d⁶versus d¹⁰, Which Is Better for Second Harmonic Generation Susceptibility? A Case Study of K₂TGe₃Ch₈ (T = Fe, Cd; Ch = S, Se)

Abstract

8 are mainly contributed by the chemical characteristics of Cd compared with Fe, which are elucidated by nonlinear optical property measurements, electronic structure calculations, and density functional theory calculations. The [CdS 4 ] tetrahedra within K 2 CdGe 3 S 8 exhibit a higher degree of distortion and larger volume compared to the [FeS 4 ] tetrahedra in K 2 FeGe 3 S 8 . This study possesses a good platform to investigate how d-block elements contribute to the SHG response. The fully occupied d 10elements are better for SHG susceptibility than d 6 -elements in this study. K 2 CdGe 3 S 8 is a good candidate as an infrared nonlinear optical material of high SHG response (2.1× AgGaS 2 , samples of particle size of 200−250 μm), type-I phase-matching capability, high laser damage threshold (6.2× AgGaS 2 ), and good stability.

Heteroanionic LaBrVIO4 (VI = Mo, W): Excellence in Both Nonlinear Optical Properties and Photoluminescent Properties

“…The W2–O7–W2 bond angles are 158.1(4)° and 158.7(4)° for LaBrWO 4 and (La 0.9 Dy 0.1 )­BrWO 4 , respectively. The importance of the distortion degree of structure motifs contributing to NLO materials has been reported in many works. − ,− The 1D [VIO 5 ] VI = Mo,W strands are similar to many well-known lambda (Λ)-shaped building units in many NLO optical materials, such as K 5 Nb 3 O 3 F 14 ·H 2 O, K 10 (Nb 2 O 2 F 9 ) 3 F, K 10 (Nb 2 O 2 F 9 ) 3 I 2 , β-Ba 2 [VO 2 F 2 (IO 3 ) 2 ]­IO 3 , K 5 (W 3 O 9 F 4 ) (IO 3 ), Sn 2 B 5 O 9 Br, etc., where the distortion of Λ-shaped building units plays a critical role in dominating NLO properties. A summary of compounds constituting Λ-shaped building units is tabulated in Table S7. ,,− LaBrWO 4 can also host more rare earth elements than LaBrMoO 4 , which exhibits intriguing PL properties.…”

“…The small amounts of dysprosium doping also dramatically enhance the SHG response of (La 0.9 Dy 0.1 )­BrWO 4 . Understanding how to enhance SHG in NLO materials is critical for pushing this field forward. − In addition to the SHG response, LaBrWO 4 also possesses better PL properties than LaBrMoO 4 (vide infra). Our further analysis confirms that the distorted 1D [VIO 5 ] VI = Mo,W strands play a critical role in determining the optical properties of LaBrVIO 4 (VI = Mo and W) (vide infra).…”

Revisiting two thiophosphate compounds constituting d0transition metal HfP2S6and d10transition metal α-Ag4P2S6as multifunctional materials for combining second harmonic generation response and photocurrent response

“…The experimental results indicate that HfP 2 S 6 is not a phase-matching material, which may originate from the strong absorption and the presence of small amounts of HfS 2 impurity. 103,104 The SHG response of α-Ag 4 P 2 S 6 is about ∼0.61 × AGS for the sample of particle size of 225 μm. More importantly, α-Ag 4 P 2 S 6 has a high LDT of ∼3.2 × AGS (Table S1†).…”

Visualizing the alignment of lone pair electrons in La3AsS5Br2 and La5As2S9Cl3 to form an acentric or centrosymmetric structure

“…Compared with centrosymmetric solids, acentric solids draw growing attention from the research community due to the chance of studying directional physical properties such as second harmonic generation, 1–15 nonreciprocal responses, 16–21 etc. From a chemistry perspective, various strategies have proved efficient to influence the creation of a noncentrosymmetric (NCS) structure, including incorporating second order Jahn–Teller distortion 22,23 and conjugated structure motifs such as distorted FeS 4 14,24 or GeS 4 tetrahedra, 25,26 WO 5 , 27 LaO 6 Br 3 , 28 etc. Another systematic way to influence a NCS structure is through incorporating atoms with stereochemically active lone pairs (SCALPs), including Tl + , Sn 2+ , Pb 2+ , As 3+ , Sb 3+ , Bi 3+ , Te 4+ , etc.…”

“…Compared with centrosymmetric solids, acentric solids draw growing attention from the research community due to the chance of studying directional physical properties such as second harmonic generation, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] nonreciprocal responses, [16][17][18][19][20][21] etc. From a chemistry perspective, various strategies have proved efficient to influence the creation of a noncentrosymmetric (NCS) structure, including incorporating second order Jahn-Teller distortion 22,23 and conjugated structure motifs such as distorted FeS 4 14, 24 or GeS 4 tetrahedra, 25,26 WO 5 , 27 LaO 6 Br 3 , 28 etc. Another systematic way to influence a NCS structure is through incorporating atoms with stereochemically active lone pairs (SCALPs), including Tl + , Sn 2+ , Pb 2+ , As 3+ , Sb 3+ , Bi 3+ , Te 4+ , etc., with many successful examples such as Tl + in Tl 4 (OH) 2 CO 3 29 and TlXF 3 (X = Be, Sr); 30 Sn 2+ in Sn 2 P 2 S 6 , [31][32][33] Sn 2 PO 4 X (X = F, Cl), 34 and Sn[B 2 O 3 F 2 ]; 35 Pb 2+ in Pb 2 P 2 S 6 , 36 Pb 3 P 2 S 8 , 15 Pb 13 O 6 Cl 4 Br 10 , 37 Pb 13 O 6 Cl 7 Br 7 , 37 and Pb 13 O 6 Cl 9 Br 5 ; 37 As 3+ in K 3 AsS 4 , 38 Li...…”