1. Eu (Eu)³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: respectively weighing raw materials containing strontium, phosphorus and europium elements according to the stoichiometric ratio of each element in the chemical formula of the fluorescent powder, homogenizing the raw materials in an agate mortar, pre-burning and re-burning the raw materials in an atmosphere of normal pressure and air to obtain a sintered product, and fully crushing, ball-milling and sieving the sintered product to obtain the fluorescent powder.

2. Eu according to claim 1³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: the raw material containing strontium element is at least one of strontium oxide, strontium hydroxide, strontium sulfide, strontium sulfate, strontium carbonate and strontium nitrate, preferably strontium carbonate.

3. Eu according to claim 1³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: the raw material containing phosphorus is at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and phosphoric acid, and ammonium dihydrogen phosphate is preferred.

4. Eu according to claim 1³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: the raw material containing europium element is at least one of europium oxide, europium chloride and europium nitrate, preferably europium oxide.

5. Eu according to claim 1³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: the presintering temperature is 600 ℃, and the heat preservation time at this stage is 2 hours; the re-sintering temperature is 900 ℃, and the heat preservation time at this stage is 2 hours.

6. Eu according to claim 1³⁺The preparation method of the activated micron-sized strontium phosphate orange red fluorescent powder is characterized by comprising the following steps of: the chemical general formula of the phosphor is Sr _x3(1-)Eu _x3P₄O₁₃Wherein 0.001 is less than or equal tox ≤ 0.6。

7. Use of the phosphor prepared according to the method of claim 1 for latent fingerprint extraction.

Background

The uniqueness, invariance and complexity of fingerprint features makes them important in a variety of applications. Extraction of latent fingerprints is an important technology in forensic medicine, and conventional physical and chemical methods for observing latent fingerprints mainly include a powder method, a silver nitrate method, an indetrione method, a laser detection method, and the like, and these chemical substances and methods usually rely on metal salts, amino acids, proteins, fats and moisture contained in sweat secreted from fingers to show the form of fingerprints through simple physical attachment or chemical reaction. However, these fingerprint extraction methods have the disadvantages of low contrast, low sensitivity, poor definition, large background interference, large toxicity of mercury-containing or lead-containing powder, serious pollution and the like. Therefore, there is a need to develop a new material or method to improve the quality of potential fingerprint extraction.

The rare earth doped inorganic luminescent material has simple synthesis method and stable physical and chemical properties, and has wide application in the fields of solid-state illumination, display, information storage and the like. At present, the nano fluorescent powder for potential fingerprint extraction, including rare earth doped oxide and inorganic oxysalt, has been reported. Similar to the nano-phosphor and the conventional magnetic particles, the micro-phosphor particles can be attached to the secretion of the fingerprint by physical adhesion. On the premise of meeting the requirement of feature identification, the micron-sized fluorescent powder has a simpler production process and lower production cost, and is a potential fingerprint extraction powder material with great application potential.

Disclosure of Invention

Aiming at the problems of high production cost, complex production process and the like of the existing nano fluorescent powder, the invention provides micron Eu for potential fingerprint extraction³⁺An ion activated strontium phosphate orange red fluorescent powder and a preparation method thereof. The fluorescent powder has simple preparation process and low synthesis temperature. The fluorescent powder shows orange red under the excitation of ultraviolet light, and has higher quantum efficiency and color purity. The fluorescent powder has good application potential in potential fingerprint extraction of various complex surfaces.

The technical scheme of the invention is as follows:

the chemical general formula of the orange red fluorescent powder is Sr _x3(1-)Eu _x3P₄O₁₃Wherein the doping concentration range of europium ions is more than or equal to 0.001x ≤ 0.6。

The invention relates to a preparation method of orange-red fluorescent powder, which comprises the following specific steps:

(1) weighing raw materials according to the stoichiometric ratio of each element in the chemical general formula of the fluorescent powder, wherein the raw materials are compounds containing strontium, phosphorus and europium respectively, and grinding and mixing the raw materials uniformly;

(2) pre-burning and re-burning the raw materials ground and uniformly mixed in the step (1) at a high temperature to obtain a sintered product;

(3) crushing, ball-milling and screening the sintered product in the step (2) to obtain Sr _x3(1-)Eu _x3P₄O₁₃And (3) fluorescent powder.

As a further improvement, the strontium-containing raw material in step (1) is at least one of strontium oxide, strontium hydroxide, strontium sulfide, strontium sulfate, strontium carbonate, and strontium nitrate, preferably strontium carbonate.

As a further improvement, the raw material containing phosphorus in the step (1) is at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and phosphoric acid, and ammonium dihydrogen phosphate is preferred.

As a further improvement, the raw material containing the europium element in the step (1) is at least one of europium oxide, europium chloride and europium nitrate, and is preferably europium oxide.

