Rare earth Sm < 3 + > ion doped thermoluminescent phosphate glass as well as preparation method and application thereof

Abstract

The invention relates to the technical field of optical glass, in particular to rare earth Sm < 3 + > ion doped thermoluminescent phosphate glass as well as a preparation method and application thereof, and the rare earth Sm < 3 + > ion doped thermoluminescent phosphate glass comprises the following raw materials in molar percentage: 60-65% of NH4H2PO4, 13-18% of K2CO3, 12-15% of BaCO3, 3-8% of Al2O3 and 0.75% of Sm2O3. According to the invention, rare earth Sm < 3 + > ions are doped as a luminescence center, after the glass is irradiated by X rays, the processes of generating defects and filling electrons are mainly carried out, and then the glass shows bright red luminescence corresponding to the luminescence of the rare earth Sm < 3 + > ions in a heat treatment process. Compared with a traditional thermoluminescent crystal material, the thermoluminescent crystal material has the advantages that the thermal response speed and the optical performance are obviously improved due to the transparency, and a better material basis is provided for high-sensitivity temperature sensing.

Description

Technical Field

[0001] The present invention relates to the technical field of optical glass, and particularly relates to a rare earth Sm 3+ ion-doped thermally luminescent phosphate glass and its preparation method and application. Background Art

[0002] Rare earth, as a strategic resource, plays an indispensable role in the field of luminescent materials. Rare earth has abundant luminescent energy levels, endowing it with excellent luminescent properties. Thermoluminescence is an energy conversion method that converts heat into light energy. With the continuous development of science and technology, the research and application prospects of thermoluminescent materials are becoming broader and broader. Temperature sensing is widely used in aspects such as control manufacturing, safety production systems, and environmental monitoring, while traditional physical temperature probes have certain limitations in dynamic and non-contact systems. Optical temperature measurement just solves this problem by using temperature-related optical parameters to monitor temperature. Therefore, thermoluminescent materials make up for this shortcoming. Currently, the efficiency and stability of thermoluminescence both need to be improved. Currently, it mainly focuses on crystal materials, mainly because defects are easily generated in such materials through the substitution of ions with unequal valence, while the development of amorphous glass for thermoluminescence is very little. Compared with amorphous materials, the dense network structure of glass endows it with higher stability and corrosion resistance. Therefore, the development of new thermoluminescent glass has become a key factor for the next-generation thermosensitive materials.

[0003] Chinese patent document CN201710507851.9 discloses a samarium-doped red phosphor with phosphate as the matrix. With phosphate as the matrix, the chemical general formula is Ca 3 Gd 1-x Na(PO 4 ) 3 F:xSm, where 0.02 ≤ x ≤ 0.1. By doping the activator ion Sm 3+ , a samarium-doped red phosphor with phosphate as the matrix is prepared to solve the problems of high color temperature and low color rendering index caused by less red components in the emission spectrum in the prior art; the present invention mainly focuses on phosphors and does not achieve thermoluminescence. The phosphate glass disclosed in the present invention has an obvious thermoluminescent effect after X-ray irradiation, expanding the application of glass in temperature-sensitive materials. In addition, due to the matching relationship between the Sm 3+ ion luminescence center and the defect energy level, the thermoluminescent characteristics of Sm 3+ can be obtained. Compared with Dy 3+ ion doping, Dy 3+ ion-doped phosphate glass cannot achieve thermoluminescence. Summary of the Invention

[0004] The purpose of the present invention is to provide a rare earth Sm 3+Ion-doped thermoluminescent phosphate glass and its preparation method and application, by doping rare earth Sm 3+ Ions as the luminescence center, after the glass is irradiated with X-rays, mainly defects are generated and the process of filling electrons follows. Subsequently, the glass exhibits bright red luminescence during the heat treatment process, corresponding to the luminescence of rare earth Sm 3+ ions.

[0005] To achieve the above technical objectives and reach the above technical effects, the present invention is realized through the following technical solutions:

[0006] A kind of rare earth Sm 3+ ion-doped thermoluminescent phosphate glass, including raw materials in the following molar percentages: NH 4 H 2 PO 4 : 60 - 65%, K 2 CO 3 : 13 - 18%, BaCO 3 : 12 - 15%, Al 2 O 3 : 3 - 8%, Sm 2 O 3 : 0.75%.

