Heat carrier medium for magnetocaloric materials

A composition comprising aqueous heat carrier medium for magnetic coolers, magnetic heat pumps and magnetic generators, comprising 10 to 70% by weight of water miscible alcohols, diols, polyols or mixtures thereof and which has a pH of at least 8 in contact with a magnetocaloric material, wherein the magnetocaloric material is a compound of the general formula (I)

• (AyB1−y)2+δCwDxEz (I)
• where
• A is Mn or Co,
• B is Fe, Cr or Ni,
• C, D and E at least two of C, D and E are different, have a non-vanishing concentration and are selected from P, B, Se, Ge, Ga, Si, Sn, N, As and Sb, where at least one of C, D and E has a non-vanishing concentration and is As or Si,
• δ is a number in the range from −0.1 to 0.1, and
• w, x, y, and z are numbers in the range from 0 to 1, where w+x+z=1.