Experimental and theoretical study to explain the morphology of CaMoO 4 crystals

Oliveira, Fernanda K.F.; Oliveira, Márcia Rozenfeld Gomes de; Gracia, Lourdes; Tranquilin, R. L.; Paskocimas, C. A.; Motta, F. V.; Longo, Elson; Andrés, Juán; Bomio, M. R. D.

doi:10.1016/j.jpcs.2017.11.019

Cited by 49 publications

(28 citation statements)

References 85 publications

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“…The observed diffraction peaks can be indexed to the CaMoO 4 scheelite type (tetragonal structure) with the space group I4 1/a and are in full agreement with the standard data (JCPDS card no. 29‐0351) 52,53 . The additional peaks were observed only in XRD pattern corresponding to the CMO:Tm‐12 sample, and they occur at 2θ = 7.8°, 23.0°, and 35.5° (Figure 1G).…”

Section: Resultsmentioning

confidence: 97%

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The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition

Feldhaus

Künzel²,

et al. 2021

J Am Ceram Soc

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The compounds based on calcium molybdate (CaMoO 4 ) are the subject of extensive research due to their excellent optical properties and a broad range of potential technological applications. In this work, we report a systematic study of CaMoO 4 :Tm 3+ phosphors synthesized by coprecipitation and processed in a microwave-hydrothermal system at low temperature (100°C) and stirring. The effect of the Tm 3+ doping content (0%-12%) is studied in full detail to understand their role in the CaMoO 4 :Tm 3+ morphological, structural, and luminescent properties. The X-ray diffraction, Raman, and Fourier Transform Infrared spectroscopic techniques revealed that all the prepared powders have a tetragonal crystal structure with a distinct density of cation vacancies and structural disorders. The band gap remains almost constant for doping levels lower than 8%, but it narrows strongly for powders doped with 12% Tm 3+ ions.The designed phosphors have shown two emission bands in which intensity depends on the Tm 3+ ions doping level. For doping levels lower than 2%, the photoluminescence profile displays a broad emission band peaking at 543 nm (green). For concentrations higher than 4%, the band centered at 543 nm decreases in intensity and the near-infrared emission band at around 800 nm, assigned to 3 F 3 , 3 H 4 → 3 H 6 transitions from Tm 3+ ion, become more intense. The outcomes of this work reveal that appropriated Tm 3+ ions doping levels can be applied to suppress the PL emission in the visible range and improve that in the near-infrared region in CaMoO 4 -based materials. K E Y W O R D Sceramic matrix composites, microwaves, optical materials/properties, photoluminescence, rare earths How to cite this article: Feldhaus CMS, Künzel R, Li MS, Marques APdA. The role of the Tm 3+ concentration on CaMoO 4 properties processed by microwave hydrothermal under stirring condition.

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Section: Resultsmentioning

confidence: 97%

“…29-0351). 52,53 The additional peaks were observed only in XRD pattern corresponding to the CMO:Tm-12 sample, and they occur at 2θ = 7.8°, 23.0°, and 35.5° (Figure 1G). These peaks are predicted theoretically through simulations for a compressed and distorted CaMoO 4 tetragonal structure.…”

Section: Xrd Analysismentioning

confidence: 99%

The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition

Feldhaus

Künzel²,

et al. 2021

J Am Ceram Soc

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“…Even, at biological level, the invention of DNA origami has deepened the understanding of how molecules could interact with each other in a complex self-assembly process and has accelerated the engineering of molecular systems with custom-designed structures and programmable behaviors [153][154][155][156][157][158][159] . In solid state, the concept of crystal origami has been introduced toward the rational design of surface structures of micro-and nano-crystallites 144,160,161 .…”

