Oxidation–decomposition facilitated reorientation of nanoparticles in reactively sintered (Ni0.33Co0.67)1−δO polycrystals

Laser ablation condensation and phase change of Ni1−xCoxO nanoparticles

“…On the other hand, Ni 1Àx Co x O solid solution was formed and partially oxidized as spinel phase when the Ni target was irradiated first by laser ablation. This spinel phase also has composition close to Co 3Àd O 4 in view of the oxidation decomposition results of the (Ni 0.33 Co 0.67 ) 1Àd O protoxide [1]. (Co-rich spinel was formed by oxidation decomposition of (Ni 0.33 Co 0.67 ) 1Àd O protoxide when annealed in atmospheric pressure below 900 1C [1], i.e.…”

“…(Radiant heating at a relative high temperature around 1000 1C was suggested responsible for the agglomeration of TiO 2 nanocondensates into close packed manner rather than NCA during the laser ablation condensation process in oxygen [33].) Oxidation decomposition could also facilitate reorientation of the attached nanocondensates analogous to the reorientation of the intragranular particles in bimodal-sized (Ni 0.33 Co 0.67 ) 1Àd O protoxide polycrystals [1].…”

“…Phase change and reorientation of nanoparticles in (Ni 0.33 Co 0.67 ) 1Àd O with protoxide rock salt-type structure have been reported for bimodal-sized polycrystals prepared via a reactive sintering route [1]. Size-dependent oxidation and decomposition in accompaniment with reorientation of the nanoparticles were found to occur in a two-phase field of protoxide and spinel structure at a relatively lowhomologous temperature (T/T m $0.45) [1].…”

“…Size-dependent oxidation and decomposition in accompaniment with reorientation of the nanoparticles were found to occur in a two-phase field of protoxide and spinel structure at a relatively lowhomologous temperature (T/T m $0.45) [1]. Paracrystalline distributions of defect clusters were observed in such (Ni 0.33 Co 0.67 ) 1Àd O polycrystals [2].…”

On the spinel formation in Co1−xO/Co2TiO4 composites via reactive sintering, exsolution and oxidation

“…By careful scrutiny of phases and microstructures in the Co 1 À x O/Co 2 TiO 4 composites prepared by a reactive sintering route from the Co 1 À x O and TiO 2 powders, the combined effects of Ti 4+ exsolution and cobalt oxidation to form spinel nanoparticles from the protoxide Co 1 À x O upon cooling in air were clarified. We focused also on the reorientation of the inter-and intragranular Co 2 TiO 4 spinel particles via a Brownian-type rotation/ coalescence process analogous to the cases in other ceramic composites prepared via a solid-state sintering route [2,[4][5][6][7][8] or oxidation decomposition route [9].…”