Experimental Investigations And Simulation Of Grinding Technology For Soft-brittle Lithium Niobate Crystals

As a kind of piezoelectric crystals,lithium niobate?LiNbO₃,LN?are of major importance in optical appliance,particularly in the field of modulator and surface acoustic wave?SAW?filter for superior ferroelectric,dielectric,electro-optic and pyroelectric properties.But fractures are usually observed during mechanical machining,which can be contributed to the “soft-brittle” characteristic.With the development of photoelectron technology,the need for photoelectron system with thinner and excellent surface quality is increasing.Thus it is urgent to develop efficient machining technology fitting for LN.Aim to obtain thin LN chips,grinding technology was employed by optimizing process parameters.Surface morphologies,crystal microstructures and theoretical analysis were conducted after machining process.Moreover,finite element analysis method was taken to simulate the process of grinding by COSMOL Multiphysics software.The main research contents are as follows:?1?The main material removal mechanisms for piezoelectric materials were introduced.The infulences of piezoelectric effect,pyroelectric effect of piezoelectric materials were considered as important factor.Fracture mechanism and experiment for piezoelectric materials were analyzed.?2?Grinding experiments for LN chips were conducted by using grinding machine.Fracture phenomenon of LN chip was proposed theoretically and experimentally.The reason for fracture was briefly discussed using crystallographic structures.?3?In order to research deformation,stress and potential for LN chip under grinding machining,finite element analysis method was employed for simulating grinding process.It turned out that stress of four symmetric area on LN chip was much bigger especially when chip was thinned to 80?m,which would lead to fracture.Referred to reported results of indention fracture mechanics,the fracture mechanism was concluded theoretically.?4?The grinding process under electric load was further analyzed by finite analysis method.The results showed that stress of LN chip were degraded which could be a way toreduce the risk of fractures.