Unusual magnetic behavior in LaFeCrO

Belayachi, A.; Loudghiri, E.; Yamani, M. El; Noguès, M.; Dormann, J.L.; Taïbi, M.

doi:10.1016/s0151-9107(98)80078-0

Cited by 19 publications

(15 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that these values are similar indicates that the Fe/Cr valences in both samples are identical, which is consistent with the stabilization of the <Fe/Cr-O> for these two samples (Figure 2). As shown in Figure 6, where previously reported results for LaFeO 3 16 and SrFeO 2.95 19 were included for comparison purposes, there is a monotonic decrease of T ord with the increase of <r A > (which mimics the Sr content) for x e 0.6. This trend is broken for x g 0.8, indicating that a different charge compensation mechanism appears in this case, corroborating the previous suggestion (see structural discussion) of an increased role for oxygen vacancy formation on the overall charge compensation regime.…”

Section: Resultsmentioning

confidence: 71%

“…In fact, both LaCrO 3 and LaFeO 3 are antiferromagnetic materials with Néel temperatures of ∼280 and 750 K, respectively. 16 In the substituted sample a ferromagnetic component due to the Fe 3+ (d 5 )-O-Cr 3+ (d 3 ) interaction was expected, although not observed. However, it was previously reported 17 that this effect would be observed only if the bond angle at the intervening anion was sufficiently close to 180°, which is not the present case (Table 4).…”

Section: Resultsmentioning

confidence: 83%

See 1 more Smart Citation

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

et al. 2006

View full text Add to dashboard Cite

A series of perovskite compounds with the general formula La 1-x Sr x Fe 0.8 Cr 0.2 O 3-δ (x) 0.2, 0.4, 0.6, and 0.8) have been synthesized using a urea/nitrates self-combustion route. Their characterization was performed using room-temperature X-ray diffraction, electrical and magnetization measurements. A structural transition from orthorhombic (x) 0.2) to rhombohedral (x > 0.2) was determined. Among the rhombohedral phases, increased Sr content caused a visible decrease in distortion. Monotonic decreases with increasing x were found for both the pseudocubic lattice parameter (a′) and bond lengths in the 0.2 e x e 0.6 range, which have been attributed to an increase in the mean oxidation state of the transition metals. The lattice expansion observed for x) 0.8, in addition to an apparent stabilization of the bond lengths for x) 0.6 and 0.8, suggested an increased role for oxygen vacancy formation as the charge compensation regime for the latter. All compounds exhibited semiconductor behavior with temperature dependencies better described by the 3d variable range hopping model. The monotonic decrease of resistivity with increasing x in the 0.2 e x e 0.6 range was found consistent with an increase in carrier density. The monotony is broken for x) 0.8, which was also associated with the change in the charge compensation regime. Increased x progressively weakened the overall antiparallel coupling of the magnetic moments, inducing a decrease of the ordering temperature for samples in the 0.2 e x e 0.8 range.

show abstract

Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 83%

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

et al. 2006

View full text Add to dashboard Cite

show abstract

“…In particular, the replacement of Fe 3+ by Cr 3+ and its effect on structural, magnetic and other properties have been reported [5][6][7] for rare earth orthoferrites. For example, in the lanthanum orthoferrites, partial replacement of Fe by Cr leads to a reduction in the Néel temperature from 750 K in LaFeO 3 to 280 K in LaCrO 3 .…”

