Transparent ZnAl₂O₄ ceramics fabricated by spark plasma sintering

Abstract

Highly transparent zinc aluminate ceramics were fabricated by the solid-state reaction using a spark plasma sintering machine. The sintered body exhibited a microstructure consisting of submicron-sized grains and extremely low porosities. Annealing of the sintered body in air improved the transmission close to the theoretical limit in a wavelength range of 15¯m. The band gap energy estimated from the absorption coefficient was 4.3 eV. The Young's modulus and the bulk modulus measured for the fully dense zinc aluminates were 282 and 211 GPa, respectively.

Theoretical study on composition‐dependent properties of ZnO·nAl2O3 spinels. Part II: Mechanical and thermophysical

“…The collected experimental values are also given. The theoretical elastic moduli coincide with the reported data 42,55,56 . The variation of the derived Poisson's ratio is shown in Figure 4B as well.…”

“…The red and dark cyan lines represent Equations () and (), respectively. The experimental results, which were collected from the ICSD database and rechecked in the corresponding literatures, 21,23,54,55 are indicated as scatters. The inset presents the derived theoretical density ( ρ )…”

“…The composition‐dependent (A) hardness and (B) elastic properties of ZnO· n Al 2 O 3 ( n = 1–4) as well as the polyhedral hardness and bulk modulus. The experimental elastic moduli of a pore‐free ZnAl 2 O 4 ceramic, 12 the synthetic Zn 0.97 Al 2.02 O 4 powder 55 and a natural single crystal with the composition of Zn 0.74 Fe 0.18 Mg 0.08 Al 1.99 O 4 63 are shown and indicated, respectively, as pentagons, diamond and crosses. The borders of a shadow area indicate the results from GGA and LDA, respectively…”

Microstructure, doping and optical properties of Co2+:ZnAl2O4 transparent ceramics for saturable absorbers: Effect of the ZnF2 sintering additive

“…Recently, transparent ZnAl2O4 ceramics were obtained by Goldstein et al by hot isostatic pressing at 1550 °C using hydrothermally synthesized powders [36]. Since then, several studies dedicated to undoped gahnite ceramics [37][38][39][40] and only few devoted to Co 2+ -doped ones [29] appeared. More recently, Ni 2+ -doped ZnAl2O4 transparent ceramics [9] were prepared by melting-vaporing procedure using TeO2 and Na2O as melting agents.…”

Preparation of ZnO·2.56Al2O3 Transparent Ceramics by Aqueous Gelcasting and Hot Isostatic Pressing

“…凝胶注模(也称作注凝成型)是一种原位聚合成 型技术, 与干压和冷等静压相比, 能使初坯具有更 好的均匀性和更高的致密度 [9][10] 。同时对于复相组 成经过反应烧结生成单相的陶瓷, 凝胶注模成型能 使两相均匀分散, 反应烧结后的陶瓷不会因为混合 不均而造成成分不均一的现象 [11] 。另外, 此成型方 式还能制备复杂形状、大尺寸样品, 减少后期机械 加工, 更适合于工业应用 [12] [15] , ZnO•2.56Al 2 O 3 透明陶瓷的光学透过域变窄, 红外截止波长由 7 μm 缩短为 6.5 μm 左右, 这与不同 n 值镁铝尖晶石的变 化趋势一致 [7] , 可能是 Al 含量的增加导致尖晶石晶 体结构变化所造成的。样品在 3 μm 左右有两处较强 的振动吸收峰, 这可能是测试过程中样品表面吸附 的-OH 伸缩振动造成的 [7,16] ZnAl 2 O 4 10.5 [5] 282 [17] ---石晶格常数更小, 晶格抗压缩性能得以提高 [18]…”