Thermal Expansion And Electrical Properties Of K_0.55WO_3.275

Thermal expansion and contraction is a common natural phenomenon,which often brings many hazards to our lives.In order to reduce the loss caused by this phenomenon,it is necessary to explore materials with low thermal expansion properties.One way is to combine the negative thermal expansion material with the positive thermal expansion material to get the material we need.However,the preparation cost of negative thermal expansion materials is generally high and is not suitable for mass production and application.Therefore,it is important to develop a new type of low thermal expansion material without obvious water absorption.The main work of this paper is as follows:1.A new type of potassium tungstate material K_0.55WO_3.275 was synthesized by solid-state sintering method.By testing the macroscopic thermal expansion curve of the sample,it was found that the sample has the characteristic of low thermal expansion about the room temperature.The coefficient of thermal expansion in the low thermal expansion was 1.54×10^-6K^-1.According to the temperature-dependent XRD pattern of the sample,all diffraction peaks in the XRD pattern can be indexed with a monoclinic unit cell,the cell parameters were a=15.9751?,b=7.7309?,c=10.9380?,?=108.4723?,respectively.The crystal structure type of the sample remains monoclinic with the temperature increasing from 153K to 573K.By fitting and calculating the data obtained from the variable temperature XRD,we got the curves of the cell volume of the sample with the change of temperature.The intrinsic line thermal expansion coefficient of the low thermal expansion region was1.01×10^-6K^-1,which was basically consistent with the macroscopic linear thermal expansion coefficient of the sample measured by the thermal expansion meter in this temperature range.The results of the thermal analysis suggested that the relative mass of the sample only increased by 1.9%and there was no weight loss in the process of increasing the test temperature from 300K to 450K.It indicated that there was no obvious water absorption characteristic.The samples emited blue-green fluorescence when irradiated with near-ultraviolet light.It can be used as phosphors of near-ultraviolet pump LED and blue green laser materials in the phosphor for near ultraviolet excitting white LED.2.In order to expand the application range of this material,K_0.55WO_3.275.275 powder was prepared by sol-gel method,Cu/K_0.55WO_3.275/Al and Al/K_0.55WO_3.275/Al were prepared by using magnetron sputtering apparatus.The electrical properties of the two devices were studied and found that Cu/K_0.55WO_3.275/Al have obvious rectification characteristic,but the Al/K_0.55WO_3.275/Al have no rectification characteristic.As a result,K_0.55WO_3.275.275 can form Schottky contact with Cu and be fabricated into Schottky junction with rectifying characteristic,which has a broad application prospect.