[0007] On the other hand, the present invention proposes a preparation method of the above glass, including the following steps:

[0008] S1: Weigh the above raw materials according to the molar percentages, then grind them evenly, load them into a ceramic crucible, and then put the crucible into a box furnace at 1100 °C and sinter for 1 h. Pour the glass melt onto a stainless steel mold preheated to 350 °C in advance and wait for the glass to cool.

[0009] S2: There are a large number of thermal stresses in the glass obtained in step S1, which causes the glass to be fragile. Subsequently, move the glass to the furnace, heat it to 380 °C with the furnace and keep it warm for 6 hours to remove the residual stress in the glass, thereby improving the mechanical strength of the glass;

[0010] S3: Grind and polish the glass prepared in step S2 for X-ray irradiation and detection;

[0011] Using the projection method, after irradiating the glass for 12 minutes, the glass exhibits red luminescence during the heat treatment process. The thermoluminescence spectrum of the glass is measured by an Ocean Optics fiber.

[0012] Furthermore, the irradiation dose of X-rays in step S3 is 7.51 μGy S -1 , and the irradiation time is 12 minutes.

[0013] On the other hand, the present invention proposes the application of the above glass in temperature sensing.

[0014] On the other hand, the present invention proposes the application of the above-mentioned glass in medical detection.

[0015] Advantages of the present invention:

[0016] By optimizing the raw material ratio, the present invention prepares a rare earth Sm 3+ ion-doped phosphate glass. Its unique amorphous structure significantly improves the transparency and optical properties of the material. The phosphate glass formed by rapid cooling after melting at a high temperature of 1100 °C avoids the common grain boundary scattering problem in crystalline materials, which enables the glass material to exhibit excellent transmittance in the visible light range, and the measured value exceeds 80%. The high transparency stems from the low light scattering characteristics of the phosphate matrix and the uniform amorphous network. The continuity of the [P-O-P] bridging bonds in its structure reduces the scattering loss during light propagation, providing a more uniform light transmission medium for the thermoluminescence process. The glass material undergoes stress release and network reconstruction during the process of heating to 380 °C in the furnace and holding for 6 hours. The high-temperature annealing effectively eliminates the microcracks and scattering centers caused by stress concentration during the cooling and quenching process. This not only improves the mechanical stability of the glass but also significantly enhances the optical transparency. The high transparency directly enhances the thermal response speed: in temperature sensing applications, the transparent matrix reduces the non-uniformity of heat transfer, makes the electron-hole recombination process more efficient, and accelerates the energy release of the excited state, thereby achieving a millisecond-level response. Compared with traditional thermoluminescent crystal materials, the transparency of the phosphate glass significantly improves the thermal response speed and optical properties, providing a better material basis for high-sensitivity temperature sensing.

[0017] By irradiating the glass with X-rays in step S3, the [P-O-P] bridging bonds in the glass matrix are broken, forming vacancies and electron traps. These irradiation-induced defects can be divided into two categories: shallow traps and deep traps. The depth difference determines the storage and release behavior of electrons ( Figure 2 ). Shallow traps have a lower activation energy and preferentially release electrons during the heat treatment process, while deep traps require a higher temperature to be activated and release stable thermally excited energy. The formation mechanism of the defects is that the high-energy photons generated by irradiation strike the phosphorus-oxygen bonds in the glass network, causing electrons to be captured at the defect sites, while holes are fixed in the local structure. The type and distribution of the defects are closely related to the irradiation dose. The gradient regulation of the thermoluminescence performance is reflected in the change of the luminescence intensity of the irradiated glass during the heat treatment process at different temperatures. The thermoluminescence spectrum of Example 3 shows that as the temperature increases, the shallow traps first release electrons and trigger a lower-intensity red light emission, while the deep traps release electrons at a higher temperature, resulting in a significant increase in the thermoluminescence intensity. This temperature-related luminescence change stems from the dynamic balance between the defect energy levels and thermal excitation: at a higher temperature, the probability of thermal excitation of electrons in the traps increases, and the electron-hole recombination process becomes more active. AsFigure 4 The shown luminous intensity has an obvious positive correlation with temperature, providing a scientific basis for the wide-temperature-response application of the glass in temperature sensing. Through the design of gradient defects induced by X-ray irradiation, the glass exhibits a highly sensitive thermoluminescence response to temperature changes and is suitable for precise temperature detection in multiple scenarios.

