Second-order Magnetic Phase Transition Research Articles

Quasi-2D-Ising-type magnetic critical behavior in trigonal Cr1.27Te2.

Single crystal Cr1.27Te2 samples were synthesized by using the chemical vapor transport method. Single crystal x-ray diffraction studies show a trigonal crystal structure with a P3̄m1 symmetry space group. We then systematically investigate magnetic properties and critical behaviors of single crystal Cr1.27Te2 around its paramagnetic-to-ferromagnetic phase transition. The Arrott plot indicates a second-order magnetic phase transition. We estimate critical exponents β = 0.2631 ± 0.002, γ = 1.2314 ± 0.007, and TC = 168.48 ± 0.031K by using the Kouvel-Fisher method. We also estimate other critical exponents δ = 5.31 ± 0.004 by analyzing the critical isotherm at TC = 168.5K. We further verify the accuracy of our estimated critical exponents by the scaling analysis. Further analysis suggests that Cr1.27Te2 can be best described as a quasi-2D Ising magnetic system.

Changes in microstructure, magnetocaloric effect and critical behavior of La0.8Sr0.2MnO3 manganites by K/Co doping

We prepared La0.8-xKxSr0.2Mn0.95Co0.05O3 (0 ⩽ x ⩽ 0.1) (LKSMCO) through the modified sol-gel method (S-G) and its structure. Then, the magnetic, magnetocaloric, and critical behavior were analyzed. LKSMCO was confirmed to be the rhombohedral structure within the R-3c space group (No.167) using transmission electron microscopy and X-ray diffraction. For validating the chemical composition of LKSMCO, X-ray photoelectron spectroscopy and EDS were applied, showing that K+ was successfully doped. Phase transition of LKSMCO from paramagnetic to ferromagnetic phase near Curie temperature (Tc) was confirmed with a Magnetic Property Measurement System (MPMS). Using normalization and Banerjee's criterion, LKSMCO was demonstrated to be the second-order magnetic phase transition (SOMPT). As shown from the applied magnetic field, the maximal magnetic entropy (−ΔSMmax) of LKSMCO near Tc was 3.87 J/(kg K) (x= 0.00), 4.28 J/(kg K) (x= 0.05) and 4.44 J/(kg K) (x= 0.10). We employed the Kouvel-Fisher approach (KF) and modified Arrott plots to confirm the values of γ, δ, and β. This indicates that critical exponents of LKSMCO were consistent with the Mean-filed model.

Large relative cooling power in van der Waals room-temperature ferromagnet Fe5GeTe2

Due to the unique structures, van der Waals (vdW) materials have advantages over traditional magnetothermal materials in manipulating magnetothermal properties through structural modification and in cooling applications in nanodevices. Here, we study the magnetothermal properties of vdW ferromagnet Fe5GeTe2 with Curie temperature around room temperature. The results show that Fe5GeTe2 is a second-order magnetic phase transition material, and its in-plane and out-of-plane values of relative cooling power are large up, respectively, to 299.3 and 269.2 J/kg for a field change of 5 T. Compared to other vdW materials reported, Fe5GeTe2 has the greatest potential for room-temperature magnetic cooling applications.

Wide temperature span and giant refrigeration capacity magnetic refrigeration materials for hydrogen liquefaction

Based on theoretical calculations and experiments, the crystal structure, electronic structure, magnetism, and magnetocaloric effect (MCE) of the Ho5B2C5 compound have been systematically investigated. The Ho5B2C5 compound with a typical metallic nature was found to crystallize in a tetragonal structure belonging to space group P4/ncc (No. 130), and its magnetic ground state was identified as ferromagnetic (FM) ordering based on theoretical and experimental results. Additionally, a second-order magnetic phase transition from FM to paramagnetic around approximately 27 K was observed in the Ho5B2C5 compound, resulting in a large MCE. Under varying magnetic fields (ΔH) from 0 to 7 T, the maximum magnetic entropy change (−ΔSMmax), refrigeration capacity (RC), and δTFWHM are 21.3 J/kg K, 1001.6 J/kg, and 60.2 K (a wide temperature range from 15.2 to 75.4 K), respectively. The outstanding MCE performance of the Ho5B2C5 compound is expected to facilitate the progress of magnetic refrigeration for hydrogen liquefaction.

