Lithium metasilicate and lithium disilicate nanomaterials: optical properties and density functional theory calculations

Alemi, Abdolali; Khademinia, Shahin; Joo, Sang Woo; Dolatyari, Mahboubeh; Bakhtiari, Akbar

doi:10.1186/2228-5326-3-14

Cited by 18 publications

(15 citation statements)

References 51 publications

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“…Different methods have been reported to synthesize Li 2 SiO 3 nanomaterials including solid state, precipitation, sol-gel, extrusion-spherodisation, rotating/melting, combustion, electrochemical and via hydrothermal. However, most of the time, a mixture of Li 2 SiO 3 , Li 2 Si 2 O 5 , Li 4 SiO 4 and SiO 2 was obtained [9,11,[14][15][16][17][18][19][20][21]23]. Recently, we have reported the synthesis of lithium metasilicate nanomaterials through a hydrothermal method at 180°C in a mixture of LiNO 3 , SiO 2 and NaOH at 2:3 Li/Si molar ratio [24].…”

Section: Introductionmentioning

confidence: 99%

Part III: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization and optical properties

2015

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Li 2 SiO 3 nanopowders were synthesized via a non-stoichiometric 2:3 (S 1 ), 1:3 (S 2 ), 1:4 (S 3 ) and 1:5 (S 4 ) Li/Si molar ratios via hydrothermal reaction for 72 h at 180°C in an aqua solution using Li 2 CO 3 and H 2 SiO 3 as raw materials. The synthesized materials were characterized by powder X-ray diffraction (PXRD) technique and Fourier transform infrared spectroscopy. PXRD data showed that the crystal structure of the obtained materials is orthorhombic with the space group of Cmc2 1 . Also, to investigate the effect of the Li/Si molar ratio on the morphology of the obtained materials, the morphologies of the synthesized materials were studied by field emission scanning electron microscopy. The technique showed that with changing the Li/Si molar ratio from S 1 to S 4 , the morphology of as-prepared samples changed from flower structures to microrod-microsphere and then to a nonhomogenous layer-like structure. Ultraviolet-visible spectra showed that the nanostructure lithium silicate powders had good light absorption properties in the ultraviolet light region. It showed that with changing the Li/Si molar ratio from S 1 to S 4 , the calculated band gap was decreased. Also, cell parameter refinement showed that with changing the Li/Si molar ratio from S 1 to S 4 the cell parameters decreased. Photoluminescence analysis of the obtained materials was studied at the excitation wavelength of 247 nm. It showed that the emission spectra of the obtained materials had a blue shift from S 1 to S 4 .

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Section: Introductionmentioning

confidence: 99%

Part III: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization and optical properties

2015

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“…As shown in Fig. 1, with the Li:Si molar ratio of 2:3 in the reaction mixture, a highly pure crystalline phase of Li 2 SiO 3 (space group of Cmc2 1 [22][23][24][25][26][27] ) was obtained after 48, 72, and 96 h. So, it shows that with lithium nitrate and SiO 2 as raw materials the main phase is lithium metasilicate. Compared to our another works using lithium carbonate and silicic acid at 2:3 Li:Si molar ratio at 180°C for 72 h, the main phase was lithium metasilicate but the morphology of the obtained materials was flower structure [28].…”

Section: Resultsmentioning

confidence: 93%

“…However, most of the time, a mixture of Li 2 SiO 3 , Li 2 Si 2 O 5 , Li 4 SiO 4 , and SiO 2 was obtained [10,12,[15][16][17][18][19][20][21]. Recently, we have reported the synthesis of highly pure and crystalline lithium metasilicate nanomaterials through a mild condition hydrothermal method using lithium nitrate and silicic acid as raw materials at 1:2 Li:Si molar ratio [22,25]. In the present study, a hydrothermal route was successfully explored to synthesize nanostructured Li 2 SiO 3 powders in a hydrothermal system of LiNO 3 , SiO 2 , and NaOH.…”

