Effect Of γ Ray Irradiation On Microstructure And Electrical Properties Of Tourmaline

Tourmaline has stable crystal structure,unique physical and chemical properties and good environmental friendliness.It has been widely used in the fields of functional materials,environmental protection and medical care.The pyroelectricity and piezoelectricity of tourmaline are the earliest discovered properties.However,due to the complex isomorphic substitution of tourmaline,it is difficult to clarify the relationship between tourmaline mineral types and electrical properties,which greatly limits the development and application of electrical properties of tourmaline mineral.According to the research status on electrical properties of tourmaline,the mineralogical characteristics of tourmaline from typical tourmaline mines in Guilin,Guangxi,Baoding,Hebei and Altay,Xinjiang were investigated in the study.The relationship among the composition,structure and electrical properties of different kinds of tourmaline is studied by means of X-ray diffraction,inductively coupled plasma emission spectroscopy,X-ray single crystal diffraction,Mossbauer spectroscopy and ferroelectric comprehensive tester.The microstructure and pyroelectric properties of tourmaline under different irradiation doses were investigated.The results are as follows:（1）In the investigation of tourmaline mineral resources and the study on mineralogical characteristics of tourmaline,comparing the mineralogical characteristics of tourmaline from Guilin,Guangxi,Baoding,Hebei and Altay,Xinjiang,it was found that due to the obvious differences in geological environment and trace element content of tourmaline from different producing areas,the original tourmaline ores collected from Guangxi,Hebei and Xinjiang differed greatly in crystal size,crystal color,crystallization degree and crystal morphology.（2）The study on the relationship among the composition,structure and electrical properties of tourmaline showed that the element composition of diverse tourmalines were obviously different,especially the content of main elements in the Y site of tourmaline and the proportion of each element were quite different,resulting in different structural polyhedron torsion parameters and inherent electric dipole moment of tourmaline.（3）The electrical properties of the four tourmalines were as follows:T-XJ-2>T-GX>T-XJ-1>T-HB-1.When the ratio of Fe³⁺/Fe _T and Li in tourmaline was higher,the internal polyhedron was more prone to stretching deformation;While the ratio of Fe²⁺/Fe _T in tourmaline was higher,the internal polyhedron was more prone to distortion deformation.And,the distortion deformation of polyhedron is easy to change the symmetry of polyhedron structure,resulting in a larger inherent electric dipole moment and better electrical properties.（4）The effect ofγray irradiation on the pyroelectric properties of tourmaline showed that the electrical properties of tourmaline firstly increased and then decreased with the increase of total gamma ray irradiation dose.Under the gamma irradiation with the dose of0-800 k Gy,the valence and occupation of Fe in T-GX sample changed,and the iron ions in Fe²⁺-Fe³⁺（Y-Z）state and Fe²⁺in Y site changed to Fe³⁺,resulting in the change of polyhedral structural parameters in tourmaline,which affected the pyroelectric properties of tourmaline.