Influence of transition metal Cr2+ doping on structural, electrical and optical properties of Mg-Zn aluminates

Saleem, M.; Varshney, Dinesh

doi:10.1016/j.jallcom.2017.03.016

Cited by 53 publications

(14 citation statements)

References 32 publications

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“…In the present study, the dielectric loss attains a maximum value at a particular frequency. This characteristic is attributed to the resonance between the applied electric field and the polaron hopping frequency [16]. The intriguing values of dielectric constant and dielectric loss at low and high frequency are given in the Table 2. …”

Section: International Journal Of Advance Engineering and Research Dementioning

confidence: 94%

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

2017

IJAERD

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IntroductionExtensive research has been carried out on ABO 3 -type manganites of the general formula R 1−x A x MnO 3 (R = La, Nd, Pr, Y, etc. and A = Ca, Sr, Ba, Pb, etc.). Because of their extraordinary magnetic and electronic properties as well as their edge for the promising technological applications, these materials gained considerable attention [1,2]. These compounds exhibit a high degree of chemical flexibility which together with a complex interplay between structures, electronic and magnetic properties leads to a very rich phase diagram involving various metallic, insulating and magnetic phases [3]. These properties are sensitive to the doping concentration x, which determine the Mn 3+ /Mn 4+ ratio to maintain charge neutrality, the average cationic radii and the ionic size mismatch between the various A-site ions.La 0.8 Sr 0.2 MnO 3 (LSMO) belong to hole doped manganite and it is a potential candidate for technological applications because of its higher ferromagnetic transition temperature (T C ) around 370 K and a large magnetic moment at room temperature and high magnetoresistance (MR) value. The LSMO with the typical composition La 0.8 Sr 0.2 MnO 3 is broadly established as the cathode material for high temperature solid oxide fuel cells (SOFCs) [4]. The particle size and microstructure of electrode are significant for the electrode performance [5,6]. Parent compound LaMnO 3 , the antiferromagnetic insulator when doped with the divalent ions (A 2+ ), it is driven into a ferromagnetic metallic state as a result of conversion of Mn 3+ to Mn 4+ through double exchange (DE) mechanism [7]. Mason and Matthias suggested that Ti 4+ ions are the influencing factor for ferroelectric nature of BaTiO 3 [8]. Barium titanate (BaTiO 3 ) is a ferroelectric oxide that undergoes a transition from a ferroelectric tetragonal phase to a paraelectric cubic phase upon heating above 130 °C. In cubic perovskite BaTiO 3 , titanium atoms are octahedrally coordinated by six oxygen atoms. Ferroelectricity in tetragonal BaTiO 3 arises due to an average relative displacement along the c-axis of titanium from its centrosymmetric position in the unit cell and consequently the creation of a permanent electric dipole. The elongation of the unit cell along the c-axis and consequently the deviation of the c/a ratio from unity are used as an indication of the presence of the ferroelectric phase [9,10]. BaTiO 3 is particularly challenging since it exhibits three solid-solid phase transitions. BaTiO 3 is the most important perovskite (ABO 3 ) oxide with excellent dielectric and ferroelectric properties. For improvement in the performance and miniaturization of electronic devices using BaTiO 3 based materials, it is important to ensure the high dielectric constant, low dielectric loss, high remnant polarization and high dielectric strength and hence is the subject of modification. A-site substitution often comes from alkaline-earth (Sr 2+ or Mg 2+ ), alkali metals (Na + , K + ) and rare-earth ions (La 3+ etc.) whose cation size effects ...

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Section: International Journal Of Advance Engineering and Research Dementioning

confidence: 94%

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

2017

IJAERD

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“…The dielectric loss arises if the polarization lags behind the applied alternating field which is introduced by the presence of impurities and structural inhomogeneities. [28][29][30][31] In the pristine and Ni-doped Mg 0:5 Zn 0:5 Al 2 O 4 samples, the dielectric loss reaches a maximum value at a particular frequency in the low frequency region. This characteristic is attributed to the resonance between the applied electric field and the polaron hopping frequency.…”

Section: Dielectric Studiesmentioning

confidence: 96%

“…The results displayed by the as prepared samples are in agreement with the reports elsewhere. [28][29][30][31] The dielectric loss (tanδ) measured as a function of log f (Hz) at room temperature is shown in Fig. 6.…”

