CN1844486A - Process for microwave synthesis of rare earth compound nano rod - Google Patents

Abstract

This invention discloses a micro-wave compound rare earth compound La1-xRexPO4 nanometer bar method, (Re=Ce,Eu or Tb; x=0.05-0.5), the steps as follows: 1) dissolving lanthanum oxidation powder and cerium oxidation, europium oxidation or terbium oxidation powder in nitric acid solution to form mixture solution, 2) adjusting the mixture solution's pH value to 2.5-4.5, disturbing the solution and adding NH4H2PO4 solution to produce gel sediment; 3) heating the gel sediment under the protecting of azote, and then cooling naturally, and then washing the gel sediment with centrifugal separation and ion-doffing water fully, finally collecting it and drying it. The advantage in this invention is that the method is simple, the efficient is high, and it saves energy. The average diameter and length of the nanometer bar made in this invention are 12-17 nanometer, 50-1100 nanometer respectively.

Description

Microwave synthesis of RE compound nanorod

Technical Field

The invention relates to a preparation method of rare earth compound nano rod, in particular to microwave synthesis of rare earth compound La_1-xRe_xPO₄(Re ═ Ce, Eu or Tb; x ═ 0.05About 0.5) nanorod approach.

Background

Due to the 4f electronic property of rare earth elements, rare earth compounds have unique physicochemical, optical, electrical and magnetic properties, and have wide application in the fields of electronics, magnetic materials, photoelectric materials, catalysis and the like. China has abundant rare earth resources, and the research and preparation of the nano material of the rare earth compound has important scientific significance and application value for the deep utilization of the rare earth resources and the development of new application fields of the rare earth resources. La_1-x-Re_xPO₄(Re ═ Ce, Eu, Tb; 0<x<1) is an important double rare earth metal compound, which has high luminous quantum efficiency and unusual magnetic characteristics, so that it has important application in special glass, laser technology, fluorescent lamp and plasma display, etc. For example La prepared by sol-gel method_0.95Eu_0.05PO₄，La_0.84Tb_0.16PO₄And La_0.8Ce_0.2PO₄The nanocrystalline thin film has good fluorescence emission performance (M.Yu, J.Lin, J.Fu, et al, Sol-gel synthesis and phosphor properties of LaPO4: A (A ═ Eu)³⁺，Ce³⁺，Tb³⁺)nanocrystalline thin films，J.of Materials Chemistry，2003，14：1413-1419)。

On the other hand, the synthesis and application of one-dimensional nanomaterials have attracted great interest in recent years. The one-dimensional nano material (such as nano wire, nano rod, nano belt and nano tube) has unique electrical property, mechanical property, magnetic property and electronic transmission property. It is undoubted that nanomaterials of one-dimensional nanostructured rare earth compounds will have new physical and chemical properties compared to bulk materials. Therefore, the synthesis and application research of the rare earth compound nano material with the one-dimensional nano structure draws wide attention. For example: europium-doped lanthanum phosphate nanowires show higher fluorescence quantum efficiencies compared to nano-and micro-sized particles (L.X.Yu, H.W.Song, S.Z.Lu, et al, luminescence Properties of LaPO4: Eu Nanoparticles andNanowires，J.Phys.Chem.B，2004，108：16697-16702)；Pr₆O₁₁The ratio of the gold nano-particles loaded by the nano-rods as carriers to Pr₆O₁₁The gold nanoparticles loaded by the nanoparticles as carriers have higher performance on CO catalytic oxidation (P.X.Huang, F.Wu, B.L.Zhu, et al, pradeodymiun hydroxide nanoparticles and Au/Pr)₆O₁₁nanorod catalysts for CO oxidation, j.phys.chem.b, 2006: 110, 1614-1620). At present, the hydrothermal technology is the main method for synthesizing rare earth compounds with one-dimensional nano structures. Such as: x.wang et al report the synthesis of Rare earth hydroxide nanorods and nanotubes using hydrothermal techniques (x.m.sun, d.p.yu, b.s.zuo, y.d.li, Rare earth compound nanotubes, Adv.Mater, 2003, 15: 1442-; R.X.Yan et al have synthesized doped and undoped rare earth ion phosphate nano-wires and nano-rods (X.M.Sun, X.Wang, Q.Peng and Y.D.Li, chem.Eur.J.2005, 11: 2183-substituted 2195) by hydrothermal treatment; L.X.Yu et al also synthesized doped Ce by similar hydrothermal technique³⁺And Tb³⁺Ionic lanthanum phosphate nanowires and nanorods (H.W.Song, Z.X.Liu, L.M.Yang,S.Z.Lu, Z.H.ZHEN J.Phys.chem.B 2005, 109: 11450-. However, the hydrothermal method requires a high reaction temperature and a long reaction time, and therefore requires a large amount of energy.

