Study of magnetic and thermal properties of SmCrO3 polycrystallites

• Published in: RSC advances 2016-01, Vol.6 (85), p.8214-8223
• Main Authors: Gupta, Preeti, Poddar, Pankaj
• Format: Article
• Language: English
• Subjects: Anomalies; Antiferromagnetism; Entropy; Magnetic properties; Operating temperature; Sol gel process; Specific heat; Thermal properties
• ISSN: 2046-2069
• DOI: 10.1039/c6ra17203b

In the present work, we have studied the magnetic and thermal properties of sol gel derived samarium chromite (SCO) polycrystallites. The magnetic measurements of SCO polycrystallites show a characteristic antiferromagnetic transition T N ∼ 190 K and spin reorientation temperature T SR ∼ 33 K, which is in the region of interest to study a possible magnetocaloric effect (MCE). The isothermal magnetic entropy change (Δ S M ) is estimated by an indirect method from the isothermal magnetization curves measured in this temperature range. The SCO polycrystallites possesses both inverse (positive) and normal (negative) MCE at and above around the spin reorientation transition ( T SR ) with −Δ S max M values of ∼−24 × 10 −2 & 13 × 10 −2 J kg −1 K −1 , respectively. The SCO also shows another normal (negative) MCE peak around its Néel transition ( T N ) with −Δ S max M ∼ 11 × 10 −2 J kg −1 K −1 . The presence of two successive MCE peaks in SCO in the temperature range of 3-50 K, leads to an ∼47 K operating temperature window with one thermodynamic cycle. In addition, the low temperature heat capacity ( C P ) measurements of SCO polycrystallites reveal a λ-shaped peak at T N which is associated with a conventional second-order, paramagnetic to antiferromagnetic (AFM), phase transition. The temperature and magnetic field dependence of the specific heat capacity was studied and analyzed to estimate the adiabatic temperature change (Δ T ad ). In addition the C P vs. T curve in SCO also shows a weak anomaly around the ∼ T SR along with a Schottky anomaly below 10 K. SmCrO 3 polycrystallites exhibits inverse and normal magnetocaloric effect at and around spin reorientation transition ( T SR ) along with normal magnetocaloric effect at Néel transition ( T N ).