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The use of readily prepared bisphosphonic acids obtained in few steps through a thio‐Michael addition of commercially available thiols on tetraethyl vinylidenebisphosphonate enables the straightforward surface modification of amorphous mesoporous zirconia nanoparticles. Simple stirring of the zirconia nanoparticles in a buffered aqueous solution of the proper bisphosphonic acid leads to the surface functionalization of the nanoparticles with different kinds of functional groups, charge and hydrophobic properties. Formation of both chemisorbed and physisorbed layers of the bisphosphonic acid take place, observing after extensive washing a grafting density of 1.1 molecules/nm2 with negligible release in neutral or acidic pH conditions, demonstrating stronger loading compared to monophosphonate derivatives. The modified nanoparticles were characterized by IR, XPS, ζ‐potential analysis to investigate the loading of the bisphosphonic acid, FE‐SEM to investigate the size and morphologies of the nanoparticles and 31P and 1H MAS NMR to investigate the coordination motif of the phosphonate units on the surface. All these analytical techniques demonstrated the strong affinity of the bisphosphonic moiety for the Zr(IV) metal centers. The functionalization with bisphosphonic acids represents a straightforward covalent approach for tailoring the superficial properties of zirconia nanoparticles, much straightforward compared the classic use of trisalkoxysilane or trichlorosilane reagents typically employed for the functionalization of silica and metal oxide nanoparticles. Extension of the use of bisphosphonates to other metal oxide nanoparticles is advisable. [ABSTRACT FROM AUTHOR]

Using the rigorous results obtained by Wiener [Acta Math. (1930), 30, 118–242] on the Fourier integral of a bounded function and the condition that small‐angle scattering intensities of amorphous samples are almost everywhere continuous, the conditions that must be obeyed by a function η(r) for this to be considered a physical scattering density fluctuation are obtained. These conditions can be recast in the following form: the V → ∞ limit of the modulus of the Fourier transform of η(r), evaluated over a cubic box of volume V and divided by V1/2, exists and its square obeys the Porod invariant relation. Some examples of one‐dimensional scattering density functions obeying the aforesaid condition are numerically illustrated. [ABSTRACT FROM AUTHOR]

Film-like and thread-like systems are, respectively, defined by the property that one of the constituting homogenous phases has a constant thickness (δ) or a constant normal cross section (of largest chord δ). The stick probability function of this phase, in the limit δ → 0, naturally leads to the definition of the correlation function (CF) of a surface or of a curve. This CF closely approximates the generating stick probability function in the range of distances larger than δ. The surface and the curve CFs, respectively, behave as 1/ r and as 1/ r2 as r approaches zero. This result implies that the relevant small-angle scattering intensities behave as or as in the intermediate range of the scattering vector magnitude ( q) and as in the outermost q range. Similarly to , pre-factors and simply depend on some structural parameters. Depending on the scale resolution it may happen that a given sample looks thread like at large scale, film like at small scale and particulate at a finer scale. An explicit example is reported. As a practical illustration of the above results, the surface and the curve CFs of some simple geometrical shapes have been explicitly evaluated. In particular, the CF of the right circular cylinder is evaluated. Its limits, as the height or the diameter the cylinder approaches zero, are shown to coincide with the CFs of a circle and of a linear segment, respectively. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate that the martensitic t → m phase transformation of ZrO2 powder stabilized with Eu3+ and Eu3+/ Y3+ ions, can be effectively monitored by photoluminescence ( PL) spectroscopy. As the luminescent properties of Eu3+ from within a host lattice are strongly influenced by the coordination geometry of the ion, we used the emission spectrum to monitor structural changes of ZrO2. We synthesized Eu3+-doped and Eu3+/ Y3+-codoped samples via the coprecipitation method, followed by calcination. We promoted the martensitic transformation by applying mechanical compression cycles with an increasing pressure, and deduced the consequential structural changes from the relative intensities of the 5D0 → 7F2 hypersensitive transitions, centered, respectively, at 606 and 613 nm whether the Eu3+ is in the eightfold coordinated site of the tetragonal phase or in the sevenfold coordinated site of the monoclinic phase. We suggest that the unique emission profile for Eu3+ ions in different symmetry sites can be exploited as a simple analytical tool for remote testing of mechanical components that are already mounted and in use. The structural changes observed by PL spectroscopy were corroborated by X-ray powder diffraction ( XRPD), with the phase compositions and volume fractions being determined by Rietveld analysis. [ABSTRACT FROM AUTHOR]