Investigations On Preparation And Luminescence Properies Of Rare Earth Doped Borate Semiconductor Phosphors

Phosphors are considered as an indispensable part of LED that can be directly related to the performance.High efficiency phosphors excited by blue chips or UV chips have become the focus of researchers in recent years.Borate phosphor is a kind of traditional fluorescent material.It has been widely used because of its low temperature,high luminous efficiency and stable chemical property.In this paper,green yellow and red phosphors excited by blue or violet chips are developed with the borate material.BaZn2(BO3)2 phosphors were prepared by high temperature solid state method in different atmospheres.The yellow emission peak of the BaZn2(BO3)2 sample prepared in air atmosphere is at 543nm,which arises from the radiative recombination of photogenerated electron close to the conduction with a deeply trapped hole in the single negatively charged interstitial oxygen ion centers in the particles.The green emission of BaZn2(BO3)2 sample was measured at 500nm in reducing atmosphere,which is attributed to the transition of a photogenerated electron close to the conduction band to a deeply trapped hole in the single ionized oxygen vacancy.BaZn2(BO3)2 phosphors have a strong absorption ultraviolet band and thermal quenching effect are well,and even in high temperature conditions,the luminescence intensity fall slowly.Therefore,BaZn2(BO3)2 phosphors have potential application in white light-emitting diode.The BaZn2(BO3)2:xEu3+ phosphor was prepared by high temperature solid state method.The excitation peak position of the host is located at 375 nm,and the excitation peak of Eu3+ is located at 393 nm,meanwhile the peak of the emission spectrum is located near 550 nn and 615 nm.The emission of wavelengths at 550 nm is due to the semiconductor luminescence of the host itself,and emission at 615 nm is due to the 5Do?7F2 transition of Eu3+.And with the addition of Eu3+ ions,the energy of the host transfers to the Eu3+.When the doping concentration is 10mol%,BaZn2(BO3)2:0.1Eu3+ phosphor has a strong red emission from 580 to 630 nm,thus it's also a potential application in white LED.The BaZn2(BO3)2:xEu2+ phosphor was prepared by high temperature solid state method.The excitation peak position is located at 376 nm,and the peak of the emission spectrum is located near 500 nm.On the one hand,the emission of wavelengths at 500 nm is due to the semiconductor luminescence of the host itself,which is attributed to the transition of a photogenerated electron close to the conduction band to a deeply trapped hole in the single ionized oxygen vacancy.On the other hand,the emission is also due to the 4f65d?4f7 transition of Eu2+.When the doping concentration is 7%mol,Ba2Zn2(BO3)2:0.07Eu2+ phosphor has a strong green emission at 500 nm,which is also a potential application in white LED.The Ba0.95Eu0.05Zn1-x(BO3)F:xMg2+ phosphor was prepared by high temperature solid state method.There is a strong absorption at the range of 200-400nm because of the energy transition between conduction and valence band of host.When the Mg2+ ions replace the Zn2+ ions,the blue shifts of emission peak at 500nm occur.The more Mg2+ ions replace Zn2+ ions,the more difficult Eu3+ ions reduce into Eu2+ ions.There is a characteristic 5D0?7F1 and 5D0?7F2 transition emission of Eu3+ from 586nm to 615nm.The emission of Ba0.95Eu0.05Zn(BO3)F is green.While Mg2+ ions partially replace Zn2+ ions,the Ba0.95Eu0.05Mg0.5Zn0.5(BO3)F phosphor have a yellow-green emission and when Mg2+ ions completely replace Zn2+ ions,there is a yellow emission of Ba0.95Eu0.05Mg(BO3)F phosphor.