High-frequency properties of oil-phase-synthesized ZnO nanoparticles * Ding Hao-Feng(丁浩峰) a)b) , Yang Hai-Tao(杨海涛) b) † , Liu Li-Ping(柳丽平) b) , Ren Xiao(任 肖) b) , Song Ning-Ning(宋宁宁) b) , Shen Jun(沈 俊) c) , Zhang Xiang-Qun(张向群) b) , Cheng Zhao-Hua(成昭华) b) , and Zhao Guo-Ping(赵国平) a)b) ‡