Section: Introductionmentioning

confidence: 99%

Dielectric relaxation and magnetic properties of Cr doped GaFeO₃

Mohamed¹,

Wang²,

Fueß³

2010

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Polycrystalline GaFe 1-x Cr x O 3 (x= 0.05, 0.1 and 0.15) samples were prepared by solid state reaction. The monophasic compounds crystallize in the orthorhombic space group P c 2 1 n and the unit cell volume decreases with increasing Cr content. The saturated magnetization and magnetic transition temperature of the ceramics decrease due to the dilution of the magnetic interaction with Cr concentration. The dielectric properties were investigated from 133 to 353 K at various frequencies (100-10 7 Hz). Whereas the dielectric constant decreases with Cr-content an increase of dielectric loss tangent was observed. The activation energy of the compounds (calculated both from loss and modulus spectrum) are the same and have values~0.22 and 0.27 eV for Cr=10 and 15%, respectively, and hence the relaxation process may be attributed to the same type of charge carrier. A separation of the grain and grain boundary properties has been achieved using an equivalent circuit model. The capacitance and resistances associated with the grain boundary were found to be higher than that associated with grain. IntroductionThe study of multiferroics is a very hot topic. It is interesting not only from the point of view of fundamental physics but also for many potential applications in electronics [1,2].GaFeO 3 has an orthorhombic crystal structure (space group P c 2 1 n) with four different cation sites labeled Ga1, Ga2 (mostly occupied by gallium) and Fe1, Fe2 (mostly occupied by iron). This material has a spontaneous polarization along the b axis and a ferrimagnetic structure below room temperature result from unequal distribution of Fe spins of nearly equal magnitude on the sublattices with a magnetic moment of the spin along the c axis [3,4].GaFeO 3 contains only trivalent metals in the structure like rare earth orthoferrites, making them attractive systems for investigations of isovalent substitutions. In particular, the replacement of Fe 3+ by Cr 3+ and its effect on structural, magnetic and other properties have been reported [5][6][7] for rare earth orthoferrites. For example, in the lanthanum orthoferrites, partial replacement of Fe by Cr leads to a reduction in the Néel temperature from 750 K in LaFeO 3 to 280 K in LaCrO 3 . Moreover, Cr doping is one of the most adopted strategies to tailor the dielectric and piezoelectric properties of ferroelectrics for practical applications. It is well known that Cr is effective in decreasing the aging effect and the dielectric loss; thus, the effect of doping of Cr 3+ is that of a stabilizer of the piezoelectric and dielectric properties [8,9].In the present work we study the (a) magnetic properties, (b) apply the variablefrequency technique of impedance spectroscopy to the samples over a wide temperature range, and (c) characterize the grain and grain boundary resistance using IS, from which one can calculate their capacitance and can model the equivalent circuit for Cr-substituted GaFeO 3 samples.

show abstract

“…Combining the structural analysis of Fe-O and the FT spectra, our results indicate that ferromagnetic coupling of Fe-O-Cr is present and phase separation is not the real reason for the absence of FM in the LaFe 1-x Cr x O 3 sample. In another paper (Belayachi et al, 1998), the authors found an unusual magnetic behaviour in LaFe 1-x Cr x O 3 when x > 0.5. In Fig.…”

Section: Testing Using the Lafe 1-x Cr X O 3 Systemmentioning

confidence: 93%

“…As a result, a ferromagnetic-ordered phase has not been obtained. In this work, powder samples of LaFe 1-x Cr x O 3 (x = 0, 1/3, 2/3) were synthesized using a standard solid-state reaction method (Belayachi et al, 1996;Louca et al, 1999). X-ray diffraction spectra indicated that all samples crystallize in the perovskite structure with orthorhombic deformation, having a space group Pbnm (Wang et al, 2007).…”

Section: Testing Using the Lafe 1-x Cr X O 3 Systemmentioning

confidence: 99%

Data analysis method to achieve sub-10 pm spatial resolution using extended X-ray absorption fine-structure spectroscopy

Wang

Jiang

et al. 2014

J Synchrotron Radiat

View full text Add to dashboard Cite

Obtaining sub-10 pm spatial resolution by extended X-ray absorption fine structure (EXAFS) spectroscopy is required in many important fields of research, such as lattice distortion studies in colossal magnetic resistance materials, high-temperature superconductivity materials etc. However, based on the existing EXAFS data analysis methods, EXAFS has a spatial resolution limit of π/2Δk which is larger than 0.1 Å. In this paper a new data analysis method which can easily achieve sub-10 pm resolution is introduced. Theoretically, the resolution limit of the method is three times better than that normally available. The method is examined by numerical simulation and experimental data. As a demonstration, the LaFe1-xCrxO3 system (x = 0, 1/3, 2/3) is studied and the structural information of FeO6 octahedral distortion as a function of Cr doping is resolved directly from EXAFS, where a resolution better than 0.074 Å is achieved.

show abstract

Unusual magnetic behavior in LaFeCrO

Cited by 19 publications

References 10 publications

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

Dielectric relaxation and magnetic properties of Cr doped GaFeO₃

Data analysis method to achieve sub-10 pm spatial resolution using extended X-ray absorption fine-structure spectroscopy

Contact Info

Product

Resources

About

Unusual magnetic behavior in LaFeCrO

Cited by 19 publications

References 10 publications

Structural and Magnetic Characterization of the Series La1-xSrxFe0.8Cr0.2O3-δ (x = 0.2, 0.4, 0.6, and 0.8)

Structural and Magnetic Characterization of the Series La1-xSrxFe0.8Cr0.2O3-δ (x = 0.2, 0.4, 0.6, and 0.8)

Dielectric relaxation and magnetic properties of Cr doped GaFeO3

Data analysis method to achieve sub-10 pm spatial resolution using extended X-ray absorption fine-structure spectroscopy

Contact Info

Product

Resources

About

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

Structural and Magnetic Characterization of the Series La_1-_xSr_xFe_0.8Cr_0.2O_3-_δ (x = 0.2, 0.4, 0.6, and 0.8)

Dielectric relaxation and magnetic properties of Cr doped GaFeO₃