Study On Preparation,Structure And Photoelectric Properties Of Niobate Glass Ceramics

With the quick growth of opto-electronic technology and power electronics industry,the materials with a single function（optical transparency/luminescence performance/optical temperature measurement/energy storage performance）unable meet the needs of the development of integrated optoelectronic devices.Therefore,the research and development of multifunctional optoelectronic materials have gradually attracted extensive attention from researchers in various countries.Rare earth doped niobate glass-ceramics has high optical transmittance,good luminous performance,high pressure resistance and electrical energy storage performance,and has potential application and development prospects in optical temperature measurement and transparent pulse energy storage capacitors.Therefore,the research on the opto-electronic properties of new niobate glass-ceramics materials is of great theoretical significance and practical value.In this paper,rare earth doped niobate photoelectric glass-ceramics materials with good thermal stability,high light transmittance,high sensitivity and high dielectric constant is explored as a starting point,The niobate glass-ceramics of BaO-Sr O-Al₂O₃-Nb₂O₅-B₂O₃-SiO₂,Ca O-Ca F₂-Al₂O₃-Nb₂O₅-B₂O₃-SiO₂,BaO-Na₂O-Nb₂O₅-Al₂O₃-B₂O₃and BaO-Na₂O-Nb₂O₅-Al₂O₃-B₂O₃-SiO₂systems were prepared by controlled crystallization after melt quenching and subsequent heat treatment.The phase structure,microstructure optical properties,luminescence/electricity and energy storage characteristics of glass-ceramics with different niobate systems were studied systematically by means of DSC,XRD,SEM,TEM,Raman,transmission spectrum,fluorescence spectrum,fluorescence attenuation spectrum,dielectric temperature spectrometer,ferroelectric tester,impedance tester,breakdown tester and charge-discharge test system.The main experimental conclusions are as follows:1.Yb³⁺/Er³⁺doped BaO-Sr O-Al₂O₃-Nb₂O₅-B₂O₃-SiO₂glasses were prepared by melt quenching method.It has been found that the single Sr_0.75Ba_0.25Nb₂O₆phase can be precipitated by heat treatment at 780℃for 3h and the average transmittance of the glass-ceramics reaches 43%in the visible light range of 500～700 nm and the average grain size is less than 50 nm.When the concentration of doped rare earth ions is5.0Yb³⁺/0.1Er³⁺,the S_r-maxand the S_a-maxof the glass-ceramics are 0.85%K^-1and 0.68%K^-1in the temperature range of 310～470 K,respectively.And the phonon energy to be about 597 cm^-1.The dielectric constant of the glass-ceramics can reach 48 at room temperature.When it is exposed to an electric field intensity of 600 k V/cm,the W_dis 0.83J/cm³,the P_dis 210 MW/cm³,and the T_0.9is less than 10 ns.2.Yb³⁺/Tm³⁺doped glasses with Ca O-Ca F₂-Al₂O₃-Nb₂O₅-B₂O₃-SiO₂system were prepared by melt quenching method.When the heat treatment time is 780℃/3h,a uniform and fine Ca Nb₂O₆crystal phase can be precipitated,and the average transmittance of the glass-ceramics can reach 65%in the visible light range of 500～700nm.The successful doping of Yb³⁺and Tm³⁺ions to replace cationic sites in the crystal phase was confirmed by Rietveld analysis,elemental mapping as well as fluorescence decay curves according to FULLPROF software.When the concentration of doped rare earth ions is 4.0Yb³⁺/0.1Tm³⁺,the phonon energy is estimated to be about 580 cm^-1,and the optical temperature measurement method with double ratios is realized by utilizing the fluorescence intensity comparison method of different emission bands.the S_a-maxis0.042%K^-1and the S_r-maxis 2.65%K^-1based on the thermal coupling energy level in the temperature range of 298 K to 573 K,the S_a-maxand S_r-maxbased on the non-thermally coupled energy levels are 20.49%K^-1and 0.23%K^-1,respectively.3.BaO-Na₂O-Al₂O₃-Nb₂O₅-B₂O₃glasses were fabricated by melt quenching method.The effects of heat treatment temperature on the structure and electrical properties were studied.The outcomes demonstrate that the host phase deposited in the glass-ceramics is Ba₂Na Nb₅O₁₅when the temperature is maintained at 740℃,770℃,800℃and 830℃for 2 h.With the increase of heat treatment temperature,Al₄B₂O₉low dielectric phase will be produced.When the heat treatment temperature is 770℃,the microcrystalline glass has a dense and uniform microstructure,and its electrical properties are optimal:the dielectric constant at room temperature can reach 216.At the applied electric field strength of 500 k V/cm,the W_d1.93 J/cm³,and the P_dis 414.4MW/cm³,which is 9.4 times that of the glass sample without overheating treatment.4.Yb³⁺/Er³⁺doped BaO-Na₂O-Nb₂O₅-Al₂O₃-B₂O₃-SiO₂glasses were prepared by melt quenching method.When the heat treatment temperature is 760℃/3h,a single Ba₂Na Nb₅O₁₅crystal phase can be precipitated,and the optical transmittance of the glass-ceramics is greater than 50%at 600 nm,the average grain size is about 23 nm,and the optical band gap is 3.08 e V.The up-conversion emission spectrum results show that the optimal doping concentration is 4.0Yb³⁺/0.1Er³⁺,and the phonon energy is estimated to be about 459 cm^-1.The relationship between the up-conversion emission intensity and the pump power proves to be a process of absorbing two photons.The temperature measurement with double ratios was realized by using the fluorescence intensity analogy method with different energy levels.S_r-maxand S_a-maxreached 1.19%K^-1and 0.68%K^-1,respectively,in the temperature range of 298～573 K.The glass-ceramics sample has a dielectric constant greater than 100,a dielectric loss less than 0.005,and exhibits low residual polarization at room temperature.When the applied electric field strength is 600k V/cm,the W_dof the glass-ceramics sample is 1.53 J/cm³,the P_dcan reach 370 MW/cm³and the T_0.9is less than 7 ns.