Syntheses, Structures, and Nonlinear Optical Properties of Quaternary Chalcogenides: Pb₄Ga₄GeQ₁₂ (Q = S, Se)

Abstract

Two noncentrosymmetric isostructural compounds Pb4Ga4GeQ12 (Q = S, Se) with their own structure type have been synthesized by solid-state reactions at high temperature. They crystallize in the tetragonal space group P42(1)c (No. 114) with a = 12.673(2) Å and c = 6.128(2) Å, and a = 13.064(7) Å and c = 6.310(5) Å, respectively, and Z = 2. The major structure motif features a three-dimensional framework constructed by chains of GaQ4 tetrahedra that are interconnected by separated GeQ4 tetrahedra at regular intervals. Interestingly, such a [Ga4GeQ12](8-) framework is flexible to allow the addition of Ag(+) or Li(+) to occupy the embedded A- or B-type of vacancies to generate the previously reported [AgGa5Q12](7-) or [LiGa5Q12](7-) interstitial compounds without symmetry breaking. The title compounds (Q = S, Se) have optical band gaps of 2.35 and 1.91 eV, respectively, and wide IR transparent regions of 0.80-22.5 and 0.75-22.5 μm, respectively. Significantly, the powder Pb4Ga4GeSe12 sample exhibits a strong second-harmonic-generation (SHG) response that is ∼2 times that of the benchmark AgGaS2 at a laser radiation of 2.05 μm with a non phase-matchable behavior. The calculated d36 coefficient agrees well with the experimental observation. The density functional theory (DFT) calculations suggest that the SHG response originates from the electronic transitions from Se 4p states to Pb 6p, Ga 4p, and Ge 4p states.

Vibration uncoupling of germanium with different valence states lowers thermal conductivity of Cs2Ge3Ga6Se14

“…1). For instance, the Ge 4+ tends to adopt a tetrahedral coordination with four nearly equidistant Ge-Q (Q = S, Se, Te) bonds [12][13][14][15][16][17][18][19], the Ge 3+ usually forms a Ge-Ge metal bond to fulfill its four coordination and generate the characteristic ethane-like Ge 3+ 2 Q 6 dimer [20][21][22][23][24][25][26][27], and the Ge 2+ is often found in an octahedron with six Ge-Q bonds [27,30]. Various arrangements of these structure building units lead to great diversity of structures [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Syntheses, crystal structures, and NLO properties of the quaternary sulfides RE3Sb0.33SiS7 (RE=La, Pr)

“…Tetrahedrally coordinated triel or tetrel metal chalcogenides have drawn considerable attentions not only for their diverse structural features but also for their second-order nonlinear optical (NLO) activity, such as: AgGaS 2 (AGS) [1], LiGaQ 2 (Q = S, Se, Te) [2], LiInQ 2 (Q = S, Se) [3], BaGa 4 Q 7 [4], K 2 Hg 3 Ge 2 S 8 [5], Li 2 Ga 2 GeS 6 [6], Li 2 In 2 MQ 6 (M = Si, Ge) [7], BaGa 2 MS 6 (M = Si, Ge) [8], Ba 2 BiInS 5 [9], Ba 2 InYSe 5 [10], Ba 4 CuGa 5 Q 12 (Q = S, Se) [11], Li 2 CdGeS 4 [12], Y 3 Zn 0.5 SiS 7 [13], Eu 2 Ga 2 GeS 7 [14], Pb 4 Ga 4 GeQ 12 (Q = S, Se) [15], Ba 3 AGa 5 Se 10 Cl 2 (A = K, Rb, Cs) [16], and ACd 4 Ga 5 Q 12 (A = K, Rb, Cs; Q = S, Se) [17]. Among them, AgGaS 2 is the well-known middle-infrared (mid-IR) benchmark NLO material exhibiting a high second-harmonic generation (SHG) coefficient and a wide transparent range.…”

A Promising White‐Light‐Emitting Material Constructed from Encapsulating Eu3+/Tb3+ Hybrid Ions into a Robust Microporous Metal–Organic Framework

“…Especially, Eu 3+ and Tb 3+ ions can be used extensively to generate intense red and green fluorescence, respectively. [31][32][33] Thus, a host framework with blue emission can generate white-light emission by introducing Eu 3+ and Tb 3+ ions. On the basis of the above consideration, the novel {[Zn(H 2 thca) 0.5 (tib)]·5H 2 O} n [1; H 6 thca = p-terphenyl-3,3′,3′′,5,5′ ,5′′-hexacarboxylic acid; tib = 1,3,5-tris(imidazolyl)benzene] MOF with blue emission was successfully synthesized for the first time by hydrothermal treatment.…”