الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Piezoelectric materials find applications in microelectromechanical systems (MEMS), such as surface acoustic wave (SAW) resonators, radio frequency (RF) filters, resonators, and energy harvesters. Inducing of such property in 2D systems via reducing the dimensionality of their corresponding 3D bulk structures which are intrinsically non-piezoelectric, because they show an inversion center of symmetry, is here explored. At first, the structural, electronic, mechanical, and piezoelectric properties of both 3D and 2D rare earth monochalcogenides RmX (Rm= Tm, Yb, Lu, and X= S, Se, Te) using the CRYSTAL code are investigated. The analysis of the structural, electronic, mechanical, and piezoelectric properties as a function of periodic sequence of Rm and X atoms is introduced and discussed. Interestingly, the 2D of LuX compounds display a buckled structure, where the Lu and X atoms protrude from the monolayer surface leading to the appearance of an additional outof-plane piezoelectric effect; (e31= 2104.84, 1770.28, 1689.79 pC/m, and d31 = 56.37, 49.76, and 147.90 pm/V for LuS, LuSe, and LuTe, respectively). Such response is more than two orders of magnitude larger that of recently calculated 2D ferroelectric MXenes, and is nearly thirty times larger than the commonly used AlN and GaN bulk structures. Furthermore, the obtained diminutive elastic constants, comparing to other 2D materials, confirm the flexibility and softness of the considered 2D systems. Indeed, the synthesis of 2D materials is usually challenged rather than it’s corresponding 1D materials, and this actually confirmed by the discovery of carbon nanotube in 1991, comparing to the discover of it’s corresponding 2D graphene in 2004. Hence, we studied one dimensional materials (nanotubes) that are expected to be easier to be fabricated. Particularly, Metal oxide nanotubes (BeO, MgO, ZnO, CaO, CdO ) are investigated in the range from n = 6 (24 atoms in the unit cell) to 48 (192 atoms in the cell). A variety of properties of the (n,0) family of the single-walled zigzag metal oxide nanotubes including relaxation energy, rolling energy, formation energy, electronic band gap, electronic and nuclear contributions of the elastic constant and piezoelectric coefficients (direct and converse) have been studied. In the limit of large tube radius, the tendency towards the hexagonal monolayer has been confirmed. These metal oxide nanotubes have a significant piezoelectric response, which makes them appropriate for nanoelectromechanical applications.