powder, and transfer it to a high-purity corundum crucible; Melting and quenching: b. The powder obtained in step a is placed in a muffle furnace at a temperature of 1200-1300° C. and calcined for 2-4 hours. The melt in the high-purity corundum crucible is quickly poured onto a steel plate, and then a steel plate is quickly pressed on to form a quenching process. After cooling, solid glass is obtained; annealing: c. annealing the solid glass obtained in step b at a temperature of 600° C. for 3 hours, and finally cooling the glass naturally to room temperature to obtain glass. Grinding the glass in an agate mortar for 4 hours to obtain glass powder; Tableting: d. Weigh 0.2 g of the powder obtained in step c and pour it into a mold with a diameter of 10 mm. Press it into a green disc using a hydraulic press with a holding pressure of 30 MPa for 60 seconds. Heat Treatment: e. Place the green disc obtained in step d into a muffle furnace for heat treatment at a temperature of 600° C. for 2 hours, and then cool naturally to room temperature to obtain rare earth Dy 3+ / Sm 3+ Doped BaZn2(PO4)2 glass-ceramic materials.

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