Enhancement of magnetocaloric effect by partial substitution of Bi in La0.60Dy0.10Sr0.30Mn(1−x)BixO3 manganites (x = 0, 0.01, 0.03, and 0.10)

In this study, the effects of Bi substitution for Mn on the magnetic and magnetocaloric properties of La0.60Dy0.10Sr0.30Mn(1−x)BixO3 manganites (x = 0, 0.01, 0.03, and 0.10) synthesized using the sol–gel method ​​were investigated. The samples x = 0, 0.01, and 0.03 had been indexed in an orthorhombic structure (space group Pnma), while sample x = 0.10 had been indexed in a hexagonal structure (space group R3c). The thermomagnetic measurements showed an increase in the Curie temperature (TC) with increasing Bi content, as well as an increase in magnetization at low temperatures. The TC values were determined as 322, 318, 327, and 360 K for x = 0, 0.01, 0.03, and 0.10 samples, respectively. Maximum magnetic entropy change (-ΔSMmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-\\Delta {S}_{M}^{max}$$\\end{document}) values ​​obtained from isothermal magnetization measurements showed an increase with the amount of Bi. The -ΔSMmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-\\Delta {S}_{M}^{max}$$\\end{document} value of 3.80 Jkg−1K−1 at 5 T for the x = 0 sample increased to 4.12 Jkg−1K−1 for the x = 0.10 sample with the highest Bi content. From the Arrott curves, it was observed that all samples exhibited a second-order magnetic phase transition. The obtained values of relative cooling power (RCP), which is an important factor in determining the performance of cooling material, are in the range of 282, 262, 251, and 232 Jkg−1 for x = 0, 0.01, 0.03, and 0.10, respectively.

Gadolinium: A DFT exploration of structural, electronic, and magnetic features in bulk and film configurations for enhanced magnetocaloric understanding

Gadolinium stands as the favored choice among magnetic refrigerant materials for numerous active magnetic regenerator (AMR) prototypes due to its remarkable ability to exhibit a substantial change in magnetic entropy. This unique characteristic arises from its status as one of the elemental ferromagnets with a high Curie temperature, closely aligning with room temperature conditions, and undergoing a second-order magnetic phase transition. In this comprehensive study, we employ density functional theory (DFT) calculations to explore the structural, electronic, and magnetic properties of both Gadolinium bulk and film configurations. Our primary objective is to gain a deeper understanding of the intricate physics underlying the intriguing magnetocaloric features observed in Gadolinium. This investigation provides valuable insights into the potential applications and the broader implications of Gadolinium in the realm of magnetic refrigeration technology.

Effect of bismuth doping on structural, morphological, Griffiths-like phase, and magnetocaloric properties in La0.9−xBixBa0.1MnO3 (x = 0, 0.05, and 0.1)

In this recent work, we have carried out the structural, morphological, Griffiths-like phase, and magneto-caloric studies of sol–gel-synthesized, nanocrystalline manganite La0.9−xBixBa0.1MnO3 (x = 0, 0.05, and 0.1). The Rietveld analysis of X-ray diffraction patterns of nanocrystalline La0.9−xBixBa0.1MnO3 (x = 0, 0.05, and 0.1) confirm the single-phase nature and orthorhombic crystal structure with Pnma space group for all samples. The images acquired with a transmission electron microscope reveal the average particle sizes ranges from 32 nm to 65 nm. The temperature-dependent magnetization measurements, for 0.05 T external applied magnetic field, have revealed paramagnetic (PM) to ferromagnetic (FM) phase transition with transition temperatures (TC) ∼ 228 K, 219 K, and 233 K for x = 0, 0.05, and 0.1, respectively. The downward divergence of temperature dependence inverse susceptibility from the Curie-Weiss fit, indicates a pronounced Griffiths singularity in the samples. The positive slopes of Arrott plots for nanocrystalline La0.9−xBixBa0.1MnO3 (x = 0.05, 0.1) confirm the second-order magnetic phase transition. We have estimated the magnetic entropy change at different values of applied magnetic field for nanocrystalline La0.9−xBixBa0.1MnO3 (x = 0.05, 0.1) samples. Further, using this magnetic entropy data, we have also estimated the magnetic cooling capacity.