[0018] It is the rare earth Sm in the present invention 3+ The energy level structure of the 4f electron orbit of the ion ensures efficient red light emission. In the glass matrix, the low phonon energy characteristic of phosphate inhibits the non-radiative relaxation of Sm 3+ , enabling the energy to be released in a radiative form. At the same time, the phosphate glass matrix has good dispersibility for Sm 3+ . The Al in the raw materials 2 O 3 provides Al 3+ ions, and these ions enhance the stability of the glass network through cross-linking with the [PO 4 3- chain, avoiding the agglomeration of rare earth ions. During the high-temperature melting preparation process, the network regulation effect of Al 3+ ensures the uniform distribution of Sm 3+ ions in the glass matrix, effectively reducing the concentration quenching effect. In addition, the K 2 CO 3 introduces K + ions as charge compensators to balance the charge mismatch problem of Sm 3+ substituting the local environment, further optimizing its luminescence performance. The irradiated glass exhibits bright red light emission ([[]] Figure 3 , Figure 4 ) during heat treatment at 250 °C, 300 °C, and 350 °C, and the intensity of the red light gradually increases with the increase in temperature. This temperature-related luminescence characteristic provides high stability and high responsiveness for the red light signal of the glass in temperature sensing and medical detection.

[0019] Of course, it is not necessary for any product implementing the present invention to simultaneously achieve all the above-mentioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0021] Figure 1 It is the transmission spectrum and glass schematic diagram of the glass obtained in Embodiment 1 of the present invention; ​

[0022] Figure 2 It is a schematic diagram of the thermoluminescence curve of the glass in Embodiment 2 of the present invention after X-ray irradiation;

[0023] Figure 3 It is a schematic diagram of the thermally stimulated luminescence spectrum of the glass in Embodiment 3 of the present invention during heat treatment at 250 °C, 300 °C, and 350 °C;

[0024] Figure 4 It is a schematic diagram of the thermally stimulated luminescence of the glass in Embodiment 3 of the present invention during heat treatment at 250 °C, 300 °C, and 350 °C. Detailed implementation manners

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Embodiment 1

[0027] A preparation method of a rare earth Sm 3+ ion-doped thermally stimulated luminescence phosphate glass includes the following steps:

[0028] S1: Take raw materials NH 4 H 2 PO 4 : 60%, K 2 CO 3 : 18%, BaCO 3 : 15%, Al 2 O 3 : 6.25%, Sm 2 O 3 : 0.75%. Weigh according to the molar percentage, then grind evenly, put it into a ceramic crucible, and then put the crucible into a box furnace at 1100 °C and sinter for 1 h. Pour the glass melt onto a stainless steel mold preheated to 350 °C and wait for the glass to cool.

[0029] S2: There are a large number of thermal stresses in the glass obtained in step S1, which causes the glass to be fragile. Then move the glass to the furnace and heat it to 380 °C with the furnace and keep it warm for 6 hours to remove the residual stress in the glass and thus improve the mechanical strength of the glass;

[0030] S3: Grind and polish the glass prepared in step S2 for X-ray irradiation and detection.

[0031] S4: Measure the transmission spectrum of the glass.

[0032] In Example 1, the glass exhibits excellent transparency. As Figure 1 shown, the transmittance of the glass exceeds 80%, providing a beneficial transmittance basis for enhancing the thermoluminescence of the glass.

[0033] Example 2

[0034] A preparation method of a rare earth Sm 3+ ion-doped thermoluminescent phosphate glass according to this example includes the following steps:

[0035] S1: Take raw materials NH 4 H 2 PO 4 : 65%, K 2 CO 3 : 14.25%, BaCO 3 : 12%, Al 2 O 3 : 8%, Sm 2 O 3 : 0.75%. Weigh according to the molar percentage, then grind evenly, load into a ceramic crucible, and then put the crucible into a box furnace at 1100 °C for sintering for 1 h. Pour the glass melt onto a stainless steel mold preheated to 350 °C and wait for the glass to cool.

