REI₅O₁₄ (RE=Y and Gd): Promising SHG Materials Featuring the Semicircle‐Shaped I₅O₁₄³⁻ Polyiodate Anion

Abstract

The first examples of rare‐earth polyiodates, namely, REI5O14 (RE=Y and Gd), have been prepared by hydrothermal reactions of RE2O3 and H5IO6 in H3PO4 (≥85 wt % in H2O), with extremely high yields (>95 %). They crystalize in the polar space group Cm and feature a brand‐new semicircle‐shaped [I5O14]3− pentameric polyiodate anion composed of two IO3 and three IO4 polyhedra. Remarkably, both compounds exhibit very large second‐harmonic generation (SHG) signals (14× and 15×KH2PO4 (KDP) upon 1064 nm laser radiation for Y and Gd compounds, respectively). Our work shows that the hydrothermal reaction in a phosphoric acid medium facilitates the formation of rare‐earth polyiodates.

From H12C4N2CdI4 to H11C4N2CdI3: a highly polarizable CdNI3 tetrahedron induced a sharp enhancement of second harmonic generation response and birefringence

“…[28][29][30][31][32][33][34] However, on the one hand, the use of SCLAP cations is known to cause red shis in absorption edges and reduce bandgaps of the resulting crystals, limiting their potential applications in the ultraviolet (UV) and deep-UV regions. [35][36][37][38][39][40] For instance, Mao's group recently reported a series of Ge 2+ -containing OIMHs, in which (CH 3 NH 3 )GeBr 3 shows a large SHG response (5. 44 and ((CH 3 ) 3 NCH 2 Cl)CdCl 3 , 46 usually possess wide bandgaps (>5.0 eV) but relatively weak SHG effects (<1.0 × KDP).…”

Structure and optical property evolution in PbM(PO4)X (M = Zn, Sn; X = halogen): SHG effect and birefringence

“…As a functional material, nonlinear optical (NLO) materials are important components for expanding the wavelengths of lasers and enhancing the performance of laser light sources. [1][2][3] Over the decades, generations of researchers have built huge collections of NLO materials around their required characteristics, which include typical borates, [4][5][6] iodates, [7][8][9] chalcogenides [10][11][12] and phosphates. [13][14][15][16] Currently, metal phosphates are an important source for NLO material applications due to their structural advantages and good physicochemical properties, with familiar KTiOPO 4 (KTP) and KH 2 PO 4 (KDP) being reported and successfully commercialized in the 1970s.…”

ε-La(IO3)3: A Polar Iodate with High Thermal Stability and a Large Second-Harmonic-Generation Response Obtained by a Supercritical Hydrothermal Method

“…As shown in the UV−vis−NIR diffuse-reflectance spectrum (Figure 2a), ε-La(IO 3 ) 3 exhibits a UV-cutoff edge at about 264 nm, which corresponds to a wide band gap of 4.05 eV. This value is not only larger than those of high-performing NLO rare-earth-metal iodates, such as Ce 2 I 6 O 18 (2.5 eV), 27 YI 5 O 14 (3.82 eV), 23 and Ce(IO 3 ) 4 (2.17 eV), 25 but also larger than those of commercial IR NLO crystals AgGaS 2 (2.62 eV) and AgGaSe 2 (2.62 eV). 35 This may result in good laser-damage threshold under high-power NLO applications.…”

“…), 19,20 (iii) highly electronegative anions (F − , Cl − , etc. ), 21,22 (iv) rareearth-metal cations without d−d/f−f electron transition (e.g., La 3+ and Y 3+ ) 23,24 and their combination in the manner of covalent substitution 25 or aliovalent substitution. 26 Among them, the rare-earth-metal iodates show great advantages for exploring new mid-IR NLO crystals due to the flexible coordinating environments and intrinsically large band gap of rare-earth-metal cations, which promoted our exploration in this field.…”