A-site K-doped lanthanum manganite nanocrystalline La0.67Ba0.33MnO3 for room-temperature micro-scale magnetic cooling

Bulk nanocrystalline La0.67Ba0.33−xKxMnO3 (with x = 0, 0.05, 0.1, and 0.2) manganites have been prepared by the modified sol-gel method (Pechini). The single-phase rhombohedral crystal structure with the R-3c (no. 167) space group was verified by X-ray diffraction (XRD) and sustained by Rietveld refinement. As follows from the results of XRD structural analyses, the increase in K-doping triggers an increase in the distortion of the MnO6 octahedra, which eventually causes the narrowing of the eg bandwidth. Mn is in a mixed valence state of Mn4+/Mn3+ as inferred by X-ray photoelectron spectroscopy. Magnetic measurements confirm that the Curie temperature decreases from 348 K for La0.67Ba0.33MnO3 to 316 K for La0.67Ba0.13K0.20MnO3. The increasing of the Mn4+ ion concentration at the B-site sublattice and A-site ionic disorder (σ2) breaks up the double exchange interaction between the Mn3+ and Mn4+ ions. The ferromagnetic to paramagnetic second-order magnetic phase transition at TC is also confirmed by electron paramagnetic resonance. According to magnetic field-dependent magnetization isotherms at different temperatures, La0.67Ba0.13K0.20MnO3 shows a relatively large magnetocaloric effect (1400 mJ cm−3 K−1 at 316 K under 5 T applied magnetic field), which raises the possibility of using this material for room-temperature micro-scale magnetic cooling.

Uncovering the universality of critical phenomenon in a ferromagnet Gd5Si4 prepared under high pressure

Manipulation of phase transition is of great interest not only because it can enhance the application ability of accompanying physical effects, but also because it allows us to uncover the physical connotations near the critical temperature point. In this work, we systematically examine the influence of high-pressure annealing (HPA) on critical phenomena in Gd5Si4 ferromagnet. A second-order magnetic phase transition is determined in the annealed sample under 3 GPa with a reduced Curie temperature. Various techniques including modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis are adopted to calculate critical exponents β, γ, and δ of HPA compound. Using the obtained parameters, we employ the renormalization group theory to calculate the spin exchange range, which satisfies J(r) ∼ r−4.454, exhibiting a longer-range-ordered ferromagnetic interaction. Our work indicates that HPA can manipulate the degree of order inside matter with a novel universality class, thus acquiring desired functionality through reasonable HPA treatment.

Influence of iron substitution on structural, magnetic, and magnetocaloric properties of Tb2Fe17−xAlx compounds synthesized by arc melting

In the present work, the structure and magnetic and magnetocaloric properties of the Tb2Fe17−xAlx compounds with x=0,0.25,0.5,0.75, and 1 were studied. These compounds were synthesized by arc furnace without subsequent annealing. Their crystal structure is a Th2Ni17 hexagonal structure with a P63/mmc space group. The Rietveld refinement of the X-ray diffractograms allowed for determining the structural parameter variations with different amounts of aluminum. Lattice parameters and the unit cell volume increase with aluminum amounts while the c/a ratio remains nearly constant. The Tb2Fe17−xAlx compounds exhibit a second-order magnetic phase transition from a ferromagnetic state to a paramagnetic state. The Curie temperature (TC) increases with the aluminum content, the observed effect is due to the magnetovolumic effect. The saturation magnetization (MS) decreases with the increase of Al content. Magnetic entropy and relative cooling power (RCP) decrease as the aluminum content increases. Tb2Fe17−xAlx compounds have a moderate magnetocaloric effect and a tunable operating temperature interval.

