RU2592899C1 - METHOD OF PRODUCING YTTERBIUM OXIDE AND IRON YbFe2O4±δ - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of complex oxides with magneto electric effects. Method of producing composite oxide of ytterbium and iron YbFe₂O_4±δ, involving preparation of mixture from preliminary dried iron oxide (III) and ytterbium oxide (III), and annealing obtained mixture at temperature of 1,000°C in gaseous mixture consisting of inert gas and oxygen, while maintaining preset oxygen pressure in mixture in range of IgPo₂= -14-19 atm. At that, inert gas used is at least one of gases, selected from group containing argon, nitrogen, and oxides drying is performed at 600°C.

EFFECT: technical result is improved quality of composite oxide YbFe₂O_4±δ.

3 cl, 3 dwg

Description

The invention relates to a technology for producing complex oxides having magnetoelectric effects. The YbFe ₂ O _{4 ± δ} compound belongs to the LnFe ₂ O ₄ family (Ln = Ho, Er, Tm, Yb, Lu) with a mixed valence of iron cations - Fe ^{+ 2} and Fe ⁺³ . The presence of metal cations of the same element of different valency can give unusual properties to oxide materials, which makes it possible to use them in the manufacture of materials for microelectronics.

A known method of producing a complex oxide of yttrium, barium and copper, in which to obtain YBa ₂ Cu ₃ O _7-δ from an aqueous solution containing yttrium, barium and copper nitrates, conduct joint sorption of yttrium, barium, copper in a given molar ratio of Y: Ba : Cu = 1: 2: 3 from the indicated solution on KB-4p-2 carboxyl cation exchange resin, further drying the obtained material and sequential heating at 110 ° C for 2 hours, at 250 ° C for 2 hours, at 450 ° C for 5 h, at 600 ° C - 3 hours, at 850 ° C - 6 hours and then 1 hour in an oxygen atmosphere. During thermal decomposition, the organic part of the ion exchanger burns out and the ions interact with the formation of the complex oxide YBa ₂ Cu ₃ O _7-δ in the form of microspheres (RF patent No. 2503621, IPC С01F 17/00, publ. 10.01.2014).

The disadvantage of this method is the complexity and duration of its implementation, due to the numerous firing operations upon receipt of complex oxides. The firing atmosphere used is oxidizing, which excludes the existence of Fe ²⁺ cations, which is a necessary condition for the production of complex iron oxides and lanthanides, for example ytterbium (YbFe ₂ O _{4 ± δ} ). In addition, these firing temperatures will not allow to obtain such oxides.

A known method for producing complex oxide materials, in particular the production of complex aluminum and magnesium oxides activated by rare-earth metal ions. The initial mixture is obtained by pre-mixing for 30 minutes a powder of cerium (III) oxide, terbium (III) oxide, aluminum metal, aluminum oxide (III), magnesium oxide (II) taken in stoichiometric ratios, an superstoichiometric amount is added to the resulting reaction mixture sodium perchlorate, followed by stirring for 30 minutes and the process of interaction of the components in the resulting reaction mixture is carried out in the mode of self-propagating high-temperature synthesis (RF patent No. 2492963, IPC B22F 3/23, publ. 09/20/2013).

The disadvantage of this method is the inability to obtain complex oxides of iron and lanthanides, for example ytterbium, because self-propagating high-temperature synthesis is carried out in air in an uncontrolled atmosphere according to the oxygen content.

The closest set of essential features is the method of producing complex iron and cerium oxide (a rare-earth element of the lantonoid subgroup), adopted as a prototype, which includes preparing a mixture of powders of iron (III) oxide and cerium (IV) oxide, previously dried at 1000 ° C, firing the resulting mixture at a temperature of 1000-1200 ° C in a gas mixture containing CO ₂ and CO or CO ₂ and O ₂ while maintaining the oxygen pressure in the mixture logPo ₂ = -7.25-15.68 atm to obtain a complex oxide CeFeO ₃ (Kitayama K., Nojiri K., Sugihara T., Katsura T. Phase equilibria in the Ce-O and Ce-Fe-O systems // J . Of Solid State Chemistry. 1985. V.56. Pl-11).

The disadvantage of this method when obtaining under its conditions a complex oxide of iron and ytterbium is the insufficiently high quality of the obtained complex oxide with a given oxygen content, because:

- the initial components can interact with CO ₂ and CO gas mixture with the formation of carbides and hydroxycarbonates (extraneous phases and impurities);

- when the oxygen content in the gas mixture is high, the resulting complex oxide additionally contains oxidized phases (Fe ₃ O ₄ and YbFeO ₃ ).

The technical result of the proposed method is to improve the quality of the obtained composite oxide YbFe ₂ O _{4 ± δ} with a given value of the oxygen index.

The specified technical result is achieved by the fact that in the method for producing complex ytterbium oxide and iron YbFe ₂ O _{4 ± δ} , comprising preparing a mixture of pre-dried iron (III) oxides and lanthanide, calcining the resulting mixture at a temperature of 1000 ° C in a gas mixture containing oxygen , according to the invention, ytterbium (III) oxide is used as the lantonoid oxide, and the prepared mixture is fired in a gas mixture consisting of an inert gas (argon or nitrogen) and oxygen, while maintaining a predetermined value of the oxygen pressure in lgPo impurity in the range of ₂ atm = -14-19. At the same time, at least one of the gases selected from the group consisting of argon and nitrogen is used as an inert gas, and the oxides are dried at a temperature of 600 ° C.

