Ba₆In₂Ge₂Te₁₅: a THz birefringent material with an intriguing quasi-[Te₅]⁴⁻ chain possessing large optical anisotropy and an ultrawide transmission range

Abstract

Exploring mid- and far-infrared (MFIR) and even terahertz (THz) birefringent crystal with a large optical anisotropy remains a great challenge. Herein, a novel THz birefringent material Ba6In2Ge2Te15, which contains the...

Ba2HgTe5: a Hg-based telluride with giant birefringence induced by linear [HgTe2] units

“…19 More importantly, metal tellurides tend to form one-dimensional chain-like structures, which are beneficial for generating large optical anisotropy. 4,17 On the other hand, tellurides possess longer IR transparency cut-off edges because of the heavy atomic mass of tellurium. 24 Previously, we have successfully synthesized several new IR birefringent crystals, namely β-BaGa 2 Te 4 and Ba 6 In 2 Ge 2 Te 15 .…”

“…24 Previously, we have successfully synthesized several new IR birefringent crystals, namely β-BaGa 2 Te 4 and Ba 6 In 2 Ge 2 Te 15 . 4,19 The former features GaTe 2 chains consisting of [GaTe 4 ] tetrahedra by edge-sharing, showing a large birefringence of 0.325@2090 nm, and the latter has an intriguing quasi-Te 5 chain and Ge 2 In 2 Te 10 chain formed by the [InGe 2 Te 8 ] clusters and [InTe 4 ] tetrahedra by vertexsharing, exhibiting a large optical anisotropy of 0.42@2090 nm (0.337@30-40 μm) in both the MFIR and terahertz (THz) bands. However, both crystals exhibit noncongruent-melting behavior, which is unfavorable for the growth of large-sized single crystals.…”

“…As a branch of the optoelectronic functional materials, birefringence materials play a significant role in adjusting the polarization of light. 1–4 Currently, birefringent crystals have been used to prepare polarizers, 5 optical isolators, 6 and phase retarders, 7 and have received continuous attention in the fields of information processing, optical communication, and laser technology. 8,9 In recent years, commercially available birefringent materials have mainly included YVO 4 , 10 TiO 2 , 11 α-BaB 2 O 4 , 12 LiNbO 3 , 13 etc .…”

ACd4Ga5Te12 (A = K, Rb, Cs): Tellurides with a Strong Nonlinear Optical Response and Purple Emission

“…For decades, plentiful chalcogenides with a DL structure have been reported, mainly including the I–III–Q 2 (I = Li, Ag; III = Al, Ga, In; Q = S, Se, Te) family, ,, I 2 –IV–Q 3 (I = Ag, Cu; IV = Si, Ge, Sn; Q = S, Se) family, − I 3 –V–Q 4 (I = Li, Ag, Cu; V = P, As, Sb; Q = S, Se) family, I 2 –II–IV–Q 4 (I = Li, Ag, Cu; II = Zn, Cd, Hg; IV = Si, Ge, Sn; Q = S, Se) family, − and I 4 –II–IV 2 –Q 7 (I = Li, Ag; II = Zn, Cd, Hg, Mn; IV = Si, Ge, Sn; Q = S, Se) family. , However, most of the compounds mentioned above are sulfides and selenides, and tellurides with DL structures are rarely reported. Compared with sulfides and selenides, tellurides generally possess a larger electronic polarization and a wider transmittance range, making them potentially more suitable candidates as MFIR NLO materials …”

“…Compared with sulfides and selenides, tellurides generally possess a larger electronic polarization and a wider transmittance range, making them potentially more suitable candidates as MFIR NLO materials. 61 Based on the above discussion, classical AgGaTe 2 was selected as the structural prototype for the exploration of telluride NLO materials with DL structures. Regretfully, although AgGaTe 2 possesses a large SHG coefficient (d eff = 77 pm/V) and a wide transmission range (∼23 μm), the light sensitivity of Ag causes a narrow band gap, resulting in a low laser damage threshold, which seriously hinders their further applications.…”