Screening Nitrides with High Debye Temperatures as Nonlinear Optical Materials

Abstract

Nitrides, in which P in pnictides is substituted by N, are proposed as nonlinear optical (NLO) materials. Herein, 34 asymmetric nitrides collected in the Inorganic Crystal Structure Database (ICSD) are evaluated and predicted by first-principles calculations. As a result, three Si-nitrides possessing wide band gaps and large NLO coefficients are screened out: BeSiN2 (6.66 eV, d24 = −1.09 pm/V), LiSi2N3 (6.51 eV, d15 = −1.38 pm/V), and LaSi3N5 (4.73 eV, d14 = −0.98 pm/V). In addition, LiGaS2-like structure MoZn3N4 is a promising infrared NLO material with a large NLO coefficient d24 = −16.70 pm/V, which is 1.2 times that of the infrared benchmark AgGaS2 (d36 = 13.4 pm/V); meanwhile, its band gap of 3.05 eV is better than that of AgGaS2 (2.73 eV). Moreover, MoZn3N4 with a higher Debye temperature of 795.5 K, which suggests higher sound speeds and longer phonon lifetimes, thus should exhibit higher thermal conductivity. These nitrides represent a new exploration family of NLO materials.