Section: Concept Of Surface Energymentioning

confidence: 99%

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

et al. 2018

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Understanding the criteria warranting the existence, stability, and activity of a given configuration of atoms has pivotal relevance in chemical and materials science. Photocatalysts, traditionally semiconductors, are essential for processes ranging from water purification to water splitting, air filtration, and surgical instrument sterilization, and harvest optical energy to drive chemical reactions. These semiconductors harvest optical energy to drive chemical reactions. With chemical reactions dictated by atomic and molecular interactions at the nanoscale, examining these processes with near-atomic resolution is necessary to understand photochemical processes in depth and to improve materials for next-generation catalysts. The performance and key electronic properties of semiconductors are dictated by the interplay between the surface chemistry and morphology, whose manipulation has inspired experimental and theoretical researchers. This interplay has been clarified by theoretical studies based on atomic-scale modelling with particular attention given to two sets of degreesof-freedom: the atomic positions and chemical configuration. This perspective article presents the major computational challenges and modern methodological strategies toward advancing the field. The ZnWO 4 material was selected as a case study, and the key concepts developed in recent years are discussed to clarify the morphology, i.e., the exposed surfaces of materials, and explain its functional properties or performance. First-principle calculations capture the geometric and electronic effects on the photocatalytic activity in agreement with experimental data. Indeed, important and often surprising structure-function relations have been observed based in depth atomistic modelling on morphological analysis. An overview of past achievements and future directions is provided according to the authors' outlook.

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“…Among the work on phosphors with good color purity and high luminous efficiency, research intended to facilitate the use of molybdate phosphors doped with rare-earth ions in various applications, such as light-emitting devices, lasers, scintillation materials, optical fibers, catalysts, and displays, is attracting attention [ 6 , 7 , 8 ]. Specifically, calcium molybdate (CaMoO 4 ) can be used in a wide range of applications due to its stable physicochemical properties and the low absorption critical energy of its scheelite structure [ 9 , 10 ]. Kim et al produced CaMoO 4 :Eu 3+ with Na + phosphors with a diameter of 5 nm from a TOA-MoO 4 complex with calcium, europium, and sodium-oleate (Ca, Eu, and Na-oleate) mixed in toluene using a solvothermal synthesis method, and suggested that the strongest red emission occurred in Ca 0.58 MoO 4 : 0.21 Eu 3+ , with 0.21 Na + nanophosphors synthesized at 120 °C [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Fabricated Flexible Composite for a UV-LED Color Filter and Anti-Counterfeiting Application of Calcium Molybdate Phosphor Synthesized at Room Temperature

Jung

2022

Materials

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Crystalline CaMoO4 and rare-earth-doped CaMoO4:RE3+ (RE = Tb, Eu) phosphors were synthesized at room temperature using a co-precipitation method. The crystal structure of the synthesized powder was a tetragonal structure with a main diffraction peak (112) phase. When CaMoO4 was excited at 295 nm, it showed a central peak of 498 nm and light emission in a wide range of 420 to 700 nm. Rare-earth-ion-doped CaMoO4:Tb3+ was excited at 288 nm and a green light emission was observed at 544 nm, and CaMoO4:Eu3+ was excited at 292 nm and a red light emission was observed at 613 nm. To take advantage of the light-emitting characteristics, a flexible composite was manufactured and a color filter that could be used for UV-LEDs was manufactured. In addition, it was suggested that an ink that could be checked only by UV light could be produced and applied to banknotes so as to prevent counterfeiting.

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Experimental and theoretical study to explain the morphology of CaMoO 4 crystals

Cited by 49 publications

References 85 publications

The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition

The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

Fabricated Flexible Composite for a UV-LED Color Filter and Anti-Counterfeiting Application of Calcium Molybdate Phosphor Synthesized at Room Temperature

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Experimental and theoretical study to explain the morphology of CaMoO 4 crystals

Cited by 49 publications

References 85 publications

The role of the Tm3+ concentration on CaMoO4 properties processed by microwave hydrothermal under stirring condition

The role of the Tm3+ concentration on CaMoO4 properties processed by microwave hydrothermal under stirring condition

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

Fabricated Flexible Composite for a UV-LED Color Filter and Anti-Counterfeiting Application of Calcium Molybdate Phosphor Synthesized at Room Temperature

Contact Info

Product

Resources

About

The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition

The role of the Tm³⁺ concentration on CaMoO₄ properties processed by microwave hydrothermal under stirring condition