Preparation and characterization of solid-state sintered aluminum-doped zinc oxide with different alumina contents

Abstract

Aluminum-doped zinc oxide (AZO) ceramics with 0−2·5 wt.% alumina (Al 2 O 3 ) content were prepared using a solid-state reaction technique. It was found that AZO grains became finer in size and more irregular in shape than undoped ZnO as the Al 2 O 3 content increased. Addition of Al 2 O 3 dopant caused the formation of phase transformation stacking faults in ZnO grains. The second phase, ZnAl 2 O 4 spinel, was observed at the grain boundaries and triple junctions, and inside the grains. In this study, a 3-inch circular Al 2 O 3 (2 wt.%)-doped ZnO ceramic target sintered at 1500 • C for 6 h has a relative density of 99·8% with a resistivity of 1·8 × 10 −3 -cm. The AZO film exhibits optical transparency of 90·3% in the visible region and shows an electrical resistivity of 2·5 × 10 −3 -cm.

Zinc aluminate spinel impurity phase in Al doped ZnO ceramic target and pulsed laser ablated films: Curse or blessing?

“…This is expected as the substrate temperature remains unaltered. No diffraction peak due to ZnAl 2 O 4 phase has been primarily detected in the films similar to earlier report (Chou et al, 2011). The value of the reaction enthalpy of ZnAl 2 O 4 is only 0.83 eV (negative) which indicates that the formation of a spinel structure is highly favored thermodynamically (Dixit et al, 2011).…”

“…The presence of multiple peaks of ZnO hexagonal structure indicates that the target ZnO material is polycrystalline in nature. The (220), (311), (400), (331), (422), (511), (440), (620) diffraction peaks corresponding to the cubic ZnAl 2 O 4 spinel phase also appear predominantly for the targets 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 sintered from 900 o C (Chou et al, 2011). The inset in the Fig.1 clearly shows a gradual increase in the intensity of the (422), (511), (440) peaks of ZnAl 2 O 4 phase with an increase in the sintering temperature.…”

“…Therefore, the ceramic targets sintered at and above 900 o C, contain ZnAl 2 O 4 spinel phase in addition to the major ZnO phase. Chou et al (Chou et al, 2011) have synthesized Al-doped ZnO ceramic target by solid state reaction of ZnO and Al 2 O 3 dopant sintered at 1500 o C for 6 hours and the XRD patterns of their Al 2 O 3 -doped ZnO samples also showed the presence of a second ZnAl 2 O 4 spinel phase. It has also been reported that when the Al 2 O 3 content has been raised from 1·5 to 2·5 wt%, the relative peak intensity of ZnAl 2 O 4 spinel phase has been increased (Fang et al, 2003).…”

Fabrication of titanium zinc oxide (TZO) sol–gel derived nanostructured thin film and investigation of its optical and electrical properties

“…In recent years, ZnO has attracted much attention as a replacement for ITO because of desirable properties such as high transmittance, non-toxicity, and lower cost. ZnO is a natural n-type semiconductor metal oxide and its transmittance in the visible region is extremely high [6][7][8][9]. ZnO thin films are also highly resistive.…”

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

“…is is because ZnO exhibits high transmittance in the visible region, and its electrical resistivity can be easily controlled by doping with elements such as Al [5][6][7][8] and Ga [9][10][11]. ZnO is also advantageous from the economic and the environmental viewpoints owing to its low cost and nontoxic properties [12][13][14].…”