Enhancement of the magnetocaloric effect driven by changes in the crystal structure of Al-doped GGG, Gd₃Ga_5−xAl_xO₁₂(0 ≤x ≤5)

Abstract

The Gd3Ga5-xAlxO12 (0 ≤ x ≤ 5) solid solution has been prepared using ceramic synthesis routes and the structural and magnetic properties were investigated using x-ray diffraction, magnetic susceptibility, χ, and isothermal magnetisation, M(H), measurements. Our results indicate a contraction of the unit cell and more significant antiferromagnetic interactions as x increases. Despite the decrease in the magnetic polarisation on the application of a field and the corresponding decrease in the change in the magnetic entropy, ΔS, we find that Gd3Al5O12 has a significantly higher observed (17%) and theoretical (14%) ΔS per unit mass than Gd3Ga5O12. The theoretical increase in ΔS per unit volume (7%) is offset by the increased antiferromagnetic interactions in Gd3Al5O12. The differences in ΔS are driven by a decrease in both the mass and the density as Al ions replace Ga ions. These results highlight the importance of changes to the crystal structure when considering materials for solid state magnetic cooling.

Size Effect in Novel Red Efficient Garnet Nanophosphor

“…The density of this compound is 6.63 g/cm 3 . The GGAG crystallize in the cubic crystal structure with space group Ia 3̅ d (Z = 8) . Gd 3+ ions enter dodecahedral positions, surrounded by 8 oxygens (positions 24c in Wyckoff notation) while Ga 3+ and Al 3+ occupies tetrahedral (24d) and octahedral (16a) positions surrounded by 4 and 6 oxygen ions, respectively.…”

Large adiabatic temperature and magnetic entropy changes inEuTiO3

“…Table I. EuO and DyTiO 3 have a magnetic ordering temperature above 40 K. It can be noted that T ad observed in EuTiO 3 is higher than other promising magnetocaloric materials for refrigeration from 1 to 40 K [14,[22][23][24][25][26][27][28][29]. Only the metal-organic framework material Gd(HCOO) 3 shows a comparable value [29].…”

Large Magnetocaloric Effect in Li3K9Gd3(BO3)7 Crystal Featuring Sandwich-Like Three-Dimensional Framework

“…For Li 3 K 9 Gd 3 (BO 3 ) 7 , the Gd···Gd separations within the zigzag [Gd–O] ∞ chains are 4.8767 Å for Gd(2)···Gd(2) and 5.2875 Å for Gd(2)···Gd(1), respectively. The nearest Gd···Gd distance in Li 3 K 9 Gd 3 (BO 3 ) 7 is larger than that in other Gd-based oxides MC materials, such as Gd 3 Ga 5 O 12 (3.79 Å), GdVO 4 (3.93 Å), and GdPO 4 (4.03 Å), which is obviously beneficial to generating a large magnetocaloric effect.…”