Research On NiZn Ferrite Materials Used For High Frequency Electrodeless Discharge Lamp

Artificial lighting is developing rapidly, and has been into the 4th generation of green lighting age now, which is represented by high frequency electrodeless discharge lamp and light emitting diode(LED). High frequency electrodeless discharge lamp has the advantages of high luminous efficiency, long service life, high color rendering index, no stroboscopic, environmental protection, etc. Therefore, it has important meanings to saving energy and reducing consumption, eye health, and green environmental protection. However, due to the Nickel series ferrite cores, which used for high frequency electrodeless discharge lamp, had the disadvantages of low Curie temperature(Tc), low cut-off frequency(fr), and bad temperature dependence of losses(Pcv) at high frequency at present; what’s more, the price is expensive. It leds to the promotion and popularization of high frequency electrodeless discharge lamp face great difficulties. So this article carried out the following work that aimed at the shortcoming of Nickel series ferrite cores used for high frequency electrodeless discharge lamp.Ni2+ was replaced by a small amount of Cu2+ so that quaternary system main formula was composed with Fe2O3, NiO, ZnO and CuO, through which reduced the sintering temperature, refined the grain, and increased the Snoek product and resistivity. Optimizing the ZnO content in main formula at the same time, to ensure that the samples with high Tc and high fr. When the content of ZnO increased from 17mol% to 24mol%, the Tc declined from 375 ℃to 275℃ gradually; initial permeability(μi) increased from 99 to 236 gradually, on the contrary, fr reduced from 75 MHz to 26 MHz gradually; When the Zn O content is 18mol%, the sample had the minimum Pcv of 714mW/cm3(3MHz, 10 mT, 100℃).NiCuZn was lightly doped with Ta2O5 and Co2O3 on the basis of the optimized main formula, respectively. The results revealed that Ta2O5 could refine the grain of NiCuZn ferrites, and consequently reduced the sintering density. At the same time, the saturation induction(Bs) and μi of samples reduced monotonously with the increased of Ta2O5 content. The coercivity(Hc) and fr, however, increased gradually. Furthermore, the Pcv firstly decreased and then increased, and the dominant factor of Pcv transformed from residual loss(Pr) to hysteresis loss(Ph), so the Pcv had a valley value when Ta2O5 content is 0.12wt%. The lowest Pcv is 139mW/cm3 at the conditions of 100℃, 3MHz and 10 mT, where Ph and Pr are 93mW/cm3 and 46mW/cm3, respectively. When Co2O3 content increased from 0 to 1.00wt%, the average grain size of the samples slightly decreased, and the μi reduced gradually, the fr, however, increased gradually. In addition, in the condition of 3MHz, 10 mT, and 25~140℃, with the Co2O3 content increasing, the Pcv decreased monotonously.Expensive NiO was replaced by a suitable amount of MgO, which reduced the cost of magnetic cores. With the increase of MgO content, sintering density decreased gradually, the Tc declined approximate linearly, droped from 362℃ to 291℃ gradually. The μi had certain degree of decline, fr had little change; Pcv also had no significant variation. When the MgO content was 8mol%, Pcv was relatively low in each temperature. Ta2O5 and Co2O3 compound addtive were used in the optimized NiMgCuZn main formula, the grain size of prepared samples were smaller and uniform; with the increases of Ta2O5 and Co2O3 addtive amount, μi reduced while fr increased gradually; When Ta2O5 and Co2O3 addtive amount were 0.50wt% and 0.36wt%, the samples had the minimum loss of only 25mW/cm3 under 3MHz, 10 mT, 100℃.Two kinds of ferrite cores of NiCuZn and NiMgCuZn were prepared through the above works eventually, their performance parameters had reached the standard of high frequency electrodeless lamp’s application, and NiMgCu Zn ferrite greatly reduced the cost of the magnetic core used for high frequency electrodeless discharge lamp. Electromagnetic couplers were twined use the two kinds of magnetic core that prepared in this paper and high frequency electrodeless discharge lamp was lightened successfully.