Congratulation for the 1st publication of Laboratory of Advanced Materials in 2020
Title: Multi-scale defects in ZnO thermoelectric ceramic materials co-doped with In and Ga
Authours: Anh Tuan Thanh Pham, Tuyen Luu Anh, Ngoc Kim Pham, Hanh Kieu Thi Ta, Truong Huu Nguyen, Dung Van Hoang, Hoa Thi Lai, Vinh Cao Tran, Jong-Ho Park, Jae-KiLee, Sungkyun Park, Ohtaki Michitaka, Su-Dong Park, Hung Nguyen Quang, Thang Bach Phan
Journal: Ceramics International; Volume 46, Issue 8, Part A, 1 June 2020, Pages 10748-10758
In this work, several X-ray and nuclear analysis techniques were used to examine ZnO materials co-doped with In and Ga, or IGZO materials. X-ray diffraction analysis, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy revealed multi-scale defects in the materials. A nanoscale secondary Ga2Zn9O12 spinel phase, mesoscale grain boundaries, and atomic-scale lattice defects were detected. The lattice defects included oxygen vacancies, zinc vacancies, and complex defects. Positron annihilation spectroscopy and Doppler broadening spectroscopy provided evidence of interactions between charge carriers and defects sites, which explained the low thermal conductivities of the IGZO materials (κtotal ≈ 3.9 W/mK) at 773 K. This combination of X-ray and nuclear analytical techniques can be viewed as a novel approach for investigating the thermoelectric properties of materials with complex crystal structures that contain atomic-scale voids, nanoscale secondary phases, and mesoscale grain boundaries.