Since the compound YbFe ₂ O _{4 ± δ} belongs to the homological series LnFeO ₃ * n FeO and contains iron in two oxidation states Fe ³⁺ and Fe ²⁺ , it cannot be obtained in air. Carrying out firing in a gas mixture consisting of an inert gas and oxygen, while maintaining a predetermined oxygen value, allows you to create the desired ratio of Fe ²⁺ and Fe ³⁺ in the complex oxide, while there is no interaction of the components of the gas mixture with the sample, except for oxygen exchange. YbFe ₂ O _{4 ± δ} oxide is obtained in the range of oxygen pressures logPo ₂ = -14-19 atm, which provides an oxygen content from a low-oxygen to a high-oxygen boundary of the homogeneity region, therefore, the ratio of Fe ²⁺ and Fe ³⁺ changes, which ensures variability of the properties of the obtained material.

When firing at an oxygen pressure of logPo ₂ <-14 atm, along with the main phase, the formation of oxidized phases — Fe ₃ O ₄ and YbFeO _{3 —} occurs, which affects the quality of the obtained oxide and leads to a change in its properties.

When firing at an oxygen pressure of logPo ₂ > -19 atm in the composite oxide, the reduced phases — Fe and Yb ₂ O ₃ — are formed along with the main phase, which also leads to a change in the composition and properties of the oxide.

Drying iron (III) and ytterbium (III) oxides at 600 ° С before mixing additionally ensures guaranteed removal of moisture from the oxide mixture, which reduces the time required to remove excess oxygen from the mixture and bring it into equilibrium with the gas phase.

The proposed method is as follows:

Dried starting oxides of ytterbium (III) and iron (III), taken in equimolar cationic proportions, according to the equation

Fe ₂ O ₃ + l / 2Yb ₂ O ₃ = YbFe ₂ O ₄ + 1 / 4O ₂

mixed and fired at a temperature of 1000 ° C in a gas mixture consisting of an inert gas (argon or nitrogen) and oxygen, while maintaining the set value of the oxygen pressure in the mixture in the range of lgPo ₂ = -14-19 atm to obtain a complex oxide YbFe ₂ O _{4 ± δ} with a given value of the oxygen index.

The claimed method is tested in laboratory conditions.

The initial oxides of ytterbium (III) and iron (III), dried at a temperature of 600 ° C to constant weight and taken in an equimolar proportion of cations, were mixed and ground for an hour in an agate mortar. From the resulting mixture, tablets with a diameter of 10 mm were pressed on a hydraulic press at a pressure of 150 kPa / cm ² , which were fired in a gas mixture consisting of argon and oxygen with a controlled partial pressure of oxygen at 1000 ° C for 48 hours. By varying Po ₂ in the reactor zone, samples of the complex oxide YbFe ₂ O _{4 ± δ of} various phase compositions were obtained.

The phase composition of the obtained samples was studied using the X-ray diffraction method on a Shimadzu XRD 7000C diffractometer.

Figure 1 shows the diffraction pattern of a sample of nominal composition YbFe ₂ O _{4 ± δ} obtained in a gas mixture Ar + O ₂ (logPo ₂ = -19 atm) at a temperature of 1000 ° C, in which, along with the reflections of the main phase, reflections of the reduced phases are visible ( Fe and Yb ₂ O ₃ ), i.e. the equilibrium is fixed at the low oxygen boundary of the homogeneity region of the YbFe ₂ O _{4 ± δ} compound, with δ = -0.071.

Figure 2 shows the X-ray diffraction pattern of a sample of nominal composition YbFe ₂ O _{4 ± δ} obtained in an Ar + O ₂ gas mixture (logPo ₂ = -14 atm) at a temperature of 1000 ° C, in which, along with the reflections of the main phase, YbFe ₂ O _{4 ± δ the} reflections of the oxidized phases (Fe ₃ O ₄ and YbFeO ₃ ) are visible, i.e. the equilibrium at the high oxygen boundary of the region of homogeneity of YbFe ₂ O _{4 ± δ was} determined, with δ = + 0.052.

From these data it follows that the compound YbFe ₂ O _{4 ± δ} at a temperature of 1000 ° C exists in the range of oxygen pressures from logPo ₂ = -14 to logPo ₂ = -19 (atm.).

Figure 3 shows the diffraction pattern of a sample of nominal composition YbFe ₂ O _{4 ± δ} obtained in an Ar + O ₂ gas mixture (logPo ₂ = -16 atm) at a temperature of 1000 ° C, in which there are no reflections of extraneous phases, i.e. This oxygen pressure in the gas phase allows one to obtain YbFe ₂ O _{4 ± δ} oxide in a homogeneous state, with δ = 0.002.

Claims (3)

1. A method of obtaining a complex oxide of ytterbium and iron YbFe ₂ O _{4 ± δ} , comprising preparing a mixture of pre-dried iron (III) oxides and lanthanide, calcining the resulting mixture at a temperature of 1000 ° C in a gas mixture containing oxygen, characterized in that Ytterbium (III) oxide is used as lantonoid oxide, and the prepared mixture is fired in a gas mixture consisting of inert gas and oxygen, while maintaining the set oxygen pressure in the mixture in the range of lgPo ₂ = -14-19 atm. 2. The method according to claim 1, characterized in that at least one of the gases selected from the group consisting of argon and nitrogen is used as an inert gas. 3. The method according to p. 1, characterized in that the drying of the oxides is carried out at a temperature of 600 ° C.

Images