CN100463950C - Preparation method of green long-lasting luminescent material activated by manganese ions - Google Patents

Abstract

The invention relates to an inverse spinel structure magnesium stannate green long-lasting phosphor activated by transition metal divalent manganese ions and the preparation thereof: Mg ₂ SnO ₄ : Mn ²⁺ , Mg ₂ SnO ₄ is a matrix, and Mn ²⁺ is an active ion . MgO) and SnO ₂ as the matrix, the dopant ion is Mn ²⁺ , added with manganese oxalate (Mn(CH ₃ COO) ₂ ·4H ₂ O), and the doping dose is 0.005-1% mole. Take MgO and SnO ₂ at a molar ratio of 2:1, weigh an activator at a molar ratio of 0.005-1%, and mix them in a crucible. The firing temperature is 950-1250°C, and the reaction time is 1-3 hours. Activated carbon as reducing agent. The reactant is released from the furnace, cooled in the air to obtain a near-white product, which can be seen after being irradiated by a 254nm ultraviolet lamp with a long green afterglow emission. When the Mn ²⁺ doping amount is between 0.2-0.3%, the luminous effect is the best, and the color coordinates are x= 0.0875, y=0.6083.

Description

Preparation method of green long-lasting luminescent material activated by manganese ions

technical field

The invention relates to a long afterglow luminescent material magnesium stannate and a preparation method thereof, more specifically to a high brightness green emission long afterglow luminescent material activated by divalent transition metal ions Mn ²⁺ and a preparation method thereof.

Background technique

Long-lasting luminescence belongs to electron-capturing materials, and it has no absolute boundary with light-excited luminescent materials and thermoluminescent materials. Long-lasting luminescent materials are a special kind of thermoluminescent materials in a sense, that is, Thermoluminescent materials. According to the general principle of long afterglow luminescence, long afterglow luminescence can be observed as long as a certain concentration and depth of defects or traps that can release stored energy through thermal disturbance at room temperature are created in the matrix. However, the development of long-lasting luminescent materials is quite slow. It took almost 100 years to extend the duration of long-lasting luminescence from more than ten minutes to more than ten hours. The main reason is the complexity of defects in materials and the lack of direct Experimental means (Appl. Phys. Lett. 2002, 80(9), 1535).

At present, most of the research on long-lasting luminescent materials is concentrated on alkaline earth metal aluminates, such as: SrAl ₂ O ₄ :Eu ²⁺ , Dy ³⁺ , CaAl ₂ O ₄ :Eu ²⁺ , Nd ³⁺ and Sr ₄ Al ₁₄ O ₂₅ : Dy, Eu, etc. There are relatively few studies on other color long-lasting luminescent materials, and the progress is relatively slow.

Contents of the invention

In order to solve the above-mentioned shortcomings of the background technology, the purpose of the present invention is to find and prepare a long afterglow luminescent material system with good chemical stability, high afterglow brightness, long afterglow duration, and various luminous colors, which is the main breakthrough point in the current long afterglow research field , The invention provides a green high-brightness long-lasting luminescent material activated by transition metal Mn ²⁺ ions. The object of the present invention is to provide a novel green long emission and long afterglow luminescent material _activated by Mn ²⁺ _ions with inverse spinel structure.

Another object of the present invention is to provide a method for preparing the above-mentioned long-lasting luminescent material.

To achieve the above object, the composition of the long afterglow luminescent material provided by the present invention is: Mg ₂ SnO ₄ :Mn ²⁺ , wherein Mg ₂ SnO ₄ of inverse spinel structure magnesium stannate is the matrix, and Mn ²⁺ is the active ion.

The raw materials for preparing the above-mentioned green long-lasting luminescent material in the present invention are analytically pure or high-purity magnesium oxide (MgO) and tin dioxide (SnO ₂ ), doped with active ions of Mn ²⁺ , and placed in a corundum crucible after being fully mixed. Cover and burn; cooling to obtain a near-white powder product.

The magnesium oxide (MgO) and tin dioxide (SnO ₂ ) are analytically pure or high-purity, weighed according to the molar ratio of 2:1; the doping concentration of the active ion is 0.005-1%; the burning The temperature is 950-1150°C, and the reaction time is 1-3 hours; after the burning, it is released from the furnace at high temperature and cooled in the air.

The activator is added in the form of manganese oxalate (Mn(CH ₃ COO) ₂ ·4H ₂ O). Activated carbon is used as a reducing agent, and a high-efficiency green long-lasting luminescent material is obtained through a high-temperature solid-state method.

