Structural and optical properties of (K,Na)NbO3 nanoparticles synthesized by a modified sol–gel method using starch media

Khorrami, Gh.H.; Kompany, Ahmad; Zak, A. Khorsand

doi:10.1016/j.apt.2014.08.013

Cited by 48 publications

(17 citation statements)

References 30 publications

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“…In each case, the fundamental (indirect) bandgap equals the energy difference between [14] and by Yang et al [15] at the same level of theory but with different exchange-correlation functionals. The observable optical bandgap, obtained by adding the quasiparticle correction of 1.64 eV and subtracting the exciton binding energy of 0.5 eV [27], is in good quantitative agreement with experimental measurements at x = 0 [35][36][37][38][39] and x = 0.5 [37,40] the Kohn-Sham eigenvalues of the highest valence-band and the lowest conduction-band state within DFT. Our results reveal that the bandgap is very similar for all six configurations of KNN50, which is plausible from the fact that the alkali-metal atoms do not contribute to the density of states near the band edges [22].…”

Section: Bandgapsupporting

confidence: 79%

“…The values of 3.15 eV [37] and 3.19 eV [40] derived in this way are essentially identical to those of KNbO 3 and confirm that the optical bandgap does not depend strongly on x. In particular, Khorrami et al [37], who analyzed samples with x = 0 and x = 0.5 using the same fabrication and measurement techniques, obtained nearly identical gaps of 3.18 eV and 3.15 eV, respectively. To enable a quantitative comparison, we add the quasiparticle correction of 1.64 eV [27], derived within the GW approximation for KNbO 3 , to the indirect Kohn-Sham eigenvalue gap and subsequently subtract the exciton binding energy of 0.5 eV [27], which equals the redshift of the absorption edge due to electron-hole attraction effects in the solution of the Bethe-Salpeter equation.…”

Section: Bandgapsupporting

confidence: 69%

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Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

2021

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We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K$$_{1-x}$$ 1 - x Na$$_{x}$$ x NbO$$_{3}$$ 3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for $$x=0$$ x = 0 and $$x=0.5$$ x = 0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K$$_{0.5}$$ 0.5 Na$$_{0.5}$$ 0.5 NbO$$_{3}$$ 3 compared to both end members of the solid solution. Furthermore, we find that the electronic bandgap varies very little between $$x=0$$ x = 0 and $$x=0.5$$ x = 0.5 , reflecting the small changes in the lattice parameters. Graphic abstract

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Section: Bandgapsupporting

confidence: 79%

Section: Bandgapsupporting

confidence: 69%

Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

2021

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“…People who suffer from lead poisoning can experience headaches, constipation, nausea, anemia, and reduced fertility. Moreover, prolonged exposure to lead can cause more serious symptoms, such as severe damage to nerves, kidneys, and brain [2]. Consequently, we must find possible lead substitutes.…”

Section: Palabras Clavementioning

confidence: 99%

Grinding methods effects on the synthesis of Potassium-Sodium Niobate powders by oxide mixing

Quintero

Rincón

Osório-Guillén

et al. 2019

TecnoL.

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Piezoelectric materials are widely used in electronic devices and, traditionally, various lead-based materials have been implemented in such applications. However, because of the damage caused by lead, other materials with similar characteristics that do not cause a negative impact on human health and the environment have been developed. A material with those characteristics is potassium-sodium niobite K0.5Na0.5 Nbo3. In this study, we investigate the thermogravimetric, structural, and microstructural properties of powders of such system obtained through oxide mixing with the aim of establishing the effect and efficiency of grinding (using a horizontal and a planetary ball mill grinder) on the production of the final material. It was determined that horizontal grinding and calcination at 900°C create the optimal conditions for obtaining K0.5Na0.5 Nbo3 powders, by oxide mixing, with the adequate structure and microstructure to continue the densification and/or doping processes.

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“…Pure KNN with a cube‐like structure was also synthesized starting from potassium and sodium carbonate, niobium hydroxide and three different chelating agents: citric acid, ethylene glycol, and ethylenediaminetetraacetic acid (EDTA) . Recently, natural gel was used as stabilizer agent for obtaining KNN nanoparticles at low calcination temperature . The starting materials were sodium and potassium nitrate, ammonium niobate (V) oxalate hydrate, and gelatin type B and starch as stabilizer agents.…”

Section: Advanced Synthesis and Properties Of Knn And Related Composimentioning

confidence: 99%

Advanced Synthesis on Lead‐Free K_xNa_(1−x)NbO₃ Piezoceramics for Medical Imaging Applications

Garroni

Senes²,

Iacomini³

et al. 2018

Physica Status Solidi (a)

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Ultrasonic imaging system is a non‐invasive medical imaging technique that has become one of the most widely used diagnostic tools in modern medicine for detecting prenatal anomalies and deep screening of biological tissues. One of the core components of the ultrasound system is represented by the probe where is located the transducer which produces mechanical energy in response to electrical signals, and conversely, produce electrical signals in response to mechanical stimulus. The ultrasound transducer in the probe is generally made of a piezoelectric ceramic material such as lead zirconate titanate (PZT), which present two important limitations as the presence of toxic material as the lead, and low acoustic impedance ascribable to its high density. For these reasons, it is necessary to focus the research on new eco‐friendly piezoelectric materials with properties comparable with PZT. Among them potassium sodium niobate is considered as a leading lead‐free candidate to replace lead‐based piezoceramics, resulting the most promising. In this review, the most relevant and advanced synthesis approaches and the unique properties of this class of lead‐free piezoceramics are presented in detail.

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Structural and optical properties of (K,Na)NbO3 nanoparticles synthesized by a modified sol–gel method using starch media

Cited by 48 publications

References 30 publications

Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

Grinding methods effects on the synthesis of Potassium-Sodium Niobate powders by oxide mixing

Advanced Synthesis on Lead‐Free K_xNa_(1−x)NbO₃ Piezoceramics for Medical Imaging Applications

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Structural and optical properties of (K,Na)NbO3 nanoparticles synthesized by a modified sol–gel method using starch media

Cited by 48 publications

References 30 publications

Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K$$_{0.5}$$Na$$_{0.5}$$NbO$$_{3}$$ from density-functional theory

Grinding methods effects on the synthesis of Potassium-Sodium Niobate powders by oxide mixing

Advanced Synthesis on Lead‐Free KxNa(1−x)NbO3 Piezoceramics for Medical Imaging Applications

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Advanced Synthesis on Lead‐Free K_xNa_(1−x)NbO₃ Piezoceramics for Medical Imaging Applications