MiniFlex Training

2. MiniFlex Training Instructions on the care and operation of the Rigaku MiniFlex+ X-ray Diffractometer

3. Topics to be covered • X-ray Safety • System Maintenance • Sample Preparation • Data Collection • Data Processing using MDI JADE

4. X-ray Safety

5. Hazards of X-ray Radiation • X-rays are energetic electromagnetic radiation that ionize matter by ejecting electrons from atoms • The extent of ionization, absorption and molecular change depends upon the quality (spectral distribution) and quantity (flux and intensity) of the radiation

6. Hazards of X-rays (cont’d) • Living organisms can be injured by exposure • Type and extent of injury is a function not only of quality and quantity of radiation, but also duration of exposure and distance from source

7. Hazards of X-rays (cont’d) • X-rays are INVISIBLE, so its impossible to see the path they take • However, the strongest intensity lies along the path of the DIRECT BEAM • Intensity from a scattered beam is MUCH LESS than the direct beam

8. Inverse Square Law applies. Intensity decreases with the square of the distance.

9. MiniFlex+ Hardware How to identify various system components

10. MiniFlex+

11. Water Chiller

12. X-ray Tube Cross-section Here is a picture of the glass insulated tube, sometimes called the European Standard tube. It comes in Long and Short Anode versions. The MiniFlex uses the Long Anode version. The Anode is a copper block onto which is welded the target. If no material is added the tube is copper. Other typical target materials are chromium, cobalt, molybdenum, and tungsten.

13. MiniFlex (with the hood up)!

14. Tube Height Adjustment

15. Divergence Slit andSample Stage

16. Diffracted Beam Opticsand Detector

17. Kß Filter Only

18. Absorber on Kß Filter

19. Correction Angle(adjust with every stage change) • The Correction Angle is determined by scanning over a major peak of a standard (like Si 111 which occurs at 28.442°2 for Cu K radiation) and calculating the correction. • Si 111 for Chrome=42.832 °2; for Fe=35.965; Co=33.151;Mo= 12.989

20. Correction Angle (cont’d) • In MANUAL MEASUREMENT Under Control select Measurement • Setup scan as above • Press Execute

21. Correction Angle (cont’d) Press Execute under Peak Search to locate top of peak

22. Correction Angle (cont’d) • Correction = Peak Position - 28.44° = 0.02 • Enter 0.02 as Correction Angle in Setting • Press Execute • Re-measure

23. Correction Angle (cont’d) Peak is within ±0.01° of reference value for standard

24. Detector HV/PHA • The Pulse Height Analyzer (PHA) is “hard wired” and cannot be adjusted. • Detector High Voltage (HV) is adjusted to give the greatest intensity.

25. Detector HV/PHA (cont’d) • In Manual Measurement Under Control select Independent mode. Select 28.44° as the target angle (for Cu tube). Press Execute. • Press SCHV/PHA.

26. Detector HV/PHA (cont’d) • Setup HV Scan as indicated below.

27. Detector HV/PHA (cont’d) Press Execute under Peak Search to locate HV value

28. Detector HV/PHA (cont’d) Enter HV value in Control Setting

29. MiniFlex+System Maintenance Procedures to ensure safe operation and optimal performance

30. MiniFlex+ System Maintenance • Cleaning • Chiller • MiniFlex • System Checks • Log Records

31. Cleaning the Chiller • Check the grill for dust buildup. Remove with a paint brush if necessary. • Check water. If it looks cloudy due to green or brown algae, flush and change with fresh DISTILLED WATER.

32. Cleaning the Chiller (cont’d) • Never add TAP or DEIONIZED WATER. Tap water contains minerals that may clog a filter inside the tube cap. Deionized water’s pH can actually damage the x-ray tube.

33. Cleaning the MiniFlex • Check for dust and dirt buildup • Card cage • Floor of measuring chamber

34. Cleaning the MiniFlex • To clean dust from card cage • Use a can of compressed air to blow out as much as possible. If big particles remain you can call Rigaku Service to remove them or carefully remove the board (POWER OFF!) and do it yourself.

35. Cleaning the MiniFlex • Cleaning the floor of the measuring chamber • Usually consists of sample debris • Recommend using rubber glover and face mask • Use a piece of paper and a small brush • Carefully sweep the debris away using the paper as a “dustpan”.

36. System Checks • System should be checked: • Weekly: A sample (like Silicon) should be checked for: • Peak Position of 111 reflection (28.44°2) • Intensity of 111 reflection • Peak Width of 111 reflection • Log results along with operator and date

37. System Checks (cont’d) • Monthly: Same standard is thoroughly checked for: • Weekly check plus • Scan from 25° to 90°2 • Use JADE’s Theta Calibration (Linear Fit) to determine Calibration Curve

38. Sample Preparation How to prepare various kinds of samples to obtain optimal data

39. Applications X-ray Diffraction (XRD) analyzes a wide variety of solid samples. Why solid? Because it needs the interaction of x-rays with the crystalline structure. Most solids have a crystalline structure that is stable. Glasses are the exception, but even they have structure. Some examples where XRD is used: Chemicals Geology (mineralogy, oil exploration) Metallurgy Polymers Catalysts

40. XRD Information • Each diffraction pattern contains sets of information • Set of local diffraction maximum positions • Set of intensities for those positions • Set of intensity distribution as a function of the diffraction angle (°2)

41. Common Errors found in XRD Data • Sample Displacement • Sample Transparency • Sample Flatness • Sample Particle Size • Axial Divergence • Preferred Orientation

42. Sample Displacement • Probably the most common and largest source of error in diffraction data. • Sample sits above or below Measuring Circle • Shifts peak position 0.01° for every ~60 m

43. Sample Displacement (cont’d) Measuring Circle

44. Sample Displacement (cont’d)

45. Sample Transparency • Error caused by diffraction from below the surface of a low absorbing sample • Asymmetrically broadens peaks • Change in 2 is a function of sin2 • Maximum effect at 90°2

46. Sample Transparency (cont’d) Measuring Circle

47. Sample Transparency (cont’d)

48. Sample Flatness • Sample surface should be as Flat as possible • Measuring circle changes curvature with 2 • Peaks shift towards lower 2 • Broadens peaks asymmetrically • Maximum effect at small 2 angles

49. Sample Flatness (cont’d) Measuring Circle

50. Sample Flatness (cont’d)