A preparation method of CsAgCl2, optical temperature sensing material and its preparation method and application

Abstract

The present invention provides a preparation method of CsAgCl2, an optical temperature sensing material and its preparation method and application, which belongs to the field of phase change technology. The present invention provides a preparation method of CsAgCl2 using a hydrothermal method, by heating or Eu 3+ Doping can produce CsAgCl2, an optical temperature sensing material with an orthorhombic crystal system in its high-temperature phase. The preparation method of the present invention is simple, easy to operate, and has low equipment costs. The optical temperature sensing material prepared by the present invention exhibits high optical temperature sensitivity in both fluorescence intensity and fluorescence lifetime modes, and has great application potential in the field of optical temperature sensing.

Description

Technical Field

[0001] The present invention relates to the field of phase change technology, and in particular to a preparation method of CsAgCl2, an optical temperature sensing material, and a preparation method and application thereof. Background Art

[0002] In recent years, metal halides have attracted increasing attention due to their excellent optoelectronic properties. Among these, lead-halide perovskites stand out due to their superior photophysical properties. However, the toxicity of lead and the instability of lead-halide perovskites in humid environments are important issues that need to be addressed. Consequently, efforts are underway to develop environmentally friendly, lead-free metal halides with enhanced stability.

[0003] The metal halide materials formed by IA and IB group halides have excellent optoelectronic properties. The low-dimensional structure formed between their molecules enhances the interaction between electrons and phonons, making the excitons more localized. In order to find a replacement material for lead-based metal halides, monovalent silver ions of IB group were introduced to replace divalent lead ions to form a new type of low-dimensional metal halide. + The introduction into cesium halide helps to accommodate all halide ions and can also adjust the emission wavelength from the ultraviolet region to the visible light region and the near-infrared region (390-820nm).

[0004] Reported methods for synthesizing CsAgCl2 include ball milling, antisolvents, and solvent evaporation, but hydrothermal methods have yet to be reported. Furthermore, current research on CsAgCl2 focuses on spectral properties, LED applications, and CO2 catalytic reduction, but no applications in optical temperature sensing have been reported. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of CsAgCl2, an optical temperature sensing material and its preparation method and application. The present invention prepares CsAgCl2 by a hydrothermal method.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing CsAgCl2, comprising the following steps:

[0008] Mixing CsCl, AgCl and concentrated hydrochloric acid, and subjecting the obtained mixed system to a hydrothermal reaction to obtain the CsAgCl2;

[0009] The mass concentration of the concentrated hydrochloric acid is 37 wt %; the molar ratio of CsCl to AgCl is 1:1;

[0010] The conditions of the hydrothermal reaction are as follows: heating from room temperature to 453 K at a rate of 10 K / min, keeping at 453 K for 10 to 20 hours, cooling to 433 K at a rate of 5 K / min, keeping at 433 K for 2 to 10 hours, cooling to 393 K at a rate of 5 K / min, keeping at 393 K for 2 to 6 hours; and then cooling naturally to room temperature.

[0011] Preferably, the volume ratio of the amount of CsCl to concentrated hydrochloric acid is 1 mol:0.8-5 mL.

[0012] Preferably, the CsAgCl2 is low temperature phase CsAgCl2.

[0013] The present invention also provides a method for preparing an optical temperature sensing material, which comprises the following steps:

[0014] Subjecting the CsAgCl2 described in the above scheme to temperature induction to obtain the optical temperature sensing material; or

[0015] The preparation method of the optical temperature sensing material comprises the following steps:

[0016] According to the preparation method described in the above scheme, Eu2O3 or EuCl3 is added to the mixed system to obtain an optical temperature sensing material.

[0017] Preferably, the temperature of the temperature-inducing process is 545-575 K, and the time is 1-10 h.

[0018] Preferably, the amount of Eu2O3 or EuCl3 is 0.5-5% of the amount of AgCl.

