General description

Gadolinium oxide (gadolinium oxide), the chemical formula is Gd_?O_? Taking monazite or mixed rare earth ore as raw material, samarium gadolinium mixed rare earth solution is prepared through purification steps such as extraction. Gadolinium oxalate is precipitated with oxalic acid, and gadolinium oxide is prepared through separation, drying and burning. Preparation method: samarium gadolinium mixed rare earth solution was prepared by extraction and other purification steps. Gadolinium oxalate was precipitated with oxalic acid, and gadolinium oxide was prepared by separation, drying and burning.

Appearance: white tasteless amorphous powder.Density: 7.407g/cm ³ The density of monoclinic system is 8.297g/cm ³  Melting point: 2330 ± 20 ℃ (some data say 2420 ℃).Solubility: insoluble in water, soluble in acid to form corresponding salt. When exposed in the air, it is easy to absorb water and carbon dioxide in the air and deteriorate. It can react with ammonia to form gadolinium hydrate precipitation.

Application

Gestodene is a progestogen hormonal contraceptive. Products containing Rare earth doped up-conversion luminescent materials have high stability, sensitivity, flexibility, and safety. As an inexpensive, environmentally friendly and recyclable up-conversion luminescent material, it has broad application prospects in the fields of infrared detecting, laser anti-counterfeiting, fingerprint identification and collection, etc. It is used as yttrium aluminum and yttrium iron garnet admixtures, sensitizing fluorescent materials in medical devices, nuclear reactor control materials, raw materials for the preparation of metal gadolinium, magnetic bubble materials and optical prism additives.

Gadolinium oxide sulfide (Gd2O2S) is an important rare earth sulfur oxide. As a luminescent material matrix, it has many advantages, such as high doping concentration of rare earth ions, excellent chemical stability, low toxicity and low phonon energy. At present, most studies on Gd2O2S: Er3+, Yb3+ systems are mainly focused on 980 nm, and a few are focused on 1064 nm or 1550 nm. Therefore, this article mainly studies the best process parameters and best formulations of Gd2O2S: Er3+, Yb3+ up-conversion luminescent materials that respond to three wavelengths. At the same time, the crystal structure and morphology, luminescence performance and luminescence mechanism of the best sample were explored. Then the screen was made by screen printing with Gd2O2S: Er3+, Yb 3+ phosphors. In order to obtain a portable high-efficiency multi-wavelength applicable infrared display detection board. ^[1]

Synthesis

At present, the industrial method of preparing rare earth oxides is usually precipitation roasting method. This method has the problems of high cost of precipitant, high energy consumption and difficult treatment of by-products and wastewater.

Thermodynamic calculations were carried out on the possible reactions in the pyrolysis of gadolinium oxide. Based on the analysis of thermodynamic data, the experimental study of citric acid assisted ultrasonic spray pyrolysis was carried out. Using pure gadolinium oxide as raw material, the feasibility of citric acid assisted ultrasonic spray pyrolysis for the preparation of rare-earth oxide was explored, and the effect of citric acid on ultrasonic spray pyrolysis was analyzed. The experimental results show that the precursor prepared by the introduction of citric acid is porous spherical shell or fragment with loose morphology, which is conducive to the entry of reaction gas and the escape of generated gas. The calcination temperature required for the conversion of precursors to gadolinium oxide products is significantly reduced. Gadolinium oxide powder products can be obtained by calcination at about 700 ℃ for 4 hours.

Figure the systhesis route of Gadolinium oxide

The effects of citric acid addition, precursor roasting temperature and roasting time on the phase and chloride content of mixed oxide complex products were deeply studied. The optimal process conditions for preparing neodymium praseodymium oxide were as follows: the precursor was 4:1, the calcination temperature was 1050 ℃ , and the calcination time was 4 h. Under these conditions, praseodymium and neodymium oxide products with a chloride content of 136 ppm can be prepared. The phases of praseodymium and neodymium oxide were Pr4O7 and A-type Nd2O.^[2]

Reference

1.Li Xueqi: preparation and application of rare earth doped gadolinium oxysulfide upconversion luminescent materials: Changchun University of technology, 2021

2.Fu Liwen: preparation of gadolinium oxide and praseodymium oxide by ultrasonic spray pyrolysis: Jiangxi University of Science and Technology, 2021