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Materials for Magnetic Refrigeration

#T-1381


Search of New Materials for Magnetic Refrigeration on the Basis Rare Earths, Germanium, Silicon and Bismuth

Tech Area / Field

  • CHE-THE/Physical and Theoretical Chemistry/Chemistry
  • MAT-ALL/High Performance Metals and Alloys/Materials

Status
3 Approved without Funding

Registration date
13.12.2005

Leading Institute
Institute of Chemistry named after V.I.Nikitin, Academy of Sciences, Republic of Tajikistan, Tajikistan, Dushanbe

Collaborators

  • Polish Academy of Science / W.Trzebiatowski Institute of Low Temperature and Structure Research, Poland, Wroclaw\nUniversita degli Studi di Genova / Dipartimento di Chimica e Chimica Ndustriale, Italy, Genova

Project summary

Problem. In February 1997 the report on the first magnetic refrigerator made in Astronautics Technology Center in Madison, Wisconsin has appeared. This report was sensation for the scientists and specialists operating in the field of rare earths.The refrigerator was generated on the basis of metallic gadolinium.

The magnetic refrigeration (MR) was aroused by large magnitocaloric effect in gadolinium, which one is a ferromagnetic with Curie temperature 290K. The magnitocaloric effect is watched for some ferromagnetic and his peak is new to temperature of magnetic ordering.

The fundamental advantages of magnetic refrigeration:

  • Smaller charge of refrigeration energy.
  • Meliorating efficiency factor up to 60%, while the usual refrigeration yields efficiency only 30%.
  • The ecologically clean now-how, which one will not utilize for refrigeration harmful chemicals.

The search of new materials for magnetic refrigeration has begun.In Ames Laboratory Iowa State University the new class of materials for magnetic refrigerators was opened. It is solid solutions of compounds Gd5Ge4 and Gd5Si4. Both compounds crystallize in orthorhombic structure such as Sm5Ge4, but Gd5Ge4 - an antiferromagnetic with Neel temperature 127 K, Gd5Si4 - a ferromagnetic with Curie temperature 336 K. Has appeared, that the solid solution of composition Gd5Ge2Si2 has magnitocaloric effect about twice as large as that exhibited by gadolinium and can be applied in magnetic refrigerators. This example illustrates as properties strongly can be changed even under small variation of composition.

As such investigations only are begun, the seach of new materials for magnetic refrigerators is actual.

In the Institute of Chemistry of TAS within 30 years regularly be ordered studies in the field of synthesizing, growing of single crystals, learning of the phase diagrams, physical and chemical properties of pnicnides of rare earths:

  • All phase diagrams of antimony and bismuth with rare earths are constructed, behind exception Eu-Sb, Eu-Bi.
  • Are designed ecology-clean methods of synthesizing, grown single crystals.
  • The long-term studies have shown, that antimonides and bismuthides have a complex of unique properties.

On the thermal properties - are refractory compounds (melting point above 1500° C)On electric - antimonides and bismuthides are metals, semimetals and semiconductors. On magnetic - at room temperature - paramagnetics, at low temperatures antiferromagnetics and ferromagnetics.

Series of compounds - ferromagnetic with high temperatures Curie have shown: Ho5Sb3 -105K, Dy5Sb3 -125K, Tb5Sb3 - 178K, Gd5Sb3 - 260K, Gd4Sb3 -260K, Gd4Bi3 -340K. Compound Gd5Bi3 and its solid solutions have Curie temperature above room temperatures.

By comparison of the phase diagrams the RE-Sb, RE-Bi, RE-Ge, RE-Si was noted their identity. Many compounds in all four systems have identical crystal structures that will allow obtaining their solid solutions in a wide spacing of concentrations.

As the studies on search of new materials for magnetic refrigerators only are begun, we have decided to expand area of looking ups.

The goal of the Project is search of new materials for magnetic refrigeration.

Development of new high performance materials on the basis of rare earths, bismuth, germanium, silicon by constructing three and four-component phase diagrams, diagrams of composition - property, evaluation of magnetocaloric effect, magnetic and thermodynamic properties.

The Scientific value of the design is, that will be:

  • Work out a new ecologically clean technology of synthesizing and preparation of single crystals of refractory materials.
  • For the first time is constructed three and four component systems by thermal and calorimetric methods.
  • For the first time are found out and the inorganic compounds of complex compositions for magnetic refrigeration.
  • For the first time are measured magnetocaloric, thermodynamic, magnetic and other properties of new inorganic compounds and solid solutions on the basis of rare earth, germanium, silicon and bismuth.

Practical value of the design.

Potential ranges of application of magnetic refrigeration:

  • Power-intensive industry, in commercial refrigerating systems, in air conditioners of the large series, separation of dross.
  • In small-sized technology such, as check behind a climate in motor vehicles and house, in home refrigerators and refrigerating installations.

Besides obtained alloys and compounds will have also practical applying:
  • As materials for permanent magnets, as thermo emission materials.

The collective of the scientists participating in the design, has long-term expertise in the field of reception, study and implementation of alloys, constructing of the phase diagrams.

The scientific principal of the design the professor Dr. Abdusalyamova M.N. and Manager of the design the PhD on physics Rachmatov O.I. - large specialists in the field of study pnicnides of rare earths.

In total on pnicnides by them is published more than 200 articles. More than 10 patents are obtained and 3 monographers are published.The professor Dr. Ganiev I.the large specialist in the field of physico-chemical analysis of complex systems. He is the co-author 5 monographers, more 350 scientific articles. The professor Dr. Pachadzhanov D.N. is the large specialist in the field of analytical chemistry. He the writer 9 monographers, more than 400 articles,

The doctor of chemical sciences Kurbonbekov A. is the large specialist in the field of X-ray diffraction studies.

Conformity of works under the design to the purposes ISTC.

  • The scientists (60 %) will take part in performance of the design, which one early were involved in weapon technology within the framework of the State programs USSR. According to the Appendix 2:

1 Missile Technology Expert. 1.1 Materials and technologies for missiles

Among the participant - four doctors of sciences (professor, Dr) and five candidates of sciences(PhD on sciences). They have wide experience as on constructing the phase diagrams, growing crystals, study of physical characteristics, development of new technology, analytical control and on introduction of results in an industry

  • During performance of the design will be adjusted new and the aged contacts to known centers of science of Europe, USA, Japan engaged studies are proceeded in the field of chemistry and physics of rare earths. It will promote federating scientists of Tajikistan in the international scientific community.
  • The development of new effective materials will allow to improve and to do more cheaply magnetic refrigerators. The creation of magnetic refrigerators will promote security of an environment, medium life of the man. The home refrigerators, conditioners, refrigerator sets, cooling of automobiles widespread in a housekeeping of man. They will utilize now for cooling chlorinated and hydrochlorocarbons and ammonium as heat transfer medium. These chemical compounds destroy ozone layer and negatively influence an environment.
  • The results of fundamental researches, development of new technology for reception of single crystals will promote a solution of various problems not only in the field of reception both use of compounds and alloys of rare earths, but also other refractory materials. It will form the basis entities small of enterprises, that will promote transferring to market economics in Tajikistan.

Role of foreign collaborators.

With foreign collaborators it is supposed following forms of co-operation:

  • Joint studies
  • Transmission of samples for study.
  • Information exchange during works on the design.
  • Joint treating of the technical reports.
  • Joint working seminars, consulting.
  • Preparation of the joint publication
  • Partnership in practical use of obtained materials, including commercial activity.


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ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.

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