[0019] The present invention also provides an optical temperature sensing material prepared by the preparation method of the above scheme, wherein the optical temperature sensing material is CsAgCl2 or Eu 3+ Doped orthorhombic CsAgCl2; the orthorhombic CsAgCl2 is a high-temperature phase and a thermodynamically stable phase.

[0020] The present invention also provides the application of the optical temperature sensing material described in the above solution in the field of optical temperature sensing.

[0021] The present invention provides a method for preparing CsAgCl2, comprising the following steps: mixing CsCl, AgCl and concentrated hydrochloric acid, and subjecting the obtained mixed system to a hydrothermal reaction to obtain the CsAgCl2;

[0022] The mass concentration of the concentrated hydrochloric acid is 37 wt %; the molar ratio of CsCl to AgCl is 1:1;

[0023] The conditions of the hydrothermal reaction are as follows: heating from room temperature to 453 K at a rate of 10 K / min, keeping at 453 K for 10 to 20 hours, cooling to 433 K at a rate of 5 K / min, keeping at 433 K for 2 to 10 hours, cooling to 393 K at a rate of 5 K / min, keeping at 393 K for 2 to 6 hours; and then cooling naturally to room temperature.

[0024] The present invention prepares CsAgCl2 by adjusting the temperature, holding time and heating rate of each stage in the hydrothermal process.

[0025] Eu of the present invention 3+ Doped CsAgCl2 has high optical temperature sensitivity, with the maximum relative sensitivity of 3.63% K in fluorescence intensity mode and fluorescence lifetime mode, respectively. -1 and 3.20%K -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flow chart of preparing optical temperature sensing material for application example of the present invention;

[0027] Figure 2 The X-ray diffraction (XRD) pattern of CsAgCl2 prepared in Example 1;

[0028] Figure 3 XRD patterns of the optical temperature sensing material prepared in Application Example 1 and CsAgCl2 prepared in Example 1;

[0029] Figure 4 TG-DSC curve of CsAgCl2 prepared in Example 1;

[0030] Figure 5 is a graph showing the linear thermal expansion ΔL / L of CsAgCl2 prepared in Example 1 as a function of temperature;

[0031] Figure 6 The excitation spectrum and emission spectrum of CsAgCl2 prepared in Application Example 1;

[0032] Figure 7 Eu prepared in Application Example 2 3+ XRD pattern of doped CsAgCl2;

[0033] Figure 8 Eu prepared in Application Example 2 3+ Excitation spectrum of doped CsAgCl2;

[0034] Figure 9 Eu prepared in Application Example 2 3+ Emission spectrum of doped CsAgCl2;

[0035] Figure 10 Eu prepared in Application Example 2 3+ Temperature-dependent fluorescence emission spectrum of doped CsAgCl2 under 260nm excitation;

[0036] Figure 11 Eu prepared in Application Example 2 3+ The relative fluorescence integrated intensity of doped CsAgCl2 changes with increasing temperature (300-525K);

[0037] Figure 12 Eu prepared in Application Example 2 3+ Dotted line graph between relative sensitivity and temperature in the fluorescence integral intensity mode of doped CsAgCl2;

[0038] Figure 13 For application example 2Eu 3+ Temperature-dependent fluorescence decay curve of doped CsAgCl2;

[0039] Figure 14 Eu prepared in Application Example 2 3+ Fluorescence decay curve fitting diagram of doped CsAgCl2;

[0040] Figure 15 Eu prepared in Application Example 2 3+ Dotted line plot of relative sensitivity versus temperature in the fluorescence lifetime mode of doped CsAgCl2. DETAILED DESCRIPTION

[0041] The present invention provides a method for preparing CsAgCl2, comprising the following steps:

[0042] Mixing CsCl, AgCl and concentrated hydrochloric acid, and subjecting the obtained mixed system to a hydrothermal reaction to obtain the CsAgCl2;

[0043] The mass concentration of the concentrated hydrochloric acid is 37 wt %; the molar ratio of CsCl to AgCl is 1:1;

[0044] The conditions of the hydrothermal reaction are as follows: heating from room temperature to 453 K at a rate of 10 K / min, keeping at 453 K for 10 to 20 hours, cooling to 433 K at a rate of 5 K / min, keeping at 433 K for 2 to 10 hours, cooling to 393 K at a rate of 5 K / min, keeping at 393 K for 2 to 6 hours; and then cooling naturally to room temperature.

