Synthesis, Crystal and Electronic Structures, Nonlinear Optical Properties, and Magnetic Properties of Two Thiophosphates: KInP2S7 and KCrP2S7

Abstract

Two thiophosphates, KInP2S7 and KCrP2S7, were structurally characterized without investigating any optical properties. Herein in this work, KInP2S7 and KCrP2S7 were revisited to investigate their optical and magnetic properties, respectively. Pure polycrystalline samples and crystals of KInP2S7 and KCrP2S7 were grown by high temperature solid state reactions, where mm-sized crystals of KCrP2S7 were collected. KCrP2S7 is isostructural to KInP2S7, which features a layered structure. KInP2S7 and KCrP2S7 possess close relationship to the layered thiophosphate M2P2S6 (M = Fe, Co, Zn, etc.). The bonding pictures of KInP2S7 were studied using the electron localization function (ELF) coupled with crystal orbital Hamilton population (COHP) calculations. The intrinsically distorted [PS4] tetrahedra and [InS6] octahedra are made by strong covalent P-S interactions and ionic In-S interactions, respectively. Electronic structure analysis confirmed that the optical properties of KInP2S7 are mainly contributed to by [PS4] tetrahedra together with small amounts of the contributions coming from [InS6] octahedra. Magnetic measurement on mm-sized crystals of KCrP2S7 verified that there is an antiferromagnetic transition around 21 K, and the Cr atoms are trivalent. KInP2S7 is predicated to be an indirect bandgap semiconductor of 2.38 eV, which is confirmed by the UV-Vis measurement of 2.4(1) eV. KInP2S7 is not a type-I phase-matching material and exhibits moderate second harmonic generation (SHG) response (0.51 × AgGaS2, sample of particle size of 100 µm). The laser damage threshold (LDT) of KInP2S7 is very high of 5.2 × AgGaS2. Bandgap engineering were undergone to enhance the SHG response of KInP2S7.

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).…”

KREP2S6 (RE = Sm, Gd, Tb, Dy): A Series of Polar Rare-Earth Thiophosphates with High Laser-Induced Damage Thresholds and Moderate Nonlinear-Optical Responses Synergistically Contributed by Isolated P2S6 Units and {[RE2S15]24–}∞ Layers

“…The tested powder LIDTs for 1 – 4 and AGS are shown in Table S7. The LIDTs of 1 – 4 are 13.9–20.1 × AGS, higher than some thiophosphates such as HgCuPS 4 , KInP 2 S 7 , Hg 3 P 2 S 8 , and SnPQ 3 , and they are also higher than those of all known NLO RE thiophosphates (Eu 2 P 2 S 6 and K 3 REP 2 S 8 39 ). The outstanding LIDTs of 1 – 4 means that RE thiophosphates can also be potential IR NLO materials.…”

Synthesis, crystal and electronic structures, linear and nonlinear optical properties, and photocurrent response of oxyhalides CeHaVIO4 (Ha = Cl, Br; VI = Mo, W)

“…Balancing these properties to satisfy these criteria is not a simple task due to the fact that many of these parameters are intrinsically correlated. [17][18][19][20][21][22][23][24][25][26][27][28][29] For example, in general, a material with a large bandgap should have a high LDT, but the SHG coefficients would be expected to be low. Inversely, small bandgap materials are more likely to have large SHG coefficients, but with the price of sacrificing the LDT.…”