Eu/Ni doping on the structure, magnetocaloric effect and critical behaviour of La0.65Sr0.35MnO3 ceramics

Magnetic refrigeration (MR) technology possesses the potential to substitute conventional gas compression technology. It is necessary to find MR materials suitable for a variety of applications. In this study, La0.65Sr0.35-xEuxMn0.95Ni0.05O3 (x = 0.05, 0.075, 0.10) (LSExMNO) ceramics were prepared using a sol-gel synthesis process. The LSExMNO ceramics were confirmed to be the R‾3c space group (rhombohedral structure) by X-ray diffraction (XRD) analysis. The particles of LSExMNO ceramic particles were irregular polyhedral particles by Scanning electron microscopy (SEM). The chemical composition of LSExMNO was determined by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Magnetic Property Measurement System (MPMS) demonstrated that the LSExMNO ceramics display second-order magnetic phase transitions (SOMPT) around Curie temperature (TC). When the Eu3+ doping level increased, the Mn–O–Mn bond angle and length increased, weakening the exchange coupling of the Mn4+-O2--Mn3+ channel and decreasing the TC. As the amount of Eu3+ doping varied, the maximum magnetic entropy (–ΔSMMax) of the LSExMNO ceramics peaked at 4.03 J kg−1K−1 and cooling efficiency parameter (RCP) = 291.2 J kg−1 at x = 0.075. The Modified Arrott plots (MAP) and Kouvel-Fisher (K–F) approaches were applied for the purpose of certifying the critical exponents of LSE0.075MNO ceramics conform to the Mean Filed model. Compared with other magnetic materials, it displays an excellent magnetocaloric effect (MCE) with a TC of 299 K.

Large cryogenic magnetocaloric effect in borosilicate Gd3BSi2O10

The adiabatic demagnetization refrigeration which is based on the magnetocaloric effect (MCE) of magnetic materials is an effective technology to attain sub-Kelvin temperature. In this paper, we report the magnetocaloric property of Gd-based borosilicate Gd3BSi2O10. It experiences a second-order magnetic phase transition at test temperatures range. Owing to the high Gd3+ ion / anion ligand ratio and weak magnetic interaction, Gd3BSi2O10 exhibits a large magnetic entropy change of 59.1 J·kg−1·K−1 at 2.6 K for Δμ0H = 7 T, which is comparable to that of the top-ranked refrigerants operating in the cryogenic range. Besides, Gd3BSi2O10 compound exhibits considerable relative cooling power of 543.7 J·kg−1 for Δμ0H = 7 T. These properties demonstrate that Gd3BSi2O10 is a promising magnetic refrigeration material.

Magnetocaloric effect over a temperature span in (Gd x Tb1-x )3Al2 compounds

As an environmentally friendly, more efficient and operation-reliable technology, magnetic refrigeration is promised to replace traditional gas compression refrigeration. In our study, we studied the influence on magnetism and magnetocaloric effect of (Gd x Tb1-x )3Al2 (x=0, 0.2, 0.4, 0.6, 0.8, 1) systematically. These results indicated that the increase of Gd concentration increased the lattice constants due to larger atomic radius of Gd atom. Simultaneously, the Curie temperature is dependent on magnetic interaction between Gd atom and Tb atom, and reduced from 279 K to 190 K for x=1 to x=0. Arrott plots indicated that (Gd x Tb1-x )3Al2 compounds showed the characteristics of second-order magnetic phase transition. Under a magnetic field of 0-2 T, the maximum isothermal magnetic entropy (-ΔSM)max of (Gd x Tb1-x )3Al2 (x=0, 0.2, 0.4, 0.6, 0.8, 1) compounds are 4.13, 3.79, 3.91, 4.08, 3.96 and 3.98 J/(kg K), respectively. Moreover, refrigeration capacity RC of (Gd x Tb1-x )3Al2 are 59.7, 69.0, 77.6, 65.0, 76.1 and 75.6 J/kg, respective. Adjustable Curie temperature, lower magnetic and thermal hysteresis, (-ΔSM) and RC suggested that, (Gd x Tb1-x )3Al2 compounds can be used as candidates for magnetic refrigeration.

An analysis of magnetic and hysteresis characteristics of a mixed spin Ising-type borophene monolayer

In recent years, borophene has developed into an incredibly promising magnetic material that is essential to many industries including superconductivity and fuel cells. In this paper, using Monte Carlo simulation, the ground-state phase diagrams and magnetic properties of an Ising-type borophene monolayer are explored specifically. The results show that induced by crystal field and exchange coupling, the second-order magnetic phase transitions and the compensation temperature are obtained. Additionally, the multiple compensation temperatures and multi-loop hysteresis characteristics are observed, which are vital in multiple magnetic recording.