[0045] In the present invention, the volume ratio of the amount of CsCl to concentrated hydrochloric acid is preferably 1 mol:0.8-5 mL, more preferably 1 mol:1-4 mL, and even more preferably 1 mol:2-3 mL.

[0046] In the present invention, the temperature is kept at 453K for 10 to 20 hours, preferably for 15 to 18 hours; the temperature is kept at 433K for 2 to 10 hours, preferably for 5 to 8 hours; and the temperature is kept at 393K for 2 to 6 hours, preferably for 3 to 4 hours.

[0047] In the present invention, after the hydrothermal reaction, the product obtained by the hydrothermal reaction is preferably dried and ground to obtain the CsAgCl2.

[0048] The present invention also provides CsAgCl2 prepared by the preparation method described in the above scheme, wherein the CsAgCl2 is low-temperature phase CsAgCl2.

[0049] The present invention also provides a method for preparing an optical temperature sensing material, comprising the following steps:

[0050] The CsAgCl2 of the above scheme is subjected to temperature induction to obtain the optical temperature sensing material;

[0051] or

[0052] According to the preparation method described in the above scheme, Eu2O3 or EuCl3 is added to the mixed system to obtain an optical temperature sensing material.

[0053] In the present invention, the method for preparing the optical temperature sensing material comprises the following steps:

[0054] The CsAgCl2 prepared by the preparation method described in the above scheme is subjected to temperature induction to obtain the optical temperature sensing material.

[0055] In the present invention, the temperature of the heating induction is preferably 545-575K, more preferably 550-560K; the time is preferably 1-10 hours, more preferably 2-8 hours, and even more preferably 4-6 hours. The heating induces the low-temperature phase CsAgCl2 to transform into CsAgCl2 having an orthorhombic crystal system; the orthorhombic CsAgCl2 is the high-temperature phase and the thermodynamically stable phase.

[0056] Alternatively, the method for preparing the optical temperature sensing material comprises the following steps:

[0057] Eu2O3 or EuCl3 is added to the raw materials in the preparation method of the above scheme to obtain the optical temperature sensing material. 3+ The doped CsAgCl2 is orthorhombic CsAgCl2.

[0058] The present invention also provides an optical temperature sensing material prepared by the preparation method of the above scheme, wherein the optical temperature sensing material is an orthorhombic CsAgCl2 or Eu 3+Doped orthorhombic CsAgCl2; the orthorhombic CsAgCl2 is a high temperature phase CsAgCl2 and a thermodynamically stable phase. In the present invention, when Eu2O3 or EuCl3 is added to the raw materials, the optical temperature sensing material is doped with Eu 3+ .

[0059] The present invention also provides the application of the optical temperature sensing material described in the above solution in the field of optical temperature sensing.

[0060] The flow chart of the application example of the present invention for preparing optical temperature sensing materials is as follows: Figure 1 As shown: AgCl, CsCl and concentrated hydrochloric acid are mixed at a temperature of 455K and subjected to a hydrothermal reaction to obtain a low-temperature phase CsAgCl2, which is then heated at a temperature of 555K to obtain an optical temperature sensing material with an orthorhombic crystal system; AgCl, CsCl, concentrated hydrochloric acid and Eu2O3 are mixed at a temperature of 455K and subjected to a hydrothermal reaction to obtain Eu 3+ Doped optical temperature sensing material with orthorhombic crystal system.

[0061] The following describes in detail the preparation method of CsAgCl2, the optical temperature sensing material, and the preparation method and application thereof provided by the present invention in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0062] Silver chloride (AgCl) and cesium chloride (CsCl) were purchased from Shanghai MacLean Biochemical Technology Co., Ltd. with a purity of 99.5%;

[0063] Concentrated hydrochloric acid (HCl) was purchased from Luoyang Haohua Chemical Reagent Co., Ltd. with a mass fraction of 37% wt;

[0064] Europium oxide (Eu2O3) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with a purity of 99.9%.

