CsCdInQ₃ (Q = Se, Te): New Photoconductive Compounds As Potential Materials for Hard Radiation Detection

Abstract

Two new compounds CsCdInQ 3 (Q = Se, Te) have been synthesized using a polychalcogenide flux. CsCdInQ 3 (Q = Se, Te) crystals are promising candidates for X-ray and γ-ray detection. The compounds crystallize in the monoclinic C2/c space group with a layered structure, which is related to the CsInQ 2 (Q = Se, Te) ternary compounds. The cell parameters are: a = 11.708(2) Å, b = 11.712(2) Å, c = 23.051(5) Å, β = 97.28(3)°for CsCdInSe 3 and a = 12.523(3) Å, b = 12.517(3) Å, c = 24.441(5) Å, β = 97.38( 3)°for CsCdInTe 3 . Both the Se and Te analogues are wide-band-gap semiconductors with optical band gaps of 2.4 and 1.78 eV for CsCdInSe 3 and CsCdInTe 3 , respectively. High-purity polycrystalline raw material for crystal growth was synthesized by the vapor transfer method for CsCdInQ 3 . Large single crystals up to 1 cm have been grown using the vertical Bridgman method and exhibit photoconductive response. The electrical resistivity of the crystals is highly anisotropic. The electronic structure calculation within the density functional theory (DFT) framework indicates a small effective mass for the carriers. Photoconductivity measurements on the as grown CsCdInQ 3 crystals gives high carrier mobility-lifetime (μτ) products comparable to other detector materials such as α-HgI 2 , PbI 2 , and Cd x Zn 1−x Te (CZT).

Synthesis, Structure and Bonding, Optical Properties of Ba4MTrQ6 (M=Cu, Ag; Tr=Ga, In; Q=S, Se)

“…This effect was also observed in A 2 Cd 3 Q 4 , A 2 Hg 6 Q 7 , and CsCdInQ 3 (A = K, Rb, Cs; Q = S, Se Te). [30,42,43] The solid-state emission spectra of Ba 4 AgGaS 6 and Ba 4 AgInS 6 were investigated at room temperature, and the results are presented in Figure 6. Upon excitation at 336 nm, both Ba 4 AgGaS 6 and Ba 4 AgInS 6 showed strong pure luminescence with two sharp bands appearing in a narrow region from 400 to 420 nm.…”

“…Similar luminescent properties were also frequently reported for some gallium chalcogenides; [44] for example, ACd 4 Ga 5 S 12 displays intense emissions at 584-595 nm and Ba 3 AGa 5 Se 10 Cl 2 (A = K, Rb, Cs) exhibits broad emission at 711-731 nm. [30,28] With regard to the luminescent mechanism of these chalcogenide analogues, electronic excitation of the title compounds should be related to delocalization of the electrons in various defect levels or energy states lying within the band gap of the materials as a result of the lack of metal activators. [45,46] Electronic Structure Calculations…”

“…For example, ACd 5 Ga 4 S 12 (A = K, Rb, Cs) compounds adopt a noncentrosymmetric structure and exhibit interesting IR nonlinear optical thermochromic properties from 298 to 10 K. [28] CsHgInS 3 and CsCdInQ 3 (Q = Se, Te) are expected to be new photoconductive compounds as potential materials for hard radiation detection. [29,30] Furthermore, In 4 Pb x Sn y Se 3 is a promising candidate for mid-temperature thermoelectric materials with an excellent figure of merit (ZT) value of 1.4 at 733 K. [31,32] Although many mixed metal multi-chalcogenides have been reported, quaternary examples containing d 10 transition-metal ions such as Cu 1 + and Ag 1 + are rare. [33][34][35] It was reported that Cu I and Ag I ions tend to exhibit highly diversified and flexible coordination numbers with chalcogens.…”

Li7Cd4.5Ge4Se16 and Li6.4Cd4.8Sn4Se16: Strong Nonlinear Optical Response in Quaternary Diamond‐Like Selenide Networks

“…[37] For the two title compounds, the CdÀSe bond lengths vary from 2.570(2) to 2.653(3) ,w hich is in good agreement with the values of 2.360(3) to 2.900(4) in La 3 CdGaSe 7 [38] and2 .609(2) to 2.631 (2) in CsCdInSe 3 . [39] The (Li/Cd)ÀSe bond lengths range from 2.314(19) to 2.750 (12) ,w hichi sc omparable to the valueso fLi ÀSe and CdÀSe bond lengths mentioned above.…”

New Lithium‐Containing Pnictides with 1‐D Infinite Chains of Supertetrahedral Clusters: Synthesis, Crystal and Electronic Structure of Ba4Li2Cd3Pn6 (Pn = P, As and Sb)

“…Such atomic packing with T2 cluster makes these materials to be structurally related to a family of supertetrahedra‐layered compounds including mostly indium or gallium sulfides, selenides and tellurides. Some representative examples are CsInSe 2 /CsInTe 2 ,24,25 RbInS 2 ,26 and TlGaSe 2 ,27 among the about 25 known compounds,28 which all crystallize in the monoclinic space group C 2/ c . The present work represents a rare case and the first instance of ordered quaternary pnictides built upon [Cd 4 Pn 10 ] adamantane‐like clusters assembled into infinite chains.…”