Comparative analysis of crystal field effects and energy level scheme of six-fold coordinated Cr4+ ion in the pyrochlores, Y2B2O7 (B=Ti4+, Sn4+)

Brik, M.G.; Srivastava, A.M.; Avram, N.M.

doi:10.1016/j.jlumin.2010.08.029

Cited by 38 publications

(5 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The crystal structural data were used to analyze the symmetry properties of the impurity ion site and generate a cluster consisting of more than 92,200 ions (this is required to ensure proper convergence of the crystal lattice sums needed for the calculations of the crystal field parameters). The details of the calculation methods as well as all relevant equations can be found in our previous publications − and are not repeated here for the sake of brevity. The nonzero crystal field parameters are listed in Table .…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

et al. 2021

View full text Add to dashboard Cite

In this work, the temperature and high-pressure behaviors of Mn 3+ -doped garnet-type Ca 3 Ga 2 Ge 3 O 12 single crystals have been investigated by means of photoluminescence and Raman spectroscopy, respectively. The Jahn−Teller stabilization energy in the 5 E ground state was found to be 1630 cm −1 , being as much as 6 times greater than that in the 5 T 2 excited state, that is, 237 cm −1 . The room-temperature emission spectrum is dominated by the spin-allowed 5 T 2 → 5 E transition at 670 nm upon 532 nm excitation. The temperature dependences of photoluminescence spectra and time decays reveal strong thermalization between 5 T 2 and 1 T 2 levels. Cooling to 50 K empties the 5 T 2 level by virtue of multiphonon transition to the lower-lying 1 T 2 level. As a result, the 1 T 2 → 3 T 1 / 5 E electric-dipole transitions are induced by coupling to odd-parity phonons. The existence of a small amount of Mn 4+ can be ascertained by lowering the temperature or applying high pressure. Upon compression up to 100 kbar, the 5 T 2 → 5 E transition of Mn 3+ undergoes a blue shift at a rate of ∼10.5 cm −1 /kbar. Since both 5 T 2 and 1 T 2 have inverse crystal field dependences, the quenching process from the 5 T 2 level becomes stronger under high pressure. Cryogenic luminescence ratiometric thermometry based on the diverse thermal quenching behaviors of Mn 3+ and Mn 4+ was explored. Furthermore, theoretical calculations employing the exchange-charge model of crystal field for Mn 3+ and Mn 4+ ions in Ga 3+ octahedral sites (C 3i ) in garnet-type Ca 3 Ga 2 Ge 3 O 12 remain in perfect agreement with the experimental data.

show abstract

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In a recent series of publications, we have explored qualitatively and quantitatively the optical properties of rare earth and transition metal ions in materials which crystallize in the cubic pyrochlore family of materials. We have also explored the electronic, physical and optical properties of the pyrochlore host lattice in the absence of the activator ions, with the purpose of assimilating the role played by the host lattice in determining the optical properties of the embedded activator ions . As the pyrochlores crystallize in the cubic system their LC is characterized by a single lattice constant, a .…”

Section: Introductionmentioning

confidence: 99%

Pyrochlore Structural Chemistry: Predicting the Lattice Constant by the Ionic Radii and Electronegativities of the Constituting Ions

Brik

Srivastava

2012

J. Am. Ceram. Soc.

View full text Add to dashboard Cite

The structural data on compounds which crystallize with the (cubic) pyrochlore structure have been analyzed to obtain a model equation that predicts their lattice constants. The model, which is based on the ionic radii and the electronegativities of the constituting ions, is applied to simple ternary and to more complicated mixed cation and anion pyrochlores. The average error between the experimental and calculated lattice constants is~0.45% for the ternary pyrochlores and~0.68% for the mixed compounds. The lattice constant of any new pyrochlore can be estimated from the model equation, which has been derived in this work. I. Tanaka-contributing editorManuscript No. 30781.

show abstract

“…6 Results of calculations.-Details pertaining to the calculations of the Mn 4+ energy level by the exchange charge mode of crystal field theory has been presented before. 7,8 The reliability and vitality of the ECM is confirmed by its success in calculating the energy level of the transition metal and rare earth ions [8, 9 and references therein]. In the following we will only provide the results of our calculations that I).…”