As a further improvement, the purities of the raw materials in the step (1) are all chemical purities or above.

As a further improvement, the presintering condition in the step (2) is normal pressure and air atmosphere, the presintering temperature is 600 ℃, and the heat preservation time is 2 hours.

As a further improvement, the reburning condition in the step (2) is normal pressure and air atmosphere, the reburning temperature is 900 ℃, and the heat preservation time is 2 hours.

The invention relates to application of the fluorescent powder prepared by the method, which is characterized in that the fluorescent powder is used for potential fingerprint extraction. Preferably, a soft brush is adopted to dip the fluorescent powder, the fluorescent powder is shaken off the surface of the fingerprint, an ear washing ball is adopted to blow off the redundant powder, and the development is completed under the irradiation of ultraviolet light.

The invention has the following advantages:

(1) the orange-red fluorescent powder provided by the invention has the advantages of simple preparation process and low synthesis temperature;

(2) the orange-red fluorescent powder provided by the invention can show orange-red fluorescence under the excitation of ultraviolet light, and has higher quantum efficiency and color purity;

(3) the particle size of the fluorescent powder prepared by the invention is micron-sized, and the fluorescent powder has good application potential in potential fingerprint extraction of various complex surfaces.

Drawings

FIG. 1 shows phosphor Sr according to an embodiment of the present invention_2.94Eu_0.06P₄O₁₃SEM image of (d).

FIG. 2 shows phosphor Sr according to an embodiment of the present invention_2.94Eu_0.06P₄O₁₃The excitation spectrum of (1).

FIG. 3 shows phosphor Sr according to an embodiment of the present invention_2.94Eu_0.06P₄O₁₃The emission spectrum of (2).

FIG. 4 shows phosphor Sr according to an embodiment of the present invention_2.94Eu_0.06P₄O₁₃A fluorescent image attached to the latent fingerprint.

FIG. 5 shows phosphor Sr according to an embodiment of the present invention_2.94Eu_0.06P₄O₁₃Usage effect maps on different surfaces.

Detailed Description

The specific steps of this example are as follows:

with SrCO₃、NH₄H₂PO₄、Eu₂O₃Weighing raw materials according to the molar mass ratio of Sr to P to Eu of 2.94 to 4 to 0.06, mixing the raw materials, fully grinding the mixed raw materials in a planetary ball mill for 60 minutes, transferring the fully ground and mixed raw materials into a corundum crucible, presintering the mixture at 600 ℃ for 2 hours in the atmosphere of normal pressure and air, and naturally cooling the mixture to room temperature to obtain an intermediate product. Placing the intermediate product in agateFully grinding in a mortar for 30 minutes, transferring the ground powder into a corundum crucible, re-burning at 900 ℃ for 2 hours in the atmosphere of normal pressure and air, and naturally cooling to room temperature to obtain a sintered product. Ball-milling the sintered product in a planetary ball mill for 60 minutes, and sieving the ball-milled product with a 300-mesh sieve to obtain Sr_2.94Eu_0.06P₄O₁₃And (3) fluorescent powder.

The SEM image of the phosphor prepared in this example is shown in FIG. 1. The fluorescent powder has uniform particle size distribution, is mainly concentrated below 10 microns and is accompanied with slight agglomeration.

The excitation spectrum of the phosphor prepared in this example is shown in FIG. 2. All excitation spectra of the fluorescent powder consist of two parts. Comprises a reaction of O^2--Eu³⁺An excitation band at 200-300 nm generated by a Charge Transfer Band (CTB), and a series of excitation peaks at 290-475 nm, the latter corresponding to Eu³⁺On 4f electron rail⁷F₀-⁵F₄（298nm）、⁷F₀-⁵H₆（317nm）、⁷F₀-⁵D₄（361nm）、⁷F₀-⁵L₇（381nm）、⁷F₀-⁵L₆（394nm）、⁷F₀-⁵D₃(413 nm) and⁷F₀-⁵D₂(464 nm) transition.

The emission spectrum of the phosphor prepared in this example is shown in FIG. 3. The fluorescent powder can be excited by deep ultraviolet and near ultraviolet, the emission peak is located in orange red light wave band, and Eu is³⁺There is an efficient phonon assisted energy transfer between the charge transport band and the 4f energy level.

The fluorescent image of the fluorescent powder attached to the latent fingerprint prepared in this example is shown in fig. 4. The fingerprint shows bright orange-red fluorescence under the irradiation of ultraviolet light, and the ridge line and multiple detailed characteristics are clearly shown.

The effect of the phosphor prepared in this example on different surfaces is shown in FIG. 5. The fluorescent powder can be applied to extracting potential fingerprints on the surfaces of PVC plastics (credit cards) and Fe-Ni alloys (coins).

The above embodiments do not limit the scope of the present invention, and the actual scope of protection is subject to the claims.