Structural, magnetic and magnetocaloric properties in R2CoMnO6 (R = Dy, Ho, and Er)

A thermomagnetic analysis of an eco-friendly nano-sized dysprosia for energy efficient cryo-cooling systems

“…At 8.5 K, the maximum entropy change (ΔS m ) of about 21.6 JKg −1 K −1 and 27.1 JKg −1 K −1 was observed for CNSD and NNSD respectively at 5 T. The substitution of transition metal (Co and Ni) ions at Dy 3+ ionic site induces a surface spin disorder in larger fraction of atoms, determining its magnetic properties. When compared with earlier reports CNSD and NNSD have large magnetic entropy change (Jia et al 2017a(Jia et al , 2017bKrishna Murthy et al 2015). The increased magnetic entropy change of Co-and Ni-doped dysprosium oxide can be explained by the decrease in lattice parameters, which may modify the exchange interactions.…”

Magnetocaloric effect and Griffiths phase analysis in a nanocrystalline Ho2NiMnO6 and Ho2CoMnO6 double perovskite

“…5 So far, numerous magnetocaloric materials have been explored for possible applications in magnetic refrigeration (MR) at a wide range of temperatures from ambient to liquid He temperature. The various materials with a substantial MCE at low temperatures, such as rare-earth based alloys, [6][7][8] rare-earth amorphous alloys, 9,10 rare earth oxides, 11,12 and double perovskites [13][14][15][16][17][18] have been extensively investigated over the years. Among them, magnetic oxides are a class of materials that are being explored for their potential applications in magnetic refrigeration technology, due to their high resistivity and low eddy current loss.…”

High-Pressure Synthesis of a B-site Co2+/Mn4+ Disordered Quadruple Perovskite LaMn3Co2Mn2O12

“…Benefiting from the structure flexibility, one may get a B-site ordered A 2 BB′O 6 double perovskite by appropriate substitution for the B site in a simple ABO 3 perovskite. The peculiar B–B′ interactions in double perovskites lead to a wide variety of interesting physical properties such as high-temperature ferro/ferrimagnetic half-metallicity, , magnetoelectric multiferroicity, colossal magnetoresistance, , ferroelectric and piezoelectric effects, etc. − Recently, the family of R 2 Co 2+ Mn 4+ O 6 manganite double perovskite has been studied widely because of their interesting magnetism and magnetodielectric properties. − Based on the Goodenough–Kanamori–Anderson (GKA) rules, − the ferromagnetic (FM) interaction is expected to occur between Co 2+ and Mn 4+ ions respectively with 3d 7 (t 2g 5 e g 2 ) and 3d 3 (t 2g 3 ) electronic configurations via the Co–O–Mn superexchange pathways, if the Co–O–Mn bond angle is close to 180°, whereas the antiferromagnetic (AFM) interaction will emerge if the bond angle is close to 90°. As shown in Figure , the magnetic phase diagram of R 2 Co 2+ Mn 4+ O 6 family, when the A-site ionic size gradually decreases to reduce the Co–O–Mn bond angle, the FM Curie temperature ( T C ) almost linearly decreases from 230 K in La 2 CoMnO 6 (LCMO) with ∠Co–O–Mn = 160.1° to 60 K in Tm 2 CoMnO 6 with ∠Co–O–Mn = 144.1°. , Further bending the bond angle to 143.2° for Yb and 142.6° for Lu, the E-type AFM ordering instead of the FM one takes place .…”