Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes
Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes
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DOI：
10.1063/1.3275868
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发表时间：
2010-01-01
影响因子：
3.2
通讯作者：
Guillermin, M.
中科院分区：
文献类型：
--
作者：
Heiroth, S.;Koch, J.;Guillermin, M.
研究了氧化钇稳定氧化锆 (YSZ) 的激光烧蚀特性与不同纳秒-[ArF、KrF 和 XeCl 准分子； Nd:YAG（钇铝石榴石）（第四次谐波）]和飞秒激光源[Ti:蓝宝石（基波和三次谐波）]。颗粒喷射会影响脉冲激光沉积 (PLD) 制备的涂层的质量，对此进行了详细分析。对于 8-9.5 mol% Y2O3 掺杂、完全稳定的氧化锆（8YSZ 和 9.5YSZ）靶材，纳秒激光脉冲会在微秒至毫秒的时间尺度内导致严重的热机械表面裂纹和微米级碎片剥落。由于材料固有的脆性，在所有测试条件下，PLD 沉积的完全稳定的 YSZ 涂层都含有颗粒。低掺杂部分稳定氧化锆 (3YSZ) 表现出优异的断裂韧性，这归因于拉曼光谱检测到的激光诱导部分转变为单斜晶相，这使得能够使用纳秒紫外激光辐射在 1.2-1.5 J/cm(2) 的中等通量下通过传统 PLD 沉积无颗粒致密薄膜。超短激光脉冲的烧蚀动力学从根本上不同于纳秒范围，例如通过时间分辨阴影成像和光散射实验所证明的。飞秒脉冲可防止微米级碎片脱落，但总是会导致亚微米颗粒的明显喷射。由此产生的 PLD 涂层是多孔的，并且由纳米粒子团聚体组成，因此具有很大的表面粗糙度。与纳秒和飞秒 UV 脉冲相比，飞秒 NIR 脉冲的材料去除率高出 2.5-10 倍。烧蚀指标，即阈值注量和有效吸收率，主要取决于激光波长，而脉冲持续时间、目标微观结构和掺杂剂水平次要。有证据表明，孵化效应在 YSZ 的纳秒和飞秒激光烧蚀中发挥着重要作用，能够在相对较低的亚带隙光子能量注量下去除材料。
The laser ablation characteristics of yttria-stabilized zirconia (YSZ) have been investigated as a function of the target microstructure and dopant level for different nanosecond- [ArF, KrF, and XeCl excimers; Nd:YAG (yttrium aluminum garnet) (fourth harmonic)] and femtosecond-laser sources [Ti:sapphire (fundamental and third harmonic)]. Particle ejection, which compromises the quality of coatings prepared by pulsed laser deposition (PLD), was analyzed in detail. Nanosecond-laser pulses cause a severe thermomechanical surface cracking and exfoliation of micron-sized fragments on a microsecond to millisecond time scale in the case of 8-9.5 mol % Y2O3-doped, fully stabilized zirconia (8YSZ and 9.5YSZ) targets. As a consequence of the intrinsic material brittleness, fully stabilized YSZ coatings deposited by PLD contained particles for all tested conditions. Lower doped partially stabilized zirconia (3YSZ) exhibits a superior fracture toughness attributed to a laser-induced partial transition to the monoclinic phase, detected by Raman spectroscopy, which enables the deposition of particle-free dense thin films by conventional PLD using nanosecond-UV laser radiation at moderate fluences of 1.2-1.5 J/cm(2). The ablation dynamics of ultrashort laser pulses differ fundamentally from the nanosecond regime as evidenced, e.g., by time-resolved shadowgraphy and light scattering experiments. Femtosecond pulses prevent the exfoliation of micron-sized fragments but result invariably in a pronounced ejection of submicron particles. The resulting PLD coatings are porous and reveal a large surface roughness as they consist of an agglomeration of nanoparticles. Femtosecond-NIR pulses provide a factor of 2.5-10 higher material removal rates compared to nanosecond- and femtosecond-UV pulses. The ablation metrics, i.e., threshold fluence and effective absorptivity, mainly depend on the laser wavelength while the pulse duration, target microstructure, and dopant level are of minor importance. Evidence is presented that incubation effects play a significant role in nanosecond- and femtosecond-laser ablations of YSZ enabling material removal at comparatively low fluences for sub-bandgap photon energies.