Fade Coloured Ice Chau Crystal Body Heat Processing And Its Optical Properties

Iceland spar crystals which play an important role in various areas of the polarizingtechnology are precious materials for the production of polarized prisms devices. Presently,Iceland spar crystals are expensive, and there are three reasons for this. The sources of it mainlydepend on the natural output, the alternatives can’t replace it completely, and the synthetictechnology of it has not reach the industrial application standards. In order to take full advantageof the existing sources of Iceland spar, in this paper, we heat the yellow and purple Iceland sparsto remove their colors.This paper includes five sections.In the first chapter, the main application of Iceland spar and the statues and significance ofthis topic are introduced. In addition, the main work of this thesis is described.In the second part, we introduce the optical properties of Iceland spar crystal, which includetransmission, refractive indices and function of polarization, and its application. We also simplyintroduce the synthesis of Iceland spar crystal.The third chapter, we introduce the color origin of colored Iceland spar crystal. At the sametime, we give a brief summary of the coloring reasons of natural calcite crystal, which isabsorbing the light selectively.In the fourth section, we design the experimental program, which try to heat yellow andpurple calcite crystals to remove there colors in ZDXS2-10-1000box furnace. The yellow andpurple crystals are with different shades and different sizes. We determine the effective fadingconditions of the yellow and purple crystal through the experiments of this part.The last part is the most important one in this paper. In this part, we select natural yellowand purple calcite crystals to execute sample processing. The experimental group and thereference group were taken from the same piece of the crystal. We measure the optical propertiesof yellow and purple crystals before and after heat treatment. The optical properties includetransmitted spectrum, extinction and refractive indices. We also analyze the measurement resultsand give some conclusion.On the basis of a lot experiments, the last two chapters are not only the core part, but alsothe innovation part of the work, which can be listed as follows:Firstly, through a lot of experiments, we found that the yellow and purple calcite crystalschange color when they are heated to a certain temperature. The effective fading conditions were390℃and470℃respectively,in circumstances that keeping that temperature for four4hours.Secondly, the measurement results of transmitted spectrums show that the range ofUV-visible light broadens significantly after heat treatment. Simultaneously we verify that thecoloring reasons of yellow and purple calcite crystal are the selective absorption of blue-violet band and yellow-green-band light respectively.Thirdly, the measurement results of extinction ratio and birefringence show that the heatingfade has no effect on these two optical properties of calcite crystals.The courses of the enhancement don’t damage calcite crystal. The samples’ physicalproperties, including transmission, extinction and birefringence, are fully in line with theirindustrial standards after heating. The experiment is successful. The method to remove the colorthrough heating and make the best use of calcite resources we have is feasible.