[0065] Example 1

[0066] CsCl (1.2 mmol) and AgCl (1.2 mmol) were placed in a 50 mL polytetrafluoroethylene liner at a molar ratio of 1:1, followed by the addition of 1 mL of 37 wt% concentrated hydrochloric acid. The liner containing the drugs was placed in a reactor. The reactor was placed in an oven and heated from room temperature to 453 K at a rate of 10 K / min, held at 453 K for 15 h, cooled to 433 K at a rate of 5 K / min, then held at 433 K for 5 h, cooled to 393 K at a rate of 5 K / min, and held at 393 K for 4 h; the temperature was then naturally cooled to room temperature, the sample was removed and dried to obtain a light white sample, which was then ground to obtain CsAgCl2.

[0067] The CsAgCl2 of Example 1 was subjected to XRD analysis, and the results were as follows: Figure 2 As shown. Figure 2 It can be seen that all diffraction peaks of CsAgCl2 in Example 1 have a good match with CsAgCl2 (PDF#28-337), indicating that pure phase CsAgCl2 can be obtained by this preparation method.

[0068] The CsAgCl2 of Example 1 was subjected to scanning electron microscopy (EDS) element mapping analysis. The test results showed that the CsAgCl2 of Example 1 contained Cs, Ag, and Cl elements, which were uniformly distributed in the sample particles; and the element ratio was Cs:Ag:Cl = 26.07:25.49:48.44, and Cs:Ag:Cl was close to the stoichiometric ratio of the CsAgCl2 compound of 1:1:2.

[0069] Application Example 1

[0070] The CsAgCl2 prepared in Example 1 was heated to 555K in a drying oven, kept at this temperature for 3 hours, and then slowly cooled to room temperature. The sample was removed and dried to obtain a light white sample, which was then ground to obtain an optical temperature sensing material.

[0071] XRD analysis was performed on the CsAgCl2 of Example 1 and the optical temperature sensing material of Application Example 1. The results are as follows: Figure 3 As shown. Figure 3 It can be seen that all X-ray diffraction peaks of the optical temperature sensing material of Application Example 1 have a good match with the X-ray diffraction peaks of orthorhombic CsAgCl2 (PDF#76-2238). In other words, the CsAgCl2 of Example 1 has been completely transformed into CsAgCl2 with an orthorhombic crystal system.

[0072] The CsAgCl2 of Example 1 was tested by TG-DSC curve, and the results were as follows: Figure 4 As shown. Figure 4 It can be seen that the sample has no obvious weight loss when the temperature is raised from room temperature to 675K, but an obvious endothermic abnormal peak is observed at 526K, indicating that a phase transition occurs. Figure 2 From the XRD test results, it can be seen that the CsAgCl2 prepared in Example 1 is a low-temperature phase, while the orthorhombic CsAgCl2 prepared in Application Example 1 is a high-temperature phase.

[0073] The linear thermal expansion ΔL / L test was carried out on the CsAgCl2 of Example 1, and the results were as follows: Figure 5 As shown. Figure 5 It can be seen that the ΔL / L transition temperature appears at 535 K, which is close to the exothermic anomaly temperature in the DSC curve, further confirming the occurrence of phase transition.

[0074] The fluorescence spectrum test of the optical temperature sensing material corresponding to Example 1 is as follows Figure 6 As shown. Figure 6 As can be seen, the left side shows the excitation spectrum (PLE) of CsAgCl2, which has a single excitation peak located at approximately 260nm. The right side shows the emission spectrum (PL) at different excitation wavelengths (255-269nm). The PL spectrum has a single emission peak, exhibiting broadband emission, covering a wavelength range of 460-850nm with a half-width of 240nm. The main emission peak is located at 620nm, indicating that its Stokes shift can be as high as 360nm. This large Stokes shift and broadband emission indicate that the luminescence of the optical temperature sensing material is self-trapped exciton emission; under excitation at different wavelengths, the emission spectrum has exactly the same shape. This spectral phenomenon indicates that the broadband emission of CsAgCl2 originates from the same self-trapped exciton center.

