Mystery phosphor

Ross Fontenot (University of Alabama A&M) and Andy Hollerman (University of Louisiana Lafayette) dropped by a couple of weeks ago to leave a triboluminescent phosphor for us to test.  It is an organic phosphor but behaves more like an inorganic phosphor.  It is doped with europium, which is good, because we know a good bit about that particular activator.  Although I don't feel right about naming the material and providing our spectral data (after all, Andy and Ross have not finished publishing on the material), I can say that the europium peaks are slightly different than those found in most ceramic oxide host lattices. In the picture you can see the characteristic europium glow under a UV flashlight.

under room light

under UV light

We are particularly excited about the material because it could hold significant promise in our LumRad project.  LumRad is the name of the DTRA funded program to identify candidate phosphors for remote radiation detection.  Our hypothesis is that radiation induced damage will change the photoluminescent properties of phosphor materials that can be queried at any time after irradiation (i.e. we are not using the material as a scintillator).

Core-shell decay measurements

The lab is working with a high-school student this semester from the Vanderbilt School for Science and Math. We'll call him BB. This is a program that brings in advanced students in the Metro Nashville public school systems to receive college-level training in science and math.  As part of their instruction, they are paired with a research lab where they spend 4 hours per week conducting research along side graduate students.  Thanks go to Sadie for helping direct him in his research activities.

Today, BB took decay measurements of a core-shell nanoparticle we received from Yuanbing Mao at University of Texas, Pan American.  The core is LZO:Eu and the shell is YBO.  The spectral response is typical of europium, but the relative intensity of the peaks is different than that of our own bulk samples of LZO:Eu.  The decay data (BB's measurements) shown in the figure have strong multi-exponential components.

single: rms = 0.0654149
        I = 0.974968(0.297568) tau = 4.53009e-06(1.40148e-11)
double: rms = 0.0557005
        I = 0.0764344(0.0151942) tau = 0.000148201(9.63947e-08)
        I = 0.985433(0.394193) tau = 3.21211e-06(1.1205e-11)
triple: rms = 0.0553772
        I = 0.072394(0.101939) tau = 5.12744e-05(2.12708e-07)
        I = 0.0316655(0.0936514) tau = 0.000307173(5.42085e-06)
        I = 0.970849(0.451075) tau = 2.97923e-06(1.54917e-11)

Introducing the TELab blog

The Thermal Engineering Lab at Vanderbilt is starting a blog.  Please visit the TElab website for details on who we are and the type of research we perform.