Disclosure of Invention

The invention aims to provide a method for synthesizing rare earth compound nanorods by microwave heating, which has simple and rapid process.

The expression of the rare earth compound nanorod synthesized by the method is La_1-xRe_xPO₄Wherein Re ═ Ce, Eu or Tb; x is 0.05-0.5, and the synthesis steps are as follows:

1) dissolving lanthanum oxide powder and cerium oxide, europium oxide or terbium oxide powder in a nitric acid solution to form a mixed solution, wherein the molar ratio of rare earth ion lanthanum to rare earth ion cerium, europium or terbium in the mixed solution is 95: 5-50: 50;

2) adjusting the pH value of the mixed solutionAdjusting the temperature to 2.5-4.5, adding excessive NH under stirring₄H₂PO₄Solution to form a colloidal precipitate;

3) and heating the jelly in a microwave oven under the conditions of nitrogen protection and reflux for 20-60 min, then naturally cooling, fully washing by using centrifugal separation and deionized water, collecting and drying.

The reaction process of the invention can be represented as follows:

the invention has the beneficial effects that:

compared with the existing hydrothermal treatment synthesis method, the method has the advantages of simple process, low cost, rapidness, energy conservation and high efficiency. Prepared La_1-xRe_xPO₄(Re ═ Ce, Eu, Tb; x ═ 0.05-0.5) the nanorods had an average diameter of 12-17 nm and a length of 50-1100 nm. Has the characteristics of stable chemical property and high light quantum yield, and has wide application in the aspects of optical glass, laser materials, fluorescent materials and plasma displays.

Detailed Description

Example 1: preparation of La_0.8Ce_0.2PO₄Nano-rod

0.456g of La₂O₃Powder and 0.115g Ce₂O₃The powder was dissolved in 50mL of 10% HNO₃Forming a mixed solution in the solution, wherein La in the mixed solution³⁺Ions and Ce³⁺Molar ratio of ions La³⁺∶Ce³⁺80: 20. Then, the pH of the mixed solution was adjusted to 2.6 with aqueous ammonia. Adding 75ml of 0.05mol/L of the mixture under electromagnetic stirringNH₄H₂PO₄Aqueous solution, a gelatinous precipitate formed. Transferring the obtained jelly into a 250ml round bottom flask, placing the jelly into a microwave oven, introducing nitrogen for 30min, then performing microwave heating for 20min under the conditions of nitrogen protection and reflux, wherein the microwave heating power is 80% of the maximum power (the maximum power is 600W), continuously introducing nitrogen after heating is finished, cooling to room temperature, performing centrifugal separation and deionized water full washing on a precipitated product, and performing vacuum drying at 80 ℃ to obtain La_0.8Ce_0.2PO₄And (4) nanorods. Transmission electron microscope observation shows that the average diameter of the nano-rods is 16 nanometers, and the length of the nano-rods is 50-600 nanometers.

Example 2: preparation of La_0.5Ce_0.5PO₄Nano-rod

0.815g of La was added₂O₃Powder and 0.820g Ce₂O₃The powder was dissolved in 35mL of 20% HNO₃Forming a mixed solution in the solution, wherein La in the mixed solution³⁺Ions and Ce³⁺The molar ratio of the ions is La³⁺∶Ce³⁺50: 50. Then, the pH of the mixed solution was adjusted to 4.5 with aqueous ammonia, and 70ml of 0.15M NH was added thereto under electromagnetic stirring₄H₂PO₄And generating colloidal precipitate, transferring the obtained colloidal precipitate into a 250ml round bottom flask, placing the colloidal precipitate into a microwave oven, introducing nitrogen for 40min, then carrying out microwave heating for 20min under the conditions of nitrogen protection and reflux, wherein the microwave heating power is 70% of the maximum power (the maximum power is 600W), continuing introducing nitrogen after heating is finished, cooling to room temperature, fully washing the precipitate by centrifugal separation and deionized water, and drying at 80 ℃ in vacuum to obtain La_0.5Ce_0.5PO₄And (4) nanorods. Transmission electron microscope observation shows that the average diameter of the nano-rods is 13 nanometers, and the length of the nano-rods is 60-1100 nanometers.

