Effect of Co2+ substitution on MgAl2O4 studied by infrared reflectance spectroscopy

Ahmad, Javed; Sabir, Maria; Awan, Muhammad Qadeer; Anwar, Shafiq; Mazhar, Muhammad; Khalil, R. Arif; Bukhari, Syed Hamad

doi:10.1016/j.ijleo.2017.08.101

Cited by 6 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…MgAl 2 O 4 has a dielectric constant less than that of lattice vibration [11]. In previous papers, we have successfully explored the optical properties of cobalt-(Co +2 ) and potassium-(K +1 ) doped MgAl 2 O 4 nanocrystalline material along with an evaluation of Szigeti and Born effective charges for each phonon mode [12,13]. The present work is an effort to investigate the dielectric and electrical properties of the system under discussion as a function of frequency.…”

Section: Introductionmentioning

confidence: 99%

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

et al. 2019

Self Cite

View full text Add to dashboard Cite

The electrical transport properties of MgAl2−xCoxO4 (where x = 0.0, 0.5, 1.0, 1.5, 2.0) were investigated at room temperature. The dielectric behavior of the samples, and the contribution of the grains and the grain boundary regions to the electric response of the samples were observed using impedance spectroscopy in the frequency range of 20 Hz to 2 MHz. The DC conduction behavior was studied by measuring current density J against electric field E. It was observed that the grains and grain boundaries both contribute equally to the variation in electric response caused by changing the dopant concentration of cobalt in MgAl2O4. The combined Z″ and M″ spectroscopic plots indicated the presence of small polaron hopping conduction in the grain region of the samples. Moreover, the 25% doped sample showed minimum conductivity among all samples, which was two orders of magnitude less than that of the pure sample.

show abstract

Section: Introductionmentioning

confidence: 99%

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

“…Due to the greater Shannon effective ionic radius of Mn 2+ (0.66 Å) compared to Mg 2+ (0.57 Å) for tetrahedral coordination, the lattice parameters and related unit cell volume rise with the increase of Mn 2+ concentration, according Vegard's rule [37]. According to the diffraction patterns in Figure 2, which demonstrate preferred orientations for the cations in the spinel structure, it is shown that peak intensities vary with dopant concentration (Mn 2+ ) [38].…”

Section: Resultsmentioning

confidence: 99%

Novel yellowish‐green single‐phased spinel Mg_1−xBa_xAl₂O₄:Mn²⁺ phosphor(s) for color rendering white‐light‐emitting diodes

Ain,

Fazal,

Iqbal

et al. 2024

Luminescence

View full text Add to dashboard Cite

For white light‐rendering research activities, interpretation by using colored emitting materials is an alternative approach. But there are issues in designing the white color emitting materials. Particularly, differences in thermal and decay properties of discrete red, green, and blue emitting materials led to the quest for the search of a single‐phased material, able to emit primary colors for white light generation. The current study is an effort to design a simple, single‐phase, and cost‐effective material with the tunable emission of primary colors by a series of Mg1−xBaxAl2O4:Mn2+ nanopowders. Doping of manganese ion (Mn2+) in the presence of the larger barium cation (Ba2+) at tetrahedral‐sites of the spinel magnesium aluminate (MgAl2O4) structure led to the creation of antisite defects. Doped samples were found to have lower bandgaps compared with MgAl2O4, and hybridization of 3d‐orbitals of Mn2+ with O(2p), Mg(2s)/Al(2s3p) was found to be responsible for narrowing the bandgap. The distribution of cations at various sites at random results in a variety of electronic transitions between the valance band and oxygen vacancies as well as electron traps produced the antisite defects. The suggested compositions might be used in white light applications since they have three emission bands with centers at 516 nm (green), 464 nm (blue) and 622 nm (red) at an excitation wavelength of 380 nm. A detailed discussion to analyze the effects of the larger cationic radius of Ba2+ on the lattice strain, unit cell parameters, and cell volumes using X‐ray diffraction analysis is presented.