In the above-mentioned long-lasting luminescent material Mg ₂ SnO ₄ :Mn ²⁺ , Mn ²⁺ ions are used as activators, and the green emission of Mn ²⁺ comes from the d-electron transition of Mn ²⁺ ions. Since the SnO ₄ ^4- anion has an optically inert structure, it can be used to construct the matrix of the luminescent material. Mg ₂ SnO ₄ is a stable cubic inverse spinel structure. Mg ₂ SnO ₄ has 96 cationic sites, 24 of which are occupied by Mg ²⁺ ions; 8 of the 64 tetrahedral sites are partially occupied by Mg ²⁺ ions, and 32 octahedral sites Sixteen of the sites are occupied by the rest of the Mg ²⁺ ions and Sn ⁴⁺ ions. In addition to a large number of unoccupied lattice sites, cation distortion simultaneously produces a large number of defects in the crystal structure of Mg ₂ SnO ₄ , and some of the defects can be used as traps for electrons or holes to store external energy, such as in the Sn ⁴⁺ lattice The Mg ²⁺ ions at the site can be used as hole traps, on the contrary, the Sn ⁴⁺ ions at the Mg ²⁺ site can be used as electron traps, and the oxygen vacancies can also be used as electron traps such as F color centers. Therefore, it can _be expected that _Mg2SnO4 is an excellent long-lasting luminescent host. The long-lasting luminescent material of the present invention has a very low optimal doping concentration, which is due to the interaction between Mn ²⁺ ions occupying tetrahedral sites and octahedral sites respectively in the Mg ₂ SnO ₄ matrix .

In the above-mentioned long-lasting luminescent material Mg ₂ SnO ₄ :Mn ²⁺ , no energy trapping agent is added, and excellent long-lasting emission can be produced by a single Mn ²⁺ ion stimulator.

The specific preparation method of Mg ₂ SnO ₄ :Mn ²⁺ long-lasting luminescent material: Weigh MgO and SnO ₂ raw materials according to the molar ratio of 2:1, and weigh the activator Mn(CH ₃ COO) ₂ according to the molar fraction of 0.005-1%. 4H ₂ O in an agate mortar by wet method, put it into a corundum crucible, compact it, cover the mouth of the crucible with a corundum sheet, then put it into a larger alumina crucible, and Put an appropriate amount of activated carbon around the corundum crucible, then cover the mouth of the large crucible tightly with a corundum sheet, place it in a high-temperature furnace, heat it to 950-1150°C, and keep the temperature constant for 1-3 hours. Take it out of the furnace at high temperature, and cool to room temperature to obtain a near-white powder. XRD identified the product as a single phase, and doping had no obvious effect on the crystal structure. According to the phosphorescence spectrum measurement, the emission peak is located at 500nm, and the phosphorescence decays exponentially. After being irradiated by ultraviolet light, the long-lasting luminescent material exhibits strong green long-lasting emission. After being irradiated with 254nm ultraviolet light, the long-lasting luminescent material has high-brightness green long-lasting emission characteristics, and can be used for displaying safe exits for crowd evacuation, signs for fire exits, and warnings for other specific occasions when power is cut in public places. The excitation wavelength of the green long afterglow luminescent material prepared by the invention is around 254nm, and it can be used in large quantities to make long afterglow lamp tubes.

Long afterglow luminescent materials use natural solar energy and other light energy to naturally convert into visible light. Due to their good light storage-luminescence characteristics, they are widely used in many aspects of industrial and agricultural production, military, fire protection and people's lives, such as building materials and decoration, Transportation, military facilities, fire emergency and daily consumer goods, etc., and can be made into a series of luminous products such as luminescent paint, luminescent ink, luminescent film, luminescent fiber, luminescent ceramics, and luminescent plastic.

Detailed ways:

Example 1

Weigh 8.0609g of spectroscopically pure magnesium oxide (MgO), 15.0709g of analytically pure tin dioxide (SnO ₂ ), 0.049g of manganese oxalate (Mn(CH ₃ COO) ₂ 4H ₂ O), and fully wet it in an agate mortar. After grinding evenly, put it into a corundum crucible, compact it, cover the crucible mouth tightly with a flat crucible cover, then put it into a larger alumina crucible, and put an appropriate amount of activated carbon around the corundum crucible, and then put The mouth of the large crucible is tightly covered with a corundum sheet, placed in a high-temperature furnace, heated to 950°C, and kept at a constant temperature for 3 hours. Take it out of the furnace at high temperature, and cool to room temperature to obtain a near-white powder. According to XRD identification, the product is magnesium stannate (Mg ₂ SnO ₄ ), and the emission spectrum includes a narrow band from 460 to 560 nm. After being irradiated with 254nm ultraviolet light for 1 minute, the luminescent material exhibits strong green long afterglow emission, and the afterglow time is about 2 hours.