High-field magnetic and magnetocaloric properties of pseudo-binary Er1−xHoxNi2 (x = 0.25–0.75) solid solutions

Hydrogen is quickly becoming a desired type of fuel, however, the energy and cost required for liquefaction using today’s cooling technology is excessively high. Magnetic cooling based on the magnetocaloric effect is an energy-efficient and environmentally friendly alternative to commonly used vapor compression, but improvements in refrigerants are crucial for this technology to succeed. Polycrystalline Er1−xHoxNi2 (x = 0.25, 0.5, 0.75) Laves-phase solid solutions obtained by the arc-melting method have been investigated due to their potential for low-temperature refrigerants. Er0.75Ho0.25Ni2 and Er0.5Ho0.5Ni2 crystallize in cubic Laves phase superstructure (space group F-43 m), while Er0.25Ho0.75Ni2, similarly to the initial ErNi2 and HoNi2 binary compounds, crystallizes with the formation of the regular cubic C15 structure (space group Fd-3 m). To evaluate how the structure affects magnetic and magnetocaloric properties, studies in a wide magnetic field range, up to 14 T, were conducted. Measurements show all samples obey the second-order magnetic phase transition from ferromagnetic to paramagnetic state, and their Curie temperatures increase with increasing Ho content from 8 K for Er0.75Ho0.25Ni2 to 12.3 K for Er0.25Ho0.75Ni2. At higher temperatures, all solid solutions are Curie-Weiss paramagnets. However, it has been observed that the formation of the superstructure with lower translational symmetry seems to affect magnetic moments and magnetic entropy values. Er0.25Ho0.75Ni2, with the regular cubic C15 structure, showed the highest entropy changes of 43.5 J/kgK around 12 K, while Er0.75Ho0.25Ni2 and Er0.5Ho0.5Ni2, with cubic superstructure, provided ∼30 % lower results of 30.3 and 35.1 J/kgK, around 8 and 10 K, respectively, for magnetic field change of 14 T. Nevertheless, relatively large and reversible values of magnetic entropy prove that these compounds can be promising candidates for magnetic cooling operating within the low-temperature range needed for hydrogen liquefaction.

Effect of annealing on magnetic and magnetocaloric properties of SmCo3B2 thin films

In this study, SmCo3B2 ternary thin films of manifold thickness were fabricated via e-beam evaporation technique. All the as-deposited SmCo3B2 thin films were subjected to electron beam rapid thermal annealing (ERTA). The X-ray diffraction studies showed amorphous nature for all the as deposited thin films and a highly crystalline hexagonal structure for all ERTA subjected thin films. The elemental composition, purity and surface morphology of the samples were analyzed using energy-dispersive x-ray spectroscopy (EDS) and High-resolution Scanning Electron Microscopy (HR-SEM). Furthermore, the study investigates the magnetocaloric properties of SmCo3B2 thin films, with significant changes depending on the thickness and annealing time. The thin films exhibited a magnetic phase transition around the Curie temperature (Tc) within the range of 40–46 K, attributed to the indirect exchange coupling of Sm–Sm sublattice interactions. Moreover, a significant shift in Tc towards higher temperatures with respect to thickness and annealing were observed in both as deposited and ERTA subjected thin films. The Arrot plots in the positive quadrant suggested the second order magnetic phase transition (SOPT) for all the films. The maximum magnetic entropy change (−ΔSm) of 1.172 Jkg−1K−1 accompanied by a relative cooling power of 5.33 Jkg-1 was achieved for 240 nm ERTA subjected thin film under a change in magnetic field of 5T. The study reveals the effect of ERTA and thickness dependent magnetic and magnetocaloric properties of SmCo3B2 thin films.