show abstract

“…While x-ray density of the doped derivatives is higher due to their larger molar mass after incorporation of the dopants. It is noticeable from the table 1 that lattice parameter, cell volume, and the x-ray density increase due to an increase in the concentration of Mn 2+ due to larger Shannon radius of Mn +2 (0.66 Å) as compared to the substituted Mg +2 (0.57 Å) for tetrahedral site occupation and thus obey the Vegard's law [38].…”

Section: Xrd Analysismentioning

confidence: 95%

“…The optical properties were mostly enhanced using rare earth cations, for example, Eu 3+ [32], Tb 3+ [33], and Dy 3+ [34]. Transition metal cations for example Cr 3+ [35], Mn 3+ [36], Ni 2+ [37], and Co 2+ [38] were used to manipulate the optical response. Mn 2+ has been an extensity used as an activator in a few reports.…”

Section: Introductionmentioning

confidence: 99%

Doped MgAl₂O₄ semiconductor host nanopowders for tunable primary color emissions for application as white LEDs

Ain¹,

Ismail²,

Khan³

et al. 2021

Semicond. Sci. Technol.

View full text Add to dashboard Cite

The emission of white light from hosts having a single phase and the compromised applicability of a very inert, chemically stable, and structurally diverse MgAl2O4 led to a quest for improving the structural, optical, thermal and electrical properties for more innovative applications. A slight modification in lattice site occupation can lead to antisite defects which alter the physical properties of the materials. The presence of larger alkaline earth Sr2+ cations at the T-sites have been found to improve the behavior of the activator Mn2+ cations which are substituted for Mg2+ at T-sites. In the current study, a series of Mn2+ doped derivatives having a general formula of Mg1−x−0.3Mn x Sr0.3Al2O4 (x = 0.1–0.5) were synthesized using the chemical co-precipitation method. Due to the larger radius of Sr2+ cations, the lattice strain was observed in the cubic crystal structure of magnesium aluminate spinel (MAS). A decrease in the bandgaps of the doped samples indicates the formation of defect states within the bandgap of MAS. Apart from the bandgap transitions, the capture of electrons at oxygen vacancies is also observed in the UV/Vis spectra. The strong tetrahedral site preference of Mn2+ is altered by the presence of Sr2+, hence, some octahedral site occupation of Mn2+ in the lattice is achieved. The antisite defects along with the occupation of both T- and O-sites by Mn2+ resulted in novel emission bands centered at 464 nm (blue), 515 nm (green), and 621 nm (red) at λ ex of 380 nm. The emission of the primary colors in a simple lattice with cost-effective and in-toxic constituents can be a possible alternative to the costly rare-earth ions doped complex materials in use to-date.

show abstract

Effect of Co2+ substitution on MgAl2O4 studied by infrared reflectance spectroscopy

Cited by 6 publications

References 16 publications

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

Novel yellowish‐green single‐phased spinel Mg_1−xBa_xAl₂O₄:Mn²⁺ phosphor(s) for color rendering white‐light‐emitting diodes

Doped MgAl₂O₄ semiconductor host nanopowders for tunable primary color emissions for application as white LEDs

Contact Info

Product

Resources

About

Effect of Co2+ substitution on MgAl2O4 studied by infrared reflectance spectroscopy

Cited by 6 publications

References 16 publications

Electrical transport properties of cobalt-doped MgAl2O4 nanoparticles

Electrical transport properties of cobalt-doped MgAl2O4 nanoparticles

Novel yellowish‐green single‐phased spinel Mg1−xBaxAl2O4:Mn2+ phosphor(s) for color rendering white‐light‐emitting diodes

Doped MgAl2O4 semiconductor host nanopowders for tunable primary color emissions for application as white LEDs

Contact Info

Product

Resources

About

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

Electrical transport properties of cobalt-doped MgAl₂O₄ nanoparticles

Novel yellowish‐green single‐phased spinel Mg_1−xBa_xAl₂O₄:Mn²⁺ phosphor(s) for color rendering white‐light‐emitting diodes

Doped MgAl₂O₄ semiconductor host nanopowders for tunable primary color emissions for application as white LEDs