News & Analysis
/
Article

Researchers demonstrate breakthrough piezoelectric possibility with Mg-Nb-AlN

SEP 11, 2017
With seminal experimentation, Japanese researchers show that Mg-Nb added to AlN increases the piezoelectric effect with Nb exhibiting multiple valences.
Researchers demonstrate breakthrough piezoelectric possibility with Mg-Nb-AlN internal name

Researchers demonstrate breakthrough piezoelectric possibility with Mg-Nb-AlN lead image

Aluminum nitride (AlN) is a very promising piezoelectric material, especially for energy harvesting and microelectromechanical systems, and also for improved film bulk acoustic resonators (FBARs) utilized in next generation smart phones. Akiyama et al. have demonstrated that the piezoelectric coefficient d33,f, dramatically increases with the addition of scandium (Sc) to AlN films. However, Sc, which is trivalent, is very expensive, so researchers have theorized combining bivalent and tetravalent elements as an alternative. Recently, a group of Japanese researchers have demonstrated that adding a magnesium (Mg) and niobium (Nb) alloy – an inexpensive option – greatly improves AlN d33,f. The researchers report their findings in Applied Physics Letters.

Lead author Masato Uehara explains that the researchers chose bivalent Mg because of its chemical stability and economic viability. After testing a few elements, they found AlN with Nb and Mg compares well to Sc. The researchers prepared the Mg-Nb-AlN by multiple element co-sputtering using three metal targets. In testing for piezoelectricity, the researchers found marked improvements when Mg and Nb were added simultaneously. Moreover, the optimal piezoelectric effect was at a 1.6 Mg-Nb ratio, while the conventional theory indicated it would be 2. With X-ray photoelectron spectroscopy, the Mg was confirmed as bivalent, while Nb had multiple valences, which supported the 1.6 ratio.

The researchers studied the crystalline structure of Mg-Nb-AlN, which had similar characteristics to (Sc,Al)N, but Uehara says future work should explore in more depth its crystalline structure and in connection to Mg-Nb valences. Uehara highlights that this research demonstrates that the Mg-Nb addition causes a giant increase in the AlN piezocoefficient and that the d33,f increase is related to the multiple states of Nb.

Source: “Giant increase in piezoelectric coefficient of AlN by Mg-Nb simultaneous addition and multiple chemical states of Nb,” by Masato Uehara, Hokuto Shigemoto, Yuki Fujio, Toshimi Nagase, Yasuhiro Aida, Keiichi Umeda, and Morito Akiyama, Applied Physics Letters (2017). The article can be accessed at https://doi.org/10.1063/1.4990533 .

Related Topics
More Science
/
Article
Pentagonal-shaped photonic-crystal lightsails could one day propel tiny spacecraft to other stars.
APS
/
Article
A new study of complex systems supports a growing trend that focuses more on analyzing a system’s collective behavior rather than on trying to uncover the underlying interaction mechanisms.
AAS
/
Article
An team of astronomers has obtained high-resolution images of all known protoplanetary disks in the Lupus star-forming region
AAS
/
Article
Could there have been two massive black holes in our galaxy’s center at one time? New modeling of fast-moving stars in the Milky Way’s halo suggests the answer is yes.