Section: Introductionmentioning

confidence: 99%

Part I: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization, and optical properties

Alemi

Khademinia

2014

Int Nano Lett

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Using LiNO 3 and SiO 2 as raw materials, Li 2 SiO 3 nano-powders were synthesized via a nonstoichiometric 2:3 Li:Si molar ratio hydrothermal reaction at 180°C for 48, 72, and 96 h in a NaOH aqueous solution system. The synthesized materials were characterized by powder X-ray diffraction technique and Fourier transform infrared spectroscopy. To investigate the effect of the reaction time on the morphology of the obtained materials, the morphologies of the synthesized materials were studied by field emission scanning electron microscopy technique. The technique showed that on increasing the reaction time, the morphology of the as-prepared samples changed from belt structures to flower structures. Ultraviolet-Visible spectra analyses showed that the nanostructured lithium silicate powders had good light absorption properties in the ultraviolet light region. Also, photo luminescence spectra and cell parameter refinement of the obtained materials were studied.

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“…This broad emission in the range of 325-650 nm could be attributed to both Ce 3+ ions and defects in the host matrix, and several bands in the emission spectrum indicate that more than one emission center is present in this phosphor. Alemi et al 41 …”

Section: Ftirmentioning

confidence: 97%

“…The excitation spectrum monitored at 400 nm contains a UV band maximum at 244 nm. Alemi et al 41 recorded the excitation spectrum of undoped Li 2 SiO 3 and Li 2 Si 2 O 5 nanomaterials. A band was observed with maxima at 360 and 250 nm.…”

Section: Ftirmentioning

confidence: 99%

Characterization, Luminescence, and Defect Centers of a Ce3+-Doped Li2Si2O5 Phosphor Prepared by a Solution Combustion Reaction

Singh

Watanabe

Rao

et al. 2015

Journal of Elec Materi

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Li 2 Si 2 O 5 doped with Ce was synthesized by solution combustion. The phosphor was characterized by powder x-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Photoluminescence was investigated by excitation with UV radiation at 244 nm. An emission peak of the Ce 3+ ion was observed at 400 nm. Gamma irradiated phosphor exhibits six thermoluminescence (TL) peaks at 110°C, 160°C, 190°C, 250°C, 320°C, and 370°C. Electron spin resonance (ESR) spectroscopy was used to study the defect centers induced in the phosphor by gamma irradiation and to identify the centers responsible for the TL process. The room-temperature ESR spectrum of the irradiated phosphor seemed to be a superposition of at least four distinct centers. One of the centers (center I) with principal g values g jj ¼ 2:0307 and g^= 2.0040 was identified as an O 2 À ion. Center II, with an isotropic g factor 2.0070, was identified as an F + -type center (singly ionized oxygen vacancy); this center correlates with the main low-temperature TL peak at 110°C. Center III was identified as a Ti 3+ center and center IV, with a hyperfine interaction with a 29 Si nucleus, as an intrinsic O À -type center with a neighboring silicon ion. A Ti 4+ ion, the precursor of the Ti 3+ center, acts as a recombination center for the 110°C TL peak whereas a Ti 3+ center relates to the main 250°C TL peak and is also the likely recombination center for this peak. An O À ion is associated with the 110°C TL peak as a possible recombination center. An additional defect center (V) was observed during thermal annealing experiments. This center (identified as an F + center) seems to originate from an F center (oxygen vacancy with two electrons) and is not related to the any of the observed TL peaks.

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Lithium metasilicate and lithium disilicate nanomaterials: optical properties and density functional theory calculations

Cited by 18 publications

References 51 publications

Part III: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization and optical properties

Part III: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization and optical properties

Part I: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization, and optical properties

Characterization, Luminescence, and Defect Centers of a Ce3+-Doped Li2Si2O5 Phosphor Prepared by a Solution Combustion Reaction

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