In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free p...In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free piezoelectric systems have been widely researched, i.e., perovskites, bismuth layer-structured ferroelectrics, and tungsten-bronze type ferroelectrics. This article presents a new type of environmental friendly piezoelectric material with simple structure, the transition-metal（TM）-doped ZnO. Through substituting Zn2＋ site with small size ion, we obtained a series of TM-doped ZnO with giant piezoresponse, such as Zno.975Vo.o250 of 170 pC/N, Zn0.94Cr0.06O of 120 pC/N, Zn0.913Mn0.0870 of 86 pC/N and Zn0.988Fe0.0120 of 127 pC/N. The tremendous piezoresponses are ascribed to the introduction of switchable spontaneous polarization and high permittivity in TM-doped ZnO, The microscopic origin of giant piezoresponse is also discussed. Substitution of TM ion with small ionic size for Zn2＋ results in the easier rotation of noncollinear TM-O1 bonds along the c axis under the applied field, which produces large piezoelectric displacement and corresponding piezoresponse enhancement. Furthermore, it proposes a general rule to guide the design of new wurtzite semiconductors with enhanced piezoresponses. That is, TM-dopant with ionic size smaller than Zn2＋ substitutes for Zn2＋ site will increase the piezoresponse of ZnO significantly. Finally, we discuss the improved per- formances of some TM-doped ZnO based piezoelectric devices.展开更多
基金supported by the National Hi-tech (R&D) Program of China (Grant Nos. 2007AA03Z426 and 2009AA034001)the National Natural Science Foundation of China (Grant Nos. 50871060 and 50772055)the National Basic Research Program of China (Grant No. 2010CB832905)
文摘In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free piezoelectric systems have been widely researched, i.e., perovskites, bismuth layer-structured ferroelectrics, and tungsten-bronze type ferroelectrics. This article presents a new type of environmental friendly piezoelectric material with simple structure, the transition-metal（TM）-doped ZnO. Through substituting Zn2＋ site with small size ion, we obtained a series of TM-doped ZnO with giant piezoresponse, such as Zno.975Vo.o250 of 170 pC/N, Zn0.94Cr0.06O of 120 pC/N, Zn0.913Mn0.0870 of 86 pC/N and Zn0.988Fe0.0120 of 127 pC/N. The tremendous piezoresponses are ascribed to the introduction of switchable spontaneous polarization and high permittivity in TM-doped ZnO, The microscopic origin of giant piezoresponse is also discussed. Substitution of TM ion with small ionic size for Zn2＋ results in the easier rotation of noncollinear TM-O1 bonds along the c axis under the applied field, which produces large piezoelectric displacement and corresponding piezoresponse enhancement. Furthermore, it proposes a general rule to guide the design of new wurtzite semiconductors with enhanced piezoresponses. That is, TM-dopant with ionic size smaller than Zn2＋ substitutes for Zn2＋ site will increase the piezoresponse of ZnO significantly. Finally, we discuss the improved per- formances of some TM-doped ZnO based piezoelectric devices.