Structural, Morphological, and Magnetocaloric Properties of Nanocrystalline Pr0.7La0.3MnO3

Abstract The structural, morphological, magnetic, and magnetocaloric properties of nanocrystalline Pr0.7La0.3MnO3 (PLMO), synthesized by using a wet chemical Sol-gel method, have been investigated. The single-phase nature of nanocrystalline PLMO with orthorhombic crystal structure along with the Pbnm space group was confirmed by Rietveld analysis of the X-ray diffraction pattern. The average crystallite size and lattice microstrain were determined using the Williamson-Hall technique, and they were found to be ~ 28 nm and ~ 0.00137, respectively. Transmission electron microscopy shows the particle size and structural characteristics of the sample. Temperature-dependent magnetization data show paramagnetic to ferromagnetic transition. According to Banerjee criterion, the positive slope of Arrott's plot for nanocrystalline PLMO indicates the second-order magnetic phase transition. In a 5 T external magnetic field, the maximum magnetic entropy change (∆SM) was found to be 2.47 J/kg K. The refrigerant capacity and relative cooling power were calculated and the values are 193.3 and 277.57 J/kg, respectively, under a 5 T applied external magnetic field.

Observation of Griffiths phase, spin glass behaviour and magnetocaloric effect in frustrated Ga2Mn2-xCrxO7 (x = 0, 0.1, 0.3, 0.5) pyrochlore compounds

New series of pyrochlore compounds Ga2Mn2-xCrxO7 (x = 0–0.5) has been synthesized by conventional solid-state reaction method. The X-ray diffraction analysis confirms a single-phase cubic structure of the prepared compounds. All compounds undergo a paramagnetic-antiferromagnetic transition at the Néel transition temperature, close to 42 K. Below ∼12 K temperature, magnetization measurements reveal a glassy behaviour. The value of frustration parameter indicates the presence of a spin frustration. All the compounds exhibit the Griffiths phase. The Arrott's plots confirmed a second-order magnetic phase transition. Moreover, under 5 T applied magnetic field, the maximum value of magnetic entropy change −ΔS was 1.36 J/kg.K for Ga2Mn2O7 compound, which slightly increased to 1.47 J/kg.K for the compound with x = 0.5. At 21 K, the relative cooling power value enhanced from 42.96 J/kg to 47.73 J/kg with Cr4+-ion content changing from x = 0 to x = 0.5.

Continuous pyroelectric energy generation with cyclic magnetic phase transition for low-grade thermal energy harvesting

Waste heat harvesting is of importance to mitigate global warming so that thermoelectric devices have often been suggested; however, such approaches are challenging because of low conversion efficiency of thermoelectrics at low temperature gradient and easy thermal equilibration. In this study, a novel thermo-magneto-pyroelectric energy generator (TMPyEG) was developed to continuously harvest waste heat and convert it into electric energy without complicated electric bias field, required in typical thermodynamic cycling-based pyroelectric generators. To enable displacement reciprocation without intervention, the second-order magnetic phase transition of the soft magnet on an actuating part was repeated in the presence of a thermal gradient. We further incorporate piezoelectric material to mitigate crest factor by filling the energy gaps between pyroelectric energy outputs. Notably, the generated energy from pyroelectric conversion in TMPyEG is superior to that from the reported thermoelectric generators under the similar thermal conditions.

Effects of Ca substitution on magnetic and magnetocaloric properties in PrBa1-xCaxMn2O6 system

In this study, we have examined the effect of Ba substitution by Ca on the magnetic, and magnetocaloric properties of PrBa1-xCaxMn2O6 (x = 0, 0.2 and 0.3) double perovskite manganites produced using sol-gel method. The samples were indexed in orthorhombic structure (with space group of Pbnm). The temperature-dependent magnetization, M(T), measurements indicate that all samples have a magnetic phase transition from ferromagnetic (FM) to paramagnetic (PM) state with increasing temperature. Curie temperature (TC) decreases with increasing Ca content in the main lattice. From the magnetic field dependence of magnetization measurements, M(H), maximum magnetic entropy change (−ΔSMmax) values were calculated as 4.07, 4.12, and 5.04 Jkg−1K−1 under 5 T for PrBaCaMn2O6, PrBa0.8Ca0·2Mn2O6, and PrBa0.7Ca0·3Mn2O6 samples, respectively. Relative cooling power (RCP) values below 5 T were determined as 214.16, 227.14 and 279.62 Jkg-1 based on the increasing Ca content. The −ΔSMmax and RCP values enhance with increasing Ca content, respectively. The nature of the phase transition, checked by Banerjee criterion and Franco's universal master curves, was found to be second order magnetic phase transition (SOMT).