The X-Ray SEF Scott Speakman

This molecule is essential to life…

D. June Sutor, Acta Cryst. 11 (1958)  (deg.) Intensity (a.u.) The crystal structure of caffeine was solved using X-ray diffraction

Caffeine is a crystal because its molecule repeats in an orderly manner to fill space

X-Ray Diffraction is used to study crystalline materials  X-rays scatter off of the atoms in a sample  If those atoms are systematically ordered, the scattered X-rays tell us:  what atoms are present  how they are arranged

Anhydrous Caffeine  (deg.) Caffeine Hydrate Intensity (a.u.) The XRD pattern of every crystalline material is as distinct as your fingerprint C 8 H 10 N 4 O 2 C 8 H 10 N 4 O 2  H 2 O

 (deg.) Intensity (a.u.) Basic Diffractometer Operation  A detector rotates around the sample, measuring intensity as a function of the diffraction angle 2theta  XRD uses information about the position, intensity, width, and shape of diffraction peaks in a pattern from a polycrystalline sample.   X-ray tube Detector

The X-ray SEF has  Rigaku High-Speed Powder Diffractometer  PANalytical X’Pert Pro Multipurpose Diffractometer  Bruker D8 Diffractometer with 2D Detector  Bruker D8 High-Resolution Thin-Film Diffractometer  PANalytical Back-Reflection Laue Single Crystal Diffractometer  Bruker Apex Single Crystal Diffractometer  Bruker Small Angle X-ray Scattering Instrument

Sample Requirements  Sample Size  Powder: 90 to 482 mm 3  minimum 1.6 mm 3  Solid: 10mm x 10mm  min: 1mm x 1mm  max: 55mm x 25mm  1” to 6” wafer  Characteristics  flat  grain size <10  m  smooth  densely packed  infinitely thick (>0.3mm)  Multilayers:  Co(10nm)/Fe(15nm)/MgO( 2nm)/Si  42 alternating layers of GaAs(104nm) and Al Ga As(127nm)  Powder  3 specks of blue paint  0.05mm thick coating of air-sensitive battery materials  brake rotor  particles in suspension The Ideal SampleReal Samples

Analyses Done Routinely in the X-ray SEF  Phase Identification  Crystallite Size Estimation  Lattice Parameter Refinement  Residual Stress Analysis  Evaluate Thin Film Quality  Reflectivity for Multilayer Thin Film Analysis  Small Angle Diffraction of Nano- and Meso- structures  Microdiffraction  Texture Analysis  In-situ Diffraction  Index and Solve Crystal Structures  Percent Crystallinity  Thin Film Analysis  Reciprocal Space Mapping  Relaxation & Strain  Defect Density  Single Crystal Diffraction  Crystal Orientation  Twinning & Other Defects  Small Angle X-ray Scattering  order/disorder of polymers  microstructure and porosity  amorphous texture Discussed TodayOther Techniques

 (deg.) Intensity (a.u.) Red Paint Pigment Mixture Phase Identification and Quantification 28 wt% Hematite, Fe 2 O 3 21 wt% Anatase, TiO 2 51 wt% Rutile, TiO 2 What phases, and how much of each, are present in this mixture of pigments?

Crystallite Size Analysis Hematite: XS> 100 nm Rutile: XS> 100 nm Anatase: XS= 25 nm Are any of the phases nanocrystalline; if so, what is their average crystallite size?

Lattice Parameter Refinement  (deg.) Intensity (a.u.) La 2 Zr 2 O 7 undoped 4% Y-doping 8% Y-doping How does doping change the lattice parameter of this fuel cell electrolyte?

in situ XRD  we can perform these analyses, and many more, as a function of:  temperature  cryostat: 11 K to RT  Powder Furnace: RT to 1200 C  Plate Furnace: RT to 900 C  environment  air  vacuum  inert gas  mildly reactive gas  time  time resolution as fast as 10 sec  more typical is 5+ min time resolution

in situ XRD of lattice parameters  (deg.) Intensity (a.u.) a axis b axis c axis angle  How does the lattice parameter of LSO change with temperature?

in situ XRD of phase composition How does the phase composition of this hydrogen storage material change with time at 150°C?

 (deg.) Intensity (a.u.) Pd Residual Stress Analysis H2H2 XRD at 50°C How do stresses in a Pd film change with H 2 and temperature? Hastelloy

Texture Pole Figures How are the grains oriented in this refractory alloy for a satellite power system? Distribution of and directions in rolled Nb-1Zr Rolled to 20% Reduction in Thickness (less deformed) Rolled 95% Reduction in Thickness (more deformed)

Thin Film Rocking Curve  (deg.) Intensity (a.u.) What is the quality of epitaxial semiconductor thin films compared to the perfect single crystal substrate? Perfect Single Crystal Substrate Good Epitaxial Thin Film Poor Epitaxial Thin Film Horrible Quality, Not Epitaxial At All, Thin Film

Thin Film Reflectivity  (deg.) Log Intensity (a.u.) What is the arrangement and surface characteristics of a thin film of GaAs on a Si substrate? Thickness (nm) Roughness (nm) Density (g/cm 3 ) C Ga 2 O GaAs SiO Si∞

nm 5.901nm 5.150nm 3.924nm d-spacing (Å)  Intensity (a.u.) Glancing Incident Angle Small Angle X-ray Diffraction Do quantum dots arrange themselves in a systematic manner with long range order? What is the average distance between the quantum dots?

Microdiffraction How does the diffraction pattern change at different positions on a sample?

Group classes are held regularly to train you to use the X-ray lab independently  Training for Self-Use Requires  1 hour X-ray Safety Course from EHS  1 hour Lab Specific Safety Training  2 hr Instrument Specific Training  2 hr Practical XRD Lecture  3 hr Data Analysis Workshop  next session: late January or early February  see prism.mit.edu/xray for schedule updates

Assisted Use  I will gladly work with you to collect and analyze data  usually needs to be scheduled ~2 weeks in advance

Contact Information  Scott Speakman  office: A  x   generally available 10 am to 4 pm  XRD Lab:  XRD Computer Room: 

Upcoming IAP Lectures  Introduction to X-Ray Diffraction  Jan 17, 2-5 pm, room  Nanocrystallite Size Analysis using XRD  Jan 24, 2-5 pm, room  Thin Film Analysis using X-rays  Jan 31, 2-5 pm, room

Workshops for Existing X-Ray Users  Basic Data Analysis with Jade  scheduled on request  Rietveld Refinement using HighScore Plus  Jan 29 and Jan 30, 1 to 5 pm  room  RSVP by Jan 25