Xiaogu Huang

Er3+-substituted W-type barium ferrite: preparation and electromagnetic properties

Abstract Er 3+ -substituted W-type barium ferrites Ba 1- x Er x (Zn 0.3 Co 0.7 ) 2 Fe 16 O 27 ( x =0.00, 0.05, 0.10, 0.15, 0.20) were synthesized by polymer adsorbent combustion method. Samples were characterized by X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and network analyzer to investigate the relationships among Er 3+ concentration, crystal structure, surface morphology and electromagnetic properties. All the XRD patterns showed pure phase of W-type barium ferrite when x =0.15, while the impurity phase of ErFeO 3 appeared when x =0.20. The pure W-type barium ferrite showed a hexagonal flake shape. In addition, the microwave electromagnetic properties of samples were analyzed in the frequency range of 2-18 GHz. It was indicated that the electromagnetic properties were significantly improved when Er 3+ doping content was 0.10. The reasons were also discussed using electromagnetic theory. The optimized ferrite exhibited excellent microwave absorption performance. The maximum of reflection loss (RL) reached about −27.4 dB and RL was below −10 dB at the frequency range from 8.4 GHz to 18 GHz, when the thickness was 2.6 mm.

Preparation and properties of Nd:YAG ultra-fine powders

Abstract Ultra-fine Nd:YAG powders with different doping concentrations were synthesized by sol-gel combustion method. The pure Nd:YAG could be prepared at the low temperature of 900 °C. Ethanol could improve the dispersity of powders, and the average size of the ultra-fine powders was around 250 nm. The reflection spectrum showed that there were several apparent characteristic absorption peaks and the intensity of these peaks enhanced with the increasing concentration of Nd 3+ . The luminescence spectrum, which was excited by 808 nm wavelength, exhibited several obvious emission bands in the range of 900-1150 nm. The emission intensity of Nd:YAG powders increased until the Nd content was above 3 mol.% due to the fluorescent quenching effect.

Influence of Different Carboxylic Acid Ligands on Luminescent Properties of Eu(Lc)3phen (Lc = MAA, AA, BA, SA) Complexes

A series of rare earth europium complexes with different carboxylic acid ligands Eu(Lc)3phen (Lc = MAA, AA, BA, SA) were synthesized. The complexes were characterized by FTIR, TG-DSC, XRD, UV absorption spectra, and photoluminescence spectra (PL) to study the structure, thermal stability, the energy absorption, and luminescent properties of the complexes. The results showed that the series complexes are all with good crystallization and relatively high thermal stability. The differences of the luminescent properties of complexes are caused by the different ligand structures. The absorption intensity of the carboxylic acid ligands, BA, was the strongest, followed by the MAA and AA and SA was the weakest. Therefore, the fluorescence intensity of the Eu(BA)3phen was the strongest, followed by the Eu(MAA)3phen and Eu(AA)3phen and the Eu2(SA)3phen2 was the weakest. All complexes showed good luminescence properties.