Publication Date:
2016-07-28
Description:
HoCrO 3 , Ho 0.67 Gd 0.33 CrO 3 , and GdCrO 3 bulk powder samples were prepared by citrate route. The phase purity and the structural properties of the samples were examined by x-ray diffraction and Raman spectroscopic measurements. The dc magnetization data revealed that the Cr 3+ ordering temperatures (Néel temperature) for the HoCrO 3 , Ho 0.67 Gd 0.33 CrO 3 , and GdCrO 3 samples are 140 K, 148 K, and 167 K, respectively, while the ac magnetization data revealed that the rare-earth (Ho) ordering occurs at ∼8 K for HoCrO 3 and Ho 0.67 Gd 0.33 CrO 3 samples. Temperature-induced magnetization reversal and spin reorientation were observed in GdCrO 3 bulk sample, which depends on applied magnetic field and disappears at ∼1500 Oe and 500 Oe, respectively. By fitting the dc magnetic data with Curie-Weiss law, the effective magnetic moments were calculated to be 11.66 μ B , 10.23 μ B , and 9.90 μ B for the HoCrO 3 , Ho 0.67 Gd 0.33 CrO 3 , and GdCrO 3 samples, respectively. The isothermal magnetization data showed that the magnetic behavior changed from canted antiferromagnetic in low temperature region (below Néel temperature) to paramagnetic at high temperature. It was found that Gd substitution considerably improves the magnetocaloric effect of HoCrO 3 . Pure GdCrO 3 bulk sample showed giant magnetocaloric entropy change (31.6 J/kg K at temperature ∼5 K and at ∼70 kOe), which is higher than that for polycrystalline RMnO 3 , RCrO 3 , and RFeO 3 bulk powder samples. This renders GdCrO 3 useful for potential applications in low-temperature magnetic refrigeration.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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