Example 2

Weigh 8.0609g of spectroscopically pure magnesium oxide (MgO), 15.0709g of analytically pure tin dioxide (SnO ₂ ), 0.049g of manganese oxalate (Mn(CH ₃ COO) ₂ 4H ₂ O), and fully wet it in an agate mortar. After grinding, put it into a corundum crucible, compact it, cover the mouth of the crucible tightly with a flat crucible lid, place it in a high-temperature furnace, heat it to 950°C, and keep the temperature constant for 1 hour. Take it out of the furnace at high temperature, and cool it to room temperature to get a light pink powder. The product becomes light pink because the sample synthesized in the air contains Mn ⁴⁺ . According to XRD identification, the product is magnesium stannate (Mg ₂ SnO ₄ ) and a small amount of unreacted tin dioxide (SnO ₂ ), and the emission spectrum includes a narrow band from 460 to 560 nm. After being irradiated with 254nm ultraviolet light for 1 minute, the luminescent material exhibits green long afterglow emission, and the afterglow time is about 1 hour.

Example 3

Weigh 8.0609g of spectroscopically pure magnesium oxide (MgO), 15.0709g of analytically pure tin dioxide (SnO ₂ ), 0.049g of manganese oxalate (Mn(CH ₃ COO) ₂ 4H ₂ O), and fully wet it in an agate mortar. After grinding, put it into a corundum crucible, compact it, cover the mouth of the crucible tightly with a flat crucible lid, place it in a high-temperature furnace, feed high-purity hydrogen, heat to 950°C, and keep the temperature constant for 2 hours. Take it out of the furnace at high temperature and cool to room temperature to get gray powder. According to XRD identification, the products were magnesium stannate (Mg ₂ SnO ₄ ) and magnesium oxide (MgO), and a small amount of gray metallic tin was also produced. The emission spectrum includes a narrow band from 460 to 560nm. After being irradiated with 254nm ultraviolet light for 1 minute, the luminescent material exhibits green afterglow emission, and the afterglow time is about 0.5 hours.

Example 4

Weigh 8.0609g of spectroscopically pure magnesium oxide (MgO), 15.0709g of analytically pure tin dioxide (SnO ₂ ), 0.061g of manganese oxalate (Mn(CH ₃ COO) ₂ 4H ₂ O), and fully wet it in an agate mortar. After grinding evenly, put it into a corundum crucible, compact it, cover the crucible mouth tightly with a flat crucible cover, then put it into a larger alumina crucible, and put an appropriate amount of activated carbon around the corundum crucible, and then put The mouth of the large crucible is tightly covered with a corundum sheet, placed in a high-temperature furnace, heated to 1100°C, and kept at a constant temperature for 3 hours. Take it out of the furnace at high temperature, and cool to room temperature to obtain a near-white powder. According to XRD identification, the product is magnesium stannate (Mg ₂ SnO ₄ ), and the emission spectrum includes a narrow band from 460 to 560 nm. After being irradiated with 254nm ultraviolet light for 1 minute, the luminescent material exhibits strong green long afterglow emission, the afterglow time is about 4 hours, and the color coordinates are x=0.0875, y=0.6083.

Example 5

Weigh 8.0609g of spectroscopically pure magnesium oxide (MgO), 15.0709g of analytically pure tin dioxide (SnO ₂ ), 0.074g of manganese oxalate (Mn(CH ₃ COO) ₂ 4H ₂ O), and fully wet it in an agate mortar. After grinding evenly, put it into a corundum crucible, compact it, cover the crucible mouth tightly with a flat crucible cover, then put it into a larger alumina crucible, and put an appropriate amount of activated carbon around the corundum crucible, and then put The mouth of the large crucible is tightly covered with a corundum sheet, placed in a high-temperature furnace, heated to 1150°C, and kept at a constant temperature for 2 hours. Take it out of the furnace at high temperature, and cool to room temperature to obtain a near-white powder. According to XRD identification, the product is magnesium stannate (Mg ₂ SnO ₄ ), and the emission spectrum includes a narrow band from 460 to 560 nm. After being irradiated with 254nm ultraviolet light for 1 minute, the luminescent material exhibits strong green long afterglow emission, and the afterglow time is about 3 hours.

Although the above embodiments have described the present invention in detail, those skilled in the art or researchers can make various changes without departing from the patent scope of the present invention as described in the claims.

Claims (2)

1. the preparation method of a manganese ion activated green long afterglow luminescent material, its material consists of: Mg ₂SnO ₄: Mn ²⁺, wherein, inverse spinel structure magnesium stannate Mg ₂SnO ₄Be matrix, Mn ²⁺Be active ions; With magnesium oxide MgO and tindioxide SnO ₂Make base starting material, doping active ions Mn ²⁺, thorough mixing is placed in the corundum crucible, adds a cover, and calcination, cooling can obtain the near-white powdered product; It is characterized in that: described calcination temperature is 950-1150 ℃, in 1-3 hours reaction times, makes reductive agent with activated carbon; Described magnesium oxide MgO and tindioxide SnO ₂Be analytical pure, take by weighing by 2:1 mole proportioning; Described activator is with manganous oxalate Mn (CH ₃COO) ₂4H ₂The O form adds.

2. the preparation method of manganese ion activated green long afterglow luminescent material according to claim 1, it is characterized in that: high temperature is come out of the stove after the calcination, cools off in air.