Study On The Preparation Process And Properties Of Copper-doped Silver Selenide

Doped materials can often make a great change in the property. Scholars fromvarious countries show much interest in using this method to research the new stru ctureand performance of materials. Small self-doped nonstoichiometric silver chalcogenideshave shown unusually large, positive and linear magneto resistance effect （LMR）, whichmeans the change of the resistivity is in linear proportion to the change of magneticfield.This exhibits a linear dependence on magnetic field from1mT to55T in the rangeof temperature from4K to300K. This peculiar phenomenon has aroused wide attention，exploring impact of the performance and the structure by doping copper in this paper.In this paper, five kinds of experimental research program is to layout to explore itsprocess feasibility of copper-dopedAg2Seprepared by chemical deposition.Theprepared powders were characterized to find that just the fifth program is appropriate.Homogeneous and non-homogeneous Silver-rich copper-doped silver selenide(Ag₂₊δSe) crystal are prepared by two-step way. The results showed that the reactiontime and sequence of adding raw materials are very important parameters. The resultsshowed that just approximate10h that is suitable. Sequence of adding raw materials canaffect obtained samples. When all the raw materials are t added the reaction vessel at thesame time is appropriate. The silver selenide bulk prepared by the solid state method haslow sintering temperature, has less volatile materials and is very dense. The highestsintering temperature and the holding time of the highest temperature are very importantprocess parameters. According to the study, completed crystallizedAg2Secrystals canbe obtained from the sintering temperature in the range from450℃to500℃.Argon ornitrogen are used as protective gas during the sintering processSelenium and copper proportion were changed and copper-doped silver-rich silver selenide nanoparticles with different silver excess (Ag₂₊δSe（0）) were prepared bychemical deposition method, and then were sintered into crystals by solid state method.The result of XRD and XRF and FSEM show that the sample is relatively suitable whenthe natural cooling to the room temperature. However, the trends of the longitudinalgrowth of the samples happened if the samples are cooled quickly.Silver excess has animpact on the growth of silver selenide. There were more excess silver which exists asatoms or clusters and arranged chainlike in the grain boundary of silver selenide.In the end, physical properties of Silver-rich copper-doped silver selenide（Ag2Se） were studied. The results show that silver selenide crystal is n-typesemiconductor, and it’s the band gap is about1.25¹.30eV,so that it is the narrow bandgap semiconductors.