Stoichiometric and Nonstoichiometric Compounds

Abstract

This chapter gives a general overview of synthesis and recent development of nickel oxide as a nonstoichiometric compound. We establish the synthesis chemistry of nickel oxide as a nonstoichiometric material, and hence successively introduce definitions and classifications of nonstoichiometric compounds as well as their point defects. The samples of nonstoichiometric nickel oxide are synthesized by thermal decomposition method. The nonstoichiometry of samples was then studied chemically by iodometric titration, and the results are further corroborated by excess oxygen obtained from the thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques are used to analyze structural phase of nonstoichiometric nickel oxide. The change in oxidation state of nickel was studied by X-ray photoelectron spectroscopy (XPS) analysis. The shift in antiferromagnetic ordering and transition temperature due to nonstoichiometry is studied by magnetic and specific heat capacity analysis.

Oxygen Vacancy‐Mediated Growth of Amorphous Discharge Products toward an Ultrawide Band Light‐Assisted Li–O2 Batteries

“…The thermogravimetric analysis (TGA) displayed more than 4% weight loss for the Bi 2 MoO 6 with oxygen vacancies in comparation with that of pure Bi 2 MoO 6 from room temperature to 800°C in N 2 atmosphere ( Figure a), which might result from the metastable property of materials with oxygen vacancies according to previous literature. [ 21–23 ] Moremore, the disordered lattice region exhibited in the TEM image (Figure S3a, Supporting Information) also indicated the probable existence of oxygen vacancies in AB‐OV/CC. Generally, the Raman vibration peak at 718.5 cm −1 is ascribed to the asymmetric stretching vibration of MoO 6 octahedrons of Bi 2 MoO 6 , which is related to the motion of equatorial oxygen atoms joining the MoO 6 octahedrons within the layers.…”

Adhesion characteristics of solution treated environmental dust

“…Since the dust particle size varies and large size particles can cause avalanche influence on the remaining small size dust particles while enhancing dust motion on the surface 4 . However, some compounds in the dust particles, such as alkaline and alkaline earth metal compounds, do not satisfy the stoichiometric elemental ratio 5 ; hence, this causes ionic forces to be created on the particle surface while contributing to the interfacial force between the dust and inclined surfaces. This also enhances the pinning effect of the dust particles on the inclined surface.…”

“…Dust composes of several elements and compounds, which depend on the geomorphologic structure of the landscapes 5 . Several studies have been carried out exploring environmental dust and its emission in the atmosphere.…”

Enhanced thermoelectric performance of hot-pressed n-type Ag2Se nanostructures by controlling the intrinsic lattice defects

“…This means that the valence states of Ag and Se in Ag 2− x Se are unaffected by the Ag/Se atomic ratio. 35…”