Mitoudi Vagourdi Eleni, Zhang Weiguo, Denisova Ksenia, Lemmens Peter, Halasyamani P Shiv, Johnsson Mats
Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Department of Chemistry, University of Houston, 77204-5003 Houston, Texas, United States.
ACS Omega. 2020 Mar 4;5(10):5235-5240. doi: 10.1021/acsomega.9b04288. eCollection 2020 Mar 17.
Transparent single crystals of two new iodates KSc(IO) and KSc(IO)Cl have been synthesized hydrothermally. Single-crystal X-ray diffraction was used to determine their crystal structures. Both compounds crystallize in non-centrosymmetric space groups. The compound KSc(IO) crystallizes in the orthorhombic space group 2. The crystal structure is made up of [ScO] octahedra, [IO] trigonal pyramids, and [KO] distorted cubes. The compound KSc(IO)Cl crystallizes in the trigonal space group 3. The building blocks are [ScO] octahedra, [KO] polyhedra, and [IO] trigonal pyramids. The Cl ions act as counter ions and reside in tunnels in the crystal structure. The second harmonic generation (SHG) measurements at room temperature, using 1064 nm radiation, on polycrystalline samples show that the SHG intensities of KSc(IO) and KSc(IO)Cl are around 2.8 and 2.5 times that of KHPO (KDP), respectively. In addition, KSc(IO) and KSc(IO)Cl are phase-matchable at the fundamental wavelength of 1064 nm. The large anharmonicity in the optical response of both compounds is further supported by an anomalous temperature dependence of optical phonon frequencies as well as their enlarged intensities in Raman scattering. The latter corresponds to a very large electronic polarizability.
通过水热法合成了两种新型碘酸盐KSc(IO)和KSc(IO)Cl的透明单晶。利用单晶X射线衍射确定了它们的晶体结构。两种化合物均结晶于非中心对称空间群。化合物KSc(IO)结晶于正交空间群2。晶体结构由[ScO]八面体、[IO]三角锥和[KO]扭曲立方体组成。化合物KSc(IO)Cl结晶于三角空间群3。结构单元为[ScO]八面体、[KO]多面体和[IO]三角锥。Cl离子作为抗衡离子，位于晶体结构的通道中。在室温下，使用1064nm辐射对多晶样品进行的二次谐波产生（SHG）测量表明，KSc(IO)和KSc(IO)Cl的SHG强度分别约为KHPO（KDP）的2.8倍和2.5倍。此外，KSc(IO)和KSc(IO)Cl在1064nm的基波波长下是相位匹配的。两种化合物光学响应中的大非谐性进一步得到光学声子频率的异常温度依赖性及其在拉曼散射中增强强度的支持。后者对应于非常大的电子极化率。
