Optical and mechanical properties of amorphous and crystalline yttria-stabilized zirconia thin films prepared by pulsed laser deposition
Optical and mechanical properties of amorphous and crystalline yttria-stabilized zirconia thin films prepared by pulsed laser deposition
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DOI：
10.1016/j.actamat.2010.12.029
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发表时间：
2011-04-01
期刊：
影响因子：
9.4
通讯作者：
Wokaun, A.
中科院分区：
文献类型：
--
作者：
Heiroth, S.;Ghisleni, R.;Wokaun, A.
亚微米厚的氧化钇稳定的氧化锆（YSZ）层（t = 400-700 nm），其含有3（3 YSZ）或8摩尔%采用脉冲激光沉积（PLD）技术，通过改变衬底温度和氧背景气压，可以生长出具有从各向同性非晶到柱状多晶的微结构和可变孔隙率的（8 YSZ）Y2 O3。通过纳米压痕实验和透射分光光度法研究了薄膜的微观结构和化学成分对薄膜力学性能和光学性能的影响。致密的非晶YSZ层表现出更高的光学透过率，0.2 eV的低带隙能量（5.5与5.7 eV），和高达25%的低硬度（11.9与16.0 GPa）和降低的弹性模量（231与278 GPa）相比，与结晶膜，无论掺杂剂水平。对于低压PLD方案，获得在2.18-2.23范围内的高折射率n（600）（nm），即接近单晶参考数据。在这些边界内，该指数随着Y2 O3含量的增加而降低，并且由于较低的原子堆积密度，与相同组成的结晶膜相比，非晶层的指数始终略小。YSZ层在高于1.0 Pa的背景压力下生长的折射率的逐渐减小标志着柱间空隙形式的孔的发展，并且可以用于膜孔隙率的灵敏定量。晶格顺序影响的断裂行为，作为非晶涂层显示剪切带介导的塑性变形，而结晶层产生环和表面裂纹压痕。与8 YSZ相比，结晶3 YSZ膜表现出增强的断裂韧性，这与部分稳定的氧化锆中的应力诱导向单斜相的转变有关。(C)2011 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Sub-micron thick yttria-stabilized zirconia (YSZ) layers (t = 400-700 nm) containing 3 (3YSZ) or 8 mol.% (8YSZ) Y2O3 with micro-structures ranging from isotropic amorphous to columnar polycrystalline and a variable porosity can be grown by pulsed laser deposition (PLD) varying the substrate temperature and oxygen background pressure. The dependence of the mechanical and optical properties on the film microstructure and chemical composition was investigated by nanoindentation experiments and transmission spectrophotometry. Dense amorphous YSZ layers exhibit a higher optical transmissivity, 0.2 eV lower band gap energy (5.5 vs. 5.7 eV), and up to 25% lower hardness (11.9 vs. 16.0 GPa) and reduced elastic moduli (231 vs. 278 GPa) compared with crystalline films, irrespective of the dopant level. High refractive indices, n(600) (nm), in the range 2.18-2.23, i.e. close to single crystal reference data, are obtained for the low pressure PLD regime. Within these boundaries the index decreases with increasing Y2O3 content and is consistently slightly smaller for amorphous layers compared with crystalline films of the same composition, due to a lower atomic packing density. The gradual decrease in the refractive index for YSZ layers grown at background pressures above 1.0 Pa marks the development of pores in the form of inter-columnar voids and can be used for sensitive quantification of the film porosity. The lattice order affects the fracture behaviour, as amorphous coatings show plastic deformation mediated by shear bands, while the crystalline layers yield hoop and surface cracks upon indentation. The crystalline 3YSZ films exhibit an enhanced fracture toughness compared with 8YSZ, which is related to the stress-induced transformation to the monoclinic phase in partially stabilized zirconia. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.