Phase modulation in nanocrystalline vanadium di-oxide (VO2) nanostructures using citric acid via one pot hydrothermal method

Saini, Meenu; Dehiya, Brijnandan S.; Umar, Ahmad; Goyat, M.S.

doi:10.1016/j.ceramint.2019.06.063

Cited by 22 publications

(6 citation statements)

References 89 publications

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“…The most intensive excitation peak at 384 nm can be assigned to the free-excitation emission. ,− The excitation peaks around ∼448 nm may be attributed to the electric charge transfer corresponding to the bonding energy of OV and O–V–O bonds . The emission peaks around 750 nm are related to the transmission of d electrons of Vanadium to the p orbitals holes of Oxygen or may be due to the oxygen vacancies in VO x thin film structures. ,, While the excitation peaks occurred at a narrower wavelength with increasing film thickness, the emission peaks arising from the oxygen vacancy became more prominent with increasing film thickness. As a result, the PL spectrum clearly revealed that oxygen vacancies exist in VO x thin films and these oxygen vacancies tend to increase with increasing film thickness.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

Ekinci,

Özkal,

Kazan

2024

ACS Omega

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The taking run on artificial intelligence in the last decades is based on the von Neumann architecture where memory and computation units are separately located from each other. This configuration causes a large amount of energy and time to be dissipated during data transfer between these two units, in contrast to synapses in biological neurons. A new paradigm has been proposed inspired by biological neurons in human brains, known as neuromorphic computing. Due to the unusual current−voltage characteristic of memristor devices such as pinched hysteresis loops, memristors are considered a key element of neuromorphic architecture. In this study, we report the basic current−voltage characteristic of the memristor devices in the form of Si/SiO 2 /Pt(30 nm)/VO x (3, 13, 25 nm)/Pt (30 nm) sandwich structure. Synaptic functions such as spike-time-dependent plasticity (STDP), paired-pulse facilitation (PPF), long-term potentiation (LTP), and long-term depression (LTD) of memristor devices were examined in detail. The oxide layer VO x has been grown by using the VO 2 target in a pulsed laser deposition (PLD) chamber. The composition and oxidation states of the oxide layer were examined using the X-ray photoelectron spectroscopy (XPS) technique. The status of oxygen vacancies, which play an active role in the operation of the devices, was examined with a photoluminescence (PL) technique. The experimental results showed that the thickness of the oxide layer can significantly influence the synaptic and resistive switching properties of the devices.

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Section: Resultsmentioning

confidence: 99%

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

Ekinci,

Özkal,

Kazan

2024

ACS Omega

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“…A sequence of controlled experiments was designed and executed to clarify the formation mechanism of 3D hierarchical flower-like solid microspheres and hollow microspheres (Figure ). C 6 H 8 O 7 is taken as an admirable chelating agent serving as a charge regulator, reducer, and stabilizer. , Therefore, the effect of C 6 H 8 O 7 content on the formation of flower-like solid microspheres was investigated in the absence of HNO 3 addition (Route A). When the molar ratio of C 6 H 8 O 7 to NH 4 VO 3 is 3:8, the C 6 H 8 O 7 content is insufficient and only acts as a reductive agent.…”

Section: Results and Discussionmentioning

confidence: 99%

VO₂ Nanosheets Assembled into Hierarchical Flower-Like Hollow Microspheres for Li-Ion Batteries

Zhong

Zou

et al. 2022

ACS Appl. Nano Mater.

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Vanadium dioxide (VO2) is a prospering material for lithium-ion cathode storage attributed to its unique structure and high specific capacity. However, the cycling and rate performance of VO2 is unsatisfactory due to low electrical conductivity and tendency to volume expansion during charging and discharging, which restricts its application. To improve its cell performance, we report 3D hierarchical flower-like VO2 hollow microspheres assembled from nanosheets (HVO) synthesized by a facile template-free hydrothermal method. In addition, by controlling the content of nitric acid (HNO3) and citric acid (C6H8O7), VO2 flower-like solid microspheres (SVO) and random nanosheets (NVO) were synthesized as control experiments. Compared with them, 3D hierarchical flower-like VO2 hollow microspheres have higher reversible capacity (delivers a capacity of 259.90 mA h g–1 at 0.1 A g–1), extraordinary rate capacity (168.51 mA h g–1 at 2 A g–1), and good cycling life (81.21% capacity retention over 500 cycles at 2 A g–1). Moreover, the HVO//graphite full cell was successfully assembled, which exhibits an initial capacity of 147.17 mA h g–1 at 2 A g–1 and maintains a high capacity of 114.97 mA h g–1 after 1000 cycles, with capacity retention of 78.12% and an average capacity decline of 0.022% per cycle. The superior performance of 3D hierarchical flower-like VO2 hollow microspheres stems from their ability to provide a considerable surface area, efficient self-expansion, and self-shrinkage buffering. The abovementioned results sufficiently confirm that 3D hierarchical flower-like VO2 hollow microspheres constituted from nanosheets have great latent potential and application prospects as a next-generation cathode material for fast-charging lithium-ion batteries.

