In this study, manganese substituted strontium hexaferrite (SrFe12−xMnxO19; x = 0, 3, 5, and 7) prepared by the sol–gel auto-combustion method are studied. We observed that the substituted Mn ...preferentially goes to the 2a and 12k sites of Fe. Raman modes related to the 12k site suggest the stiffening of the lattice. The transformation of the grain's shape from hexagonal (x = 0 and 3) to rhombohedral (x = 7) was observed, as shown in the micrographs obtained from FESEM. The thermomagnetic curves show the shift of TC to lower temperatures with the increase in the Mn content. From x = 5 onwards, the growth of another magnetic phase (FiM2) of lower coercivity apart from the parent phase (FiM1) of higher coercivity is seen. The FiM2 phase was found to increase with the Mn content in the sample (16.4(3)% for x = 5 but 66.2(5)% for x = 7). Although the magnetization for both FiM1 and FiM2 decreases with the increase in temperature, both magnetic phases behave in contrast to each other for x = 5 and x = 7. The study suggests a transformation of the compound from high magnetic anisotropy (x = 0) to low magnetic anisotropy (x = 7). The x = 5 composition sample displays the highest value of the first-order ME coefficient (0.83(2) mV × cm−1 × Oe−1). The observed value for x = 5 composition is ∼2.5 times higher than that of the parent x = 0 composition sample (0.33(2) mV × cm−1 × Oe−1). The studies thus suggest that the x = 5 composition is one of the viable candidates for magnetoelectric applications.
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•Critical concentration of oleic acid facilitates CoFe2O4 mesoscale assembly formation.•Hydrophobic interaction among the particles promotes the initial aggregation step.•Extremely ...good or poor stability conditions do not allow the secondary growth process.•Magnetic properties reflect the interparticle interaction effect in the assemblies.
Mesoscale hierarchical assemblies have emerged out as a new class of structures between fine dimension nanoparticles and bulk structures, having distinctly different physical properties from either side. Controlling the self-assembly process of primary nanoparticles and subsequent secondary growth mechanism is the key aspect for achieving such ordered structures. In this work, we introduce a new insight on achieving hierarchical assemblies of CoFe2O4 nanoparticles based on the temporal stability of the primary nanoparticles, where, the growth and stability of the primary particles are controlled by using oleic acid. It is found that the developed particles, at a critical concentration of oleic acid, prefer a secondary growth process, rather than promoting their individual growth. Domination of the attractive hydrophobic interaction over steric repulsion among the primary particles at this critical concentration of oleic acid is found to be the key factor for the initial aggregation of the primary particles, which eventually leads to the formation of spherical hierarchical assemblies via oriented attachment. It is also realized that the extremely well or poor stability conditions of the primary particles do not allow this secondary growth process. Estimated values of Co2+ distribution factor show that the cation distribution factor of CoFe2O4 system is not affected by the nature of dominant growth processes, when these are controlled. Interestingly, magnetic measurements reflect the stronger interparticle interaction in the hierarchical system and high magnetic moment values at low magnetic field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this study, manganese substituted strontium hexaferrite (SrFe
Mn
O
;
= 0, 3, 5, and 7) prepared by the sol-gel auto-combustion method are studied. We observed that the substituted Mn ...preferentially goes to the 2a and 12k sites of Fe. Raman modes related to the 12k site suggest the stiffening of the lattice. The transformation of the grain's shape from hexagonal (
= 0 and 3) to rhombohedral (
= 7) was observed, as shown in the micrographs obtained from FESEM. The thermomagnetic curves show the shift of
to lower temperatures with the increase in the Mn content. From
= 5 onwards, the growth of another magnetic phase (FiM2) of lower coercivity apart from the parent phase (FiM1) of higher coercivity is seen. The FiM2 phase was found to increase with the Mn content in the sample (16.4(3)% for
= 5 but 66.2(5)% for
= 7). Although the magnetization for both FiM1 and FiM2 decreases with the increase in temperature, both magnetic phases behave in contrast to each other for
= 5 and
= 7. The study suggests a transformation of the compound from high magnetic anisotropy (
= 0) to low magnetic anisotropy (
= 7). The
= 5 composition sample displays the highest value of the first-order ME coefficient (0.83(2) mV × cm
× Oe
). The observed value for
= 5 composition is ∼2.5 times higher than that of the parent
= 0 composition sample (0.33(2) mV × cm
× Oe
). The studies thus suggest that the
= 5 composition is one of the viable candidates for magnetoelectric applications.
