Enhancement of piezoelectric property in MgTMAlN (TM = Cr, Mo, W): First-principles study. (May 2021)

• Record Type: Journal Article
• Authors: Hirata, Kenji; Yamada, Hiroshi; Uehara, Masato; Anggraini, Sri Ayu; Akiyama, Morito
• Is Part Of: Journal of physics and chemistry of solids. Volume 152(2021)
• Publication Date: 2021-05
• Subjects: First-principles calculation -- Piezoelectric material -- Nitride -- Thin film; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2020.109913
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: We report large enhancement in piezoelectric response ( d 33 ) of wurtzite-AlN by addition of Mg and TM (TM = Cr, Mo, W). The piezoelectric properties of wurtzite Mg x TM y Al(1− x−y ) N was calculated by using first-principles calculations. In the composition range of 0.25 ≦ x + y ≦ 0.5, MgMoAlN and MgWAlN exhibit higher d 33 values than MgCrAlN. Among them, MgWAlN exhibited the highest d 33, where the d 33 value was found to be 10 times higher than that of AlN ( d 33 ≃ 5.3 pC/N), and 1.5 times higher than that of ScAlN ( d 33 ≃ 30 pC/N). We have also revealed that a higher elastic softening is the main contribution to the increase of d 33 in MgMoAlN and MgWAlN. From Bader charge analysis, Mg, Mo, and W have a lower charge than that of Al which indicate that the ionic bonding character is a weaker than Al. From crystal orbital Hamilton population analysis, covalent bonding between Mg–N and Mo/W–N are also found to be weaker than Al–N. Thus, a weaker ionic and covalent bonding are considered to play an important role in promoting elastic softening for MgMoAlN and MgWAlN, which eventually promoted significant enhancement in piezoelectricity. Highlights: Piezoelectric properties of Mg x TM y Al(1− x−y ) N (TM = Cr, Mo, W) are evaluated by first-principles calculation. MgTMAlN exhibits higher piezoelectric properties compared with AlN. Mg x TM y Al(1− x−y ) N (TM = Mo, W) show promise as alternatives to ScAlN. Elastic softening contributes to the increase of d 33 in MgTMAlN. Weaker ionic and covalent bonding plays a role in promoting elastic softening.