New Type Of Antimony Iodates Synthesis, Structure And Optical Properties

The asymmetric I-O groups can be formed because of existing a pair of unpaired electrons in iodate group,and are susceptible to the formation of flexible compounds which are populared in a lot of application prospect,such as semiconductor and non-linear fields.Also,the element antimony usually shows two kinds of valence:Sb_<sup>3+and Sb⁵⁺.It can form flexibility and diversity of asymmetric triangular pyramid Sb O₃ and symmetric Sb O₆ groups in structure,and antimonates are widely studied owing to its semiconductor property and potential applications in nonlinear,photocatalysis and other fields.Therefore,to synthesis new crystal materials with novel structure and properties,combination of the Sb-O group and iodate group is a good method to identify and design the complex oxides.In this work,the new antimony iodate compounds were obtained,and the structure and properties were investigated to estimate their potential application.This work will be to a concrete analysis of these compounds,and the content is mainly divided intofive chapters as below:In the first chapter,the research background is concisely introduced by illustrating recent advances on mental iodate materials and antimonates.And the aims and advances of this work are outlined.In the second chapter,Two new antimony iodine compounds were reported,this is,antimony potassium iodate KSb I₆O₁₈ and antimony iodide amine?NH₄?₂?H₃O??Sb₂I₉?.KSb I₆O₁₈ crystallizes in trigonal space group R-3 with cell parameters of a = 11.3057?6??,c= 11.3340?8??,? = 120° and z = 3.Six corner-shared IO₄ groups form cyclic S6-symmetric chiral I₆O₁₈ that are linked by Sb⁵⁺to form anionic [Sb(I₆O₁₈)]-framework with cavities filled by K+ions.In this paper,its infrared,powder,thermogravimetric properties were also studied.Optical diffuse reflectance spectra analysis indicates that KSb I₆O₁₈ is a potential semiconductor with optical band gap of 2.96 e V.The other compound?NH₄?₂?H₃O??Sb₂I₉?crystallizes in hexagonal space group P-62 c with cell parameters of a=9.8686?4??,c=23.2605?10??,?=90°,?=120°.In?NH₄?₂?H₃O??Sb₂I₉?,Sb atom and I atom are directly linked together to form anionic [Sb₂I₉]^3-framework.Optical diffuse reflectance spectra study indicates that?NH₄?₂?H₃O??Sb₂I₉?is also a potential semiconductor with optical band gap of 2.5 e V.In the third chapter,antimony fluorhydric acid Sb₃O₄ F was synthesized by reaction of the compounds Sb₂O₃ and BaF₂.It crystallizes in monoclinic space group P21/c with cell parameters of a = 5.6376?2??,b = 4.7151?1??,c = 20.3660?7??,? = 90°,?= 94.354?3?°,?= 90°,z = 4.The compound Sb₃O₄ F exhibits a layer structure in which is consititued by one-dimensional [Sb₄O₈]₄–chains and [SbF]²⁺groups.One-dimensional [Sb₄O₈]₄ –chains along the c axis is formed by neiboring [Sb₂O₄]^2-groups via corner-sharing oxygen atoms.Optical diffuse reflectance spectra measurement indicates that Sb₃O₄ F is a potential broadband gap semiconductor with optical band gap of 3.58 e V.In the fourth chapter,we reported a new iodate magnesium,?-Mg I₂O₆.It crystallizes in monoclinic space group P21 with cell parameters of a = 5.4968?4??,b = 5.1170?10??,c = 9.4489?7??,?=90.314?7?°,z = 2.It includes a magnesium ion and two iodine ions in?-Mg I₂O₆ unit cell,Mg O₆ group and IO₃ group are linked together to form a distortion structure.Hence,?-Mg I₂O₆ is a nonlinear optical crystal with macro polarity along-b axis.In the last chapter,a concise conclusion was drawn.