[0075] Application Example 2

[0076] The preparation of the optical temperature sensing material in Application Example 2 is different from that in Example 1 only in that 0.036 mmol Eu2O3 is added to the raw materials.

[0077] Corresponding to Eu prepared in Example 2 3+ Doped CsAgCl2 was tested by XRD, and the results were as follows Figure 7 As shown. Figure 7 It can be seen that the Eu prepared in Example 2 3+ The X-ray diffraction peaks of the doped sample match well with those of orthorhombic CsAgCl2 (PDF#76-2238), indicating that Eu 3+ The doped sample is CsAgCl2 with an orthorhombic crystal system. Figures 2 to 5 It can be seen that Eu 3+ Doping can induce the CsAgCl2 prepared in Example 1 to transform into an orthorhombic phase.

[0078] Corresponding to Eu prepared in Example 2 3+ Scanning electron microscopy (EDS) elemental mapping analysis of orthorhombic CsAgCl2 was performed. The results showed that the sample contained Cs, Ag, Cl, and Eu, which were evenly distributed throughout the particles. The elemental ratio (Cs:Ag:Cl:Eu) was 24.63:26.88:48.09:0.40, with the Cs:Ag:Cl ratio approaching the theoretical stoichiometric ratio of 1:1:2 for the CsAgCl2 compound.

[0079] Corresponding to Eu prepared in Example 2 3+ Fluorescence spectrum test of CsAgCl2 was performed, and the results were as follows Figures 8-9 As shown. Among them, Figure 8 is the excitation spectrum, Figure 9 is the emission spectrum. Figure 8 It can be seen that the Eu prepared in Example 2 3+ The PLE spectrum of doped CsAgCl2 is mainly composed of two parts, one is a broad excitation band in the wavelength range of 240-290nm, and the other is a linear excitation peak in the wavelength range of 290-400nm. Figure 6 The positions of the linear excitation peaks of the latter are 298nm, 318nm, 362nm, 376nm, 380nm, 385nm and 394nm, which are attributed to Eu 3+ The characteristic excitations of Eu 3+ Ground state electrons 7 F0→ 5 F2, 7 F0→ 5 H6, 7 F0→ 5 D4, 7 F0→ 5 G2, 7 F0→ 5 G3, 7 F0→ 5 G4 and 7 F0→ 5 L6 jump.

[0080] Depend on Figure 9 It can be seen that the Eu prepared in Example 2 3+ The PL spectrum of CsAgCl2 doped with MgCl2 exhibits broadband emission with emission peaks covering the wavelength range of 400-850 nm, among which the linear emission peaks at 593 nm, 616 nm, 650 nm and 699 nm are attributed to Eu 3+ The characteristic emission of Eu 3+ Excited state electrons 5 D0→ 7 F1, 5 D0→ 7 F2, 5 D0→ 7 F3, 5 D0→ 7 F4 jump.

[0081] Under 260nm wavelength excitation, the Eu prepared in Example 2 3+ The PL emission spectrum of CsAgCl2 doped with the temperature increased from 300K to 525K was tested. Figure 10 As shown. Figure 10It can be seen that the maximum fluorescence peak of the PL emission spectrum is located at 616nm, and the emission spectrum covers a wide range of 400 to 850nm. There are two obvious Eu 3+ characteristic emission peaks.

[0082] Eu prepared in Application Example 2 3+ The relative fluorescence integrated intensity of doped CsAgCl2 changes with increasing temperature (300~525K) as shown in the following figure: Figure 11 As shown. Figure 11 It can be seen that with the increase of temperature, the PL fluorescence intensity decreases significantly.

