Structural features of ZrO2-Y2O3 and ZrO2-Gd2O3 nanoparticles formed under hydrothermal conditions

Very wide-bandgap undoped and Y 2 O 3-doped ZrO 2 nanoparticles were synthesized and their structural, optical, morphological and energy characteristics were investigated. It was found that the bandgap value in ZrO 2 decreases with Y 2 O 3 doping. The developed materials were used for fabrication of nanostructured photoelectrodes for perovskite solar cells (PSCs) with the architecture of glass/FTO/ZrO 2-Y 2 O 3 /CH 3 NH 3 PbI 3 /spiro-MeOTAD/Au. The power conversion efficiency in the PSCs based on ZrO 2-Y 2 O 3 photoelectrodes was significantly higher than that for undoped ZrO 2 photoelectrodes. We have found that nanostructured layers, based on very wide-bandgap materials could efficiently transfer the injected electrons via a hopping transport mechanism.

Section: Resultsmentioning

confidence: 99%

Very wide-bandgap nanostructured metal oxide materials for perovskite solar cells

Larina¹,

Alexeeva²,

Almjasheva³

et al. 2019

“…Both the above mentioned ML-ALD method of chemical layer deposition [195] and the method based on selforganization of nanoparticles of variable composition can be used for this purpose, for example, during the formation thereof in hydrothermal conditions due to displacement of the excessive components in composition from the resulting solid 'core' solution to a 'shell' that surrounds it [196][197][198].…”

Section: Fig 17mentioning

confidence: 99%

High-temperature superconductivity: From macro- to nanoscale structures

Коваленко¹

2016

The analysis of achievements, problems and prospects of high-temperature superconductivity (HTSC) in the macro-and nanostructured materials has been given. The main experimental results and theoretical models describing the physical mechanisms of the superconductivity appearance at phenomenological and microscopic levels, including change in the energy spectrum of atoms in these materials with the advent of the 'superconducting' gap at temperatures below the critical transition, as well as the above-critical temperature 'pseudo-gap' have been analyzed.Although the origin of the pseudo-gap is not completely understood, it can be considered as an independent phase transition in the substance prior to the transition to the zero resistance state and insusceptibility (or insensitivity) to external magnetic field in high-temperature superconductors. Features of multi-gap and gapless superconducting materials as well as their ability to further increase the temperature of supercritical transition are discussed. Large resources to create the necessary electron and phonon spectra in the process of high-temperature superconductivity formation are associated with the use of nanoscale structures and nanoparticles of conductors and dielectrics. Electrical conductive contacts between nanoparticles and tunnel chains of nanoclusters, where delocalized electron spectra form similar energy shells to the atomic or nuclear shells, play a significant part here. It is required to further investigate the occurrence of high-temperature superconductivity at the level of interphase layers (non-autonomous phases) in nanostructures containing a large fraction of the substance in this condition. It is essential to develop adequate methods for synthesis of nanoparticles of variable size, structure and morphology, as well as techniques for their consolidation that would ensure the preservation of superconductivity of individual nanoparticles, their chemical, thermal, magnetic and current stability in the dissipative processes with functional and fluctuation effects.

“…As a rule, the conditions of hydrothermal synthesis (HTS), significantly affect the composition, structure, and size of particles and crystallites of the synthesized products [1][2][3][4][5][6][7]. Important factors in this case are the sequence and rate of reagents mixing and the pH of the hydrothermal fluid [8,9].…”

Section: Introductionmentioning

confidence: 99%

Influence of hydrothermal synthesis conditions on the composition of the pyrochlore phase in the Bi2O3-Fe2O3-WO3 system

Lomakin¹,

Проскурина²,

Гусаров³

2020

The paper deals with a study of the effect which the hydrothermal fluid pH has on the formation of a pyrochlore-structured phase in the Bi 2 O 3-Fe 2 O 3-WO 3 system. It was shown that at pH of 1 and 8, the formation of pyrochlore-structured phase particles with crystallite sizes of 38 and 118 nm, respectively, is accompanied by the formation of the Bi 2 WO 6 compound with the Aurivillius phase structure. At pH values from 2 to 7, only pyrochlore-structured nanocrystalline particles with a variable composition are formed. Under these conditions, the dependence of the average size of crystallites of the pyrochlore-structured phase particles on pH is extreme, as the size increases from ∼ 67 nm at pH 2 up to ∼ 126 nm at pH 5 and then decreases to ∼ 102 nm at pH 7. The samples obtained at pH 3-4 have a composition that is the closest to that specified for the synthesis. When pH increases up to 10, there forms a non-single-phase product that contains the Bi 2 WO 6 phase and δ-Bi 2 O 3-based phase.