Effects of different types of rare earth oxide additives on the properties of silicon nitride ceramic substrates. Issue 9 (15th June 2019)

• Record Type: Journal Article
• Authors: Liu, Wei; Tong, Wenxin; Lu, Xinxin; Wu, Shanghua
• Is Part Of: Ceramics international. Volume 45:Issue 9(2019)
• Page Start: 12436
• Page End: 12442
• Publication Date: 2019-06-15
• Subjects: Si3N4 -- Microstructure-final -- Mechanical properties -- Thermal conductivity; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2019.03.176
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: 5 wt% of different types of rare earth oxides (Re2 O3, Re = Lu, La, Yb, Y, Nd, Er, Sm, Ce, Dy, Eu, Gd) and 2 wt% MgO as additives were selected in this study based on previous studies on rare earth oxide additive concentrations. The effects of rare earth oxide type on the microstructure, phase composition, thermal conductivity, mechanical properties, and dielectric properties of silicon nitride ceramics were systematically investigated. Samples doped with rare earth oxides with smaller ionic radii (such as Yb2 O3, Lu2 O3, Er2 O3, and Dy2 O3 ) showed higher thermal conductivity. Samples doped with Eu2 O3 and Yb2 O3 showed fine-grained microstructures due to inhibition of dissolution, diffusion, and re-precipitation of silicon nitride. Silicon nitride ceramics doped with Eu2 O3 showed the lowest thermal conductivity and dielectric constant (<8) compared to the other samples. Samples doped with Y2 O3 showed the maximum fracture toughness of 8.4 MPa m 1/2 . Meanwhile, it was observed that the addition of rare earth oxides with the largest (La2 O3 ), moderate (Eu2 O3 ), and smallest (Lu2 O3 ) ionic radii could all effectively improve the fracture toughness of silicon nitride ceramics. Samples doped with rare earth oxides with large ionic radii, such as Nd2 O3, Ce2 O3, and La2 O3, had larger dielectric constants. The dielectric loss of silicon nitride ceramics prepared here was between 0.005 and 0.02 and dependence on the type of rare earth oxide was not observed.