Magnetic and structural properties of Lu2(Fe, Mn)17Hy hydrides
The Lu2Fe17−xMnxHy, x = 0–2, y = 0–3, hydrides with the Th2Ni17-type crystal structure were prepared and their structural and magnetic parameters were studied. The lattice parameters measured at room temperature increase smoothly with H content. The magnetic measurements indicate that the Lu2Fe17Hy hydrides (with y up to 1.77) are antiferromagnets at high temperatures and ferromagnets at low temperatures. The Lu2Fe16.5Mn0.5 compound also has a high temperature antiferromagnetic state, but its hydrides are ferromagnets only. The Lu2Fe17−xMnxHy hydrides, with x = 0.7 and 2, are ferromagnets with Tc monotonically increasing with H content. The saturation magnetization measured for Lu2Fe17−xMnxHy, (x = 0,0.5,0.7,2 and 0
Instability of the ferromagnetic ground state in Lu2Fe17−XMnX [x = 0.5, 0.7]
The magnetic properties of polycrystalline Lu2Fe16.5Mn0.5 and Lu2Fe16.3Mn0.7 compounds have been studied under hydrostatic pressure up to 10 kbar in the temperature range of 5–300 K and at magnetic fields up to 5 T. The Lu2Fe16.3Mn0.7 compound is in the ferromagnetic (FM) state, and the Lu2Fe16.5Mn0.5 is in the FM state at low temperatures and in the antiferromagnetic state at high temperatures at ambient pressure. We have revealed that the FM state is very sensitive to volume changes and even moderate pressure is sufficient to complete its suppression. The critical pressures are 4 kbar for Lu2Fe16.5Mn0.5 and 7 kbar for Lu2Fe16.3Mn0.7. The suppression of the FM ground state is observed at practically the same volume of the elementary cell. The pressure induced Neel temperature, TN, of both compounds decreases with increasing pressure, dTN/dp = −2.5 K/kbar and dTN/dp = −3.4 K/kbar, for Lu2Fe16.5Mn0.5 and Lu2Fe16.3Mn0.7, respectively. The remarkable strengthening of the FM ground state by the Mn substitutio...
Role of the (H,C,N) interstitial elements on the magnetic properties of iron-rare earth permanent magnet alloys
Abstract A comparison is made between the intermetallic compounds R2Fe14B, R2Fe17 and RFe12−xMx (R = rare earth metal and M = Ti, Mo) and their interstitial derivatives (hydrides, carbides and nitrides). The role of the different interstitial elements on the magnetic properties will be reviewed through their crystal structure (in particular the localization of the interstitial) and through experimental work done by magnetic susceptibility, Curie point measurements and neutron diffraction.