Section: Discussionmentioning

confidence: 99%

Interpretation of the Spectroscopic Properties of α-LiAlO₂: Mn⁴⁺

Srivastava

Brik

2017

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The energy position of the 2 E g → 4 A 2g emission transition of Mn 4+ in α-LiAlO 2 is identified and the electronic energy levels calculated using the exchange charge model of crystal field theory. The results of our calculations yield the crystal field splitting and Racah parameters of Dq = 2351 cm −1 , B = 650 cm −1 and C = 3469 cm −1 , with C/B = 5.3. The calculated Mn 4+ energy levels are in good agreement with the experimental spectra that have been presented in the literature. A study that develops the relationship between the energy of the 2 anions. The Mn 4+ with the 3d 3 electronic configuration prefers to occupy an octahedral site due to the attainment of large crystal field stabilization energy when each of the 3d electron occupy singly each t 2g orbital. The Mn 4+ will occupy the Al 3+ site in α-LiAlO 2 due to closeness in the electronic charges and ionic radii; the Shannon and Prewitt ionic radii for Al 3+ = 67 pm, Mn 4+ = 68 pm and Li + = 88 pm, respectively.4 Charge compensation could be attained via cation vacancies. The hexagonal α-LiAlO 2 transformed to the tetragonal (γ) modification beyond 700 C. 3 The latter structure which was fully formed at 900• C does not support Mn 4+ luminescence because in this structure the Al 3+ ions occur in tetrahedral coordination. Although the local symmetry differs from the ideal O h , in what follows we shall use the "cubic" crystal field notation t 2g and e g , and we shall denote by those symbols the groups of levels arising from the t 2g and e g states after they are split by the low symmetry component of crystal field. We shall also keep the cubic crystal field notations for the groups of levels arising from the split orbital triplets and doublets of the Mn 4+ ions.The energy of the Mn 4+ 2 E g → 4 A 2g emission transition in α-LiAlO 2 is not properly identified in the work of Aoyama et al. 3 The purpose of this paper is to identify the energy position of this transition and to calculate the electronic energy levels using the exchange charge model of crystal field theory. The calculated energy levels are compared with the experimental data. The calculations yield the extraction of three principal physical parameters of interest (1) the crystal field splitting (10Dq) and, (2) the Racah parameters, B and C. In this paper, we also develop relationship between the energy of the 2 E g → 4 A 2g emission transition with the connectivity of the octahedral moieties and the deviation of O-Mn-O bond angle in the equatorial plane from the ideal value of 90• . * Electrochemical Society Member. z E-mail: srivastava@ge.com Crystal Structure of α-LiAlO 2The structural modification of LiAlO 2 studied in the present work is described by the R-3m space group (No. 166), 2 with the lattice constants (in Å) a = b = 2.8003, c = 14.216 and three formula units per unit cell. One unit cell of α-LiAlO 2 is depicted in Fig. 1. Both Li and Al ions are six-fold coordinated by the oxygen ions forming trigonally distorted octahedra. The Li-O bond distances are 2.11 Å and the Al-O bond ...

show abstract

Comparative analysis of crystal field effects and energy level scheme of six-fold coordinated Cr4+ ion in the pyrochlores, Y2B2O7 (B=Ti4+, Sn4+)

Cited by 38 publications

References 28 publications

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

Pyrochlore Structural Chemistry: Predicting the Lattice Constant by the Ionic Radii and Electronegativities of the Constituting Ions

Interpretation of the Spectroscopic Properties of α-LiAlO₂: Mn⁴⁺

Contact Info

Product

Resources

About

Comparative analysis of crystal field effects and energy level scheme of six-fold coordinated Cr4+ ion in the pyrochlores, Y2B2O7 (B=Ti4+, Sn4+)

Cited by 38 publications

References 28 publications

Effect of Temperature and High Pressure on Luminescence Properties of Mn3+ Ions in Ca3Ga2Ge3O12 Single Crystals

Effect of Temperature and High Pressure on Luminescence Properties of Mn3+ Ions in Ca3Ga2Ge3O12 Single Crystals

Pyrochlore Structural Chemistry: Predicting the Lattice Constant by the Ionic Radii and Electronegativities of the Constituting Ions

Interpretation of the Spectroscopic Properties of α-LiAlO2: Mn4+

Contact Info

Product

Resources

About

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

Effect of Temperature and High Pressure on Luminescence Properties of Mn³⁺ Ions in Ca₃Ga₂Ge₃O₁₂ Single Crystals

Interpretation of the Spectroscopic Properties of α-LiAlO₂: Mn⁴⁺