The recent literature concerning the magnetocaloric effect (MCE) has been reviewed. The MCE properties have been compiled and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values. These families include: the lanthanide (R) Laves phases (RM2, where M = Al, Co and Ni), Gd5(Si1−xGex)4 ,M n(As1−xSbx), MnFe(P1−xAsx), La(Fe13−xSix) and their hydrides and the manganites (R1−xMxMnO3, where R = lanthanide and M = Ca, Sr and Ba). The potential for use of these materials in magnetic refrigeration is discussed, including a comparison with Gd as a near room temperature active magnetic regenerator material. (Some figures in this article are in colour only in the electronic version)

https://iopscience.iop.org/article/10.1088/0034-4885/68/6/R04/pdf

Recent developments in magnetocaloric materials

Critical phenomena and renormalization-group theory

Magnetocaloric effect and magnetic refrigeration

M Agnetocaloric M Aterials

Magnetocaloric effect: From materials research to refrigeration devices

The catalytic activities of first row transition metal oxides in the conversion of p-nitrophenol to p-aminophenol were investigated The conversion was carried out at room temperature (30° C) using aqueous sodium borohydride The reduction process was accelerated by CuO, Co 3 O 4 , Fe 2 O 3 and NiO The oxides such as TiO 2 , V 2 O 5 , Cr 2 O 3 , MnO 2 and ZnO were found to be inactive towards the conversion of the nitrophenol The active catalysts were analyzed before and after the reaction by XRD and the reduction reaction was monitored and confirmed by UV–vis, HPLC, 1 H NMR and FT-IR techniques

Catalytic activity of first row transition metal oxides in the conversion of p-nitrophenol to p-aminophenol

Copper substituted hydroxyapatite and fluorapatite: Synthesis, characterization and antimicrobial properties

Antimicrobial and cytotoxicity evaluation of aliovalent substituted hydroxyapatite

This paper describes the development of an automated sample translatory type apparatus capable of measuring the magnetocaloric effect of potential magnetic refrigerants over the temperature range 10 to 325 K in applied fields of up to 9 T. A Quantum Design® Physical Property Measurement System has been used as the host platform. The emphasis of the design is on rapid and accurate automated measurements with field slew rates of 9 T per second. Measurement repeatabilities of ±30 mK have been achieved. Results are presented for the rare earth metals gadolinium, dysprosium and holmium, and a gadolinium-yttrium alloy.

A sample translatory type insert for automated magnetocaloric effect measurements

Certain applications of magnetic materials require the knowledge of the magnetocaloric effects, ie, the adiabatic change of temperature or the isothermal change of the entropy upon application or removal of magnetic field While the isothermal magnetic entropy change can be calculated from magnetic data only, the calculation of the adiabatic temperature change requires the knowledge of the field-dependent specific heat as well To compare magnetocaloric effect results obtained from magnetic-only, thermal-only, or combined methods requires the evaluation of the mutual reliability of all methods In crystalline materials it usually does not present a problem to perform thermal and magnetic measurements on the same sample or at least on samples of identical state For amorphous materials, unfortunately, thermal measurements are extremely difficult to perform on the ribbons themselves so usually pellets pressed from powdered ribbons, with silver as a binder, are applied After the magnetic entropy change calculated from thermal measurements performed on such a composite did not agree with the data obtained from magnetic measurements performed on the original ribbon, magnetic measurements were carried out on the pellet and its predecessor powders Comparison of the results revealed that the pellet’s properties do not reflect the properties of the original ribbon However, comparison of magnetic and thermal measurements carried out on the pellet itself show good agreement if proper numerical methods are used for evaluation The study concludes that amorphous ribbons are far more competitive for certain applications than the thermal measurements, performed on the pellet only, would indicate

Buvaneswari Gopal

Papers

Catalytic activity of first row transition metal oxides in the conversion of p-nitrophenol to p-aminophenol

Copper substituted hydroxyapatite and fluorapatite: Synthesis, characterization and antimicrobial properties

Antimicrobial and cytotoxicity evaluation of aliovalent substituted hydroxyapatite

A sample translatory type insert for automated magnetocaloric effect measurements

Effect of sample preparation on the magnetic and magnetocaloric properties of amorphous Gd70Ni30