Neutron diffraction measurements, performed in the presence of an external magnetic field, have been used to show structural evidence for the kinetic arrest of the first order phase transition from ...(i) the high temperature austenite phase to the low temperature martensite phase in the magnetic shape memory alloy Ni37Co11Mn42.5Sn9.5, (ii) the higher temperature ferromagnetic phase to the lower temperature antiferromagnetic phase in the half-doped charge ordered compound La0.5Ca0.5MnO3 and (iii) the formation of glass-like arrested states in both compounds. The cooling and heating under unequal fields protocol has been used to establish phase coexistence of metastable and equilibrium states, and also to demonstrate the devitrification of the arrested metastable states in the neutron diffraction patterns. We also explore the field-temperature dependent kinetic arrest line TK(H), through the transformation of the arrested phase to the equilibrium phase. This transformation has been observed isothermally in reducing H, as also on warming in constant H. TK is seen to increase as H increases in both cases, consistent with the low-T equilibrium phase having lower magnetization.
•Effect of Mn in Ni55Fe19Ga26 on microstructure and MCE is presented.•Mn stabilizes 14M martensite in place of NM martensite.•Increasing Mn also leads to a drastic reduction in γ-phase content.•MCE ...shows significant improvement with increasing Mn.•A maximum value of ΔSM= −19.8J/kgK has been observed at 9T for the Mn-10 alloy.
Ni–Fe–Ga-based Ferromagnetic Shape Memory Alloys (FSMAs) show considerable formability because of the presence of a disordered FCC γ-phase, but they lack in magnetocaloric property. Addition of Mn has been explored as a way to improve their magnetocaloric property. The current study presents a detailed structural and magnetization analyses of a two-phase ternary Ni55Fe19Ga26 alloy and its quaternary counterparts obtained by partial replacement of Fe by Mn, Ni55Fe19−xMnxGa26 (x=2.5, 2.75, 3, 5, 10). Characterization of these alloys has been carried out using Optical and Scanning Electron Microscopy, Electron Probe Microanalysis, X-ray (XRD) and Neutron Diffraction (ND), Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC) and DC magnetization measurement. Ni55Fe19Ga26 alloy shows predominantly non-modulated (NM) internally-twinned martensite, with traces of a modulated 14M martensite and the parent L21 phase along with the FCC γ-phase. Quaternary addition of Mn in partial replacement of Fe stabilizes14M martensite, drastically reduces the amount of γ-phase, keeps the martensitic transition temperatures unchanged, but raises TC considerably. Magnetocaloric effect improves significantly with increasing Mn-content and a maximum value of −19.8J/kgK for ΔSM has been observed at 9T for the alloy containing 10at.% Mn.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Demonstration of spin-phonon coupling in trirutile magnetoelectric Fe2TeO6.•Dimeric (d(5/2)-d(5/2)) interaction induced short-range magnetic correlation.•Exploration of unknown magnetic anomaly at ...150 K below the familiar sharp transition (TN ∼ 210 K) corresponding to long-range order.•µSR study reveals of three dynamically distinguishable temperature regime as (I) T > TN, (II) TN > T > 150 K, and (III) T < 150 K.
