Polar surface structure of oxide nanocrystals revealed with solid-state NMR spectroscopy oleh Junchao Chen, Xin-Ping Wu, Michael A. Hope, Kun Qian, David M. Halat, Tao Liu, Yuhong Li, Li Shen, Xiaokang Ke, Yujie Wen, Jia-Huan Du, Pieter C. M. M. Magusin, Subhradip Paul, Weiping Ding, Xue-Qing Gong, Clare P. Grey, Luming Peng