Example 3: preparation of La_0.95Eu_0.05PO₄Nano-rod

0.542g of La₂O₃Powder and 0.031g Eu₂O₃The powder was dissolvedin 50mL of 10% HNO₃Forming a mixed solution in the solution, wherein La in the mixed solution³⁺And Eu³⁺In a molar ratio of La³⁺∶Eu³⁺95: 5. Then, the pH of the mixed solution was adjusted to 2.9 with aqueous ammonia, and 75ml of 0.05M NH was added under electromagnetic stirring₄H₂PO₄Water solution to generate colloidal precipitate, transferring the obtained colloidal precipitate into a 250ml round bottom flask, placing the colloidal precipitate into a microwave oven, introducing nitrogen for 30min, then carrying out microwave heating for 40min under the conditions of nitrogen protection and reflux, wherein the microwave heating power is 60% of the maximum power (the maximum power is 600W), after heating, continuously introducing nitrogen to cool to room temperature, fully washing the precipitate by centrifugal separation and deionized water, and drying at 80 ℃ under vacuum to obtain La_0.95Eu_0.05PO₄And (4) nanorods. Transmission electron microscope observation shows that the average diameter of the nano-rods is 17 nanometers, and the length of the nano-rods is 50-650 nanometers.

Example 4: preparation of La_0.8Eu_0.2PO₄Nano-rod

0.326g of La was added₂O₃Powder and 0.088g Eu₂O₃The powder was dissolved in 50mL of 10% HNO₃Forming a mixed solution in the solution, wherein La in the mixed solution³⁺And Eu³⁺In a molar ratio of La³⁺∶Eu³⁺80: 20. Then, the pH of the mixed solution was adjusted to 3.3 with ammonia water, and 70ml of 0.05M NH was added thereto under electromagnetic stirring₄H₂PO₄In aqueous solution, a gelatinous precipitate formed. Transferring the obtained jelly into a 250ml round-bottom flask, placing the jelly into a microwave oven, introducing nitrogen for 20min, then performing microwave heating for 20min under the conditions of nitrogen protection and reflux, wherein the microwave heating power is 60% of the maximum power (the maximum power is 600W), continuously introducing nitrogen after heating is finished until the temperature is cooled to room temperature, fully washing a precipitated product by centrifugal separation and deionized water, and drying at 80 ℃ in vacuum to obtain Eu-doped La (lanthanum oxide) preparation_0.8Eu_0.2PO₄And (4) nanorods. Transmission electron microscope observation shows that the average diameter of the nano-rods is 15 nanometers, and the length of the nano-rods is 55-800 nanometers.

Example 5: preparation of La_0.8Tb_0.2PO₄Nano-rod

0.639g of La₂O₃Powder and 0.183g ofTb₄O₇The powder was dissolved in 25mL concentrated HNO₃Forming a mixed solution in the solution, wherein La in the mixed solution³⁺And Eu³⁺In a molar ratio of La³⁺∶Tb³⁺80: 20. Then the pH of the mixed solution was adjusted to 2.7 with 2M potassium hydroxide solution, and 75ml of 0.07M NH was added under electromagnetic stirring₄H₂PO₄In aqueous solution, a gelatinous precipitate formed. Transferring the obtained jelly into a 250ml round bottom flask, placing the jelly into a microwave oven, introducing nitrogen for 40min, then carrying out microwave heating for 40min under the conditions of nitrogen protection and reflux, wherein the microwave heating power is 60% of the maximum power (the maximum power is 600W), continuously introducing nitrogen after heating is finished until the temperature is cooled to room temperature, fully washing a precipitated product by centrifugal separation and deionized water, and drying at 80 ℃ in vacuum to obtain La_0.8Tb_0.2PO₄And (4) nanorods. Transmission electron microscope observation shows that the average diameter of the nano-rod is 13 nanometers, and the length is 55-870 nanometers.

Claims (1)

1. The microwave synthesis process of RE compound nanometer rod features that the RE compound nanometer rod has the expression La_1-xRe_xPO₄Wherein Re ═ Ce, Eu or Tb; x is 0.05-0.5, and the synthesis steps are as follows:

1) dissolving lanthanum oxide powder and cerium oxide, europium oxide or terbium oxide powder in a nitric acid solution to form a mixed solution, wherein the molar ratio of rare earth ion lanthanum to rare earth ion cerium, europium or terbium in the mixed solution is 95: 5-50: 50;

2) adjusting the pH value of the mixed solution to 2.5-4.5, and adding excessive NH while stirring₄H₂PO₄Solution to form a colloidal precipitate;

3) and heating the jelly in a microwave oven under the conditions of nitrogen protection and reflux for 20-60 min, then naturally cooling, fully washing by using centrifugal separation and deionized water, collecting and drying.