Sintering characteristics of nanocrystalline ZnO

Aluminum doped zinc oxide sputtering targets obtained from nanostructured powders: Processing and application

“…As expected, from XRD results no influence of holding time or temperature rise was observed in terms of spinel phase concentration between 1150 and 1400 • C. Second phase quantification show similar amounts of spinel phase for all analyzed targets, (approximately 3.4 wt% ZnAl 2 O 4 ) which is consistent with theoretical values considering that we are working with a constant doping level above the solid solubility of Al in ZnO. 31,33 The microstructures of Al-doped ZnO ceramic targets sintered at different temperatures (1100-1400 • C) for 2 h are presented in Fig. 9a-d. As shown, ZnAl 2 O 4 spinel phase (darker spots confirmed by EDS analysis) appeared well dispersed inside the ZnO matrix for all sintered targets and become more visible for higher sintering temperatures (growing of ZnAl 2 O 4 crystals with temperature).…”

“…Preferably, secondary phase ZnAl 2 O 4 forms in grain boundaries during the sintering densification, inhibiting the grain growth and reducing the driving force for sintering of Al-doped ZnO composites. 31,35 However, using higher temperatures the number of grain boundaries decreases substantially with grain growth and a part of the spinel phase is embedded within the grains (Fig. 9d).…”

“…Earlier densification and higher sintering rate observed on AM AZO compacts comparing to BM AZO can be explained by several factors like the higher surface energy related to smaller particle size and higher specific surface area, 28,29 together with an increased fraction of mass transport by grain-boundary diffusion, resulting from the large boundary area associated to nanoparticles. 30,31 According to these results, the sintering study performed in this work was restricted to AM AZO powder since it allows us to achieve higher densities at significantly lower temperatures than BM AZO powder. Fig.…”

Role of defects in tailoring structural, electrical and optical properties of ZnO

“…Suitable choice of temperature [66,[109][110][111], time [112,113] and annealing ambient environment [76,111,114], rate of heating and cooling of annealing [22,115,116] has been proved beneficial to monitor material properties in a controllable fashion. However, an effective control over thermally generated unwanted defects could not be established till date.…”

Microstructure and Density of Sintered ZnO Ceramics Prepared by Magnetic Pulsed Compaction

“…erefore, detailed analyses are required to synthesize high-quality compacts and to understand the effects of compacting conditions on the physical properties of the sintered ZnO ceramics [15][16][17][18][19]. In this study, three different compacting methods, namely, (1) conventional uniaxial pressing, (2) cold isostatic pressing (CIP), and (3) magnetic pulsed compaction (MPC), were used for fabricating high-quality sintered ZnO ceramics, and the properties of the three different samples were compared.…”