Section: Dielectric Studiesmentioning

confidence: 99%

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates

2019

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This paper throws light on the preparation of transition metal-doped Mg[Formula: see text]Zn[Formula: see text]Al2O4 ([Formula: see text], 0.05 and [Formula: see text], Ni, Cu) aluminates via solid-state reaction route. The X-ray diffraction characterization analysis confirmed that all the samples have crystallized into the psuedocubic phase having space group Fd3[Formula: see text] and were single phased. The incorporation of transition metals viz. Co[Formula: see text], Ni[Formula: see text], Cu[Formula: see text] in the Mg[Formula: see text]Zn[Formula: see text]Al2O4 matrix does not result in the appearance of new peaks or any considerable shift in diffraction peaks within the limits of XRD experimentation. This infers homogeneous dispersion of dopants at the Mg-site which is attributed to nearly same ionic radii of the dopants to that of Mg-site in Mg[Formula: see text]Zn[Formula: see text]Al2O4. Lattice structure, bonding nature and hence the spinel formation were verified through Raman scattering technique. The compositional verification was carried out via energy dispersive analysis of X-rays (EDAX). The surface morphology and hence the microstructural studies were carried out using field emission scanning electron microscopy (FESEM). The synthesized Mg[Formula: see text]Zn[Formula: see text]Al2O4 ([Formula: see text], 0.05 and [Formula: see text], Ni, Cu) aluminate samples were tested for polarization studies keeping their insulating nature into consideration and they displayed a sign of well-behaved P-E loop.

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“…In the composite system, the inter-diffusion of phases reduce bandgap value and in the response of which the movement of electrons becomes easier. 41,42 The lower value of " 0 of (0.75) La 0:9 Na 0:1 CrO 3 þ (0.25) Ni 0:5 Cu 0:5 Fe 2 O 4 compared to (0.5) La 0:9 Na 0:1 CrO 3 þ (0.5) Ni 0:5 Cu 0:5 Fe 2 O 4 can be due to lesser crystallinity and nonuniform distribution of NCFO phase in the LNCO matrix as revealed from the FESEM micrographs. The mechanism through which the polarization takes place is similar to that in conduction process which highly relies on the synthesis method, chemical composition, crystallite size and cation distribution.…”

Section: Dielectric Propertiesmentioning

confidence: 99%

“…Furthermore, the ac conductivity tends to attain maximum value with increasing frequency as the immigration of electrons is increased. [39][40][41][42][43][44][45]49 The ac conductivity can be seen increasing with increase in frequency and becomes independent of frequency after a certain value. The lower part of frequency will give direct current conductivity ð dc Þ.…”

Section: Dielectric Propertiesmentioning

confidence: 99%

Study of structural and dielectric properties of La0.9Na0.1CrO₃- and Ni0.5Cu0.5Fe₂O₄-based composites

2019

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The preparation of [Formula: see text][Formula: see text]CrO3 (LNCO), [Formula: see text][Formula: see text]Fe2O4 (NCFO) and their composites of the type [Formula: see text] [Formula: see text][Formula: see text]CrO3 (LNCO) [Formula: see text] ([Formula: see text]) [Formula: see text][Formula: see text]Fe2O4 (NCFO) [Formula: see text], 0.50[Formula: see text] through solid state route is reported. From X-ray diffraction data analysis, the parent [Formula: see text][Formula: see text]CrO3 was found to crystallize in orthorhombic structure (Pnma) while [Formula: see text][Formula: see text]Fe2O4 has crystallized into the cubic structure (Fd3[Formula: see text]) further verified via Retvield refinement. The morphology and compositional studies were carried out using field emission scanning electron microscopy (FESEM) and energy dispersive analysis of X-rays (EDAX), respectively. Lattice structure was confirmed via Raman characterization for the prepared samples. The sample formation was further verified through Fourier transform Infra-Red (FTIR) spectroscopy. The dielectric studies reveal the [Formula: see text][Formula: see text]CrO3[Formula: see text] and [Formula: see text][Formula: see text]Fe2O4[Formula: see text] exhibit high dielectric constant. However, their composites show abrupt drop in dielectric constant. The electric modulus study confirmed that the samples exhibit non-Debye character with spread of relaxation time constants.

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Influence of transition metal Cr2+ doping on structural, electrical and optical properties of Mg-Zn aluminates

Cited by 53 publications

References 32 publications

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates

Study of structural and dielectric properties of La0.9Na0.1CrO₃- and Ni0.5Cu0.5Fe₂O₄-based composites

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Influence of transition metal Cr2+ doping on structural, electrical and optical properties of Mg-Zn aluminates

Cited by 53 publications

References 32 publications

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

Structural, Morphological and Dielectric Studies of (0.5) LA0.8SR0.2MNO3 + (0.5) BA0.5K0.5TIO3 Composite

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al2O4 aluminates

Study of structural and dielectric properties of La0.9Na0.1CrO3- and Ni0.5Cu0.5Fe2O4-based composites

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Product

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Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates

Study of structural and dielectric properties of La0.9Na0.1CrO₃- and Ni0.5Cu0.5Fe₂O₄-based composites