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“…Note that the reagents used in the experiments were all of analytical purity and could be used without further purification. A one-step hydrothermal method was used to synthesize monoclinic VO 2 , in which V 2 O 5 and citric acid monohydrate serve as the vanadium source and reducing agent, respectively . In a typical experiment for the synthesis of monoclinic VO 2 , the molar ratio of V 2 O 5 as the vanadium source and citric acid monohydrate as the reducing agent was 1:5.…”

Section: Experimental and Calculation Detailsmentioning

confidence: 99%

“…A one-step hydrothermal method was used to synthesize monoclinic VO 2 , in which V 2 O 5 and citric acid monohydrate serve as the vanadium source and reducing agent, respectively. 36 In a typical experiment for the synthesis of monoclinic VO 2 , the molar ratio of V 2 O 5 as the vanadium source and citric acid monohydrate as the reducing agent was 1:5. Specifically, 5 mmol of V 2 O 5 was dissolved in 40 mL of deionized water and stirred in a water bath at 60 °C for 15 min to obtain a yellow solution.…”

Section: Experimental and Calculation Detailsmentioning

confidence: 99%

Microflowers Composed of VO₂ Nanoflakes for Selective Detection of Acetone and Ammonia

Qin,

Wang,

Zhou

et al. 2024

ACS Appl. Nano Mater.

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As a typical phase-transition material, VO 2 could show great potential in the process of precise modulation of gassensing selectivity. However, the effect and mechanism of the phase transition on its gas sensitivity have not yet been clearly elucidated. In this paper, a temperature-controlled VO 2 gas sensor capable of phase change has been created using a one-step solvothermal method. With controllable transition of VO 2 from the monoclinic phase to the rutile phase by adjusting the operating temperature, the corresponding VO 2 sensor shows obvious changes in gas-sensing selectivity from acetone to ammonia. At room temperature (∼25 °C), the monoclinic VO 2 sensor produces response values of 93 and 29% to 10 ppm of acetone vapor and ammonia gas, respectively. Comparatively, the response values for the sensor based on rutile-phase VO 2 that operates at 100 °C are 41 and 95% for 10 ppm of acetone vapor and ammonia gas. Based on the first-principles mortise−tenon-style construction as well as Lewis acid−base theory, the mechanism of dual selectivity generated with the phase transition of VO 2 is demonstrated in terms of crystal structure, electronic orbitals, and adsorption energy calculations. The unique characteristic of adjustable dual-phase detectability of VO 2 contributes to the selective capability of gas sensing. It thus presents an effective strategy for developing gas sensors with regulated selectivity by phase transition of certain special semiconductor oxides.

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Phase modulation in nanocrystalline vanadium di-oxide (VO2) nanostructures using citric acid via one pot hydrothermal method

Cited by 22 publications

References 89 publications

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

VO₂ Nanosheets Assembled into Hierarchical Flower-Like Hollow Microspheres for Li-Ion Batteries

Microflowers Composed of VO₂ Nanoflakes for Selective Detection of Acetone and Ammonia

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Phase modulation in nanocrystalline vanadium di-oxide (VO2) nanostructures using citric acid via one pot hydrothermal method

Cited by 22 publications

References 89 publications

Investigation of Resistance Switching and Synaptic Properties of VOx for Neuromorphic Applications

Investigation of Resistance Switching and Synaptic Properties of VOx for Neuromorphic Applications

VO2 Nanosheets Assembled into Hierarchical Flower-Like Hollow Microspheres for Li-Ion Batteries

Microflowers Composed of VO2 Nanoflakes for Selective Detection of Acetone and Ammonia

Contact Info

Product

Resources

About

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

Investigation of Resistance Switching and Synaptic Properties of VO_x for Neuromorphic Applications

VO₂ Nanosheets Assembled into Hierarchical Flower-Like Hollow Microspheres for Li-Ion Batteries

Microflowers Composed of VO₂ Nanoflakes for Selective Detection of Acetone and Ammonia