Scientists from Siberian Federal University (SFU) together with their colleagues from the Institute of Chemistry and Chemical Technology of Siberian Department of Russian Academy of Sciences and Kirensky Institute of Physics of Siberian Department of Russian Academy of Sciences used a new method for synthesizing iron-dysprosium garnet. Magnetic materials of this class are used in microwave and magnetic photon equipment. Iron-dysprosium garnet is understudied and may have previously unknown properties. The article was published in Materials Science and Engineering journal.
Although the method of anion resin exchange precipitation has been known since 1960s-1970s, it was only used to synthesize the hydroxides of aluminum, chrome (III), iron (III), indium (III), and several other compounds. No valuable breakthroughs have been made in this area in the past 40 years, and there are almost no modern publications on it.
A team of Siberian scientists was the first to use anion exchange resin to obtain complex oxide systems. This work is only one of a series of publications prepared by a group of scientists from SFU and the Institute of Chemistry of Siberian Department of Russian Academy of Sciences.
"Our laboratory has been working on the method of anion resin exchange precipitation applicable to different systems for two decades now, and using it we've obtained materials with magnetic properties," told Svetlana Saikova, professor of the department of inorganic chemistry of SFU, and doctor of chemistry.
Anion resin exchange precipitation is a method of the so-called "wet" chemistry. The process takes place at room temperature and under atmospheric pressure. The product is being synthesized from a mixture of water solutions of salts, but instead of traditional precipitation agents (alkali or ammonia) an anion exchange resin is used. It is a polymer - an insoluble matrix in the form of small (0.25-0.5 mm radius) microbeads trapping of anions from initial salts.
Traditional precipitation of metals often leads to the formation of non-crystalline loose deposits (i.e. finely dispersed particles without any structure) that are difficult to separate from the subsided electrolyte. The use of anion exchange resin prevents the pollution of the product with cations.
Moreover, due to the fact that the anions of the initial salt are trapped by polymer beads, scientists were possible to obtain pure metals hydroxides. Moreover, the anion resin exchange precipitation has good results as ions of the solution form insoluble compounds or transfer to the sorbent phase.
Another advantage of this method is that it allows to obtain the product in controlled conditions without high temperatures or aggressive substances. All reaction products are generated at the same time which makes their further interaction easier.
Due to the ability to optimize the correlation between reacting substances, to choose the ion-exchange resin, and, if required, to add substances regulating the precipitation rate to the system scientists can carry out the synthesis with fixed pH values. It is important, if the final product should have certain properties, such as metastable or active phases which is impossible during regular alkali subsidence because of the local oversaturation effect.
This method is much more convenient, cheaper, and better controlled that the widely spread solid phase garnet synthesis method that is used today to obtain the majority of garnet-structured compounds. In this method finely milled mixtures with particular composition are baked in the air or vacuum at different temperatures. Depending on the initial mixture, the process may take different time. Then, taking into account the required properties of the final product, temperature within the range of 1300-1350°? is selected. Moreover, for the composition to be homogeneous, milling and baking are done several times.
The deposit obtained in the course of anion-exchange subsidence is also processed with heat. However, it requires 700-900°? and less baking time. All products are subsided at the same time, the components start to interact on the stage of reaction, and further thermal processing only increases the interaction speed. Due to high activity of nanosized precursors (substances that participate in the reaction), materials obtained using this method may have unusual properties.
In particular, this method allowed the scientists to synthesize a substance with the formula Dy3Fe5O12 - iron-dysprosium garnet. Physical methods showed that the deposits consisted of 2-30 nm nanoparticles with crystal structure. Magnetic properties of the garnet were studied using magnetic circular dichroism.
The interest in these substances is determined by the wide range of garnet's physical properties. For example, almandine, natural iron and aluminum garnet (Fe3Al2Si3O12) is often used in jewelry due to its bright crimson color and hardness. Many garnets have magnetic properties as well. In particular, aluminum-yttrium (Y3Al5O12) and iron-yttrium garnets (Y3Fe5O12) are widely spread and quite well-studied. They are widely used as components of microwave devices, circulators, phase switchers, magnetic photon devices, and insulators. Nanocrystals of these materials play a huge role in physics and technology of magnetic materials. The authors studied magnetic properties of iron-dysprosium garnet and found out that they changed if yttrium is replaced with dysprosium. The group plans an extensive study of garnets with yttrium replaced with other rare earth elements.
Yaroslava Zhigalova | EurekAlert!
Barely scratching the surface: A new way to make robust membranes
13.12.2018 | DOE/Argonne National Laboratory
Topological material switched off and on for the first time
11.12.2018 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy