Shock wave-induced optical band gap engineering on pure and dye-doped potassium dihydrogen phosphate crystals

Sivakumar, A.; Dhas, S. Sahaya Jude; Dhas, S. A. Martin Britto

doi:10.1007/s10854-020-03928-0

Cited by 12 publications

(9 citation statements)

References 32 publications

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“…5, the control sample has the direct bandgap energy 2.20 eV and the bandgap energy values of the shocked samples are found to be 2.17, 2.15 and 2.10 eV for 50, 100, and 150 shocks, respectively. As per the observed values, the bandgap values are identified to be linearly reducing in accordance with the number of shock pulses and the observed changes may be due to the occurrence of the Franz-Keldysh effect [37,38].…”

Section: Optical Propertiessupporting

confidence: 70%

“…7). In the general cubic ferrite cases, the reduction of the magnetization value is associated with extrinsic properties such as size and shape effects, surface changes and spin canting effects as well as migration of ferric ions occurring from the octahedral to the tetrahedral sites [36] and also intrinsic magnetic properties of spin orientation and magneto crystalline anisotropy [36,38]. But, in the present case, migration of ferric ions occurring from the octahedral to the tetrahedral sites is not applicable since in the case of barium monoferrite, octahedral sites are only in barium and oxygen atoms.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

“…But, in the present case, migration of ferric ions occurring from the octahedral to the tetrahedral sites is not applicable since in the case of barium monoferrite, octahedral sites are only in barium and oxygen atoms. Hence, surface defects and spin canting effects might have taken place so that the magnetization value is reduced [15,36,38]. On the other hand, basic anisotropy level of Ba atom might have been changed by the impact of shock waves.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

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Assessment of shock resistance of barium ferrite at dynamic shocked conditions

Sivakumar

Mowlika²,

Dhas³

et al. 2021

J Mater Sci: Mater Electron

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This research work probes into the crystallographic and magnetic structural stability of barium ferrite nanoparticles (BaFe 2 O 4 NPs) at dynamic shock waveexposed conditions. Barium ferrite NPs have been prepared by co-precipitation method and the structural stability of the title ferrite has been scrutinized subsequent to the impact of shock waves (Mach number 2.2) at different counts of shocks viz., 50, 100 and 150, respectively, and their performance on shock resistance has been analyzed by the techniques of X-ray diffraction (XRD), ultraviolet diffused reflectance spectroscopy (UV-DRS), and vibrating sample magnetometry (VSM). Based on the results of the observed analytical measurements, it is substantiated that the test sample has not undergone any of the crystallographic phase transitions even though it has the crystal structure of polymorphism which manifests as the viable witness for the structural stability of the test sample that has been also authenticated by the XRD results. Very few slight changes are observed in the optical and magnetic properties of BaFe 2 O 4 NPs at shocked conditions. More interestingly, the existence of mixed magnetic phase (ferro and anti-ferromagnetic) is witnessed at 50 and 100 shocked conditions because of the shock wave-induced directional disorder of the spin orientations of the test samples which is typically called ''kink behavior''. The observed results reveal that the divalent ferrite NPs of BaFe 2 O 4 have high shock resistance than that of the technologically important ferrites such as ZnFe 2 O 4 and a-Fe 2 O 3 NPs. Hence, the title material could be considered as a prospective candidate for the aerospace device fabrication because of the exceptional stability of its structure against the shock wave impact.

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Section: Optical Propertiessupporting

confidence: 70%

Section: Magnetic Propertiesmentioning

confidence: 99%

Section: Magnetic Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of shock resistance of barium ferrite at dynamic shocked conditions

Sivakumar

Mowlika²,

Dhas³

et al. 2021

J Mater Sci: Mater Electron

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“…Moreover, the impact of shock waves on optical properties is less understood as compared to the crystallographic phase stability aspects. As per the results of recent publications, optical properties such as optical transmittance and absorption edges of both bulk and nano-materials are significantly altered with respect to the number of shock waves., [21,22,[47][48][49][50][51] Hence, in the present work, as per the XRD and Raman spectral results, investigation of optical properties is highly required since it is an optically transparent crystal such that it could provide scope for better justifying the obtained changes through diffraction and vibrational spectral results of the test crystal at shocked conditions. Varian Cary 5 E UV-Vis spectrometer has been utilized to assess the optical transmittance of the test crystal at shocked conditions and the recorded optical transmittance profiles of the crystals are presented in Figure 10.…”

Section: Uv-vis Spectral Analysismentioning

confidence: 99%

“…Hence, on the one hand, the net concentration of grains might have increased such that it resists the optical transmittance of the test crystal. [47,48] On the other hand, the test crystal's octahedral and tetrahedral sites and their bond lengths as well as bond angles might have been significantly altered with respect to the number of shock pulses. Followed by these changes, the electron density around transition metal cations might have been affected as and when some of the cation octahedral have experienced the highly orientational disorder that could have enlarged the unit cell which could be attributed to the uneven d-electron distribution and as a result, different absorption edge positions have been observed with respect to the number of shock pulse.…”

Section: Uv-vis Spectral Analysismentioning

confidence: 99%

Switchable Phase Transition from Crystalline to Amorphous States of Cadmium Sulfate Octahydrate Single Crystals by Shock Waves

Sivakumar

Dhas²,

Showrilu³

et al. 2022

Physica Status Solidi (b)

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Even slight changes occurring in the lattice positions of solid materials enforced by the external forces may give rise to remarkable results in the crystallographic nature. The materials which undergo phase‐change without modifying their overall chemistry are the prominent candidates to be the driving forces for the applications involving phase transitions. In the present context, the authors present and demonstrate the switchable phase transition occurring between crystalline and amorphous nature of cadmium sulfate octahydrate single crystals (3CdSO4·8H2O) impacted by shock waves with which the transition is authenticated via diffraction, vibrational and optical spectroscopic techniques such as powder X‐ray diffractometry, Raman and UV‐Vis spectral analyses. Based on the results attained from diffraction and spectroscopic analyses, it is observed that the switchable phase transition sequence is crystalline–crystalline–amorphous–crystalline–crystalline with respect to the control, one, two, three, and four shock‐wave‐loaded conditions, respectively. Due to the outstanding switching behavior, the title material is strongly suggested for the applications of molecular switching and optical data storage systems.

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Optical and structural properties of nanocomposites based on HMW‐PMMA reinforced by spherical and rod‐shaped titanium dioxide nanoparticles

Jouamaa,

Panniello,

El Fengouchi

et al. 2023

Polymer Composites

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This work presents an investigation on the optical and structural properties of two series of nanocomposites based on the incorporation of spherical‐ (NDs) or rod‐shaped (NRs) semiconductive crystalline titanium dioxide (TiO2) nanoparticles (NPs) into an insulating amorphous polymethylmethacrylate (PMMA) matrix. The UV–visible absorbance and reflectance measurements reveal that the increase in TiO2 NP concentration within the polymer matrix reduces the forbidden band size for both NDs and NRs, leading to an improvement of the refractive index. SEM and TEM morphological characterizations were performed to investigate the size, size distribution and NPs dispersion within the polymeric matrix. The structural analyses performed by using X‐ray diffraction show peaks ascribed to the TiO2 crystalline structure while infrared (FT‐IR) spectra indicate the occurrence of interactions between nanofillers and the polymer chain of the host matrix.

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Shock wave-induced optical band gap engineering on pure and dye-doped potassium dihydrogen phosphate crystals

Cited by 12 publications

References 32 publications

Assessment of shock resistance of barium ferrite at dynamic shocked conditions

Assessment of shock resistance of barium ferrite at dynamic shocked conditions

Switchable Phase Transition from Crystalline to Amorphous States of Cadmium Sulfate Octahydrate Single Crystals by Shock Waves

Optical and structural properties of nanocomposites based on HMW‐PMMA reinforced by spherical and rod‐shaped titanium dioxide nanoparticles

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