Spin-phonon coupling originated from spin-lattice correlation depends upon different exchange interactions in transition metal oxides containing 3d magnetic ions. Spin-lattice coupling can influence the coupling mechanism in magnetoelectric material. To understand the spin–lattice correlation in inverse trirutile Fe2TeO6 (FTO), magnetic properties and phonon spectra are studied. Signature of short-range magnetic correlation induced by 5/2–5/2 dimeric interaction and magnetic anomaly at 150 K is observed apart from the familiar sharp transition (TN ∼ 210 K) corresponding to long-range order by magnetization and heat capacity measurements. The magnetic transitions and the spin dynamics are further locally probed by muon spin resonance (μSR) measurement in both zero fields (ZF) and longitudinal field (LF) mode. Three dynamically distinct temperature regimes; (i) T > TN, (ii) TN > T > 150 K, and (iii) T < 150 K, are observed. A change in the spin dynamics is realized at 150 K by μSR, though previous studies suggest long-range antiferromagnetic order. The renormalization of phonon frequencies observed in Raman spectra below 210 K suggests the existence of spin-phonon coupling in the material. The coupling strength is quantified as in the range 0.1–1.2 cm−1 following the mean-field and two-spin cluster approximations. We propose that the spin-phonon coupling mediated by the Fe-O2-Fe interbilayer exchange play a significant role in magnetoelectric ME coupling observed in the material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The present study was conducted to evaluate the genetic variability for morphological and qualitative traits of Coccinia for development of trait specific lines at ICAR-Central Horticultural ...Experiment Station (CIAH-RS), Panchmahals (Godhra), Gujarat during 2020-2022. In this study, we evaluated 26 gynoecious accessions to assess the genetic divergence through principal component and cluster analysis. The experiment was carried out in a randomized complete block design with three replications under rainfed semi-arid conditions. High values of PCV and GCV were observed for variables such as NFFP (25.13 and 22.20), PL (23.14 and 20.69), FD (24.01 and 21.46), AFW (22.98 and 20.13), NFPY (26.38 and 24.40), FYP (37.57 and 31.29), FY (35.55 and 33.20), AsC (28.65 and 27.73), Ac (24.32 and 21.06), TSS (37.23 and 35.94), DPPHL (20.71 and 20.38), FRAPL (21.08 and 20.92), TPF(20.81 and 20.45) respectively. High heritability coupled with high genetic advance as per cent of mean was observed for vine length (VL), internodal length (IL), number of female flowers per plant (NFFP), fruit length (FL), peduncle length (PL), fruit diameter (FD), average fruit weight (AFW), number of fruit per plant per year (NFPY), fruit yield per plant (FYP), fruit yield (FY), ascorbic acid (AsC), acidity (Ac), total soluble solids (TSS), total phenols in leaves TPL), total flavonoids in leaves TFL, CUPRAC in leaves (CUPRACL), DPPH in leaves (DPPHL), FRAP in leaves (FRAPL), Total phenols in fruits (TPF), Total flavonoids in fruits (TFF), CUPRAC in fruits (CUPRACF) and DPPH in fruits (DPPHF). The FYP exhibited a significant positive correlation with variables like VL (0.6833), IL (0.2991), NFFP (0.8107), FD (0.5245), AFW (0.6766), NFPY (0.7659), ASC (0.4611), TSS (0.5004) and TPF (0.4281). The estimates of genetic parameters revealed scope for further improvement of fruit yield by selection. Of the eight principal components, PC-I through PC-VIII had eigen values greater than 1 and it accounts 85.02% of the total variation for 26 gynoecious accessions of Ivy gourd. The eigen values of PC-I comprised 5.775% of total variation followed by PC-II (4.250%), PC-III (3.175%), PC-IV (2.588%), PC-V (1.828%), PC-VI (1.447%), PC-VII (1.179%) and PC-VIII (1.013%).The cluster VI and cluster I having highest mean values for most of traits under study. Thus, genotypes from the distinct cluster like cluster VI and I for should be used for selection of parents and varietal improvement for further breeding programme in ivy gourd.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
We report an enhanced magnetodielectric (MD) coupling in antiferromagnetic Bi
2
Fe
4
O
9
(BFO) lightly substituted by gadolinium (Gd
3+
). Rietveld refined X-ray diffraction and Raman spectra reveal ...the formation of orthorhombic phase for all the synthesized samples. Gd
3+
substitution results in a notable increase of antiferromagnetic transition (
T
N
) from 250 K (
x
= 0, BFO) to 256 K (
x
= 0.02, BGFO2). At the same time, deviation from linear
M
-
H
behaviour in the substituted samples at
T
≤ 30 K implies the onset of weak ferromagnetic ordering, along with a sudden rise in magnetisation around ∼30 K. This result indicates the magnetically active nature of Gd
3+
ions possessing a large magnetic moment of ∼8
μ
B
and this is explained by considering the two sub-lattice mode. The temperature dependence of the dielectric study shows unusual oppression in
′ and tan loss plots at
T
∼
T
N
which hints a plausible MD coupling in the above studied samples. A contrasting behaviour in the temperature dependant MD% is seen for BFO and the substituted samples have an enhancement of ∼30% for BGFO2 at 300 K. Further, confirmation to this coupling is drawn by studying frequency and magnetic field dependant MD% at 300 K, where it is found that both obey a power law of the form ∝exp(
ω
)
n
and ∝(
H
)
m
respectively. Interestingly, the values of '
n
' and '
m
' obtained from fitting are found to lie in the range 0.45-0.5, thus signifying a similar dependence of MD on frequency as well as magnetic field. Lastly, the effect of Gd
3+
substitution on
P
-
E
loop of BFO and its substituted samples at room temperature have been discussed.
