This review article summarizes the last few decades of research on nickel hydroxide, an important material in physics and chemistry, that has many applications in engineering including, significantly, batteries. First, the structures of the two known polymorphs, denoted as α-Ni(OH) 2 and β-Ni(OH) 2 , are described. The various types of disorder, which are frequently present in nickel hydroxide materials, are discussed including hydration, stacking fault disorder, mechanical stresses and the incorporation of ionic impurities. Several related materials are discussed, including intercalated α-derivatives and basic nickel salts. Next, a number of methods to prepare, or synthesize, nickel hydroxides are summarized, including chemical precipitation, electrochemical precipitation, sol-gel synthesis, chemical ageing, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwaveassisted synthesis, and sonochemical methods. Finally, the known physical properties of the nickel hydroxides are reviewed, including their magnetic, vibrational, optical, electrical and mechanical properties. The last section in this paper is intended to serve as a summary of both the potentially useful properties of these materials and the methods for the identification and characterization of 'unknown' nickel hydroxide-based samples.

The present work utilizes Raman and infrared (IR) spectroscopy, supported by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to re-examine the fine structural details of Ni(OH) 2 , which is a key material in many energy-related applications. This work also unifies the large body of literature on the topic. Samples were prepared by the galvanostatic basification of nickel salts and by aging the deposits in hot KOH solutions. A simplified model is presented consisting of two fundamental phases (α and β)o fN i ( O H ) 2 and a range of possible structural disorder arising from factors such as impurities, hydration, and crystal defects. For the first time, all of the lattice modes of β-Ni(OH) 2 have been identified and assigned using factor group analysis. Ni(OH) 2 films can be rapidly identified in pure and mixed samples using Raman or IR spectroscopy by measuring their strong O−H stretching modes, which act as fingerprints. Thus, this work establishes methods to measure the phase, or phases, and disorder at a Ni(OH) 2 sample surface and to correlate desired chemical properties to their structural origins.

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We apply perturbative effective mass theory as a broadly applicable theoretical model for quantum confinement (QC) in all Si and Ge nanostructures including quantum wells (QWs), wires (Q-wires) and dots (QDs). Within the limits of strong, medium, and weak QC, valence and conduction band edge energy levels (VBM and CBM) were calculated as a function of QD diameters, QW thicknesses and Q-wire diameters. Crystalline and amorphous quantum systems were considered separately. Calculated band edge levels with strong, medium and weak QC models were compared with experimental VBM and CBM reported from X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS) or photoluminescence (PL). Experimentally, the dimensions of the nanostructures were determined directly, by transmission electron microscopy (TEM), or indirectly, by x-ray diffraction (XRD) or by XPS. We found that crystalline materials are best described by a medium confinement model, while amorphous materials exhibit strong confinement regardless of the dimensionality of the system. Our results indicate that spatial delocalization of the hole in amorphous versus crystalline nanostructures is the important parameter determining the magnitude of the band gap expansion, or the strength of the quantum confinement. In addition, the effective masses of the electron and hole are discussed as a function of crystallinity and spatial confinement.

The thermal reaction of undecylenic acid with a hydrogen-terminated porous silicon surface takes place at 95°C to yield an organic monolayer covalently attached to the surface through Si-C bonds. The acid terminal group remains intact and is not affected by the chemical process. Under the same conditions, alcohols break the Si-Si back bonds of the PSi matrix. In contrast, the acid function does not react with either the Si-H or the Si-Si bonds of the PSi surface and the reaction takes place at the terminal CvC double bond of the molecule. When the reaction was carried out with decanoic acid, under the same conditions, the reaction was not complete. The functionalized surfaces were characterized using transmission infrared and X-ray photoelectron spectroscopies. The effect of the chemical process on the photoluminescence has been studied, and the stability against corrosion in 100% humidity was verified using chemography. We have demonstrated that the derivatized surface with undecylenic acid can be activated by a simple chemical route using N-hydroxysuccimide in the presence of N-ethyl-NЈ-͑3-dimethylaminopropyl͒ carbodiimide hydrochloride.

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Alloy semiconductor magic-size clusters (MSCs) have received scant attention and little is known about their formation pathway. Here, we report the synthesis of alloy CdTeSe MSC-399 (exhibiting sharp absorption peaking at 399 nm) at room temperature, together with an explanation of its formation pathway. The evolution of MSC-399 at room temperature is detected when two prenucleation-stage samples of binary CdTe and CdSe are mixed, which are transparent in optical absorption. For a reaction consisting of Cd, Te, and Se precursors, no MSC-399 is observed. Synchrotron-based in-situ small angle X-ray scattering (SAXS) suggests that the sizes of the two samples and their mixture are similar. We argue that substitution reactions take place after the two binary samples are mixed, which result in the formation of MSC-399 from its precursor compound (PC-399). The present study provides a room-temperature avenue to engineering alloy MSCs and an in-depth understanding of their probable formation pathway.