[0083] Relative sensitivity S r It is one of the important parameters of temperature sensing performance. In order to evaluate the fluorescence temperature sensing performance, according to the change of fluorescence intensity with increasing temperature, the Eu prepared in Example 2 was used. 3+ The temperature sensitivity of the fluorescence intensity mode is calculated by doping CsAgCl2. The relative sensitivity of the PL emission intensity to temperature can be defined as:

[0084]

[0085] Where I is the integrated emission intensity and T is the absolute temperature. Figure 12 For Eu 3+ The dotted line graph of the relative sensitivity of the integrated intensity of PL emission of CsAgCl2 as it changes with temperature. Figure 12 It can be seen that in the temperature range of 300~525K, the relative sensitivity S at 325K is r Maximum, up to 3.63% K -1 .

[0086] Corresponding use case 2Eu 3+ The doped CsAgCl2 was tested for temperature-dependent fluorescence attenuation (where the excitation wavelength was 260 nm and the monitoring wavelength was 616 nm). The test results are as follows: Figure 13 As shown. Figure 13 The fluorescence decay curve of Figure 14 As shown. Figure 14 It can be seen that as the temperature increases from 300K to 475K, the Eu prepared in Example 2 3+ The fluorescence lifetime of CsAgCl2 doped with Br is reduced from 1.96μs to 0.99μs; when the temperature is increased from 475K to 525K, the Eu prepared in Example 2 is 3+ The fluorescence lifetime of doped CsAgCl2 gradually increases from 0.99μs to 2.97μs.

[0087] In order to further evaluate the fluorescence temperature sensing performance, according to the change of fluorescence lifetime with increasing temperature, the Eu prepared in Example 2 was used. 3+ The temperature sensitivity of the fluorescence lifetime model is calculated by doping CsAgCl2. The relative sensitivity of PL fluorescence lifetime to temperature can be defined as

[0088]

[0089] Where τ is the fluorescence lifetime and T is the absolute temperature. Figure 15 For Eu 3+ The dot-line diagram of the relative sensitivity of the PL fluorescence lifetime of CsAgCl2-doped nanoparticles to temperature. Figure 15 It can be seen that in the temperature range of 300~525K, the relative sensitivity S at 475K is r Maximum, up to 3.20%K -1 .

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an optical temperature sensing material, comprising the following steps: subjecting CsAgCl2 to temperature-inducing treatment to obtain the optical temperature sensing material; The CsAgCl2 is a low temperature phase CsAgCl2; The preparation method of the CsAgCl2 comprises the following steps: Mixing CsCl, AgCl and concentrated hydrochloric acid, and subjecting the obtained mixed system to a hydrothermal reaction to obtain the CsAgCl2; The mass concentration of the concentrated hydrochloric acid is 37 wt %; the molar ratio of CsCl to AgCl is 1:1; The hydrothermal reaction conditions are as follows: heating from room temperature to 453 K at a rate of 10 K / min, holding at 453 K for 10 to 20 hours, cooling to 433 K at a rate of 5 K / min, holding at 433 K for 2 to 10 hours, cooling to 393 K at a rate of 5 K / min, holding at 393 K for 2 to 6 hours; and then cooling naturally to room temperature; or The preparation method of the optical temperature sensing material comprises the following steps: According to the preparation method of CsAgCl2, Eu2O3 or EuCl3 is added to the mixed system to obtain an optical temperature sensing material.

2. The preparation method according to claim 1, characterized in that The volume ratio of the amount of CsCl to concentrated hydrochloric acid is 1 mol:0.8-5 mL.

3. The preparation method according to claim 1, characterized in that The temperature of the heating induction is 545-575K, and the time is 1-10 hours.

4. The preparation method according to claim 1, characterized in that The amount of Eu2O3 or EuCl3 is 0.5-5% of the amount of AgCl.

5. The optical temperature sensing material prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The optical temperature sensing material is CsAgCl2 or Eu of orthorhombic system 3+ Doped orthorhombic CsAgCl2; the orthorhombic CsAgCl2 is a high-temperature phase and a thermodynamically stable phase.

6. Use of the optical temperature sensing material according to claim 5 in the field of optical temperature sensing.

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