We report an enhanced magnetodielectric (MD) coupling in antiferromagnetic Bi
2
Fe
4
O
9
(BFO) lightly substituted by gadolinium (Gd
3+
).
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IJS, KILJ, NUK, UL, UM, UPUK
•We report a rare magnetoelectric property in double perovskite La3Ni2TaO9.•Indicating transition from magnetic to spin glass state.•Rare combination of magnetoelectric and relaxor properties.
We ...report a rare magnetoelectric relaxor phenomenon in double perovskite La3Ni2TaO9. To unveil this exotic property, we have systematically examined its physical characteristics via magnetic and electric susceptibilities. DC magnetization shows magnetic anomaly at 25 K (Tg) and becomes irreversible under ZFC and FC protocol. The thermal profile of dielectric constant (ε) and loss (tanδ) exhibit anomaly in the vicinity of magnetic ordering temperatures and the peaks shift towards higher temperatures at higher frequencies. This co-occurrence indicates a strong correlation between magnetic and dielectric properties. To further corroborate, we measured dielectric constant ε(T), in presence of external magnetic fields. It is observed that upon application of magnetic field ε(T) increases and tanδ(T) shows upturn, near Tg, which confirms magneto-electric nature of La3Ni2TaO9. Additionally, it is observed that the DC magnetic susceptibility exhibits an upturn up to Tg along with broad anomaly. Inverse of AC susceptibility is fitted with modified Curie–Weiss law which shows non-linear characteristics. Dielectric and magnetic properties collectively establish that La3Ni2TaO9 belongs to the magnetoelectric relaxor family.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Improved strain derivative of −0.255 ppm/G for holmium substituted cobalt ferrite.•Investigation of magnetoelectric effect in PSLZT –Ho substituted cobalt ferrite.•Improved ...interfacial coupling between magnetostrictive and piezoelectric phase by co-sintering the bi-layered composites.•Maximum α31 for glued composites is 9.9 mV/Oe-cm, and 556 mV/Oe-cm for co-sintered composites at resonance frequency.
The magnetoelectric bilayer composites of Ho substituted cobalt ferrite as piezomagnetic phase and Sr, La modified PZT (PSLZT) as a piezoelectric phase were prepared to study magnetoelectric effect. The Ho substituted cobalt ferrite CoFe2-xHoxO4 where, x = 0.0, 0.01, 0.02, 0.03, 0.05 and 0.15, were successfully synthesized by sol-gel auto combustion method. The phase formation of synthesized Ho substituted cobalt ferrite series has been confirmed by using X-ray diffraction (XRD). For the samples up to x = 0.05 formation of single spinel ferrite phase and for higher concentration i.e. x = 0.15, along with spinel ferrite phase secondary ortho-ferrite phase have been observed. FTIR and Raman spectroscopic analysis has been carried out to confirm the presence of metal oxide functional group at tetrahedral and octahedral sites of spinel structure. Morphological analysis of all the samples under investigation has been carried out using Scanning Electron Microscopy. The magnetostrictive properties were measured at room temperature and the influence of Ho substitution on magnetostrictive properties of cobalt ferrite has also been investigated. Further, the strain derivative (dλ/dH) has been determined in order to understand the piezomagnetic properties of the samples. The strain derivative of Ho substituted cobalt ferrite attains maximum value at a low magnetic field with respect to cobalt ferrite which is useful in stress sensors applications. Finally, the magnetoelectric properties of PSLZT -Ho substituted cobalt ferrite layered composite structure have been investigated. The relation between magnetoelectric properties of the composites and piezomagnetic properties of the ferrite samples has been elucidated based on the theoretical model proposed in the literature by Bichurin et al.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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