02173nas a2200193   4500008004100000022001400041245012500055210006900180260007100249300001600320490000800336520139700344100001501741700001901756700001701775700003201792700002501824856013001849       2008                        eng d  a1932-744700aSize dependent coordination behavior and cation distribution in MgAl2O4 nanoparticles from Al-27 solid state NMR studies0 aSize dependent coordination behavior and cation distribution in   a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP  a14737-147440 v1123 a<p>Nanoparticles of spinel-type oxides such as ferrites offer great advantages and applications in many important areas. Decreasing the size of the particles to nanometer size will increase the surface-to-volume ratio and this will strongly influence the physical and chemical properties of these materials. For magnetic nanoparticles, the exchange interactions at the surface of a particle will be different from those inside due to changes in the coordination behavior at the surface. Therefore, studying and understanding the coordination and distribution behavior of the different metal ions in the nanoparticles of spinel-type oxides is very important. Solid state NMR is a useful and important technique to obtain information on local structural variations. The degree of the distribution of the Al3+ ions in the tetrahedral and octahedral sites in the nanoparticles of the nonmagnetic spinet MgAl2O4 having different particle sizes has been determined by Al-27 magic-angle spinning (MAS) NMR spectroscopy. It has been observed that the inversion parameter decreases with increasing particle size. Apart from the usual tetrahedral and octahedral coordinations present in the bulk material, the presence of five- and three-coordinated At has been observed in nanoparticles with sizes less than 18 nm and a second octahedral coordination is observed for nanoparticles of larger sizes.</p>1 aSreeja, V.1 aSmitha, T., S.1 aNand, Deepak1 aAjithkumar, Thalasseril, G.1 aJoy, Pattayil, Alias  uhttps://library.ncl.res.in/content/size-dependent-coordination-behavior-and-cation-distribution-mgal2o4-nanoparticles-al-27-0