[0036] S2: There are a large number of thermal stresses in the glass obtained in step S1, resulting in the glass being fragile. Then move the glass to the furnace and heat it to 380 °C with the furnace and keep it warm for 6 hours to remove the residual stress in the glass, thereby improving the mechanical strength of the glass;

[0037] S3: Grind and polish the glass prepared in step S2 for X-ray irradiation and detection.

[0038] S4: Perform a thermoluminescence curve test on the irradiated phosphate glass;

[0039] In Example 2, the thermoluminescence curve of the irradiated glass is as Figure 2 shown. The thermoluminescence curve characterizes the depth of defects. It can be seen from the figure that both deep / shallow defects coexist, and these defects provide the possibility for the thermoluminescence phenomenon of the glass.

[0040] Example 3

[0041] A preparation method of a rare earth Sm 3+ ion-doped thermoluminescent phosphate glass according to this example includes the following steps:

[0042] S1: Take raw materials NH 4 H 2 PO 4 : 65%, K2 CO 3 : 17%, BaCO 3 : 14.25%, Al 2 O 3 : 3%, Sm 2 O 3 : 0.75%; Weigh according to the molar percentage, then grind evenly, put it into a ceramic crucible, and then put the crucible into a box furnace at 1100 °C and sinter for 1 h. Pour the glass melt onto a stainless steel mold preheated to 350 °C and wait for the glass to cool.

[0043] S2: There are a large number of thermal stresses in the glass obtained in step S1, which causes the glass to be fragile. Then move the glass to the furnace and heat it to 380 °C with the furnace and keep it warm for 6 hours to remove the residual stress in the glass, thereby improving the mechanical strength of the glass;

[0044] S3: Polish the glass prepared in step S2 for X-ray irradiation and detection.

[0045] S4: Move the glass to 250 °C, 300 °C, and 350 °C for heat treatment to explore its thermally stimulated luminescence process.

[0046] In this Example 3, the irradiated glass shows strong thermally stimulated luminescence during the heat treatment at 250 °C, 300 °C, and 350 °C respectively. As Figure 3 shown, with the increase of the heat treatment temperature of the irradiated glass, its thermally stimulated luminescence intensity increases. Figure 4 The thermally stimulated luminescence photos of 3+ show that the red luminescence of the glass gradually increases. There is a correlation between the luminescence of the glass and the heat treatment temperature. These examples show that the novel thermally stimulated luminescence phosphate glass doped with rare earth Sm

[0047] In summary, the novel thermally stimulated luminescence phosphate glass doped with rare earth Sm 3+ ions of this application has more advantages in temperature sensing and safety detection than the existing thermally stimulated luminescence crystal materials. The main reason is that the transparency of the glass can increase its thermal response speed and show stronger thermally stimulated luminescence.

[0048] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A rare earth Sm 3+ Ion-doped thermoluminescent phosphate glass, characterized in that: The invention comprises raw materials in the following molar percentages: NH4H2PO4: 60-65%, K2CO3: 13-18%, BaCO3: 12-15%, Al2O3: 3-8%, and Sm2O3: 0.75%.

2. The method for preparing glass according to claim 1, characterized in that: The following steps are involved: S1: The above raw materials are weighed by molar percentage, then ground evenly, and loaded into a ceramic crucible. The crucible is then placed in a box furnace at 1100°C for 1 hour, and the glass liquid is poured into a stainless steel mold preheated at 350°C, and the glass is allowed to cool. S2: moving the glass obtained in step S1 into a furnace, heating it to 380° C. in the furnace, and keeping it warm for 6 hours to remove residual stress in the glass, thereby improving the mechanical strength of the glass; S3: Grind and polish the glass obtained in step S2 to obtain rare earth Sm 3+ Ion-doped thermoluminescent phosphate glass for X-ray irradiation and detection.

3. The rare earth Sm as claimed in claim 2 3+ Ion-doped thermoluminescent phosphate glass, characterized in that: The X-ray irradiation dose in step S3 is 7.51 μGy S -1 , the irradiation time is 12 minutes.

4. The rare earth Sm as claimed in claim 1 3+ Application of ion-doped thermoluminescent phosphate glass in temperature sensing.

5. The rare earth Sm as claimed in claim 1 3+ Application of ion-doped thermoluminescent phosphate glass in medical testing.

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